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Main Index | Introduction | Hydraulics | MP200 | Super Span | Structural Design | End Treatments | Installation

Main Index

Asset International

Stephenson Street

Newport, Gwent

NP19 4XH

Tel: +44 (0)1633 637505

Fax: +44 (0)1633 290519

Email: [email protected]

INTRODUCTION

HYDRAULIC DESIGN

MULTIPLATE MP 200

MULTIPLATE SUPER-SPAN

Scotland Office

Asset International

1 McMillan Road

Netherton Industrial Estate

Wishaw, Lanarkshire

Scotland. ML2 0LA

Tel: +44 (0)1698 355838

Fax: +44 (0)1698 356184

Email: [email protected]

STRUCTURAL DESIGN

(including BD12/01)

END TREATMENTS

MULTIPLATE INSTALLATION PROCEDURES

© Asset International 2013 - all rights reserved

mailto:[email protected]

mailto:[email protected]


Main

Introduction Next

MULTIPLATE CORRUGATED

STEEL BURIED STRUCTURES

Background to Usage

APPLICATIONS

Culverts / Storm Sewers

Vehicular,Pedestrian & Livestock

Underpasses

Utilities and Other Applications

ECONOMIC CONSIDERATIONS



•Main

Hydraulic Design •Next

INTRODUCTION

Introduction - Page 1

Page 2

CULVERT & CHANNEL HYDRAULICS

OPEN CHANNEL FLOW THEORY

CULVERTS - INLET CONTROL

Inlet Control - Page 1

Page 2

Page 3

Page 3

CULVERTS - OUTLET CONTROL

Page 1

Page 2

Page 3

Page 4

Page 5

Page 6

Page 7

Page 8

Flow Theory - Page 1

Page 2

SUMMARY - CULVERT SIZING

WORKED EXAMPLE

Example - Page 1

Page 2

SEWER DESIGN

Sewer Design - Page 1

Page 2



Main

MULTIPLATE MP 200 Next

INTRODUCTION

SHAPE AND SIZE RANGE

PROFILE DATA:

Pipe

Pipe Arch

Underpass

Arch (BD12/01 Compliant)

Arch (Other)

Vertical Ellipse

Horizontal Ellipse

PHYSICAL PROPERTIES

COMPONENTS:

Plates

Nuts and Bolts

Arch Seating Channel

Alternative Arch Seating

SPECIFICATION



Main M u l t i p l a t e

SUPER-SPAN Next

INTRODUCTION


PROFILE DATA:

Horizontal Ellipse

Low Profile Arch

High Profile Arch

ACCESSORIES:

Thrust Beams

SPECIFICATION



•Main

Structural Design •Next

DESIGN METHODS

Design - BD12/01

DURABILITY

LIVE LOAD STANDARDS:

Highway Loading - UK (page 1)

(page 2)

(page 3)

Railway Loading - UK (page 1)

(page 2)

Highway & Railway Loading -USA

HEIGHT OF COVER TABLES



•Main

END TREATMENTS •Next

INTRODUCTION and TYPICAL DETAILS

SKEW AND BEVEL DETAILS

COLLAR AND RING BEAMS



•Main

INSTALLATION

PROCEDURES •Next

GENERAL REQUIREMENTS BACKFILL

Trench and Embankment Conditions

Material Selection

Backfill Placement

Good and Bad Backfill Practices

Notes on Excavation and Backfill

Multiple Structures

Backfill Summary

BASE PREPARATION:

Flat Bedding

Shaped Bedding

SPECIAL GROUND

CONDITIONS:

Rock Foundations

Soft Foundations

MULTIPLATE ASSEMBLY:

Unloading and Handling

Assembly Procedure and

Methods

Bolt Tightening



Index M u l t i p l a t e

SUPER-SPAN Next

Introduction

ASSET MULTIPLATE Super-Span products are long span

corrugated steel buried structures developed to safely, effectively

and economically cover wider spans than are normal for this type of

construction. The special feature of Super-Span structures is that

they utilise a cast in situ concrete 'Thrust-Beam' to generate the

maximum available lateral ground from the adjacent compacted

backfill.

All Super-Span structures are designed to customer requirements

by ourselves on a design and supply basis.

There are many thousands of Super-Span structures worldwide, the first of many in this country being installed

under the A1(M) in 1971. An ASSET MULTIPLATE Super-Span structure can be designed and constructed in a

fraction of the time taken for other forms of construction such as reinforced concrete.

All our Super-Span structures utilise our MP200 material the material properties of which can be found in the

MP200 section of this manual.

The only item not included in the MP200 section of the manual is the 'Thrust-Beam', which is fully detailed later in

this section.




SUPER-SPAN Next


The following diagrams show typical shapes and sizes of

ASSET MULTIPLATE Super-Span structures.

Other profiles are available upon request.



SUPER-SPAN Next

PROFILE DATA: Horizontal Ellipse

This table lists a small selection of available sizes.

Please contact ASSET International for further

information.

All dimensions are to inside of corrugation

ANGLE A1 ALWAYS = 80 DEGREES


OTHER DIMENSIONS ARE TO INSIDE OF

CORRUGATIONS.

INTERNAL DIMENSION

RADII

STEP STRUCTURE

REFERENCE

Max Span

(m)

Max Rise

(m)

End Area

(m2)

Top

Radius

R1 (m)

Side

Radius

R2 (m)

Min. Step

(m)

6.599 4.590 23.58 4.177 1.720 0.97 25-E-13

6.816 4.669 24.74 4.345 1.720 1.01 26-E-13

7.032 4.748 25.93 4.514 1.720 1.05 27-E-13

7.248

4.826

27.13

4.682

1.720

1.09

28-E-13

7.681 4.984 29.62 5.019 1.720 1.17 30-E-13

8.162 6.015 38.38 5.019 2.393 1.17 30-E-18

7.898

5.063

30.90

5.187

1.720

1.21

31-E-13

8.475 6.300 41.76 5.187 2.528 1.21 31-E-19

8.114 5.141 32.20 5.355 1.720 1.25 32-E-13

8.787

6.585

45.28

5.355

2.662

1.25

32-E-20

8.330 5.220 33.52 5.524 1.720 1.29 33-E-13

9.004 6.664 46.92 5.524 2.662 1.29 33-E-20

8.547

5.299

34.87

5.692

1.720

1.33

34-E-13

9.220 6.743 48.58 5.692 2.662 1.33 34-E-20

8.763 5.378 36.24 5.860 1.720 1.37 35-E-13

9.436

6.822

50.26

5.860

2.662

1.37

35-E-20

8.979 5.456 37.63 6.029 1.720 1.41 36-E-13

9.653 6.900 51.97 6.029 2.662 1.41 36-E-20

9.196

5.535

39.05

6.197

1.720

1.44

37-E-13

9.869 6.979 53.70 6.197 2.662 1.44 37-E-20

9.412 5.614 40.49 6.365 1.720 1.48 38-E-13



10.085

7.058

55.45

6.365

2.662

1.48

38-E-20

9.628 5.693 41.95 6.533 1.720 1.52 39-E-13

10.302 7.137 57.22 6.533 2.662 1.52 39-E-20

9.845

5.771

43.44

6.702

1.720

1.56

40-E-13

10.518 7.215 59.02 6.702 2.662 1.56 40-E-20

10.999 8.247 70.98 6.702 3.336 1.56 40-E-25

10.061

5.850

44.95

6.870

1.720

1.60

41-E-13

10.735 7.294 60.85 6.870 2.662 1.60 41-E-20

11.216 8.326 73.03 6.870 3.336 1.60 41-E-25

10.374

6.135

48.72

7.038

1.855

1.64

42-E-14

10.951 7.373 62.69 7.038 2.662 1.64 42-E-20

11.432 8.404 75.10 7.038 3.336 1.64 42-E-25

10.590

6.214

50.32

7.207

1.855

1.68

43-E-14

11.648 8.483 77.19 7.207 3.336 1.68 43-E-25

10.807 6.293 51.94 7.375 1.855 1.72 44-E-14

11.865

8.562

79.31

7.375

3.336

1.72

44-E-25

11.600 7.609 68.37 7.543 2.662 1.76 45-E-20

12.273 9.053 86.87 7.543 3.605 1.76 45-E-27


SUPER-SPAN Next

PROFILE DATA: Low Profile Arch



information.




RADIUS R2 ALWAYS = RADIUS R3


CORRUGATIONS.

INTERNAL DIMENSION

RADII

ANGLE

STEP

STRUCT.

REF.

Max

Span

(m)

Rise

(m)

Bottom

Span

(m)

End

Area

(m)

Top

Radius

R1 (m)

Side

Radius R2/R3

(m)

AngleA3

(DEG)

Min.

Step

(m)

6.095 2.233 6.032 10.90 4.009 1.316 12.55 1.04 24-A-5-1

6.311 2.272 6.248 11.47 4.178 1.316 12.55 1.08 25-A-5-1

6.528 2.311 6.465 12.04 4.346 1.316 12.55 1.12 26-A-5-1

6.744

2.351

6.681

12.63

4.514

1.316

12.55

1.16

27-A-5-1

6.690 2.390 6.897 13.23 4.683 1.316 12.55 1.20 28-A-5-1

7.393 2.469 7.330 14.46 5.019 1.316 12.55 1.27 30-A-5-1

7.609

2.508

7.546

15.09

5.187

1.316

12.55

1.31

31-A-5-1

8.018 2.756 7.965 17.52 5.356 1.586 10.46 1.35 32-A-6-1

8.235 2.795 8.182 18.23 5.524 1.586 10.46 1.39 33-A-6-1

8.451

2.834

8.398

18.94

5.692

1.586

10.46

1.43

34-A-6-1

8.667 2.874 8.615 19.67 5.861 1.586 10.46 1.47 35-A-6-1

8.884 2.913 8.831 20.40 6.029 1.586 10.46 1.51 36-A-6-1

9.100

2.953

9.047

21.15

6.197

1.586

10.46

1.55

37-A-6-1

9.701 3.634 9.573 28.37 6.366 2.124 14.10 1.59 38-A-8-2

9.918 3.673 9.790 29.28 6.534 2.124 14.10 1.63 39-A-8-2

10.134

3.713

10.006

30.20

6.702

2.124

14.10

1.67

40-A-8-2

10.350 3.752 10.222 31.13 6.871 2.124 14.10 1.71 41-A-8-2

10.567

3.791

10.439

32.08

7.039

2.124

14.10

1.75

42-A-8-2



10.783 3.831 10.655 33.04 7.207 2.124 14.10 1.79 43-A-8-2

10.999 3.870 10.871 34.01 7.375 2.124 14.10 1.83 44-A-8-2

11.216 3.910 11.088 34.99 7.544 2.124 14.10 1.86 45-A-8-2


SUPER-SPAN Next

PROFILE DATA: High Profile Arch



information.




RADIUS R3 ALWAYS = RADIUS R1


CORRUGATIONS.

Step

25-A-6-7

28-A-6-7

32-A-6-7

34-A-6-7

35-A-10-7

37-A-6-7

INTERNAL DIMENSIONS RADII ANGLE STEP

STRUCT.

REF.

Max

Span

(m)

Total

Rise

(m)

Bottom

Span

(m)

End

Area

(m2)

Top/Side

Radius

(m)

Corner

Radius

(m)

Angle A3

(DEG)

Min.

(m)

6.287

6.504

6.720

3.795

3.839

3.883

5.583

5.828

6.069

20.47

21.42

22.37

4.009

4.178

4.346

1.586

1.586

1.586

24.19

23.22

22.32

0.94

0.98

1.02

24-A-6-7

26-A-6-7

6.936

7.153

7.585

3.925

3.968

4.052

6.308

6.547

7.018

23.33

24.31

26.28

4.514

4.683

5.019

1.586

1.586

1.586

21.50

20.73

19.35

1.06

1.10

1.17

27-A-6-7

30-A-6-7

7.801

8.019

8.788

4.094

4.135

5.398

7.252

7.486

7.926

27.28

28.30

40.55

5.187

5.356

5.356

1.586

1.586

2.663

18.73

18.14

23.14

1.21

1.25

1.25

31-A-6-7

32-A-10-9

8.235

8.451

9.220

4.177

4.218

5.484

7.718

7.949

8.407

29.32

30.36

43.20

5.524

5.692

5.692

1.586

1.586

2.663

17.59

17.07

21.78

1.29

1.33

1.33

33-A-6-7

34-A-10-9

8.668

9.437

8.884

4.259

5.526

4.300

8.180

8.647

8.410

31.41

44.55

32.46

5.861

5.861

6.029

1.586

2.663

1.586

16.58

21.15

16.12

1.37

1.37

1.41

35-A-6-7

36-A-6-7

9.653

9.100

9.869

5.569

4.340

5.611

8.885

8.638

9.121

45.90

33.53

47.26

6.029

6.197

6.197

2.663

1.586

2.663

20.57

15.69

20.01

1.41

1.45

1.45

36-A-10-9

37-A-10-9

9.509

4.361

9.174

34.91

6.366

1.855

13.17

1.49

38-A-7-6



10.089 5.653 9.357 48.64 6.366 2.663 19.48 1.49 38-A-10-9

9.725 4.401 9.399 35.98 6.534 1.855 12.83 1.53 39-A-7-6

10.302

5.694

9.592

50.02

6.534

2.663

18.99

1.53

39-A-10-9

10.687 5.659 10.248 50.97 6.534 3.201 14.88 1.53 39-A-12-7

9.942 4.441 9.263 37.07 6.702 1.855 12.51 1.57 40-A-7-6

10.518

5.736

9.825

51.41

6.702

2.663

18.51

1.57

40-A-10-9

10.158 4.481 9.847 38.18 6.871 1.855 12.21 1.61 41-A-7-6

10.736 5.777 10.059 52.82 6.871 2.663 18.06 1.61 41-A-10-9

11.120

5.740

10.703

53.72

6.871

3.201

14.16

1.61

41-A-12-7

10.374 4.521 10.071 39.29 7.039 1.855 11.91 1.65 42-A-7-6

10.952 5.819 10.291 54.23 7.039 2.663 17.63 1.65 42-A-10-9

11.336

5.780

10.929

55.11

7.039

3.201

13.82

1.65

42-A-12-7

11.529 7.308 10.184 72.13 7.039 3.471 25.25 1.65 42-A-13-13

10.591 4.561 10.294 40.42 7.207 1.855 11.64 1.69 43-A-7-6

11.168

5.860

10.522

55.65

7.207

2.663

17.22

1.69

43-A-10-9

11.552 5.820 11.154 56.51 7.207 3.201 13.50 1.69 43-A-12-7

11.745 7.352 10.430 73.93 7.207 3.471 24.66 1.69 43-A-13-13

10.807

4.601

10.517

41.55

7.375

1.855

11.37

1.73

44-A-7-6

11.384 5.901 10.752 57.09 7.375 2.663 16.83 1.73 44-A-10-9

11.768 5.861 11.379 57.92 7.375 3.201 13.19 1.73 44-A-12-7

11.961

7.396

10.675

75.74

7.375

3.471

24.10

1.73

44-A-13-13

11.216 4.847 10.932 45.39 7.544 2.124 11.12 1.76 45-A-8-6

11.601 5.942 10.983 58.54 7.544 2.663 16.45 1.76 45-A-10-9

11.985

5.901

11.605

59.36

7.544

3.201

12.90

1.76

45-A-12-7

12.178 7.440 10.920 77.56 7.544 3.471 23.56 1.76 45-A-13-13



SUPER-SPAN Next

ACCESSORIES: Thrust Beams




SUPER-SPAN Next

SPECIFICATION

ASSET MULTIPLATE SUPER-SPAN SPECIFICATION GUIDE

Please refer to the MP 200 section of this manual as the Specification Guide given there also applies to ASSET

MULTIPLATE SUPER-SPAN material.



•Main

•Index

•Next Structural Design

DESIGN

Corrugated Steel Buried Structures (CSBS) have been in service

since the late nineteenth century and have manufactured in the UK

since 1954.

Since the 1960's the design has been based on the Ring

Compression Theory, where structures are considered as flexible

soil / steel rings in compression.

Until the mid 1980's standard U.K. practice was to undertake

structural design using the design procedures developed by the

American Iron and Steel Institute (AISI) with modifications to suit

national loading requirements.

It is current standard UK practice to design CSBS to the Highway Agency Department Standard BD 12/01.

This standard is still based on the Ring Compression Theory and also includes durability calculated to

provide a 120 year design life.

Use of BD12/01 is mandatory for all CSBS under motorways and trunk roads within the UK and is used for all

low and medium cover applications by ASSET.

BD12/01 does not cover the use of corrugated steel buried structures in the repair of other types of

structures, e.g. as a liner for failing brick arch structures. However, in these situations, Asset International

can provide specialist advice and will carry out the design of such an application as a departure from the

standard.

For special applications such as aggregate tunnels and high fill situations BD12/01 is generally inappropriate

and the AISI design method is used.

The AISI method is still commonly used for many non UK applications.


•Main

•Index


Design - BD12/01

Typical Fill Requirements for Minimum Excavation Option

1. TRENCH CONDITION


2. PARTIAL TRENCH CONDITION


•Main

•Index


DURABILITY

It is standard UK practice to design corrugated steel buried structures to BD12/01 which requires a design life of

120 years.

The relevant properties of the surrounding soil and ground water, the effluent flowing through the structure, the

availability for maintenance of the interior surfaces and protection provided by additional protective coatings are

all considered and assessed. The most severe condition will be used in the design.

Calculations are then carried out to determine the thickness of extra or sacrificial steel that is required to achieve

the design life.

It is possible to vary the design life of a structure to suit special requirements within the methodology of BD

12/01.

In some cases durability is not a consideration e.g. temporary or short working life structures.

Environments that are deleterious to steel and zinc such as environments having pH values less than 5 or

greater than 9, chlorine concentrations greater than 250 ppm and sulphate concentrations greater than 0.6g/l as

SO4 should be avoided.

Secondary protective coatings shall be applied to all galvanised steel surfaces by utilising a paint system within

BD35. Aplication of such a paint system should be in accordance with BA27.

It is not intended that the life of this minimum secondary protective coating shall be taken into account when

calculating sacrificial steel requirements. Where it is intended to take the life of the secondary protective coating

into account, that coating must carry a current BBA certificate. At the time of publishing, the secondary coatings

used by Asset do not yet carry BBA certification. However, it is Asset's intention to pursue such certification.

For culvert applications, anti-abrasion invert protection is a requirement. i.e. a concrete slab or a proprietary

invert protection system (clause 8.14 to 8.20 of BD12/01 refers).


•Main

•Index


Highway Loading - UK

Generally, the definitions as specified by BS 5400 are:

Basis of HA and HB highway loading

Type HA loading is the normal design loading for Great Britain, where it represents the effects of normal

permitted vehicles other than those used for the carriage of abnormal indivisible loads.

For loaded lengths up to 30 m, the loading approximately represents closely spaced vehicles of 24 t laden weight

in each of two traffic lanes. For longer loaded lengths the spacing is progressively increased and medium weight

vehicles of 10 t and 5 t are interspersed. It should be noted that although normal commercial vehicles of

considerably greater weight are permitted in Great Britain their effects are restricted, so as not to exceed those of

HA loading, by limiting the weight of axles and providing for increased overall length.

In considering the impact effect of vehicles on highway bridges an allowance of 25% on one axle or pair of

adjacent wheels was made in deriving HA loading. This is considered an adequate allowance in conditions such

as prevail in Great Britain.

This loading has been examined in comparison with traffic as described for both elastic and collapse methods of

analysis, and has been found to give a satisfactory correspondence in behaviour.

HB loading requirements derive from the nature of exceptional industrial loads (e.g. electrical transformers,

generators, pressure vessels, machine presses, etc) likely to use the roads in the area.

HA loading is normally taken as a combination of Uniformly Distributed Load (UDL) and Knife Edge Loading

(KEL) as described in BS 5400. However, this concept is more suited to complex bridge structures than to

ASSET buried steel structures and, consequently, UDL and KEL are recommended in the DTp Standard BD

12/01 as not to be used. Instead, the Standard recommends the adoption of the Single Nominal Wheel Load

alternatively described in paragraph 6.2.5. of BS 5400.

This is a single 100 M wheel exerting a

pressure of 1111.1111 kN/m' over a square

area with 0.300 m sides. The pressure is

dispersed downwards at a gradient of 2:1.

Although the pressure is dispersed over a two-

dimensional area, only a onedimensional cross

section of the pressure cone need be

considered, as shown, since the design of the

structure is based upon a single metre length

of the culvert at right angles to the cross

section.


•Main

•Index


Highway Loading - UK (cont)

HB loading must be taken into account where a highway is liable to be used by exceptional industrial loads such

as transformers, generators, pressure vessels, machine presses, etc. The HB unit is considered to be a 4-axle

transporter with each axle carrying 10 kN distributed on to four wheels, such that each wheel is pressing down

with a force of 2.5 M. 25 units would be a wheel load of 62.5 M and 45 units a wheel load of 112.5 M. The

drawing below shows the wheel and axle distribution for HB loading together with the pressure cone 'footprints'

at different depths below the highway surface. BS 5400 allows for variable separation of the axle pairs, but we

consider that for buried steel structures, the 6 m separation will provide the most concenti-ated load, and will thus

provide the ,worst case' condition.

It is therefore necessary to establish in the first instance whether the road over the structure is to be used only by

normal HA loadings, or whether HB loadings are to be experienced as well. If HB loadings are to be experienced,

then the technical approving authority must decide whether the minimum 25 units or more, up to the normal

maximum of 45 units of HB loading must be catered for. It is generally acceptable to adopt 45 units of HB loading

for ASSET buried steel structure design, whenever there is doubt as to the potential utilisation of the highway.

45 HB is a sixteen wheel load, with each 112.5 kN wheel exerting a pressure of 1111.1 kN/M2 over a square

area with 0.3182 m sides. The pressure is dispersed downwards at a gradient of 2:1.

Note that area changes are allowed for at 0.68 m when four wheels overlap.

1.48 m when two axles overlap.

5.68 m when four axles overlap.

Live load design, therefore, either caters for HA alone or HA plus HB. The diagram on the previous page

indicates how HA and HB (45 units) disperse downwards and the areas over which they act.

HB loading usually governs except in occasional circumstances when less than 45 units are considered.


•Main

•Index


Highway Loading - UK (cont)

For determining the design vertical live load pressure, dispersal of the wheel loads may be assumed to occur

from the contact area on the carriageway to the level of the crown of the buried structure at a slope of 2 vertically

to 1 horizontally. This pressure is subsequently to be assumed as acting over the whole span. Wheel loads not

directly over the structure shall be considered if their dispersal zone falls over any structure. Braking loads and

temperature effects may be ignored.



•Main

•Index


Railway Loading - UK

British Standard BS5400: Part 2: 1978 is referred to for live loading, including allowance for dynamic effects.

The distribution of stresses due to live loading for buried structures is not referred to in BS5400. Therefore the

same method of dispersal as adopted by the Department of Transport for highway loading on buried structures is

adopted. (Department of Transport, Technical Memorandum (Bridges) No. BE1/77 - Standard Highway

Loadings).

RU Loading RU loading allows for all combinations of vehicles currently running or projected to run on railways in the

continent of Europe, including the United Kingdom, and is to be adopted for the design of bridges carrying main

line railways of 1.4 m gauge and above.

The type RU loading acting on two tracks on the rail, sleeper and ballast arrangements shown below, will

produce vertical stresses within the subgrade as indicated on the graph opposite.



•Main

•Index


Railway Loading - UK (cont)

Dynamic Effects The standard railway loading specified is an equivalent static loading and should be multiplied

by appropriate dynamic factors to allow for impact, oscillation and other dynamic effects, including those caused

by track and wheel irregularities. The dynamic factors given in Table 15 of BS5400 are used. The dynamic factor

is multiplied by the static vertical stress. The vertical stress due to embankment, sleeper and rail loading is then

added to the dynamic stress on the crown of the buried pipe PV.

Example Assume a 2.48 metre diameter MultiPlate

Pipe, with a cover of 2.78 metre from

crown of pipe to underside of sleeper.

(Assume ballast depth B = 0.375m).

From the graph of vertical stress due to

static loading, the vertical stress due to

static loading, the vertical stress at crown

of pipe, Pv1 = 39.2 KN/m2.

Dynamic Factor I:

S = T +( Hc - B) + (2B tan 5o)

S = 2.48 + (2.78 - 0.375) + (0.75 tan 5o)

S = 4.95m

Therefore L =4.95 + 3.0 = 7.95m

Therefore

I = 0.73 + 2.16

7.95-0.2

= 0.73 + 2.16 = 0.73 + 0.78

2.78

I = 1.51

Therefore dynamic live load

Pv2 = I x Pv1

= 1.51 x 39.2

Pv2 = 59.19 KN/m2

Dead load pressure, assuming the

embankment height to rail level to allow for

weight of sleeper plus rails.

Pv3 = 18.85 (2.78 + 0.367)

Pv3 = 59.32 KN/m2

Therefore total pressure of crown of pipe

Pv = ( Pv2 + Pv3)

Pv = (59.19 + 59.32) = 118.51 KN/m2

S = T + (Hc-B) + (2B tan 5o)

L = S + 3.0

From geometry of pipe size and

position, S and L are calculated.

The dynamic factor (bending) is

then determined from:


Dimension L Dynamic

Factor

<3.6

2.0

0.73 +

3.6 to 67 2.16

L -

>67

0.2

1.0

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•Index


USA Highway andRailway Loading

Summary of USA Highways and Railway Loading



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•Index


Height of Cover Tables - UK

The tables below show height of cover limits in metres for both ASSET MP200 structures. These

limits are based upon the UK Highways Agency design method BD 12. The calculation takes into account the

maximum allowable corner bearing pressure of 300Kn/m2 and assumes HA and 45 units of HB loading.


HEIGHT OF COVER TABLE MP100

Steel Thickness (mm)

1.5 mm

(10bits/m)

2.0 mm

(10bits/m)

2.5 mm

(10bits/m)

3.0 mm

(10bits/m)

3.5 mm

(10bits/m)

Diameter/Span (m) Min Max Min Max Min Max Min Max Min Max

0.8 0.65 9.6 0.65 11.2 0.65 14.0 0.65 15.7 0.65 15.7

1.0 0.65 7.5 0.65 8.8 0.65 11.1 0.65 15.7 0.65 15.7

1.2 0.65 6.0 0.65 7.1 0.65 9.1 0.65 14.0 0.65 14.1

1.4 0.65 4.9 0.65 5.9 0.65 7.6 0.65 11.9 0.65 12.0

1.6 0.65

3.9

0.65 4.9 0.65 6.5 0.65 10.4 0.65 10.4

1.8 0.65 4.0 0.65 5.6 0.65 9.1 0.65 9.1

2.0 0.65 3.2 0.65 4.8 0.65 8.1 0.65 8.1

2.2 0.65

2.1

0.65 4.1 0.65 7.2 0.65 7.3

2.4 0.65 3.5 0.65 6.5 0.65 6.6

2.6 0.65

2.8

0.65 5.9 0.65 5.9

2.8 0.65

5.4

0.65 5.4

3.0

0.65

4.9

HEIGHT OF COVER TABLE MP200

Steel Thickness (mm)

3.0 mm

(10bits/m)

4.0 mm

(10bits/m)

5.0 mm

(10bits/m)

6.0 mm

(15bits/m)

7.0 mm

(20bits/m)

8.0 mm

(20bits/m)

Diameter/Span (m) Min Max Min Max Min Max Min Max Min Max Min Max

1.5 0.65 13.4 0.65 15.4 0.65 15.4 0.65 15.4 0.65 15.4 0.65 15.4

2.0 0.65 11.5 0.65 15.7 0.65 15.7 0.65 15.7 0.65 15.7 0.65 15.7

2.5 0.65 9.0 0.65 13.3 0.65 15.7 0.65 15.7 0.65 15.7 0.65 15.7

3.0 0.65 7.3 0.65 11.0 0.65 15.7 0.65 15.7 0.65 15.7 0.65 15.7

3.5 0.7 6.1 0.7 9.3 0.7 13.5 0.7 15.7 0.7 15.7 0.7 15.7

4.0 0.8

5.1

0.8 8.0 0.8 11.7 0.8 15.7 0.8 15.7 0.8 15.7

4.5 0.9 7.0 0.9 10.3 0.9 15.0 0.9 15.7 0.9 15.7

5.0 1.0

6.1

1.0 9.2 1.0 13.2 1.0 15.7 1.0 15.7

5.5 1.1 8.3 1.1 12.2 1.1 14.3 1.1 15.7

6.0 1.2 7.5 1.2 10.7 1.2 12.7 1.2 14.3

6.5 1.3 6.8 1.3 9.5 1.3 11.3 1.3 12.6

7.0 1.4

6.2

1.4 8.3 1.4 9.9 1.4 11.1

7.5 1.5

7.2

1.5 8.7 1.5 9.7

8.0

1.6

7.6

1.6

8.5


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•Next END TREATMENTS

INTRODUCTION and TYPICAL DETAILS

The design of a buried structure under an

embankment must consider the end treatment

most suitable for the particular structure.

Obviously, the function of the structure and its

geographical location are major factors in

reaching a decision.

For example, the end treatment of a culvert

under an unsurfaced access road in

mountainous country might well differ from that

required for a similar culvert under a motorway.

If the structure is an underpass for vehicles or

pedestrians, the end treatment might well differ

from that where the underpass is required for the

passage of livestock.

If the structure is a culvert, then the designer

could consider erosion, undermining, hydrostatic

forces, debris, energy dissipation or fish

passage amongst other effects.

Multiplate corrugated steel structures have many advantages in overcoming end treatment problems when

compared with other forms of construction, not least being the inherent flexibility of the structures.

A wide variety of end finishes can be fabricated in our factory to suit specific site conditions.

ASSET can supply skewed ends, bevelled ends, skew / bevelled ends, part bevelled ends and other

combinations providing the designer with a wide choice. For example the designer may opt for plain ends

with or without headwalls; ends full or part bevelled tied to a concrete ring beam, stone pitching or gabions.

Many other possibilities exist which may be applicable for a specific installation.


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SKEW AND BEVEL DETAILS

Severe skews and bevels are not recommended for Multiplate structures. For skews in excess of 15 degrees

special end treatments should be designed with skew ends in excess of 45 degrees not being recommended.

To avoid confusion when specifying cut end skews, the designer should specify a 'skew number' which is the

angle between the axis of the embankment and the centre-line of the culvert, measured in a clockwise direction.

Skew Details

Bevel Details: - For all bolted plate structures except Super-Span.

Bevelled ends are usually specified to match the slope of the embankment. This slope must be clearly stated

when ordering bevelled ends. Orders should make clear that the specified slope relates to the horizontal.

The culvert invert slope should be detailed on the order if more than 2% as with steep invert slopes the two ends

of a culvert may have to be bevelled differently to match the symmetrical slopes of the embankment.

The length of Multiplate structures relates to the 'net laying length' (refer to MP200 sections) of the

structure as manufactured and is measured from centre of bolt hole to centre of bolt hole at either end of a

structure.

It should be remembered when ordering Multiplate that the actual structure extremities will extend a distance

beyond the centre of the bolt holes dependent upon the structure corrugation.


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COLLAR AND RING BEAMS

The practical positioning of anchor bolts and

stirrups is easy to envisage where the collar is

vertical.

However, detailed positioning on a skewed end, or

on a bevel with a sloping collar, is more difficult,

since the corrugations run vertically.

Therefore, bolts are set in a measured distance

from the cut edge with a 470mm vertical step, but

placed on the nearest corrugation crest or trough,

so that the bolts project radially from the structure.

NB. Plate layout diagrammatic only



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INSTALLATION

PROCEDURES

GENERAL

This chapter presents information of fundamental importance

regarding installation and construction procedures including base

preparation, unloading and assembly, and placement and

compaction of backfill.

A well situated, properly bedded, accurately assembled and

carefully backfilled corrugated steel structure will function properly

and efficiently over its entire design life. Although smaller structures

may demand less care in installation than larger ones, reasonable

precautions in handling base preparation, assembly and backfilling

are required for all sizes of structures.

Because of their strength, lightweight and modular construction, ASSET Multiplate corrugated steel structures

can be installed quickly, easily and economically.

The flexible steel shell is designed to distribute loads throughout its periphery and into the backfill. Flexibility

allows a degree of unequal settlement and dimensional change that could cause failure in a rigid structure.

This advantage is further enhanced when a corrugated steel structure is installed on a well prepared

foundation with a well-compacted, stable backfill placed around the structure.

Adherence to these requirements satisfies design assumptions and ensures a satisfactory installation.

During design reasonable care during installation is assumed; indeed the selection of steel thickness and

associated design criteria are based on this assumption. Just as with concrete or other structure types,

careless installation of corrugated steel structures can undo the work of the designer.

Minimum cover requirements are required for corrugated steel structures under highway or other live loadings.

These are based on fundamental design criteria, as well as long term experience.

However, it must be emphasised that such minimum cover may not be adequate during the construction

phase, because of the possibility of high live loads from construction traffic.

Therefore when construction equipment which produces higher live loads than those for which the pipe has

been designed is to be driven over or pass too close to the structure, it is the responsibility of the contractor to

provide any additional cover needed to avoid possible damage to the pipe.



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INSTALLATION

PROCEDURES

BASE PREPARATION: Flat Bedding

Pressures developed in the structure wall by the weight of the backfill and live loads are transmitted both to the

side fill and the strata underlying the pipe. The supporting soil beneath the pipe, generally referred to as the

foundation, must provide a reasonable uniform resistance to the imposed pressures, when viewed along both

longitudinal and transverse lines. Requirements when soft foundations or rock foundations are encountered are

discussed later in this section.

Bedding is defined as that portion of the foundation in contact with the bottom or invert of the structure.

Depending upon the size and type of structure, the bedding may either be flat or shaped. With flat bedding the

pipe is placed directly on the fine-graded upper portion of the foundation. Soil must then be compacted under the

haunches of the structures in the first stages of backfilling.

For structures with invert plates exceeding 3700mm in radius, the bedding should be shaped to the approximate

profile of the bottom portion of the structure. Alternatively, the bedding can be shaped to a shallow 'Vee' shape.

Shaping the bedding provides a more uniform support for the relatively flat bottoms of pipe-arches and avoids

creating zones that are difficult to compact under large structures. The shaped portion need not extend across

the entire bottom of the structure, but must be wide enough to permit compaction of backfill under the remainder

of the structure.



INSTALLATION

PROCEDURES

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BASE PREPARATION: Shaped Bedding

The diagrams above illustrate the shaped bedding of a pipe-arch. Note that the soil adjacent to the corners of a

pipe-arch must be of excellent quality and well compacted to support the higher pressures that can develop at

these locations.

Whether the bedding is flat or shaped, the upper 50 to 100mm layer should be composed of relatively loose

material so that the corrugations can seat in the bedding. This is usually referred to as a compressible bedding

lift. The material in contact with the structure should not contain gravel larger than 75mm, frozen soil, chunks of

highly plastic clay, organic matter, or other deleterious material.



INSTALLATION

PROCEDURES

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SPECIAL GROUND CONDITIONS: Rock Foundations

If rock ledges are encountered in the foundation, they may create hard points that tend to concentrate loads on

the pipe. Such load concentrations are undesirable since they can lead to distortion of a structure. Large rocks or

ledges must be removed and replaced with suitable compacted fill before preparing the pipe bedding.

When the pipe foundation makes a transition from rock to a compressible soil, special care must be taken to

provide for reasonable uniform longitudinal support so as to minimise longitudinal settlement.

Illustrated below are typical treatments for a transition zone.



INSTALLATION

PROCEDURES

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SPECIAL GROUND CONDITIONS: Soft Foundations

Evaluation of the construction site may require subsurface exploration to detect undesirable foundation materials,

such as soft compressible soil or rock ledges. Zones of soft material give uneven support and can cause the pipe

to shift and settle non-uniformly after the embankment is constructed.

These materials should be removed and replaced with suitable compacted fill to provide a continuous foundation.

The extent of soft material removed should be such that the column of fill adjacent to the structure has at least as

good a foundation as that beneath the structure.

The depth and width of soft material removed will depend on the quality of the existing soil, the size of the

structure and the load to be carried.

SKETCH DEMONSTRATING THE

PRINCIPLE OF A YIELDING FOUNDATION.

Note: If replacement material in Zone A is of less depth

and less compacted than the replacement materials in

Zone B and C, the side columns of fill above Zones B

and C will tend to offer support to the central column of

earth which overlies the flexible structure.

Load on the structure is thereby reduced and any

tendency to deform is greatly diminished.

The heavy arrows show the support tendency.



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INSTALLATION

PROCEDURES

MULTIPLATE ASSEMBLY: Unloading and Handling Multiplate

Assembly of ASSET Multiplate is straightforward provided our basic recommendations are followed.

This should include careful reading and understanding of the assembly instructions before any plates are laid out

or connected to each other.

Unloading and Handling Multiplate

Plates for Multiplate structures are shipped nested in bundles complete with all bolts and nuts necessary for

assembly. Included with the shipment are detailed assembly instructions.

Bundles are normally 2 tonne maximum weight for ease of handling. Normal care in handling is required to keep

plates clean and free from damage by rough treatment.

Early reference to the assembly instructions is advised so that the plates needed first are readily accessible and

those following can do so without unnecessary rehandling of bundles.

All bundles are tagged with a reference number which enable identification of the plates in the bundle from the

packing list included with the assembly instructions. Each bundle's contents are listed with details of plate length,

width, radius and whether the individual plate is uncut or cut.

The identifying mark of a plate will be shown in the packing list and the accompanying plate layout drawing will

give its unique position in the structure.


INSTALLATION

PROCEDURES

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MULTIPLATE ASSEMBLY: Assembly Procedure and Methods

Assembly Procedure

The first essential is to read and understand the assembly instructions provided.

All Multiplate structures are supplied with typewritten assembly instructions together with a diagrammatic sketch.

This sketch, sometimes referred to as a 'bullseye' sketch, shows the positions of each plate in the 'rings' of the

structure and the recommended sequences of plate laying where 'plate by plate' assembly procedure is followed.

For all but the simplest structures, we provide an additional plate layout drawing unique to the structure which

must be followed exactly using the 'bullseye' sketch only as a guide to the order of plate assembly.

Unless the plate layout drawing is followed exactly with regard to the positioning of plates with reference to the

invert centreline then there is risk of elbows, bevels, etc. begin incorrectly angled in the structure.

Having studied the assembly instructions and drawings, there are generally two approaches to the actual

assembly method:

1. Plate-by-plate assembly

2. Component sub-assembly (or prefabrication of units).

Plate-by-Plate Assembly

This is commonly used for the assembly of Multiplate pipe structures as distinct from pipe-arch structures,

although the pre-assembly method can be used for assembly of large diameter pipes. When assembling pipes

by the plate-by-plate method, the procedure is to lay out and bolt together a considerable number of invert plates

which are then followed by side plates. The side plates are placed alternatively on either side of the invert to

maintain balance, and top or roof plates follow.

The single most important thing to remember when assembling Multiplate is to assemble the structures with as

few bolts as possible initially until several rings are closed. When several rings have been assembled, work can

proceed with placing and tightening all remaining bolts. During assembly, only a few bolts should be placed in

the longitudinal seams. Two bolts near each end and two near the centre of the plates are quite sufficient and

these bolts should be tightened with a hand wrench only (not an air impact wrench). Circumferential bolts should

all be positioned and tightened to hold adjacent plates together.

Nuts may be placed inside or outside the structure. It is a good idea to put all nuts in the lower half of the

structure on the inside and on the outside in the upper half to facilitate the use of air wrenches.

As long as all nuts and bolts are positioned and tightened, it does not matter - structurally - which way round the

bolts are placed.

It is important that the curved side of the nut is placed against the plate (like the wheel nuts on a car). Final bolt

placement and tightening should always be kept at least one full ring behind plate assembly.

Avoid placing too many side plates before closing the top or roof to prevent the structure 'spreading'.

When starting assembly on the prepared bed and throughout the whole assembly, it is important that the bed

itself is uniform in gradient; that invert plates are individually checked for correct position of invert centreline and


that the structure is kept plumb and on line as assembly proceeds.

It also advisable to keep a check on the rise and span dimensions of the structure during assembly and

backfilling.

Component Sub-Assembly This can be used for the assembly of larger structures of all shapes and all pipe-arches and arches.

As arches rest in unbalanced channels in previously constructed abutments plate-by-plate assembly would

involve propping until rings are complete.

The quickest method for arch assembly to is to pre-assemble each full ring on the ground frequently resting on

its 'side'. All nuts are placed on the outside of the arch but left loose. Each pre-assembled ring is then lifted on to

the abutments, shingle lapping with its neighbouring ring. Obviously it is essential that both unbalanced changes

are laid true to line and gradient at the correct distance apart. They must also be angled correctly (as shown on

the contract drawings) depending on the rise / span ratio of the arch specified. The short leg of the channel is to

the inside of the abutment and the anchoring lugs in the base of the channel should be bent down at right angles

and twisted through 90 degrees before pouring the abutment concrete. It should also be noted that unbalanced

channel lengths always correspond with the net plate lengths, i.e., multiples of 3 metres and 2 metres. This

results in the plates at the end of the structure protruding beyond the ends of the unbalanced channel by 50mm

at each end of the structure.

On medium size and large arch structures when pre-assembling rings, it may be helpful to adopt the 'strength

and squeeze' technique to facilitate bolt placement when shingle lapping rings.

Pipe-arches are commonly assembled using a combination of component sub-assembly and plate-by-plate

methods.

All pipes-arches have comparatively large radius inverts and as proper placement and compaction of backfill can

be a problem it is usual to lay this type of structure on a shaped bed.

When laying pre-assembled invert sections on a shaped bed a problem can arise with placement of the

circumferential seam bolts which connecting these sections on the bed. This is overcome using the spring clips

provided by means of which the circumferential seam bolts on the ring are positioned ready to receive the next

ring.

The procedure for pipe-arches is to pre-assemble invert sections lying on their sides making sure to place all

nuts inside. These pre-assembled rings are then connected together on the shaped bed with the aid of the spring

clips discussed above and all bolts tightened up. It is important to note that attention must be paid to the width of

the pre-shaped bedding which must be kept clear of the seams which connect corner plate to invert plates.

Having placed all the invert plates and tightened up all the nuts, it is usual to place corner plates equally on both

sides plates-by-plate.

Avoid placing too many corner plates to prevent the structure 'spreading' and do not tighten invert / corner seams

at this stage. Then position side and top plates one at a time, or in pre-assembled sections equally to both sides

of the structure, closing the crown as soon as possible to avoid structure spread. Bolt placement and tightening

may then proceed, always keeping at least one full ring behind plate assembly.

The assembly of vertical and horizontal ellipse shaped structures is similar to the procedure for pipes.

In all Multiplate structures, except arches, the aim should always be to achieve a 'staircase' effect when the

structure being assembled is viewed from one side. This effect is achieved by having a closed ring at the starting

end with side plates gradually stepping down to invert plates only at the advanced end. As soon as a ring is

closed, it should be checked for span and rise (or diameter) and adjusted if necessary before proceeding further.

This 'staircase' method of assembly should be adopted in preference to any other method of assembly except for

arch structures.


•Main

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INSTALLATION

PROCEDURES

MULTIPLATE ASSEMBLY: Bolt Tightening

Recommended torque values are in the range 135Nm to 270Nm.

Placing of all the bolts and tightening up to full torque should never proceed without at least one full ring existing

between this operation and the assembly crew.

When tightening bolts to full torque, always work from the centre of seams towards the plates corners. Do not

insert corner bolts until all other are placed. Alignment of bolt holes is easier when bolts are loose.

The bolts should all be torqued to a maximum of 270 Nm and bolt tightening should proceed from one end of

the structure progressively ring by ring.

Good Fit of Plates - one to another is more important than precise torque figures

Backfilling will inevitably cause torque variation, usually a tendency towards slight decrease. The degree of

torque change is a function of metal thickness, plate match and change of structure shape during backfilling. This

is normal and not a cause for concern should checks be made at a later stage.

Assembly of Multiplate Super-Span Structures

The foregoing procedures apply equally to Multiplate Super-Span structures. Continual monitoring of structure

shape is most important in Multiplate Super-Span installation.

Advice on all aspects of assembly and backfilling is available from our staff as required.



INSTALLATION

PROCEDURES

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BACKFILL: Trench and Embankment Conditions

Trench Condition

In trench installation, the trench should be kept as narrow as possible but sufficiently wide to permit tamping

under the haunches of the structure. Generally trench width will range from 500mm to 800mm greater than the

span of the structure. For structures above 1.50 metre span or where mechanical tamping equipment is to be

used, greater trench width may be required.

Excavations for multiple installations must take into account the additional width required for spacing between

structures. Side walls should be as vertical as practical, at least to an elevation above the top of the structure.

Embankment Condition

For structures in embankments, the area of controlled backfill should extend to at least one diameter or span on

each side of the structure.


INSTALLATION

PROCEDURES

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BACKFILL: Material Selection

Backfill should be selected in accordance with the requirements of The Department of Transport Manual of

Contract Documents for Highway Works - Volume 1 - Specification for Highway Works - clause 623.

Alternatively, backfill material should preferably be granular to provide good structural performance and be free

from large stones, organic or frozen material. This select structural backfill material should conform to one of the

following classifications of soil from AASHTO Specifications M-145 Table 2.



INSTALLATION

PROCEDURES

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BACKFILL: Backfill Placement

Backfill material should be placed in horizontal uniform layers not exceeding 200mm in thickness before

compaction, and should be brought up equally on both sides of the structure.

Pipe-arches require that the backfill at the corners be of the best material and especially well compacted.

Each layer of backfill should be compacted to 90% of maximum density at optimum moisture content as

determined by British Standard 1377 and in accordance with the requirements of the Department of Transport

Manual of Contract Documents for Highway Works - Volume 1 - Specification for Highway Works - clause 623.

Tamping can be done with hand or mechanical equipment, tamping roller or vibrating compactors, depending

upon field conditions. More important than method is that it be done carefully to ensure a thoroughly compacted

backfill without excessive distortion of the structure.

Particular care should be taken in backfilling arches to avoid peaking or rolling during the backfill operation.

Protection from Construction Traffic

For adequate protection from heavy construction equipment, it may be necessary to temporarily locally increase

the height of cover over a structure.

How much additional fill is needed depends upon the wheel loads of equipment used, distribution, and frequency

of loading.



INSTALLATION

PROCEDURES

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BACKFILL: Good and Bad Backfill Practices

Good Backfilling Practice

To ensure that no pockets of uncompacted fill are placed next to the structure, it is necessary to ensure that all

equipment runs parallel to the length of the structure.

Poor Backfilling Practice

The possibility of pockets of uncompacted fill or voids next to the structure can arise with equipment operating at

right angles to the structure.



INSTALLATION

PROCEDURES

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BACKFILL: Notes on Excavation and Backfill

1) Excavation shall be carried out in accordance with the contract except that additional excavation will be

required to remove pockets of soft soil, loose rock and any voids shall be filled with 6K lower bedding material.

2) Lower bedding material class 6K ( 20mm down ) shall have its top surface shaped during compaction to

match the structure profile when the bottom radius is greater than 3700mm.

When the radius is less than 3700mm the lower bedding shall be compacted in layers to a depth of span/10 and

a layer of uncompacted class 6L ( sand ) 50mm deep placed 1000mm wide along the centre of the structure. (

This will allow access for positioning bolts in the invert longitudinal seams on multiplate structures. ) The lower

bedding under the structure shall be well compacted using a suitably sized length of timber. Lower bedding shall

extend a width 800mm ( 500mm for structures up to 3m span ) beyond the span on each side of the structure

and 300mm beyond each end of the structure.

Lower bedding shall extend to a depth such that it supports the bottom radius ( rb ) of the structure or 20% of the

circumference for round pipes.

The depth of lower bedding shall be increased by 300mm if rock is encountered at the base of the bedding. Also

if the height of cover is greater than 8m then the depth shall be increased by another 40mm for each metre of

cover to a maximum additional depth of 600mm.

3) Surround material class 6M ( 75 down ) shall extend a span either side of the structure for embankment

construction and 800mm ( 500mm for structures up to 3m ) for trench conditions. Structures in part trench / part

embankment may use a combination of backfill widths. Surround material shall extend to a height of span/5 or

1m ( 650mm for structures up to 3m span ) whichever is the greater above the crown of the structure or to the

formation level if lower.



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INSTALLATION

PROCEDURES

BACKFILL: Multiple Structures

Multiple Structures When two or more structures are laid parallel, the space between structures in normally one half diameter or

span, with a minimum of 600mm and maximum 1000mm. These spacings should be treated as minimum

recommendations, as the spacings may need to be increased to leave sufficient room for mechanical compaction

equipment to operate, and for tamping the fill under the haunches of the structures.

Minimum Clearance Between Conduits


SHAPE

PROFILE

SPAN S

MINIMUM VALUE

OF b

1. CIRCULAR

PIPES

UP TO 2 m

GREATER THAN 2m

HALF S OR 600 mm

WHICHEVER IS

GREATER

1 m

2. PIPE ARCHES

AND

UNDERPASSES

UP TO 3 m

GREATER THAN 3m

THIRD S OR 600 mm

WHICHEVER IS

GREATER

1.0 m

3. ARCHES

ALL SIZES

0.6 m


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INSTALLATION

PROCEDURES

BACKFILL: Summary

The key points in the backfilling operations are:

1. Use good quality backfill material.

2. Ensure adequate compaction under haunches.

3. Maintain adequate width of backfill.

4. Place backfill material in thin uniform layers.

5. Balance fill either side as fill progresses.

6. Compact each layer before adding next layer.

7. Maintain design shape.

8. Do not allow construction equipment over the structure, without

adequate protection, until minimum depth of cover is achieved.

9. Place and compact backfill parallel to structure.



Index


INTRODUCTION

ASSET International are a Quality Assured Company to BS EN ISO 9002: 1994 - Certificate No FM 12306.

ASSET MP200 is made in compliance to BBA Certificate No 91/59 and has Highway Agency Type Approval

Certificate No. BE 1/1/97.

ASSET MP200 meets all the requirements of the relevant parts of the Specification for Highway Works Part 2

Series 600 and Part 6 Series 2500 (6th edition) and Notes for Guidance on the Specification for Highways Works

Part 2 Series NG600.

ASSET MP200 structures are available in a wide range of shapes and sizes to suit a wide range of applications.

ASSET MP200 can be additionally protected with a variety of secondary coatings.

ASSET MP200 is normally designed in accordance with the Highway Agency Departmental Standard BD 12/01

for the Design of Corrugated Steel Buried structures.

ASSET sells a computer programme to assist the sizing of structures and structural calculations.


Index



MP200 is manufactured in the range of shapes and sizes shown in the table below. All MP200 steel plates are

fabricated with corrugations 200mm pitch x 55mm depth.

Tunnels or Vehicle Tunnels

headroom is limited.

PROFILE

SHAPE

SIZE RANGE

SOME TYPICAL USES

Round Pipe

Diameter

0.8m - 8.0m

Culverts, Underpasses,

Service, Recovery Tunnels,

Piling or Back Shutters.

Low Profile Pipe

Arch

Span

1.0m - 8.0m

Culverts, Tunnels or Re-lining

where headroom is limited.

Underpass

Span

1.0m - 8.0m

Underpasses beneath

embankments for pedestrians,

livestock or vehicles, culverts.

Vertical Ellipse

Span

1.0m - 8.0m

Culverts, Underpasses, Service

Horizontal Ellipse

Span

1.0m - 8.0m

Culverts or Tunnels where

Arch

Span

1.0m - 8.0m

Culverts, Tunnels or Re-lining


Note: All the above structures may be used for lining failing structures by either assembling inside the failing structure

where working space permits or hauling the assembled MP200 structure in from outside where working space is

insufficient. Grout connections can be provided to assist filling the annular space between the new lining and the

failing structure.

All these structures may be used for extending existing structures.

Larger sizes than those shown are available. Please contact ASSET International Ltd. for further advice.

Other shapes are available for special applications.


Index


PROFILE DATA: Pipe

All dimensions are to the inside of corrugations.

66

69

INTERNAL STRUCTURE

REFERENCE Dia (m) Area (m2)

4.73

4.88

4.95

5.10

5.18

17.55

18.68

19.26

20.44

21.04

64

67

70

5.25

5.40

5.48

5.63

5.70

21.66

22.91

23.55

24.85

25.52

71

73

74

76

77

5.77

5.92

6.00

6.15

6.22

26.19

27.56

28.27

29.69

30.42

78

80

81

83

84

6.30

6.45

6.52

6.67

31.16

32.65

33.41

34.97

85

87

88

90

6.75

6.82

6.97

7.05

7.20

35.75

36.55

38.17

38.99

40.67

91

92

94

95

97

7.27

7.35

7.50

7.57

7.72

41.52

42.38

44.12

45.01

46.80

98

99

101

102

104

7.79

47.71

105

INTERNAL

STRUCTURE

REFERENCE

Dia (m)

Area

(m2)

1.74 2.36 24 1.81 2.57 25 1.96 3.02 27 2.03 3.25 28

2.11

3.49

29 2.26 4.01 31 2.33 4.28 32 2.48 4.84 34 2.56 5.14 35

2.63

5.44

36 2.78 6.08 38 2.86 6.41 39 3.01 7.10 41 3.08 7.46 42

3.16

7.83

43 3.31 8.58 45 3.38 8.98 46 3.53 9.79 48 3.61 10.21 49

3.68

10.64

50 3.83 11.52 52 3.90 11.91 53 4.05 12.91 55 4.13 13.39 56

4.20

13.88

57 4.35 14.88 59 4.43 15.40 60 4.58 16.46 62

4.65 17.00 63


7.87 48.63 106


Index


PROFILE DATA: Pipe Arch



information.

All of these profiles conform to BD12/01

All dimensions are to inside of corrugation.

INTERNAL DIMENSION

INTERNAL RADII

SUBTENDED ANGLES

STRUCT

REF

Span

(m)

Rise (m)

Area

(m2)

Top

R1(m)

Corner

R2(m)

Bottom

R3(m)

Top

A1(deg)

Corner

A2(deg)

Bottom

A3(deg)

1.93 1.53 2.31 1.00 0.60 1.35 130.4 85.5 58.6 10-4-6

2.28

1.72

3.12

1.15

0.60

2.76

160.1

85.5

29.0

14-4-6

2.64 1.85 3.79 1.38 0.60 2.14 133.2 85.5 55.8 14-4-9

2.89

2.00

4.53

1.47

0.60

3.32

152.8

85.5

36.2

17-4-9

3.38 2.17 5.60 1.85 0.60 2.57 121.7 85.5 67.3 17-4-13

3.48

2.63

7.17

1.76

0.85

3.01

158.3

76.5

48.7

21-5-11

3.84 2.77 8.19 1.99 0.85 2.80 140.3 76.5 66.7 21-5-14

3.71

2.79

8.21

1.86

0.85

4.12

171.3

76.5

35.7

24-5-11

4.08 2.93 9.29 2.07 0.85 3.50 153.7 76.5 53.3 24-5-14

4.56 3.12 10.82 2.42 0.85 3.21 132.1 76.5 74.9 24-5-18

4.23

3.29

11.10

2.12

1.05

4.62

175.6

74.8

34.8

28-6-12

4.72 3.48 12.80 2.39 1.05 3.91 155.7 74.8 54.7 28-6-16

5.09 3.62 14.15 2.63 1.05 3.69 141.7 74.8 68.7 28-6-19

5.55 3.82 16.04 3.00 1.05 3.58 124.6 74.8 85.8 28-6-23

4.79

3.82

14.47

2.40

1.28

4.25

172.1

71.9

44.0

31-7-14

5.14 3.96 15.92 2.59 1.28 3.99 159.2 71.9 56.9 31-7-17

5.61 4.16 17.96 2.89 1.28 3.85 143.2 71.9 72.9 31-7-21

5.95 4.31 19.56 3.13 1.28 3.81 131.9 71.9 84.2 31-7-24

5.44

4.18

17.98

2.73

1.28

5.04

171.0

71.9

45.1

35-7-17

5.93 4.38 20.13 3.01 1.28 4.61 155.2 71.9 60.9 35-7-21

6.29 4.52 21.82 3.24 1.28 4.46 144.1 71.9 72.0 35-7-24

6.75 4.72 24.18 3.59 1.28 4.36 130.2 71.9 85.9 35-7-28



5.65

4.35

19.61

2.83

1.28

6.16

179.1

71.9

37.0

38-7-17

6.16 4.54 21.84 3.10 1.28 5.35 163.5 71.9 52.6 38-7-21

6.53 4.68 23.60 3.32 1.28 5.05 152.5 71.9 63.6 38-7-24

7.01 4.88 26.03 3.66 1.28 4.84 138.7 71.9 77.4 38-7-28

7.35 5.03 27.94 3.93 1.28 4.76

129.0 71.9 87.1 38-7-31

6.44 4.76 24.24 3.22 1.28 6.67 173.9 71.9 42.2 42-7-21

6.83 4.90 26.07 3.44 1.28 6.06 163.1 71.9 53.0 42-7-24

7.33 5.10 28.62 3.75 1.28 5.63 149.5 71.9 66.6 42-7-28

7.70 5.24 30.61 4.01 1.28 5.44 139.9 71.9 76.3 42-7-31

7.03

5.07

28.01

3.52

1.28

7.05

170.5

71.9

45.6

45-7-24

7.56 5.26 30.64 3.83 1.28 6.35 157.0 71.9 59.1 45-7-28

7.93 5.41 32.69 4.08 1.28 6.05 147.4 71.9 68.7

45-7-31

7.84

5.48

33.46

3.94

1.28

7.54

166.3

71.9

49.8

49-7-28

Index


PROFILE DATA: Underpass



information.



INTERNAL

DIMENSION

INSIDE RADII (m)

SUBTENDED ANGLES

STRUCT.

REF

Span

(m)

Rise

(m)

Area

(m2)

Top

R1(m)

Corner

R2 (m)

Bottom

R3 (m)

Top A1

(deg)

Corner A2

(deg)

Bottom A3

(deg)

2.35

2.14

3.97

1.173

0.87

1.592

190.20

60.00

49.80

17-4-6

2.66

2.37

4.89

1.329

0.87

2.496

208.00

60.00

32.00

21-4-6

2.97 2.54 5.95 1.486 0.87 2.238 186.60 60.00 53.40 21-4-9

2.88

2.55

5.78

1.442

0.87

3.902

219.50

60.00

20.50

24-4-6

3.19 2.71 6.80 1.597 0.87 3.902 198.70 60.00 41.30 24-4-9

3.48

2.96

7.97

1.741

0.87

4.444

212.90

60.00

27.10

28-4-9

3.93 3.17 9.72 1.963 0.87 3.412 189.10 60.00 50.90 28-4-13

4.31

3.35

10.67

2.066

0.87

4.250

199.20

60.00

40.80

31-4-13

4.41

3.59

11.99

2.203

0.87

6.019

211.10

60.00

28.90

35-4-13

4.76 3.75 13.69 2.378 0.87 4.839 195.70 60.00 44.30 35-4-16

4.95

3.93

14.71

2.476

0.87

5.989

204.20

60.00

35.80

38-4-14

5.15

4.28

16.76

2.577

1.09

8.143

216.90

60.00

23.10

42-5-14

5.60 4.48 19.27 2.801 1.09 5.996 199.80 60.00 40.20 42-5-18

5.96 4.64 21.50 2.982 1.09 5.382 187.80 60.00 52.20 42-5-21

5.80

4.67

20.56

2.902

1.09

7.238

206.70

60.00

33.30

45-5-18

6.16 4.82 22.79 3.079 1.09 6.235 194.90 60.00 45.10 45-5-21



6.01

5.02

23.02

3.006

1.32

9.453

217.30

60.00

22.70

49-6-16

6.34 5.18 25.17 3.171 1.32 7.513 206.10 60.00 33.90 49-6-19

6.81 5.38 28.41 3.405 1.32 6.431 192.10 60.00 47.90 49-6-23

6.84

5.46

27.30

3.241

1.54

8.795

214.10

60.00

25.90

52-7-17

6.92 5.67 30.37 3.459 1.54 7.157 200.70 60.00 39.30 52-7-21

7.27 5.83 32.98 3.634 1.54 6.579 191.10 60.00 48.90 52-7-24

7.20

5.92

32.65

3.599

1.54

8.743

207.80

60.00

32.20

56-7-21

7.54 6.07 35.28 3.768 1.54 7.760 198.50 60.00 41.50 56-7-24

7.41

6.10

34.39

3.703

1.54

10.37

212.80

60.00

27.20

59-7-21

7.75

6.26

37.06

3.873

1.54

8.827

302.50

60.00

36.50

59-7-24

Index


PROFILE DATA: Arch (BD12/01 Compliant)



information.



INTERNAL DIMENSION

RADII

SPAN

SUBTENDED

ANGLES

Rise/Span

Ratio

Span (m)

Rise (m)

Area (m2)

Radius

R1 (m)

Bottom

Span

(m)

Subtended

Angle

A1 (deg)

2.00

1.41

2.37

1.00

1.82

228.90

0.71

2.50

1.74

3.65

1.25

2.30

226.20

0.70

3.00

1.96

4.88

1.00

2.86

215.40

0.65

3.50

2.28

6.65

1.75

3.33

215.40

0.65

3.50 2.61 7.68 1.75 3.05 238.50 0.74

4.00

2.50

8.25

2.00

3.88

208.70

0.62

4.00 2.93 9.88 2.00 3.54 238.60 0.73

4.50

2.82

10.50

2.25

4.35

209.40

0.63

4.50 3.15 11.91 2.25 4.12 227.40 0.70

5.00

3.03

12.47

2.50

4.88

204.70

0.61

5.00 3.48 14.59 2.50 4.60 226.20 0.70

5.50

3.36

15.21

2.75

5.36

205.60

0.61

5.50 3.70 16.99 2.75 5.16 220.30 0.67

5.50 4.12 19.10 2.75 4.77 239.90 0.75

6.00

3.57

17.55

3.00

5.89

202.00

0.60

6.00 4.02 20.16 3.00 5.64 219.90 0.67

6.00 4.35 21.94 3.00 5.36 233.40 0.72

6.50

3.90

20.78

3.25

6.337

203.00

0.60

6.50 4.24 22.92 3.25 6.19 215.40 0.65

6.50 4.67 25.55 3.25 5.84 232.00 0.75

7.00

4.11

23.48

3.50

6.89

200.00

0.59

7.00 4.57 26.58 3.50 6.67 215.40 0.65



7.00 4.89 28.74 3.50 6.42 227.00 0.70

7.50

4.44

27.20

3.75

7.37

201.10

0.59

7.50 4.78 29.71 3.75 7.12 211.80 0.64

7.50 5.22 32.83 3.75 6.90 226.20 0.70

7.50 5.54 34.98 3.75 6.59 237.00 0.74

8.00

5.10

33.86

4.00

7.69

212.10

0.64

8.00 5.44 36.39 4.00 7.46 222.00 0.68

8.00

5.87

39.50

4.00

7.08

235.60

0.73

Index


PROFILE DATA: Arch (Other) This table lists a small selection of available sizes.


information.

These profiles do not conform to BD12/01


INTERNAL DIMENSIONS

RADII

SPAN

SUBTENDED

ANGLES

Rise/Span

Ratio

Span

(m)

Rise

(m)

Area

(m2)

Radius

A1 (m)

Bottom

Span

(m)

Subtended

Angle

R1 (deg)

2.50

0.90

1.65

1.32

2.50

143.20

0.36

3.00

1.11

2.44

1.57

3.00

146.00

0.37

3.50

1.45

3.82

1.78

3.50

158.60

0.41

4.00

1.23

3.50

2.24

4.00

126.20

0.31

4.00 1.66 4.99 2.04 4.00 158.60 0.41

4.50

1.44

4.65

2.48

4.50

130.50

0.32

4.50 2.00 6.85 2.26 4.50 166.60 0.44

5.00

1.80

6.59

2.63

5.00

143.20

0.36

5.00 2.21 8.39 2.52 5.00 165.70 0.44

5.50

2.01

8.10

2.89

5.50

144.60

0.37

5.50 2.54 10.74 2.76 5.50 170.80 0.46

6.00

2.36

10.51

3.09

6.00

152.60

0.39

6.00 2.75 12.65 3.01 6.00 169.90 0.46

6.50

2.13

9.99

3.54

6.50

133.10

0.33

6.50 2.75 12.40 3.34 6.50 153.30 0.39

6.50 3.08 15.49 3.25 6.50 173.90 0.47

7.00

2.34

11.84

3.79

7.00

135.00

0.33

7.00 2.90 15.28 3.57 7.00 158.60 0.41

7.00 3.29 17.77 3.50 7.00 172.90 0.47

7.50

2.70

14.82

3.95

7.50

143.20

0.36

7.50 3.11 17.54 3.82 7.50 158.60 0.41

7.50 3.61 21.09 3.75 7.50 175.80 0.48



8.00

2.45

14.01

4.48

8.00

126.20

0.31

8.00 3.91 17.04 4.21 8.00 143.90 0.36

8.00 3.45 20.92 4.04 8.00 163.30 0.43

8.00

3.82

23.75

4.00

8.00

174.90

0.48


Index


PROFILE DATA: Vertical Ellipse



information.




INTERNAL

DIMENSIONS

SIDE

TOP/BOTTOM

STRUCT. REF

Span

(m)

Rise

(m)

Radius

R2 (m)

Angle

A2 (m)

Radius

R1 (m)

Angle

A1 (deg)

Area

(m2)

1.223

1.655

0.996

94.60

0.448

85.40

1.56

7-3

1.705 2.307 1.579 58.60 0.746 121.40 3.14 7-7

2.096 2.8369 1.784 74.20 0.861 105.80 4.67 10-7

2.617 3.5410 2.111 88.10 0.995 91.90 7.19 14-7

2.979 4.030 2.547 73.10 1.230 106.90 9.44 14-10

3.460 4.682 3.214 58.10 1.517 212.90 12.92 14-14

3.851 5.210 3.399 66.80 1.635 113.20 15.88 17-14

4.373 5.915 3.693 76.00 1.782 104.00 20.30 21-14

4.734 6.404 4.163 67.40 2.004 112.60 23.98 21-17

5.215 7.056 4.848 58.00 2.287 122.00 29.36 21-21

5.607 7.585 5.024 63.90 2.406 116.10 33.74 24-21

6.128 8.290 5.300 70.70 2.558 109.30 40.05 28-21

6.489 8.779 5.787 64.80 2.775 115.20 45.16 28-24

6.970

9.430

6.484

57.90

3.057

122.10

52.44

28-28


Index


PROFILE DATA: Horizontal Ellipse



information.




INTERNAL

DIMENSIONS

SIDE

TOP/BOTTOM

STRUCT.

REF

Span

(m)

Rise

(m)

Radius

R1 (m)

Angle

A1 (m)

Radius

A2 (m)

Angle

R2 (deg)

Area

(m2)

1.514

1.369

0.596

64.50

0.786

115.50

1.61

3 - 7

2.133 1.930 0.907 100.50 1.156 79.50 3.24 7 - 7

2.609 2.391 1.082 84.70 1.383 95.30 4.82 7 - 10

3.245 2.936 1.303 70.70 1.695 109.30 7.43 7 - 14

3.709 3.356 1.541 85.70 1.969 94.30 9.75 10 - 14

4.329 3.916 1.842 100.70 2.347 79.30 13.34 14 - 14

4.805 4.348 2.019 92.00 2.571 88.00 16.39 14 - 17

5.441 4.923 2.248 82.80 2.878 97.20 20.96 14 - 21

5.905 5.343 2.478 91.30 3.157 88.70 24.75 17 - 21

6.524 5.903 2.777 100.70 3.538 79.30 30.30 21 - 21

7.001 6.334 2.954 94.80 3.761 85.20 34.83 21 - 24

7.637 6.909 3.186 87.90 4.064 92.10 41.35 21 - 28

8.101 7.330 3.413 93.80 3.346 86.20 46.62 24 - 28

8.720

7.890

3.711

100.80

4.720

79.20

54.12

28 - 28


Index


PHYSICAL PROPERTIES

Bolts/M

Notes:

Steel thickness marked ( * ) in bold are preferred thicknesses.

Seam strengths for MP200 as approved by the Highways Agency.


Seam Strengths kN/m

Steel

Thickness

t (mm)

Section

Area

(mm2/m)

Moment

of Inertia

(mm4/mm)

Section

Modulus

(mm3/mm)

Radius of

Gyration

(mm)

Steel

Thickness

(mm)

10

Bolts/M

15

Bolts/M

20

2.75 3248 1242 43.00 19.55 2.75 582 657 719

*3.00 3544 1356 46.77 19.56 *3.00 667 738 827

3.25 3840 1471 50.52 19.58 3.25 752 819 934

*4.00 4729 1819 61.67 19.61 *4.00 961 1264 1368

4.75 5618 2171 72.66 19.66 4.75 1255 1428 1784

*5.00 5915 2289 76.29 19.67 *5.00 1354 1561 1915

5.50 6509 2526 83.51 19.70 5.50 1584 1872 2221

*6.00 7103 2766 90.68 19.73 *6.00 0 1996 2402

6.25 7400 2886 94.25 19.75 6.25 0 2049 2479

*7.00 8293 3251 104.88 19.80 *7.00 0 0 2859

*7.75 9187 3621 115.41 19.85 *7.75 0 0 3188

Index


COMPONENTS: Plates

MP200 structures are built up from a combination of plate sizes, involving two lengths and four width variations,

combinations of which permit structures to be supplied in a wide range of span/rise ratios and 1.0 metre bottom

length increments as standard.

The 'length' of a plate is taken as being in the same direction as the longitudinal axis of the structure and the

'width' of the plate is at right angles to that axis. The corrugations run circumferentially around the structure.

Standard bolt hole punching allows for 10 bolts per metre of longitudinal seam. This can be increased to 15 or 20

bolts per metre, if required by structural design.

All dimensions in mm unless otherwise indicated

Optional 15 bolts/m

Hole Configuration

for MP200

Optional 20bolts/m

Hole Configuration

for MP200


Index


COMPONENTS: Nuts and Bolts

Bolt head may be placed on corrugation crest or trough whichever is deemed most convenient by the installer.

On underpass structures, however, many specifiers call for all bolt heads to be placed inside the structure to

avoid projecting bolt shanks.

HEADWALL ANCHOR BOLT


Index


COMPONENTS: Arch Seating Channel

MP200 seating channel is designed to be cast into concrete footings, and also to allow for the bolting of plates in

their correct positions. It is asymmetrical in cross-section, and has casting lugs pre-punched along the base.

The asymmetrical channel must be angled to match the arch base, and therefore will have to be set into the

concrete in any one of the different basic configurations as shown.


In Case 1, care should be taken in designing the concrete footings, so that the concrete surface does not impede

access for inserting and tightening bolts.

In Case 2, which is the 'neutral case', concrete can be level on both sides of the channel, at a cast-in depth of

50mm.

In Case 3, care should be taken that sufficient concrete is maintained at point 'A', so that the stresses from the

arch thrust forces can be properly absorbed without spalling or failure.



Index


COMPONENTS: Alternative Arch Seating


Index


SPECIFICATION

General

MP200 corrugated galvanised steel bolted segmental structures are manufactured in accordance with BBA

Roads and Bridges Certificate No 91/59.

Material

MP200 culverts shall be made from steel: Grade HR4 to BS 1449: Section 1.1: 1991

Tolerance to BS EN 10051: 1992

Minimum yield strength of 229/mm2.

Fabrication

Standard plates are pressed, punched, curved and then hot dip galvanised to BS EN ISO 1461: 1999.

Average zinc thickness shall be 0.053mm on steel thickness up to and including 4.00mm and 0.064mm on steel

thickness above 4.00mm.

Plates supplied shall be a combination of circumferential widths to provide the specification profile of the

structure and in net laying lengths to provide the specified structure length.

Cut edges of special plates shall be free from notches, gouges, oxides or dross. Where possible all fabrication

shall be performed before hot dip galvanising. All special plates shall be marked to correspond to the assembly

drawing.

Corrugations

The corrugation shall form smooth continuous curves and tangents with dimensions 200mm pitch by 55mm

depth, tolerance ±5%. When installed the corrugations shall form circumferential rings about the longitudinal axis

of the structure.

Dimensions (Diameter, Span and Rise)

Dimensions for Diameter for single radius structures and Span and Rise for multi-radius structures are in metres

and are subject to a tolerance of ± 5%.

Bolt Holes

Bolt holes diameter shall be 25mm, tolerance ±1mm.

Bolts holes shall be punched on a corrugation crest or valley and on the edges of the plates so as to enable

structure assembly.

Bolt holes on the longitudinal plates edges shall staggered in two rows 50mm apart, furnished to accommodate

10, 15 or 20 bolts / metre.

Bolt holes on the circumferential plate edges shall be at 235mm centre to centre.

Accessories

All MP200 accessories shall be hot dip galvanised to BS EN ISO 1461:1999.

Bolts shall be 20mm diameter and conform to BS 6104 : Part 1: 1981: Grade 10.9

Nuts shall be 20mm diameter and conform to BS 6104 : Part 2: 1981: Grade 10.9

Bolt lengths shall be sufficient to ensure a full thread in the nut when the plates are drawn together.

Anchor nuts and bolts shall conform to BS 3692 Grade 4.8.


Arch seating channels shall be minimum 5mm thick

Repair of Damage

Damage to galvanised coatings shall be made good in accordance with BS 729:1980 by the use of zinc rich

paint.

Inspection

Subject to prior notification all materials and relevant Quality Assurance records can be inspected at the works

during or after manufacture.



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•Index Hydraulic Design:

INTRODUCTION •Next

The importance of the following three considerations cannot be emphasised too strongly because

they draw the designer's attention to all the fundamental elements which have to be confronted

before embarking on the detailed hydraulics calculations for culvert or sewer.

First, in considering the hydraulic design of pipes and pipe-arch structures it is vitally important,

before all else, to differentiate between two basic types of conduit

(1) CULVERTS

(2) LONG PIPELINES (e.g. storm water sewers or stream enclosures).

If the structure in question is classed as a culvert, then culvert hydraulics formulae are applicable.

If the structure is of sufficient length to be classed as a long pipeline or sewer then sewer

hydraulics formulae should be applied. (Pages 3.25-3.26). As a guideline, a conduit over 100

metres in length in which a uniform flow pattern can develop might be classed as a sewer rather

than a culvert.

Secondly, it must be recognised that both culverts and sewers can operate under two basic types

of flow conditions, namely

(1) INLET CONTROL

(2) OUTLET CONTROL.

Under INLET CONTROL, the important factors are:

(1) Cross sectional area of the culvert barrel.

(2) Hydraulic efficiency of the inlet (related to the inlet geometry)

(3) Depth of headwater or amount of ponding.

Under OUTLET CONTROL, the important factors in addition to those for inlet control are:

(1) Elevation of the tailwater in the outlet channel.

(2) Slope, roughness and length of the conduit barrel.

Thirdly, it is important to bear in mind that the capacity required for any drainage structure is

governed by three very vital factors:

(1) Runoff.

(2) Debris.

(3) Maintenance.


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INTRODUCTION (cont) •Next

In any formula used to calculate runoff, several factors are involved which are only rough

approximations. Also, unless regular maintenance is carried out on clearing debris, conduit

capacity can be seriously reduced. By comparison to the scale of error which these factors can

induce, pipe wall roughness is a comparatively minor consideration.

In the pages following, the hydraulics of culverts and sewers (or long pipe-lines) are considered in

some detail. Before embarking on this we think it would be helpful and wise to discuss some

characteristics and deficiencies of culverts in particular and to make some comments thereon.

A reputable authority on the design of culverts from the Highway Engineer's viewpoint listed the

following desirable features:

Characteristics of Good Culvert Design (a) The culvert, together with its appurtenant entrance and outlet structures, should properly take

care of water, bed-load and floating debris at all stages of flow.

(b) It should cause no unnecessary or excessive property damage.

(c) Normally it should provide for transportation of the material without detrimental change in flow

pattern above and below the structure.

(d) It should be designed so that future channel and highway improvement can be made without

too much loss or difficulty.

(e) It should be designed to function properly after fill has caused settlement.

(f) It should not cause objectionable stagnant ponds.

(g) It should be designed to accommodate increased run-off occasioned by anticipated land

development.

(h) It should be economical to build, hydraulically adequate to handle design discharge,

structurally durable and easy to maintain.

(i) It should be designed to avoid excessive poncling_ at entrance, which may cause property

damage, accumulation of'drift, culvert clogging, saturation offills or detrimental upstream deposits

of debris.

(j) Entrance structure should be designed to screen out material which will not pass through the

culvert, reduce entrance losses to a minimum, make use of the velocity of approach in so far as

practical, and by use of transitions and increased slopes as necessary, facilitate channel flow

entering the culvert.

(k) The design of culvert and outlet should be effective in re-establishing tolerable, non-erosive

channel flow within the right-of-way or within a reasonably short distance below the culvert.

(l) The outlet should be designed to resist undermining and washout.

(m) Culvert dissipaters (at outlet) if used should be simple, easy to build, economical and

reasonably selfcleaning during periods of heavy flow.

(n) Where culverts will be used by humans, cattle or fish, necessary provisions should be made.

(o) Culverts should not be death-traps for children.

The same authority listed culvert design deficiencies which are:

Common Culvert Deficiencies (1) Poor functioning or damage to road or property due to faulty location of culverts.

(2) Barrel failures due to load or to differential foundation settlement.

(3) Barrel failures due to erosion or corrosion.

(4) Damage to roadway, outlet features, or to downstream properties due to excessive velocities.

(5) High maintenance costs due to clogging or channel silting.

(6) Inadequate facilities to catch drift which will not pass through culvert.

(7) Inadequate size.

(8) Culvert shape not in agreement with channel shape.

(9) No provision for maintenance access to ends of structure.

(10) Failure to anticipate future roadway widenings or improvements changing channel run-off

characteristics.

(11) Poorly designed inlets or poorly designed outlets.

Conclusions


It is important to understand the difference between inlet and outlet control flow conditions.

An outlet control designed culvert will tend to be on a flat gradient and will tend to flow generally

full or part full for part or all of its length. It will be designed almost certainly, to have a fully

submerged inlet at anything approaching peak flow conditions and frequently will have a

submerged outlet. Such a culvert runs severe risks of blockage from floating debris and could

also cause extensive damage downstream if discharging like a fire hose. In severe storm

conditions, upstream ponding is likely to increase dramatically with resulting property damage

apart from the very real risk of over-topping and loss of the whole embankment.


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INTRODUCTION (cont) •Next

It has to be remembered also, that calculations done to estimate the amount of water arriving at

the upstream end of a culvert are fraught with approximations. It must, then, be reasonable to

allow extra crosssectional area in the conduit to cope with the hazards of severe flooding andlor

timber, brushwood, rubbish, dead animals and low standards of maintenance.

An inlet control designed culvert will tend to be a larger conduit on a slightly steeper gradient

though not necessarily so. Its outlet end will discharge freely and never be submerged. Any

drastic increase in the amount of water arriving at the upstream end will be dealt with comfortably,

provided the inlet end itself will admit the extra flow.

TO SUM UP CULVERT DESIGN Based upon our experience, which extends to75 years, it is Asset's opinion that over 95% of all

culverts are and SHOULD BE DESIGNED FOR INLET CONTROL conditions of flow. There is no

doubt that any culvert designed to flow under outlet control conditions runs a risk of causing

property damage (with resulting ciaims) and possibly a risk of failure.

DESIGN APPROACH It is generally considered that there are two basic types of flow found in hydraulic culverts:

1) Flow with INLET CONTROL, and 2) Flow with OUTLET CONTROL.

In simple terms, inlet control means that varying conditions on the inlet side of the culvert affect

the amount of water flowing through. This is because the cross sectional area of the culvert barrel

is sufficiently large, and the outlet so free, that it can transport away all the water that can enter

through the inlet, even if the inlet is totally inundated and under hydraulic pressure. Thus it is

variations in the inlet condition that govern the flow rate in the culvert.

Conversely, outlet control means that the gradient of the pipe is so flat and the outlet so

encumbered that variations in conditions at the outlet affect the amount of water which can enter,

and thus can vary the flow capacity of the culvert.

For each type of control, different factors and formulae are used to compute the hydraulic

capacity of the culvert. Under inlet control, the cross-sectional area of the culvert barrel, the inlet

geometry and the amount of headwater or ponding at the entrance are of primary importance.

The roughness and length of the barrel have no effect on the capacity of the culvert. Outlet control

involves the additional consideration of the elevation of the tailwater in the outlet channel and the

gradient, roughness and length of the culvert barrel.

It is difficult in many instances to predict the type of flow likely to occur for any given discharge

and culvert installation. The type of flow or the location of the control is dependent on the quantity

of flow, roughness of the culvert barrel, changes in alignment, obstructions, sediment deposits,

type of inlet structure, flow pattern in the approach channel and other factors. In some instances

the flow control changes with change in discharge and occasionally the control fluctuates from

inlet control to outlet control and vice versa for the same discharge. Thus, to design culverts, it is

necessary to have an understanding of both types of flow, so that calculations can be made for

each type and the final design based upon the more adverse flow condition.

The following tabular and nomographic methods for selecting culvert sizes under different

conditions, are based upon systems developed by the U.S.A. Bureau of Public Roads. They have

been supplemented where necessary, and have been aligned specifically to the range of Asset

MULTI-PLATE structures of circular and PIPE-ARCH cross section.



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CULVERT & CHANNEL HYDRAULICS •Next

Modern road design concepts are based upon the aims of maximising cost-effectiveness of effort,

and minimising construction costs. This invariably necessitates construction based on a 'cut-and-

fill' concept. Material excavated from cuttings is used to fill the valleys and other low points along

the route. Consequently, earth embankments are almost invariably the cheapest type of valley

crossing which can be designed. In exceptional cases, elevated structures in the form of viaducts

can be adopted - for example, for aesthetic purposes, or perhaps to overfly areas of particular

ground problems such as unstable mine shafts.

Nonetheless, when a valley is to be crossed by an earth embankment for the purpose of carrying

a road or railway line, provision must be made for any river or drainage system to pass beneath

the embankment safely. The serious potential consequences of inadvertantly blocking the valley's

drainage, necessitates that any such drainage scheme must be properly designed. In particular,

this includes an assessment of the required normal flow conditions, as well as the extreme 'worst

case' conditions which are acceptable during time of flood.

In essence, culverts can either perform as simple open channels, or as pressure pipes,

depending upon the quantity of water passing through. Naturally, when water flows are low, the

culvert pipe acts as a simple open channel, but as inflow volumes rise, the pipe itself becomes

increasingly full.

The water level of the upstream side of the culvert can become sufficiently high that the inlet

mouth of the culvert becomes completely submerged. This is a normal phenomenon, and is an

essential part of a design, in the interests of economy. If this did not occur during occasional

storm conditions, then the selected culvert would be far too large and expensive for the vast

majority of its working life.

The point at which the culvert turns from open channel flow to pressure pipe flow will depend

upon the diameter, length and gradient of the pipe, and on the physical conditions at the outlet

side. If, for example, in a steep valley, flooding cannot occur on the downstream side of the

embankment, then full-bore flow may never be established. Conversely, in lowland areas, where

roads are carried on culverted embankments, flooding may occur on the downstream side,

submerging the outlet mouth of the culvert, and generating pressure pipe flow driven by a

differential water head as the upstream water level increases.

The embankment design detail may have to cater for upstream water ponding during storm

conditions. Prior to the design of the embankment, therefore, a study must be made of the

meteorological, physical and dimensional conditions of the catchment area. Such a study

provides the guidance for typical day-to-day flow capacity requirements, and expected storm run-

off accumulation under exceptional conditions.

The objective of the hydraulic design is therefore to determine the most economic dimension that

can provide the passage of a designed discharge without exceeding the allowable head of water

which will build up on the upstream side of the embankment. It is Asset's view that designers

should attempt to design culverts to flow under inlet control at all times, thus avoiding the inherent

technical problems associated with 'full-bore' flow, large area water collection on both sides of the

embankment and correspondingly high water levels.

In practical terms, during the design of the embankment, soil mechanics considerations become

intrinsically involved with the hydraulic design of the culvert, as a cyclical and somewhat iterative

series of assumptions, modifications, and calculations are made to obtain the appropriate balance

between the various constraints.



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OPEN CHANNEL FLOW THEORY •Next

The major components of a culvert normally include the inlet structure, the pipe barrel itself, the

outlet structure, and an outlet flow energy dissipator where necessary.

Inlet structures protect embankments from erosion, and are designed to increase the rate of

acceptance of flow of any given culvert cross-section. Outlet structures are designed to both

improve the outflow hydraulics, and to protect the outlet environment from scouring. When

considering the acceptability of concentrated flow into the down stream channel, it may be

desirable to design and install a turbulence-generative device to extract energy from the water

before releasing it from the culvert system.

The hydraulic operation of culverts may be classified into four categories:

1 . Flow with unsubmerged inlet.

2. Inlet submerged, but pipe only partially filled.

3. Inlet submerged, pipe completely filled, but free discharge at outlet.

4. Submerged inlet and outlet.

In addition, there are the special conditions pertaining at the transition points between the above

clearly-defined cases.

SOME THEORETICAL CONSIDERATIONS OF FLOW IN AN OPEN CHANNEL

In order to ensure adequate cleansing and flow, a culvert is usually laid at a slightly steeper

gradient than the average of the stream channel in which it is being inserted. It thus normally

comprises a hydraulic flow environment as illustrated below.

The water flow geometry in such an open channel is a function of the velocity, the slope and cross-section of the

channel and the roughness of the channel walls.


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OPEN CHANNEL FLOW THEORY

(cont) •Next

At point A the water is streaming calmly with subcritical velocity. Roughness and possible

changes in crosssectional area are of primary importance in determining water flow and depth in

the channel. Any abrupt reduction in slope in section A would increase the water depth and

reduce the velocity of the water simply because of the loss of fall. Similarly, any sharp increase in

gradient causes velocity to increase and water depth to decrease accordingly. This occurs at the

inlet mouth of the culvert, as shown opposite. Therefore, the water flowing in section A is flowing

under OUTLET CONTROL since it is flowing at less than the critical velocity, and therefore any

change in outlet conditions induces an upstream effect on the water in section A.

It is interesting to note that the inlet structure of the culvert pipe actually comprises the OUTLET

CONTROL point of the upstream section of the system.

In section B, where the gradient is so great that the water is flowing with supercritical velocity, a

change of the slope would not affect the water flow. Any induced flow deceleration cannot

produce upstream-effects when the down-stream velocity is supercritical. The circumstances at

the entrance of the culvert are the important factors for the water flow, and consequently the flow

within the culvert, whilst super-critical, is controlled by the inlet conditions, and is thus under

INLET CONTROL.

Somewhere between the points A and B the water flow increases to a critical velocity and a

critical depth, dc

dc x g = V2 Thus:

and subsequently

where

v = (dc x g)

v = mean velocity (m/sec)

g = gravitational acceleration (9.81 m/sec2)

dc = critical depth (m)

The critical velocity is the same as that for the propagation of a small surface wave. When the

velocity of the water flow reaches such a speed that any induced surface wave cannot travel

against the flow, the velocity is critical, becoming supercritical with any further increase.

If the flow velocity within the culvert is below critical speed, then any hydraulic effect or change at

the exit of the culvert will propagate upward through the culvert, and consequently the culvert flow

conditions will be under OUTLET CONTROL.

Note that the control changes from outlet control to inlet control when the velocity changes from

subcritical to supercritical.

As shown in the diagram above, if the external channel flow velocity is subcritical (as is often the

case), water depth increases rapidly, causing the development of a'hydraulic jump' at point C.

This results in a useful loss of energy due to the generation of strong turbulence. The high exit

velocity and the subsequent induced turbulence may cause localised erosion. This should be

catered for, where necessary, in the design of the exit structure. The water flow will continue

calmly at subcritical velocity after the hydraulic jump.



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INLET CONTROL •Next

CULVERTS FLOWING WITH INLET CONTROL

As described previously, inlet control means that the discharge being effected by the culvert is controlled at the

culvert entrance by the depth of the headwater (HW), the entrance geometry and the type of inlet (head wall,

wing walls, etc.).

Sketches of inlet-control flow are shown below.

PROJECTING END - UNSUBMERGED

This is the classical concept of inlet controlled flow, where the culvert gradient is sufficient to induce a

supercritical flow velocity throughout its entire length.

When the hydrostatic head at the entrance is less than 1.2 x D, air will break into the barrel, and the culvert will

flow under no pressure. Due to the sudden reduction in water area at the entrance, the water usually enters the

culvert in a supercritical condition. The critical depth is passed through at the entrance to the barrel.

PROJECTING END - UNSUBMERGED


Since the culvert slope and the barrel wall friction determine the flow condition in the culvert (open channel

flow), cases can occur where the absorption of energy by wall friction reduces the flow velocity below the critical

velocity within the culvert barrel. This happens where the rate of energy dissipation is higher than can be gained

from the barrel slope, so that the depth of flowing water increases in the downstream direction. Depending on

the tail water level, the supercritical flow may convert to subcritical flow through a hydraulic jump within the

barrel. The assessment of such a possible condition is not dealt with here, but can be addressed through the

attached bibliography list, and solved by the application of water surface profiles developed for open channel

design.


•Main


INLET CONTROL (cont) •Next

PROJECTING END - SUBMERGED

TWhere the headwater height is greater than 1.2 x D, but the in-barrel velocity is supercritical with a free

discharge at the outlet, a partially-full pipe flow condition will normally result, as shown above.

The discharge being effected by the culvert will simply depend upon how much water is forced into the entrance

by the hydraulic head. The culvert is still flowing under INLET CONTROL, and the discharge can be calculated

by

Q = Cd x A x Sq. Root (2 x g x h)

Where h is the hydrostatic head above the centre of the orifice and A is the cross-sectional area. Cd is the

coefficient of discharge; common values varying from 0.62 for square-edged inlet structures, to 1.0 for well

rounded ones.

In the light of the above theoretical analyses, it is most important to recognise that UNDER INLET CONTROL,

THE ROUGHNESS AND LENGTH OF THE CULVERT BARREL AND OUTLET CONDITIONS ARE NOT

FACTORS IN DETERMINING CULVERT CAPACITY.

There is therefore no advantage in specifying smooth wall structures into such designs, and under inlet control

conditions, where corrugation roughness can be ignored, the inherent advantages of continuous flexible ASSET

structures makes them considerably more attractive than any other type of culvert.

As explained above, for inlet controlled conditions, culvert design is reduced to the determination of the expected

excess water height on the upstream side of the embankment, for any given water flow through the entrance.To

reduce numerical calculations,the following nomograms have been developed to give headwater discharge

relationships for culverts flowing with inlet control through a range of headwater depths and discharges. In

particular, they include the case of non-circular pipe-arch sections which are more difficult to quantify

numerically.



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INLET CONTROL

Nomograph No. 1 •Next

MULTIPLATE PIPE CULVERT WITH INLET CONTROL

Nomograph No. 1

Inlet control nomograph for corrugation steel pipe culverts. Where possible it is recommended

that HW/D is kept to a maximum of 1.5 and preferably to no more than 1.0.


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INLET CONTROL

Nomograph No. 2 •Next

MULTIPLATE PIPE CULVERT WITH INLET CONTROL

Nomograph No. 2

Inlet control and headwater depths for pipe arch culverts. Headwater depth should be kept low

because pipe-arches generally are used where headroom is limited.



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OUTLET CONTROL •Next

If the gradient of a culvert is insufficientto generate a flow velocity equal to or greater than the

critical velocity, then downstream effects will be transmitted upstream through the culvert, and

theculvert is flowing under outlet control.

Culverts flowing with outlet control can flow with the culvert barrel full or part full as shown in the

following figures.



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OUTLET CONTROL (cont) •Next

The calculation procedures given here provide methods for the accurate determination of

headwater depth for the flow conditions shown in the first three cases. With regard to the last

figure shown opposite, being a non-full flow condition, the given solution for headwater depth

decreases in accuracy as the headwater decreases towards 0.75D. It is invalid where HW<0.75D.

The head H or energy required to pass a given quantity of water through a culvert flowing with

outlet control is:

H = Hv + He + Hf

or

H = V2

2g

+ ke x

2g

V2 + 2gL x V2

K2 X R4/3

simplified for full flow to

H = 1 + ke + 2gL x V2

2g

......... (3.2)

K2 R4/3 x



•Main



The figure on page 3.15 shows the terms of equation 3.2, where

H = loss of energy = energy required to pass a given quantity of water through a culvert

flowing in outlet control (m)

Hf = friction loss (m)

Hv = V2 = velocity head (m)

2g

He = ke x v2 = entrance loss (m)

2g

ke = entrance loss coefficient as shown below.

L = length of culvert (m)

K = Manning's coefficient (m1/3/sec)

G = gravitational acceleration (m/sec2)

R = hydraulic radius (m)

v = mean velocity in the culvert barrel (m/sec)

TYPE OF INLET

Projecting from fill (no headwalls)

Headwall, or headwall and wingwalls square edge

End-section conforming to fill slope

Bevelled Ring

ke

0.9

0.5

0.5

0.25

The equation for H can be readily solved using the full flow nomograms 5 and 6.

Because of the low velocities in most entrance pools, the upstream velocity is considered to be

negligible, and thus the headwater depths obtained using charts can sometimes be slightly higher

tjian might occur in practice.

The headwater depth, HW, can be expressed by

HW = H + ho - (L x So) ...........(3.3)

where: ho is equal to the tailwater depth TW, when the outlet is submerged.

L is the culvert length.

So is equal to the slope gradient of the culvert invert. If gradient = 0.4%, then So = 0.004.

When ho is less than D or the waterflow so small that the tailwater elevation is below the top of the

culvert (figures on previous pages), equation 3.3 is not valid.

To get an approximate answer in these cases, ho is the greater of the two values:

TW depth or 0.5 (dc + D)

dc , is the critical water depth at the outlet for a given water flow, and can be taken from charts A

and B on the following pages.


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CHART A


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CHART B



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For a different Manning's coefficient (Kx), from that (K), shown on the chart, use the length scales shown with an

adjusted length Lx calculated by

Lx = (K)2 x L

(Kx)2

Manning's coefficient can be taken from the following graph:


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NOMOGRAM 5


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NOMOGRAM 6



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SUMMARY of CULVERT SIZING •Next

SUMMARY OF PROCEDURE FOR SELECTION OF CULVERT SIZE

Step 1 List design data (See suggested tabulation form below)

Step 2 Choose type of culvert.

Step 3 Assume inlet control and determine the headwater depth HW.

Step 4 Assume outlet control and calculate HW according to equation 3.3.

H can be taken from charts A and B.

ho is the greater of the two values TW and 0.5 (dc + D).

Compare the results of HW derived from steps 3 and 4. If the calculation under the

assumption of inlet control gives the greater headwater level, then the water flow in

the culvert is under inlet control.

Step 5

Step 6 Determine the outlet velocity, thus making it possible to estimate the danger of erosion.

With inlet control the velocity is calculated using Manning's formula:

R2/3 1/2 V = K So

With outlet control the velocity is:

v = Q

Ao

Ao is the cross sectional area of flow in the culvert barrel at the outlet.



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WORKED EXAMPLE •Next

WORKED EXAMPLE (See partially completed hand-written tabulation form below.)

Step 1 Design discharge 0 = 16 m3/s

Allowable headwater AHW = 3.2 m

Tailwater TW = 2.0 m

Slope S = 0.4%

Length L = 100 m

Step 2 Choose a circular pipe with projecting end (Column C on nomogram l.)

Step 3 INLET CONTROL CALCULATION

Assume HW = 1.5

D

From nomogram 1, D = 2.43 m

HW = 1.5 x D

= 1.5 x 2.43

= 3.65 m AHW

Now on nomogram 1, assume D = 2.74 m

Therefore, HW = 1.1

D

HW = 1.1 x 2.74

= 3.01 m AHW

(This is slightly less than the permitted maximum of 3.2 rn, and is therefore acceptable.)



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WORKED EXAMPLE (cont) •Next

Step 4 OUTLET CONTROL CALCULATION

Since D = 2.74 m, K can be read off the graph at

page 6 as K. = 47.5

It can be seen that nomogram 5 gives K = 31.8

for a diameter of pipe = 2.74 m. This is arrived at

by examination of the Manning's Coefficient

table on that nomogram, and interpolating

between 31.2 and 32.1.

Length correction on the nomogram is necessary:

Lx = (31.8)2 x 100

(47.5)2

= Approximately 45 m

On Nomogram 5, Connect L = 45 m and D = 2.74 m.

Read off H = 1.27 m for a 16 cumec flow.

From chart A, read off dc = 1.80 m

0.5 (dc + D) ho = 2.27 m

= 0.5 (1.80 + 2.74) = 2.27 m

HW = H + ho - (L x So) .........(3.3)

= 1.27 + 2.27 - (100 x 0.4 ) = 3.14 m

100

Step 5 HW from step 4 (OUTLET CONTROL)

is greater than

HW from step 3 (INLET CONTROL).

Therefore, the culvert is flowing under outlet control.

Step 6 v = Q

Ao.

= 16

5.25

= 3 m/s

This is quite a high velocity, and therefore some protection

against erosion might be necessary.



•Main


SEWER DESIGN •Next

SEWER DESIGN The Manning and Kutter equations are the more common flow equations used today. These formulae are based

on fluid resistance as it applies to the turbulent flow conditions most often experienced in storm sewers.

Both the Manning and Kutter Formulae are widely used in open channel flow calculations, but the Manning

Formula may also be applied to closed conduit and pressure flows.

Nomogram 7 may be used for estimating steady uniform flows for pipes flowing full, using the Manning Equation.

In cases where pipes are only flowing partly full, the corresponding hydraulic ratios may be determined from

Charts C and D.

NOMOGRAM 7 - Solution of Manning's Formular for Sewer Pipes Flowing Full



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SUMMARY •Next



Index

Next Introduction:

Background to Usage

ARMCO Culverts were firstly installed in the United Kingdom in 1913,

having been developed in the USA in 1896. Since that time,

corrugated steel pipe has become a major construction material

throughout the world.

ARMCO construction and drainage products were first approved for

use by the Department of Transport in 1954 and have subsequently

been installed on numerous sites throughout the United Kingdom.

ASSET International as successors to ARMCO Ltd. in the United Kingdom, have continued to serve the market

to ensure that they remain at the forefront of the corrugated steel construction products industry.

ASSET International's corrugated buried steel products have Highways Agency approval and BBA certification

for all products in this manual contained within the Highways Agency Design Manual for Roads and Bridges.

When designed, constructed and installed in accordance with Highways Agency requirements, a 120 year design

life is specified; an independent testament to the proven durability of corrugated steel buried structures.

The continuing promotion of good engineering practice has instigated the publication of this updated design

manual, which has been prepared to provide engineers, at all stages of a project, with useful guidance and

assistance in the use of corrugated steel buried structures.

Perhaps even more impressive than the durability to these structures is the variety of applications and shapes

developed over past decades. Simple arches and circular culverts have developed into pipe-arch and underpass

shapes and these in turn have been joined by the impressive 'Super-Span' structures for such applications as

major highway and railway crossings.



•Main

•Index

•Next Introduction


In assessing the feasibility of using a buried corrugated steel structure to meet a particular need for a conduit, it

is first necessary to examine the end use.

These functions can be broadly categorised as:-

CULVERT / STORM SEWER * VEHICULAR * PEDESTRIAN / LIVESTOCK * UTILITY


The distinction between culverts and storm sewers is made mostly on

the basis of length and types of inlets / outlets. A culvert is defined as

an enclosed channel serving as a continuation of and/or a substitute

for an open stream, where that stream meets an artificial barrier such

as a roadway or embankment of any kind. A storm sewer on the

other hand, is a collection system for storm and surface water,

exclusive of domestic and industrial wastes and is usually a series of

tangent sections with manholes or inlets at all various points.

A culvert may also be classified as a type of bridge. Normally, the rigid definition of a bridge requires that the

deck of the structure also be the roadway surface, and simply an extension of the roadway. The use of

corrugated steel buried structures alters this conventional definition.

Full round pipe is suitable for many applications, but a pipe-arch profile may be more suitable where there is

limited headroom.

This low wide pipe-arch profile is hydraulically more efficient at low water levels than a round pipe.

Many bridges have been identified as being in need of repair and maintenance. These structures can often be

replaced or strengthened quickly and economically with corrugated steel buried structures.



Index

Next Introduction:

APPLICATIONS

Vehicular Underpasses

Conventional structures for rail and vehicular underpasses have

traditionally been of concrete or steel construction.

In the late 1960's, developments were made which involved adding

stiffening members to corrugated steel bolted plate products which

permitted the use of larger spans. This concept made it possible to

achieve the economies and speed of construction of corrugated steel

with clear spans in excess of twelve metres, a size range often

suitable for road or rail underpasses.

The range of shape and sizes available in Multiplate MP200 and Multiplate 'Super-Span' profiles is given later on

in this manual.

In the years since their introduction, this range of structures have proven their ability to meet cost-effectively the

needs of many applications road and rail projects, particularly as bridge replacements where a rapid, economic

solution is required.

Pedestrian / Livestock Underpasses

Pedestrian underpasses find their principle use in protecting people

who would otherwise be forced to cross dangerous roads.

Safety is not the only advantage. Where an institution is divided by a

busy road, a buried corrugated steel underpass is often the most

convenient and economical solution.

Similarly, large farms can also be divided by a road, requiring livestock to make repeated, dangerous crossings.

A cattle pass under the road is often the most satisfactory solution to this problem.

Corrugated steel underpasses can be made attractive and functional by suitably selected end treatments, interior

painting, lighting and paving.

Where speed of installation is of the essence - in order to reduce closure time of an existing road for instance -

the structure can be pre-assembled, either complete or in two halves and lifted into position onto a prepared bed.



Index

Next Introduction:

APPLICATIONS

Utilities

Utilities must often pass below or between buildings or beneath

embankments or other surface obstacles. Good engineering practise

calls for placing utilities within a conduit to protect amongst other

things against direct loading, impact, corrosion, temperature

extremes, sabotage or vandalism.

A conduit large enough to walk through provides better access for inspection and repair. Brackets, hangers or

cushioning bases are easily installed. Existing utility lines can also be encased with two piece sections of

corrugated steel conduit bolted together.

Other Applications

Stockpile Reclaim Tunnels

For many years, corrugated steel products have been used for

materials recovery tunnels. These can range from comparatively

small sizes of about three metre diameter up to vehicular size tunnels

where road or rail vehicles pass through the tunnel to load from

hoppers placed at intervals along the tunnel roof.



Index

Next Introduction

ECONOMIC CONSIDERATIONS

Corrugated steel has been used for many years for a wide range of

important functions in every sector of construction. It is a material for

which design parameters have been developed and correlated to

decades of actual experience. Using proved techniques, the engineer

confidently can select the corrugated steel product and design that is

right for his particular job.

The decision to select any particular material or alternative should be on careful analysis. It is fundamental

responsibility of the engineer to make the right choice on the basis of fact. To evaluate corrugated steel products

objectively for specific uses calls for a value analysis approach on the part of the engineer. When given this type

of consideration, corrugated steel will frequently justify selection in the best interest of the client.

Some of the benefits to be gained by the use of corrugated steel structures are:

1. Strength and durability.

2. Ability to accommodate differential settlement.

3. Resistance to disjointing.

4. Quick straight forward design process.

5. Lightweight; minimising foundation requirements.

6. Ease of handling during construction.

7. Low tech assembly procedures.

8. Speed of manufacture.

9. Speed of installation.

10. Ready for use immediately after backfilling.


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