Friction in Temporary Works

8/6/2019 Friction in Temporary Works

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HSEHealth & Safety

Executive

Friction in temporary works

Prepared by theUniversity of Birmingham

for the Health and Safety Executive 2003

RESEARCH REPORT 071


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HSEHealth & Safety

Executive

Friction in temporary works

Dr N J S Gorst, Dr S J Williamson,

Eur Ing P F Pallett and Professor L A ClarkSchool of Engineering

The University of Birmingham

Edgbaston

Birmingham

B15 2TT

United Kingdom

During initial assembly, temporary works often rely upon friction to provide lateral stability. Frictional

resistance is also utilised in temporary works design as a means of transferring horizontal forces

through falsework or formwork to points of restraint.

The results are presented of an investigation to verify existing claimed values of static coefficient of

friction and to establish practical values of the coefficient for the latest commonly used materials in

temporary works. Friction tests were undertaken on 260 combinations of different material faces used

in temporary works, including both "dry" and saturated timber. The tests generated data for

combinations for which no codified data exist and also generated data which could be compared with

existing British and German codified data.

For material combinations for which codified data exist, the friction values obtained in the current

research tended to lie between the maximum and minimum bound code values, but closer to the

minimum values. Recommendations are made for code friction values for all material combinations. It

is considered that further research is required to investigate the variation in some measured friction

values.

This report and the work it describes were funded by the Health and Safety Executive. Its contents,including any opinions and/or conclusions expressed, are those of the authors alone and do not

necessarily reflect HSE policy.

HSE BOOKS


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Crown copyright 2003

First published 2003

ISBN 0 7176 2613 X

All rights reserved. No part of this publication may bereproduced, stored in a retrieval system, or transmitted inany form or by any means (electronic, mechanical,photocopying, recording or otherwise) without the priorwritten permission of the copyright owner.

Applications for reproduction should be made in writing to:Licensing Division, Her Majesty's Stationery Office,St Clements House, 2-16 Colegate, Norwich NR3 1BQor by e-mail to [email protected]


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CONTENTS

CONTENTS ...............................................................................................................iii

1. INTRODUCTION........................................................................................................ 1

2. THEORY AND CURRENT INFORMATION .....................................................3

3. EXPERIMENTAL PROCEDURES .....................................................................7

4. RESULTS .............................................................................................................13

5. COMPARISON OF RESULTS WITH CURRENT INFORMATION..................19

6. CONCLUSIONS...................................................................................................21

7. RECOMMENDATIONS ......................................................................................23

8. ACKNOWLEDGEMENTS ....................................................................................... 25

9. REFERENCES ........................................................................................................... 27

ABBREVIATIONS............................................................................................................... 29

APPENDIX A Friction Test Data ............................................................................ 31

APPENDIX B Saturation Test Data ........................................................................ 53


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SUMMARY

Friction tests were undertaken on 260 combinations of different material faces used in temporary

works, including both "dry" and saturated timber. The tests generated data for combinations for

which no codified data exist and also generated data which could be compared with existing

British and German codified data.

For material combinations for which codified data exist, the friction values obtained in the

current research tended to lie between the maximum and minimum bound code values, but closer

to the minimum values.

Recommendations are made for code friction values for all material combinations.

It is considered that further research is required to investigate the variation in some measured

friction values.


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1 INTRODUCTION

Temporary works of falsework and soffit formwork include arrangements of multiple levels of

bearers, beams and grillages. Often these members are seated on each other with little or no

positive connection. Lateral stability is an important consideration in all temporary works

structures and, during the initial assembly, temporary works often rely upon friction to provide

such stability.

Frictional resistance is often used in temporary works design calculations as the means of

transferring horizontal forces through the structure to points of suitable restraint.

This project was carried out as a result of a recommendation from The Health and Safety

Executive (HSE) report "Falsework Design Comparative Calculations" (Ref 1) which required

that confidence be established in the existing proposed values for friction. The aim of the work

was to verify existing claimed values of static coefficient of friction and to establish practical

values of the coefficient for the latest commonly used materials in temporary works. The main

experimental work was completed in December 1999. Following comments from industry it was

decided to extend the experimental work to include a second phase, which would investigatefriction on wet timber.


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2 THEORY AND CURRENT INFORMATION

When two items are placed one on top of the other and are not in motion there is a certain value

of lateral force which can be resisted across the interface. In theory this force is a constant ratio

of the applied load, is dependent on the materials in contact and is independent of the contact

area; the ratio is known as the coefficient of static friction. The coefficient of static friction is

given by the expression (see Figure 1):

mq

qq= = =

F

R

W

W

f sin

costan [1]

where: R is the reaction force normal to the surface (N)

Ffis the limiting value of the frictional force (N)

Wis the vertically applied force (N)q is the minimum angle from the horizontal, for a particular pair of materials

at which sliding will commence

W

q

fF

P

R

Figure 1 Restraint provided by friction

In practice it has been found that measured values of the coefficient can vary widely. It has been

suggested that the coefficient is in fact a function of the load and that it may be affected by the

location of the member, i.e. whether it is the upper load bearing member or the lower load

receiving member. Values of coefficient of static friction recommended in Table 19 of BS

5975:1996 (Ref 2), Table 1, indicate that the coefficient is independent of member location.


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Table 1: Minimum value of coefficient of static friction, BS 5975:1996 (Ref 2)

Lower load-accepting

member

Upper load-accepting member

Plain steel Painted steel Concrete Softwoodtimber Hardwood

Plain steel 0.15 0.1 0.1 0.2 0.1

Painted steel 0.1 0.0 0.0 0.2 0.0

Concrete 0.1 0.0 0.4 0.4 0.3

Softwood timber 0.2 0.2 0.4 0.4 0.3

Granular soil 0.3 0.3 0.4 0.3 0.3

Hardwood 0.1 0.0 0.3 0.3 0.1

The current UK Code of Practice, BS 5975:1996 (Ref 2) on falsework gives values for guidance

on friction for a few materials only and friction values have remained unaltered since its first

publication in 1982. It has not been possible to find the origin of these values.

In April 1997 the European Draft, prEN 12812 (Ref 3) on performance and general design of

falsework was published for comment. Many of the diagrams and content are copied from the

original Table 7 in German standard DIN 4421 (Ref 4). The German standard quotes minimum

and maximum values of coefficient of static friction: these are reported in Table 2. It is

understood that the DIN 4421 values were from research by Professor Mohler, at Karslruhe

University. Comparison of the English and German data shows that the British values agree quitewell with the German minimum values.


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Table 2: Friction coefficients, m, from German Standard DIN 4421 (Ref 4) andprEN 12812 (Ref 3)

Building material combination Friction coefficient, m

Maximum Minimum

1 wood / wood (rubbing surfaces parallel to grain or at right

angles to grain)

1.0 0.4

2 wood / wood (one or both rubbing surfaces at right angles to

grain (cross cut) or end grain)

1.0 0.6

3 wood / steel 1.2 0.5

4 wood / concrete

wood / mortar bed

1.0 0.8

5 steel / steel 0.8 0.2

6 steel / concrete 0.4 0.3

7 steel / mortar bed 1.0 0.5

8 concrete / concrete 1.0 0.5

The committee drafting the European Standard (CEN/TC53/WG6, Falsework) expects to have

published a European standard shortly, which will see the withdrawal in the UK of BS 5975 and

any of the conflicting information, such as the table on friction coefficients.

The future design of falsework will almost certainly require a specific calculation for positional

stability, and a detailed check for sideways restraint using friction will be a requirement for all

falsework calculations.

If reliable friction values do not exist, and fixings between members are specified, they will

involve both man-hours for assembly and dismantling, and the use of expendable items such as

bolts or nails. Of greater concern is the likely reduction in quality and/or re-use potential of the

equipment. Items with drilled holes for bolted connections will reduce their load carrying

capacity, and, in the case of extensive nailing, may be reduced to scrap. The use of more accurate

friction values will lead to a reduction in the number of positive connections required and hence

reduced erection and dismantling times, lower labour costs and extended life of temporary worksitems.


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3 EXPERIMENTAL PROCEDURES

The originally specified test combinations are presented in Table 3. It was agreed with the HSE

that the tests with fresh concrete as one member would not be carried out, simply because of the

extra variability in results which would be introduced by factors such as mix type, age and test

method.

It was originally envisaged that each material combination would be tested three times at three

load levels (0kg, 25kg, 50kg) and with members in both the upper and lower position. Once

testing was underway, however, it appeared that three load levels and alternating positions were

not necessary. This allowed the original programme to be reduced and permitted tests of extra

combinations to be undertaken; the extent of this testing is indicated in Table 4.

Coefficient of friction was measured by placing the two materials on a tilting table, illustrated in

Figure 2. The table was raised manually by winding the handle, which operated a jack situated

below the table. In order to avoid inconsistencies caused by change of operator a constant

winding speed of approximately 60 rpm (equivalent to about 34o per minute) was agreed after

preliminary testing. The table was raised until the point where slip occurred was reached and theangle at slip was recorded. A list of the materials used and their sources can be found in Table 5.

Figure 2 Test rig


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Table 3: Coefficients of static friction (m) for originally specified test combinat

Lower load-accepting member Upper load-bearing member

Plain steel Galv. Steel Painted steel Aluminium Wet concrete Hard concrete Softwood

Max Min Max Min Max Min Max Min Max Min Max Min Max Min

Plain steel 0.8 0.15 tba tba tba 0.1 tba tba 0.4 0.1 tba tba 1.2 0.2

Galvanised steel

Painted or oiled steel tba 0.1 tba tba 0.0 0.0 tba tba tba 0.0 tba tba tba tba

Aluminium tba tba tba tba tba tba tba tba tba tba tba tba tba tba

Softwood timber rubbing surface

parallel to the grain

1.2 0.2 tba tba 1.2 0.2 tba tba 1.0 0.4 tba tba 1.0 0.4

Softwood timber rubbing surface

right angle to the grain or on end

grain

1.2 0.2 tba tba 1.2 0.2 tba tba 1.0 0.4 tba tba 1.0 0.4

Hardwood timber rubbing surface

parallel to the grain

tba 0.1 tba tba tba 0.0 tba tba 1.0 0.3 tba tba tba 0.3

Hardwood timber rubbing surface

right angle to the grain or on end

grain

tba 0.1 tba tba tba 0.0 tba tba 1.0 0.3 tba tba tba 0.3

Proprietary timber tba tba tba tba tba tba tba tba tba tba tba tba tba tba

Plywood tba tba tba tba tba tba tba tba tba tba tba tba tba tba

Note: Values of coefficients taken from BS 5975 Table 19 (Ref 2) and prEN 12812 Table 7 (Ref 3)

Where not known, i.e. to be determined in current study, shown as tba


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Table 4a: Material combinations tested

Upper Load-Bearing MemberLower Load-Accepting

MemberSteel Alum. Timber

Softwood Hardwood

Dry Wet Dry Wet

Prop. b

Plainunrusted

Plainrusted

Galv. Prop.painted

Prop.waling

Par. Perp. Par. Perp. Par. Perp. Par. Perp.Re-

used

Plain

unrusted x x + +

Plain rusted + +

Galvanised

Steel

Prop.

painted + +Alum. Prop.

waling + +

Dry

softwood x x

Wetsoftwood + + + +

Dry

hardwood

Wet

hardwood + +

Prop. beam

reused

Timber

Prop. beam

new x x

Tests required by original programme

Additional tests required by modified programmeX Tests repeated with planed all round softwood

+ Additional test with saturated timber


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Table 4b: Material combinations tested


Member Steel Alum. Timber

Softwood Hardwood

Dry Wet Dry Wet

Proprie

beamPlain

unrusted

Plain

rustedGalv.

Prop.

painted

Prop.

walingPar. Perp. Par. Perp. Par. Perp. Par. Perp.

Re-

used

dry good

one side x x wet good

one side + +

Combi ply

faced

Film faced

Finnish

Film faced

quality

Plywood

used film

face

trowelled

face Hardened

Concrete

cast face +

Tests required by original programme

Additional tests required by modified programme

X Tests repeated with planed all round softwood

+ Additional test with saturated timber


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Table 5: Materials used in the test programme

Material Trade Name Source

Plain unrusted steel -- University of Birmingham

Plain rusted steel -- University of Birmingham

Proprietary painted steel Multijoist RMD Kwikform LtdGalvanised steel -- University of Birmingham

Aluminium Alform RMD Kwikform Ltd

Softwood rough cut -- University of Birmingham

Softwood planed all round University of Birmingham

Hardwood -- University of Birmingham

Proprietary timber GT24 PERI Ltd

Plywood good one side -- University of Birmingham

Plywood Beto film, Wisaform,

Wisaform special

Kymmene Schauman

Concrete -- University of Birmingham

On completion of the main test programme and consideration of the data with the HSE, it was

deemed pertinent to carry out two further test programmes to investigate the effect of member

position and the effects of time and/or bedding effects on friction values. These two additional

test programmes utilised two material pairs: plain unrusted steel/ proprietary painted steel and

aluminium/plywood.

The effect of time on coefficient of friction was investigated by performing a zero load test,

leaving the test set-up for two days then repeating the test. The effect of bedding on coefficient of

friction was investigated by performing a loaded test, leaving the test set-up for two days then

repeating the test.

Following comments from industry it was decided to extend the experimental work to include a

further phase, which would investigate friction on wet timber. In order to produce saturated

timber specimens, timber test specimens were stored underwater and the level of surface

saturation was monitored over time by taking three measurements of surface moisture content

using a commercial moisture meter. A timber specimen was deemed to be saturated, and thus

ready for friction testing, when the measurements of surface moisture content remained

approximately constant over time. The saturated timber samples were stored in water between

individual friction tests and were only removed from the water immediately before the start of a

test.


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4 RESULTS

The main body of results is presented in Table 6a and Table 6b on pages 14 and 15. Each piece of

data from the current study included in this table is the average of three tests; the raw data can be

found in Appendix A. The second line of values present in some cells of Table 6 are coefficients

measured using a planed softwood as one member rather than the rougher softwood used in othertests. The rough softwood is more representative of that found on site.

The raw data for the saturation phase of the experimental work is contained in Appendix B. It is

emphasised that the tabulated data have not been corrected for timber species and are intended

simply to demonstrate that "saturation" had been achieved.

It was observed that the value of coefficient of friction was generally independent of member

position (upper or lower). Hence, tests on pairs of materials were not repeated with each member

in both the upper and lower position. On examination of the final results, however, it appears

that, of the thirty-six pairs which were tested with each member in both upper and lower

positions, eight are affected by location. The affected pairs are presented in Table 7.

Table 7: Combinations where coefficient of friction was affected by member position

Member 1 Member 2 Member 1 Upper

Member 2 - Lower

Member 2 Upper

Member 1 - Lower

Max Min Max Min

Plain unrusted steel Prop. painted steel 0.4 0.3 0.6 0.5

Plain rusted steel Galvanised steel 0.6 0.4 0.4 0.3

Plain unrusted steel Softwood 0.4 0.3 0.6 0.5

Prop. painted steel Hardwood 0.7 0.5 0.5 0.4

Plain rusted steel Plywood 0.6 0.4 0.4 0.3

Aluminium Prop. timber (new) 0.4 0.2 0.5 0.5

Aluminium Plywood 0.5 0.3 0.3 0.2

In order to investigate this behaviour, the further tests given in Table 8 were carried out. These

measured the friction values for pairs of (a) plain unrusted steel and proprietary painted steel and

(b) aluminium and plywood. In both cases the pair were tested on both faces and in both upper

and lower position. The apparent location dependence of the friction value was not manifested in

the further test data, although slightly different values were obtained depending on which face

was used. The results of the further tests suggest that the initial variations may either have been

simply due to the natural scatter in friction values, or that different specimen faces with slightly

different surface qualities were used when members were in the upper and lower positions, or a

combination of both these factors. Hence, any future test programme with more replicate

specimens would improve the reliability of the friction values obtained.


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Table 6a Coefficients of static function obtained from current study



Softwood Hardwood

Dry Wet Dry WetPr

Plain

unrusted

Plain

rustedGalv.

Prop.

painted

Prop.


Re

use

Plain

unrusted

0.4

0.3

0.5

0.4

0.3

0.3

0.6

0.5

0.4

0.3

0.6

0.5

(0.5)

0.4

0.4

(0.3)

0.7

0.7--

0.5

0.5

0.5

0.5

0.7

0.6-- --

Plain rusted --0.5

0.4

0.4

0.3-- -- -- --

0.8

0.8-- -- --

0.8

0.8-- --

Galvanised0.4

0.3

0.6

0.4

0.3

0.2

0.5

0.5

0.4

0.2

0.5

0.4

0.5

0.5-- --

0.5

0.5

0.5

0.5-- -- --

Steel

Prop.

painted

0.4

0.3

0.7

0.6

0.4

0.4

0.8

0.7

0.4

0.4

0.5

0.4

0.7

0.4

0.8

0.7--

0.5

0.4

0.6

0.5

0.9

0.9-- --

Alum. Prop.

waling

0.3

0.2

0.5

0.3

0.4

0.2

0.5

0.4

0.4

0.2

0.4

0.4

0.5

0.4

0.6

0.6

--0.5

0.4

0.5

0.3

0.7

0.6

-- --

Dry

softwood

0.4

0.3--

0.5

0.4

0.5

0.5

0.4

0.4

0.7

0.6

(0.5)

0.6

0.5

(0.3)

-- --0.5

0.4

0.5

0.4-- -- --

Wet

softwood-- -- -- -- -- -- --

1.1

0.9

0.9

0.9-- --

0.8

0.8

1.0

0.7--

Dry

hardwood

0.5

0.4

0.6

0.6

0.5

0.5

0.7

0.5

0.4

0.4

0.5

0.5

0.4

0.4-- --

0.5

0.4

0.5

0.5-- -- --

Wet

hardwood-- -- -- -- -- -- -- -- -- -- --

0.8

0.8

0.9

0.8--

Prop. beam

- reused--

0.6

0.6-- -- -- -- -- -- -- -- -- -- -- --

Timber

Prop. beam

- new

0.6

0.5

0.5

0.4

0.5

0.4

0.6

0.5

0.4

0.2

0.5

0.4

(0.5)

0.4

0.3

(0.4)

-- --0.4

0.4

0.4

0.4-- -- --

KEY: 0.60.5

(0.6)

Maximum value

Minimum value

Values for softwood planed all round


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Table 6b Coefficients of static function obtained from current study



Softwood Hardwood

Dry Wet Dry WetPr

Plain

unrusted

Plain

rustedGalv.

Prop.

painted

Prop.


Re

use

Dry good

one side

0.4

0.3

0.6

0.4

0.2

0.2

0.4

0.4

0.5

0.3

0.3

0.2

(0.4)

0.4

0.3

(0.2)

-- --0.3

0.3

0.4

0.3-- -- --

Wet good

one side-- -- -- -- -- -- -- -- -- -- --

0.9

0.8

0.8

0.7--

Combi ply

faced--

0.2

0.2--

0.2

0.2

0.3

0.2

0.3

0.2

0.2

0.2-- -- -- -- -- -- --

Film faced

Finnish --

0.2

0.2 --

0.2

0.2

0.4

0.2

0.3

0.3

0.4

0.2 -- -- -- -- -- -- --

Film faced

quality

0.1

0.1

0.2

0.2

0.2

0.1

0.3

0.1

0.1

0.1

0.2

0.2

0.2

0.1-- --

0.2

0.2

0.2

0.2-- -- --

Plywood

Used film

face--

0.6

0.4

0.3

0.3

0.4

0.3

0.3

0.3

0.5

0.5

0.3

0.3-- -- -- -- -- --

0.4

0.4

Trowelled

face

0.6

0.5

0.7

0.7

0.3

0.2

0.7

0.6

0.6

0.4

1.1

1.0

0.8

0.7-- --

0.7

0.7

0.8

0.6-- --

0.8

0.8

Hardened

Concrete

Cast face -- -- -- -- --0.8

0.8

0.7

0.7

0.9

0.8--

0.6

0.5

0.7

0.7-- -- --

KEY: 0.60.5

(0.6)

Maximum value

Minimum value

Values for softwood planed all round


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Table 8 Investigation of effect of member position (upper/lower)

Coefficient of static frictionm

Lower Member Upper Member

0 kg 25 kg

Plain unrusted steel (face 1)

Prop. painted steel (face 1)



0.6

0.7

0.6

0.6





0.5

0.7

0.5

0.6

Aluminium (face 1)

Plywood (face 1)

Plywood (face 1)

Aluminium (face 1)

0.3

0.3

0.3

0.3

Aluminium (face 2)

Plywood (face 2)

Plywood (face 2)

Aluminium (face 2)

0.4

0.3

0.4

0.3

Prior to the commencement of testing it was anticipated that if loading had any effect on the

value of coefficient of friction it would be to cause an increase, and this was in fact generally

found to be the case. In certain cases, however, the measured friction value actually reduced

with an increase in load. To check whether the reduction in friction was due to surfacechanges, such as polishing, the zero load test was repeated each time this occurred. Member

combinations affected by this behaviour and the corresponding results are summarised in

Table 9.

Table 9 Tests where measured coefficient of friction reduced with increasing load

Upper Member Lower Member Coefficient of static

friction, m

Comment

0 kg 25 kg 0 kg

Aluminium Plain rusted steel 0.6 0.5 0.5 Returned to higher value on re-

testing at zero load

Plywood (used

film faced)

Plain rusted steel 0.6 0.4 0.4 Reduced from initial value to loaded

value on re-testing at zero load

Plain rusted steel Galvanised steel 0.4 0.3 0.3 Reduced from initial value to loaded


Aluminium Galvanised steel 0.4 0.2 0.3 Increased but did not reach initial


Galvanised steel Aluminium 0.4 0.2 0.3 Increased but did not reach initial


Plywood (combi

ply faced)

Aluminium 0.3 0.2 0.3 Returned to higher value on re-

testing at zero loadPlywood (film

faced Finnish)

Softwood perp. 0.4 0.2 0.2 Reduced from initial value to loaded


Aluminium Hardwood par. 0.5 0.4 0.5 Returned to higher value on re-

testing at zero load

Aluminium Hardwood perp. 0.5 0.3 0.4 Increased but did not reach initial


Prop. painted

steel

Prop. timber

(new)

0.6 0.5 0.6 Reduced from initial value to loaded


Plywood (good

one side)

Plywood (film

faced quality)

0.3 0.2 0.3 Returned almost to initial values on

re-testing


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One possible explanation for this behaviour is the existence of a cohesive element of sliding

resistance, which is only perceptible between certain member combinations. The limiting

frictional force would then be expressed as:

Ff = c + mR [2]

where: R is the reaction force normal to the surface (N)

c is the cohesive reaction force (N)

Ff is the limiting value of the frictional force (N)

This relationship is illustrated in Figure 3. It is clear from the figure that if the behaviour is as

represented in equation 2, but is assumed to be as represented in equation 1, then an increase

in reaction force from say point A to point B on Figure 3 will result in an apparent reduction

in the friction angle from q2 to q3, whereas the true friction angle remains constant at q1.

= c + mRFf

c

Ff

Ff= mR

q1

B

A

R

q2 q3

tan q1 = true friction coefficient

tan q2, tan q3 = apparent friction coefficients calculated using F = mR

Figure 3 Friction behaviour with cohesive component

The effect of time on coefficient of friction was investigated by performing a zero load test,

leaving the test set-up for two days then repeating the test. From the data, presented in Table

10, it appears that friction values are not affected by time.


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Table 10 Investigation of bedding/time effects

Coefficient of static friction,m

Lower Member Upper Member

0 kg 25 kg

Plain unrusted steel (face 1) Prop. painted steel (face 1) 0.6 0.7

Plain unrustedsteel (face 1)

Repeated after 48 hrs


Repeated after 48 hrs0.6 0.7

Aluminium (face 1) Plywood 0.3 0.3

Aluminium (face 1


Plywood (face 1)

Repeated after 48 hrs0.3 0.3

For material combinations for which experimental data exist for dry timber, the friction

values obtained in the current research for saturated timber exceeded the corresponding

values for dry timber. One possible explanation for the increase in frictional resistance is that

the surface roughness of saturated wood is greater than that of "dry" wood and that this

hypothesised increase in surface roughness outweighs the lubricating effect of surface

moisture.

For material combinations for which codified data exists, the experimental values obtained in

this research for saturated timber lie between the maximum and minimum values quoted in

the codes, with one exception. In the case of wet softwood lying parallel to wet softwood the

maximum experimental value in this study exceeded the maximum value of the coefficient of

static friction quoted in prEN 12812 (Ref 3).


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5 COMPARISON OF RESULTS WITH CURRENT

INFORMATION

The existing data are presented in Tables 1 and 2, and the data from the current study inTable 6a and Table 6b. Where both British and German data already exist, the data from the

current study (Table 6a and Table 6b) lie between the existing maximum and minimum

values (Tables 1 and 2) and are closer to the British values with one exception. In the case of

wet softwood lying parallel to wet softwood the maximum experimental value in this study

exceeded the maximum value of the coefficient of static friction quoted in prEN 12812

(Ref 3) for dry timber. The only cases where there are large discrepancies between data are

where the existing British values appear rather low and correspond to friction angles of zero

or around five degrees; see for example the data for the hardwood/plain steel combination.

Absolute agreement with either set of existing data would not be expected as the coefficient

of static friction is an inherently variable quantity and susceptible to variation in test method

and the surface quality of material used in the test. Unfortunately, it has not been possibleeither to determine the quality of the surface finishes of the materials used to obtain the data

reported in the British and German Standards, or to locate details of the test methods.

The observed level of agreement between existing data and that from the current study

implies that the friction values for previously untested material combinations, presented in

this report, can be used with confidence in temporary works calculations. A summary of the

friction values recommended for use as a result of this investigation is presented in Table 11.

The values in bold italics are minimum values of the coefficient of static friction contained

in BS 5975: 1996 (Ref 2).


27/62

20

Table 11 Recommended Friction values

SURFACE 1

Steel Alum. Timber

Soft wood Hard woodSURFACE 2

Plain

Unrusted

Plain

rusted

Galv. Prop.

painted

Prop.

waling Parallel Perp Parallel Perp

Proprieta

beam

Plain unrusted 0.3 0.4 0.3 0.3 0.2 0.3 0.4 0.4 0.5 0.5

Plain rusted 0.4 0.4 0.3 0.6 0.3 -- -- 0.6 -- 0.4

Galvanised 0.3 0.3 0.2 0.4 0.2 0.4 0.5 0.5 0.5 0.4

Steel

Proprietary painted 0.3 0.6 0.4 0.7 0.4 0.4 0.4 0.4 0.5 0.5

Aluminium Proprietary waling 0.2 0.3 0.2 0.4 0.2 0.4 0.4 0.4 0.3 0.2

Parallel 0.3 -- 0.4 0.4 0.4 0.6 0.5 0.4 0.4 0.4 Softwood

Perpendicular 0.4 -- 0.5 0.4 0.4 0.5 -- 0.4 -- 0.3

Parallel 0.4 0.6 0.5 0.4 0.4 0.4 0.4 0.4 0.5 0.4 HardwoodPerpendicular 0.5 -- 0.5 0.5 0.3 0.4 -- 0.5 -- 0.4

Timber

Proprietary beam 0.5 0.4 0.4 0.5 0.2 0.4 0.3 0.4 0.4 0.5

Good one side 0.3 0.3 0.2 0.4 0.2 0.2 0.3 0.3 0.3 0.3

Combi ply faced -- 0.2 -- 0.2 0.2 0.2 0.2 -- -- --

Film faced Finnish -- 0.2 -- 0.2 0.2 0.3 0.2 -- -- --

Plywood

Film faced quality 0.1 0.2 0.1 0.1 0.1 0.2 0.1 0.2 0.2 0.1

Cast face 0.1 -- -- 0.0 -- 0.8 0.7 0.5 0.7 -- Hardened

Concrete Trowelled face 0.5 0.7 0.2 0.6 0.4 1.1 0.7 0.7 0.6 0.6

Soil Granular 0.3 -- -- 0.3 -- 0.3 0.3 0.3 0.3 --


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21

6 CONCLUSIONS

1. The value of coefficient of static friction does not appear to be affected by member

position, i.e. upper or lower. Further testing of member combinations, where initial datasuggested that friction values may be a function of position, did not produce any pattern

indicating that the variation was either due to natural scatter or the testing of different

faces in different positions.

2. Application of load to the upper member generally results in a small increase in friction

value. Subsequent increases in load do not, however, appear to affect the friction

coefficient.

3. The sliding resistance between two materials with contacting surfaces may consist of a

cohesive component in addition to the frictional resistance.

4. Friction values quoted in BS 5975 are similar to the minimum values quoted by DIN4421.

Where friction values have been obtained in this research for material combinations

already quoted in existing standards, the results (with one exception) lie between the

maximum and minimum values of the existing data and tend to be closer to the minimum

values. For use in temporary works the recommended values from this research may be

used as lower bound values (Table 11).

5. The agreement between current minimum values of friction coefficient and those obtained

in the current study suggests that friction values obtained for combinations of materials

not previously tested are acceptable for use as lower bound values of friction coefficient.

6. Conclusions 4 and 5 imply that the use of current minimum values of friction coefficientdoes not have adverse safety implications.


29/62

22


30/62

23

7 RECOMMENDATIONS

The amount of scatter observed in a few of the tests which were repeated with each member

in both upper and lower position suggests that more replicates are needed in future testing.

The possibility that sliding resistance consists of a cohesive as well as a frictional component

requires further investigation.

The material combinations tested to date are representative of the head, i.e. soffit, level in

temporary works. Material combinations also need to be tested which represent the various

interfaces at the base level.


31/62

24


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25

11 ACKNOWLEDGEMENTS

The following companies provided materials for the tests:

Mr T C PageKymmene Schaumann (UK) Ltd

Stags End House

Hemel Hempstead

Hertfordshire HP2 6HN

Tel No. 01582 794661

Mr I Fryer

Chief Engineer

RMD - Kwikform Ltd

Stubbers Green Road

Aldridge

WalsallWest Midlands WS9 8BW

Tel No. 01922 743743

Mr C Heathcote

Chief Executive

Peri Ltd

Market Harborough Road

Clifton-upon-Dunsmore

Rugby

Warwickshire CV23 OAN

Tel No. 01788 861600


33/62

26


34/62

27

12 REFERENCES

1 HEALTH AND SAFETY EXECUTIVE Falsework Design - Comparative

Calculations, File No. 617/DST/1004/1998, Report 300-207-R01, October 1998,

113pp.

2 BRITISH STANDARDS INSTITUTION, BS 5975: 1996: Code of Practice for

Falsework, London, March, 1996, 134pp. ISBN 0 580 24949 2 including AMD

9289 December 1996.

3 BRITISH STANDARDS INSTITUTION, Draft prEN 12812 Falsework -

Performance requirements and general design, Draft for Public Comment

97/102975DC, London, April 1997, 40pp.

4 DEUTSCHES INTSTITUT FUR NORMUNG, Falsework - Calculation, design

and construction DIN 4421: 1982, Beuth Veriag GmbH, Berlin 30, August 1982,20pp.


35/62

28


36/62

29

ABBREVIATIONS

alum. Aluminium

BS British Standards InsitututionCEN Comite Europeen de Normalisation

DIN Deutsches Institut fur Normung

galv. galvanised

HSE Health and Safety Executive

par. parallel

perp. perpendicular

prop. proprietary


37/62

30


38/62

31

APPENDIX A

Friction Test Data


39/62


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33

Upper member: Plain rusted steel

Coefficient of frictionLower Member Test

0 kg 25 kg 50 kg

1 0.5 0.4

2 0.5 0.4

Plain unrusted steel

3 0.4 0.41 0.5 0.5

2 0.4 0.5

Plain rusted steel

3 0.4 0.5

1 0.6 0.4

2 0.6 0.4

Galvanised steel

3 0.5 0.4

1 0.8 0.6

2 0.6 0.7

Proprietary painted steel

3 0.5 0.7

1 0.5 0.4 0.5

2 0.6 0.3 0.5

* Aluminium

3 0.5 0.4 0.5

1

2

Softwood (parallel)

31

2

Wet softwood (parallel)

3

1 0.5 0.6

2 0.6 0.5

Hardwood (parallel)

3 0.6 0.6

1

2

Wet hardwood (parallel)

3

1 0.7 0.6

2 0.6 0.6

Proprietary timber beam (old)

3 0.6 0.5

1 0.4 0.5

2 0.4 0.5

Proprietary timber beam (new)

3 0.5 0.5

1 0.6 0.4

2 0.5 0.4

Plywood good one side

3 0.7 0.4

1

2

Wet plywood good one side

3

1 0.2 0.2

2 0.2 0.2

Plywood combi ply faced

3 0.2 0.2

1 0.2 0.2

2 0.2 0.2

Plywood film faced Finnish

3 0.2 0.2

1 0.2 0.2

2 0.2 0.2

Plywood film faced quality

3 0.2 0.2

1 0.6 0.4 0.4

2 0.6 0.4 0.4

* Plywood used phenol faced

3 0.6 0.4 0.5

1 0.8 0.8

2 0.8 0.7

Hardened concrete (trowelled face)

3 0.7 0.8

1

2

Hardened concrete (cast face)

3

Note: * indicates that the third set of tests was a repeat of the zero load test and not a 50 kg test.


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34

Upper member: Galvanised steel


0 kg 25 kg 50 kg

1 0.2 0.3

2 0.3 0.2


3 0.3 0.31 0.4 0.3 0.3

2 0.4 0.2 0.3

* Plain rusted steel

3 0.4 0.2 0.3

1 0.3 0.3

2 0.3 0.2

Galvanised steel

3 0.3 0.2

1 0.4 0.3

2 0.4 0.4


3 0.3 0.4

1 0.4 0.2 0.3

2 0.3 0.1 0.4

* Aluminium

3 0.4 0.2 0.3

1 0.5 0.5

2 0.4 0.5

Softwood (parallel)

3 0.4 0.51

2


3

1 0.5 0.4

2 0.5 0.5

Hardwood (parallel)

3 0.5 0.5

1

2


3

1

2


3

1 0.4 0.6

2 0.4 0.5


3 0.5 0.5

1 0.3 0.2

2 0.2 0.2


3 0.2 0.2

1

2


3

1

2


3

1

2


3

1 0.2 0.1

2 0.2 0.1


3 0.2 0.1

1 0.3 0.3

2 0.3 0.4

Plywood used phenol faced

3 0.3 0.3

1 0.4 0.3

2 0.3 0.2


3 0.3 0.2

1

2


3



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35

Upper member: Proprietary painted steel


0 kg 25 kg 50 kg

1 0.5 0.6 0.6

2 0.5 0.6 0.6


3 0.5 0.7 0.61

2

Plain rusted steel

3

1 0.5 0.5

2 0.5 0.5

Galvanised steel

3 0.6 0.5

1 0.8 0.7

2 0.8 0.7


3 0.7 0.7

1 0.5 0.5 0.5

2 0.5 0.4 0.5

Aluminium

3 0.5 0.4 0.4

1 0.5 0.5

2 0.5 0.5

Softwood (parallel)

3 0.5 0.51

2


3

1 0.5 0.7 0.6

2 0.6 0.6 0.7

Hardwood (parallel)

3 0.5 0.6 0.6

1

2


3

1

2


3

1 0.5 0.6 0.5

2 0.5 0.6 0.6


3 0.5 0.7 0.6

1 0.4 0.4 0.4

2 0.4 0.5 0.4


3 0.4 0.4 0.4

1

2


3

1 0.2 0.2

2 0.2 0.2


3 0.2 0.2

1 0.2 0.2

2 0.2 0.3


3 0.2 0.2

1 0.1 0.2 0.2

2 0.1 0.2 0.3


3 0.2 0.2 0.3

1 0.3 0.4

2 0.3 0.4


3 0.3 0.4

1 0.6 0.7

2 0.6 0.7


3 0.6 0.6

1

2


3



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36

Upper member: Aluminium


0 kg 25 kg 50 kg

1 0.4 0.5 0.3

2 0.3 0.3 0.3


3 0.4 0.3 0.31

2

Plain rusted steel

3

1 0.4 0.2 0.3

2 0.4 0.2 0.2

* Galvanised steel

3 0.3 0.2 0.2

1 0.5 0.3

2 0.4 0.4


3 0.4 0.4

1 0.2 0.4

2 0.3 0.4

Aluminium

3 0.2 0.4

1 0.4 0.4

2 0.3 0.5

Softwood (parallel)

3 0.4 0.41

2


3

1 0.4 0.4

2 0.4 0.4

Hardwood (parallel)

3 0.4 0.4

1

2


3

1

2


3

1 0.2 0.4

2 0.2 0.4


3 0.2 0.4

1 0.5 0.3

2 0.4 0.3


3 0.5 0.3

1

2


3

1 0.2 0.2 0.3

2 0.3 0.2 0.3

* Plywood combi ply faced

3 0.3 0.2 0.3

1 0.4 0.2

2 0.4 0.2


3 0.4 0.2

1 0.1 0.1

2 0.1 0.1


3 0.1 0.1

1 0.3 0.3

2 0.3 0.3


3 0.3 0.3

1 0.4 0.6

2 0.3 0.6


3 0.4 0.7

1

2


3



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37

Upper member: Softwood (parallel)


0 kg 25 kg 50 kg

1 0.5 0.5

2 0.6 0.6


3 0.5 0.61

2

Plain rusted steel

3

1 0.4 0.5

2 0.4 0.5

Galvanised steel

3 0.3 0.5

1 0.4 0.6

2 0.4 0.5


3 0.5 0.5

1 0.4 0.4

2 0.4 0.4

Aluminium

3 0.4 0.4

1 0.8 0.6

2 0.7 0.6

Softwood (parallel)

3 0.6 0.51

2


3

1 0.4 0.6

2 0.5 0.5

Hardwood (parallel)

3 0.5 0.5

1

2


3

1

2


3

1 0.5 0.6

2 0.4 0.5


3 0.4 0.4

1 0.3 0.2

2 0.3 0.2


3 0.3 0.2

1

2


3

1 0.3 0.2

2 0.3 0.2


3 0.3 0.3

1 0.3 0.2

2 0.3 0.3


3 0.3 0.3

1 0.2 0.2

2 0.2 0.2


3 0.2 0.2

1 0.5 0.5

2 0.6 0.5


3 0.6 0.5

1 1.0 1.0

2 1.1 1.2


3 1.0 1.1

1 0.8 0.8

2 0.8 0.8


3 0.7 0.8



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38

Upper member: Softwood (perpendicular)


0 kg 25 kg 50 kg

1 0.4 0.4

2 0.4 0.4


3 0.5 0.41

2

Plain rusted steel

3

1 0.5 0.5

2 0.5 0.5

Galvanised steel

3 0.6 0.5

1 0.4 0.6

2 0.4 0.6


3 0.4 0.7

1 0.5 0.4

2 0.5 0.4

Aluminium

3 0.5 0.4

1 0.5 0.6

2 0.6 0.6

Softwood (parallel)

3 0.5 0.61

2


3

1 0.4 0.5

2 0.4 0.4

Hardwood (parallel)

3 0.4 0.4

1

2


3

1

2


3

1 0.4 0.4

2 0.5 0.3


3 0.4 0.3

1 0.3 0.3

2 0.3 0.3


3 0.4 0.3

1

2


3

1 0.2 0.2

2 0.2 0.2


3 0.2 0.2

1 0.4 0.2 0.2

2 0.3 0.2 0.2

* Plywood film faced Finnish

3 0.4 0.2 0.2

1 0.1 0.2

2 0.1 0.2


3 0.1 0.2

1 0.3 0.3

2 0.3 0.3


3 0.3 0.4

1 0.8 0.9

2 0.7 0.8


3 0.7 0.8

1 0.7 0.7

2 0.7 0.7


3 0.7 0.7



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39

Upper member: Wet softwood (parallel)


0 kg 25 kg 50 kg

1 0.7

2 0.7


3 0.71 0.8

2 0.8

Plain rusted steel

3 0.8

1

2

Galvanised steel

3

1 0.7

2 0.8


3 0.7

1 0.6

2 0.6

Aluminium

3 0.6

1

2

Softwood (parallel)

31 1.0

2 0.9


3 1.1

1

2

Hardwood (parallel)

3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1 0.9

2 0.9


3 0.8



47/62

40

Upper member: Wet softwood (perpendicular)


0 kg 25 kg 50 kg

1

2


31

2

Plain rusted steel

3

1

2

Galvanised steel

3

1

2


3

1

2

Aluminium

3

1 0.9

2 0.9

Softwood (parallel)

3 0.91

2


3

1

2

Hardwood (parallel)

3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3



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41

Upper member: Hardwood (parallel)


0 kg 25 kg 50 kg

1 0.5 0.5

2 0.5 0.5


3 0.5 0.51

2

Plain rusted steel

3

1 0.5 0.6

2 0.5 0.5

Galvanised steel

3 0.4 0.6

1 0.4 0.3

2 0.5 0.4


3 0.5 0.5

1 0.6 0.4 0.5

2 0.5 0.4 0.5

* Aluminium

3 0.5 0.4 0.5

1 0.5 0.4

2 0.4 0.4

Softwood (parallel)

3 0.5 0.51

2


3

1 0.5 0.5

2 0.5 0.4

Hardwood (parallel)

3 0.5 0.5

1

2


3

1

2


3

1 0.5 0.4

2 0.4 0.4


3 0.4 0.4

1 0.3 0.3

2 0.3 0.3


3 0.3 0.3

1

2


3

1

2


3

1

2


3

1 0.2 0.2

2 0.2 0.2


3 0.2 0.2

1 0.0 0.0

2 0.0 0.0


3 0.0 0.0

1 0.7 0.7

2 0.6 0.7


3 0.7 0.7

1 0.5 0.6

2 0.5 0.6


3 0.5 0.7



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42

Upper member: Hardwood (perpendicular)


0 kg 25 kg 50 kg

1 0.5 0.5

2 0.5 0.5


3 0.5 0.51

2

Plain rusted steel

3

1 0.5 0.5

2 0.5 0.5

Galvanised steel

3 0.5 0.5

1 0.5 0.6

2 0.5 0.6


3 0.5 0.6

1 0.6 0.3 0.4

2 0.5 0.3 0.4

* Aluminium

3 0.6 0.3 0.4

1 0.4 0.5

2 0.5 0.5

Softwood (parallel)

3 0.4 0.51

2


3

1 0.5 0.5

2 0.5 0.5

Hardwood (parallel)

3 0.6 0.5

1

2


3

1

2


3

1 0.3 0.4

2 0.4 0.4


3 0.4 0.4

1 0.5 0.4

2 0.4 0.3


3 0.4 0.3

1

2


3

1

2


3

1

2


3

1 0.2 0.2

2 0.2 0.2


3 0.2 0.2

1

2


3

1 0.7 0.8

2 0.6 0.8


3 0.6 0.7

1 0.7 0.7

2 0.7 0.7


3 0.7 0.6



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43

Upper member: Wet hardwood (parallel)


0 kg 25 kg 50 kg

1 0.7

2 0.6


3 0.61 0.8

2 0.8

Plain rusted steel

3 0.8

1

2

Galvanised steel

3

1 0.9

2 0.9


3 0.9

1 0.7

2 0.7

Aluminium

3 0.6

1

2

Softwood (parallel)

31 0.8

2 0.8


3 0.8

1

2

Hardwood (parallel)

3

1 0.8

2 0.8


3 0.8

1

2


3

1

2


3

1

2


3

1 0.9

2 0.8


3 0.8

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3



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44

Upper member: Wet hardwood (perpendicular)


0 kg 25 kg 50 kg

1

2


31

2

Plain rusted steel

3

1

2

Galvanised steel

3

1

2


3

1

2

Aluminium

3

1

2

Softwood (parallel)

31 0.7

2 1.0


3 0.9

1

2

Hardwood (parallel)

3

1 0.9

2 0.8


3 0.8

1

2


3

1

2


3

1

2


3

1 0.7

2 0.7


3 0.8

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3



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45

Upper member: Proprietary timber beam (old)


0 kg 25 kg 50 kg

1

2


31

2

Plain rusted steel

3

1

2

Galvanised steel

3

1

2


3

1

2

Aluminium

3

1

2

Softwood (parallel)

31

2


3

1

2

Hardwood (parallel)

3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1 0.4 0.4

2 0.4 0.3


3 0.4 0.3

1 0.8 0.8

2 0.8 0.8


3 0.8 0.8

1

2


3



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46

Upper member: Proprietary timber beam (new)


0 kg 25 kg 50 kg

1 0.6 0.5 0.5

2 0.5 0.6 0.5


3 0.5 0.5 0.51

2

Plain rusted steel

3

1 0.4 0.4 0.0

2 0.4 0.4 0.0

Galvanised steel

3 0.4 0.4 0.0

1 0.6 0.5 0.5

2 0.6 0.5 0.5

* Proprietary painted steel

3 0.6 0.5 0.5

1 0.5 0.5 0.5

2 0.5 0.4 0.4

Aluminium

3 0.5 0.5 0.5

1 0.5 0.5

2 0.6 0.5

Softwood (parallel)

3 0.6 0.51

2


3

1 0.5 0.4

2 0.5 0.4

Hardwood (parallel)

3 0.5 0.4

1

2


3

1

2


3

1 0.6 0.5 0.4

2 0.5 0.4 0.4


3 0.5 0.5 0.5

1 0.4 0.4 0.4

2 0.3 0.4 0.3


3 0.3 0.4 0.3

1

2


3

1

2


3

1

2


3

1 0.2 0.2 0.2

2 0.1 0.2 0.2


3 0.1 0.2 0.2

1 0.4 0.4

2 0.4 0.4


3 0.5 0.4

1 0.6 0.7

2 0.7 0.6


3 0.6 0.7

1

2


3



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47

Upper member: Plywood good one side


0 kg 25 kg 50 kg

1 0.3 0.4 0.3

2 0.3 0.4 0.3


3 0.3 0.3 0.31 0.4 0.4

2 0.3 0.4

Plain rusted steel

3 0.3 0.4

1 0.2 0.2

2 0.2 0.3

Galvanised steel

3 0.2 0.2

1 0.4 0.5 0.4

2 0.5 0.5 0.5


3 0.5 0.5 0.4

1 0.2 0.3 0.3

2 0.2 0.3 0.3

Aluminium

3 0.2 0.3 0.2

1 0.3 0.3

2 0.4 0.3

Softwood (parallel)

3 0.3 0.31

2


3

1 0.3 0.4

2 0.3 0.3

Hardwood (parallel)

3 0.3 0.3

1

2


3

1

2


3

1 0.3 0.3 0.3

2 0.3 0.3 0.3


3 0.3 0.3 0.3

1 0.5 0.3 0.4

2 0.5 0.3 0.4


3 0.5 0.3 0.3

1

2


3

1 0.3 0.2

2 0.3 0.2


3 0.3 0.2

1 0.3 0.2

2 0.3 0.2


3 0.3 0.2

1 0.2 0.2 0.2

2 0.1 0.2 0.2


3 0.2 0.2 0.2

1 0.4 0.4

2 0.3 0.3


3 0.3 0.3

1 0.3 0.4

2 0.4 0.3


3 0.4 0.3

1 0.4 0.3

2 0.4 0.3


3 0.4 0.3



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48

Upper member: Wet plywood good one side

Coefficient of frictionLower Member

Test

0 kg 25 kg 50 kg

1 0.5

2 0.6


3 0.61

2

Plain rusted steel

3

1

2

Galvanised steel

3

1 0.7

2 0.7


3 0.7

1

2

Aluminium

3

1

2

Softwood (parallel)

31

2


3

1

2

Hardwood (parallel)

3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1 0.7

2 0.6


3 0.7



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49

Upper member: Plywood combi ply faced


0 kg 25 kg 50 kg

1

2


31

2

Plain rusted steel

3

1

2

Galvanised steel

3

1

2


3

1

2

Aluminium

3

1

2

Softwood (parallel)

31

2


3

1

2

Hardwood (parallel)

3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1 0.3 0.2

2 0.3 0.3


3 0.3 0.3



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50

Upper member: Plywood film faced Finnish


0 kg 25 kg 50 kg

1

2


31

2

Plain rusted steel

3

1

2

Galvanised steel

3

1

2


3

1

2

Aluminium

3

1

2

Softwood (parallel)

31

2


3

1

2

Hardwood (parallel)

3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1

2


3

1 0.3 0.3

2 0.3 0.2


3 0.3 0.3



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Upper member: Plywood film faced quality


0 kg 25 kg 50 kg

1 0.2 0.1 0.1

2 0.2 0.1 0.1


3 0.2 0.1 0.21

2

Plain rusted steel

3

1 0.1 0.1

2 0.1 0.1

Galvanised steel

3 0.1 0.1

1 0.2 0.3 0.2

2 0.2 0.3 0.3


3 0.2 0.3 0.3

1 0.2 0.1 0.1

2 0.2 0.1 0.1

Aluminium

3 0.2 0.1 0.1

1 0.2 0.2

2 0.2 0.2

Softwood (parallel)

3 0.2 0.21

2


3

1 0.2 0.2

2 0.2 0.2

Hardwood (parallel)

3 0.2 0.2

1

2


3

1

2


3

1 0.2 0.2

2 0.2 0.2


3 0.2 0.2

1 0.3 0.2 0.3

2 0.3 0.2 0.3

* Plywood good one side

3 0.3 0.2 0.2

1

2


3

1

2


3

1

2


3

1 0.2 0.2

2 0.2 0.1


3 0.2 0.1

1

2


3

1

2


3

1 0.2 0.2 0.0

2 0.3 0.2 0.0


3 0.2 0.2 0.0



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Effect of Member Position

Coefficient of frictionLower Member Upper Member Test

0kg 25kg


(face 1)

Prop. painted steel

(face 1)

1

23

0.5

0.60.6

0.5

0.60.6

Prop. painted steel

(face 1)


(face 1)

1

2

3

0.7

0.7

0.7

0.6

0.6

0.6


(face 2)

Prop. painted steel

(face 2)

1

2

3

0.4

0.5

0.6

0.4

0.5

0.5

Prop. painted steel

(face 2)


(face 2)

1

2

3

0.7

0.7

0.7

0.6

0.6

0.6

Aluminium (face 1) Plywood (face 1) 1

2

3

0.3

0.3

0.3

0.2

0.3

0.3

Plywood (face 1) Aluminium (face 1) 1

2

3

0.3

0.3

0.4

0.3

0.3

0.2

Aluminium (face 2) Plywood (face 2) 1

2

3

0.4

0.4

0.4

0.4

0.3

0.4

Plywood (face 2) Aluminium (face 2) 1

2

3

0.4

0.3

0.3

0.3

0.4

0.4

Investigation of bedding/time effects

Coefficient of frictionLower Member Upper Member Test

0kg 25kg


(face 1)

Prop. painted steel (face 1) 1

2

3

0.6

0.6

0.7

0.7

0.7

0.7


(face 1)




1

2

3

0.6

0.6

0.7

0.7

0.7

0.7Aluminium (face 1) Plywood (face 1) 1

2

3

0.3

0.3

0.3

0.3

0.3

0.3

Aluminium (face 1)


Plywood (face 1)


1

2

3

0.3

0.3

0.3

0.3

0.3

0.3


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APPENDIX B

Saturation Test Data


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Time (days) Specimen Moisture Content (% water)

Reading 1 Reading 2 Reading 3 Average

Softwood 1 6 6 6 6.0

Softwood 2 6 6 6 6.00 Plywood 0 0 0 0.0

Hardwood 1 12 14 12 12.7

Hardwood 2 14 14 14 14.0

Softwood 1 25 25 23 24.3

Softwood 2 25 23 25 24.3

1 Plywood 28 28 28 28.0

Hardwood 1 25 26 26 25.7

Hardwood 2 28 26 28 27.3

Softwood 1 26 26 26 26.0

Softwood 2 26 25 26 25.7

5 Plywood 28 28 26 27.3Hardwood 1 26 28 28 27.3

Hardwood 2 26 26 28 26.7

Softwood 1 26 26 26 26.0

Softwood 2 28 26 26 26.7

14 Plywood 28 28 26 27.3

Hardwood 1 28 28 26 27.3

Hardwood 2 28 28 28 28.0

Softwood 1 26 26 26 26.0

Softwood 2 26 26 26 26.0

19 Plywood 26 26 26 26.0

Hardwood 1 26 28 26 26.7Hardwood 2 28 26 26 26.7

Printed and published by the Health and Safety Executive

C1.25 02/03


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Friction in Temporary Works

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Transcript of Friction in Temporary Works