Reinforcement Detailing

Design and drawing of RC Structures

CV61

Dr. G.S.Suresh

Civil Engineering Department

The National Institute of Engineering

Mysore-570 008

Mob: 9342188467 Email: [email protected]

1

DETAILING OF BEAMS

2

Learning out Come Introduction Simply supported rectangular beams Continuous rectangular beams Cantilever rectangular beams Flanged beams

3

Dr.G.S.Suresh4

Introduction Carries Transverse External Loads That

Cause Bending Moment, Shear Forces And InSome Cases Torsion

Concrete is strong in compression and veryweak in tension.

Steel reinforcement is used to take up tensilestresses in reinforced concrete beams.

Mild steel bars or Deformed or High yieldstrength deformed bars (HYSD)

HYSD bars have ribs on the surface and thisincreases the bond strength at least by 40%

Dr.G.S.Suresh5

Introduction

Drawinsg generally include a barbending scheduleThe bar bending schedule describes thelength and number, position and theshape of the bar

Introduction

Sl.No. Type of bar and mark Shape No. Length in m

Weight per unit lengthin Kg

Weight in Kg

6

Anchorage in steel bars is normallyprovided in the form of bends and hooksThe anchorage value of bend of bar istaken as 4 times the diameter of bar forevery 450 bend subjected to maximum of16 times the diameter of bar.

Introduction

7

Standard hooks

8

The beams are classified as: According to shape: Rectangular, T,

L, Circular etc According to supporting conditions:

Simply supported, fixed, continuous and cantilever beams

According to reinforcement: Singly reinforced and doubly reinforced

Introduction

9

Minimum cover in beams must be 25 mm or shall not be less than the larger diameter of bar for all steel reinforcement including links.

Nominal cover specified in Table 16 and 16A of IS456-2000 should be used to satisfy the durability criteria.

Introduction

10

Generally a beam consists of following steel reinforcements:Longitudinal reinforcement at tension and compression face.Shear reinforcements in the form of vertical stirrups and or bent up longitudinal bars are provided. Side face reinforcement in the web of the beam is provided when the depth of the web in a beam exceeds 750 mm. (0.1% of the web area and shall be distributed equally on two faces at a spacing not exceeding 300 mm or web thickness whichever is less)

Introduction

11

Specification for the reinforcement in beams is given in clause 8.1 to 8.6 of SP34

12

Different forms of stirrups used in beams

18

Typical drawing of a simply supported beam

19

PROBLEM No. 1Draw the Longitudinal section, cross section and prepare bar bending schedule of a rectangular simply supported RCC beam with the following data:Clear span =3.5mWidth of beam = 220mmOverall depth of beam = 300mmBearing width in support = 200 mmMain reinforcement = 5 Nos -12 mm diameter bars with 2 bars bent up at L/7 from centre of supportAnchor/hanger bars= 2-10 mm diameterStirrups = 6 mm diameter @ 200 mm c/c.Materials : Mild steel, M20 grade concrete

21

PROBLEM No. 1

22

PROBLEM No. 1 contd.Bar Bending Schedule:Bottom straight bar (12 dia)= Total length of beam +2 x16 -2 x 3 -2 x end cover= (3500+2 x 200)+26 x 12-2 x 25 =41624200 mmLength of bent up bar (12 dia)= Length of straight bar +2 x (0.42 x depth of bend) =4162+2 x 0.42 x 250 =43724400 mmLength of hanger bar (10 dia)= Length of straight bar =41624200 mmStirrups:

Number of stirrups = Length of bar (end to end)/c/c distance of stirrup= [(3500+2x200)-2x25]/200 = 17

Length of stirrup = 2 ( A+B)+24 of stirrup = 2x(250+170)+24 x 6 = 984 mm 1000 mm

23

PROBLEM No. 1 contd.

24

PROBLEM No. 2Draw the Longitudinal section, cross section and prepare bar bending schedule of a rectangular simply supported RCC beam with the following data:Clear span =4.5mWidth of beam = 250mmOverall depth of beam = 300mmMain reinforcement = 5 Nos -18 mm diameter bars with 2 bars bent up at 900mm from inside of each end supportAnchor/hanger bars= 2-12 mm diameterStirrups = 6 mm diameter @ 200 mm c/c.Concrete cover = 25 mmMaterials : HYSD bars, M20 grade concrete

25

PROBLEM No. 2

26

PROBLEM No. 2 contd.Bar Bending Schedule:Bottom straight bar (18 dia)= Total length of beam -2 x end cover

= (4500+2 x 200) -2 x 25 =4850 mmLength of bent up bar (18 dia) = Length of straight bar +2 x (0.42 x depth of bend) =4850+2 x 0.42 x 250 =5050 mmLength of hanger bar (12 dia)= Length of straight bar =4850 mmStirrups:Number of stirrups = Length of bar (end to end)/c/c distance of stirrup = [(4500+2x200)-2x25]/200 = 24.25 25

Length of stirrup = 2 ( A+B)+24 of stirrup= 2x(250+200)+24 x 6 = 1044 mm 1100

mm 27

PROBLEM No. 2 contd.

28

PROBLEM No. 3Draw the Longitudinal section and two cross sections one near the

support and other near the mid span of a RCC continuous beam with the following data:Clear span of beams = 3m eachWidth of beam = 200mmOverall depth of beam = 300mmWidth in intermediate supports = 200 mmMain reinforcement = 4 Nos -12 mm diameter bars with 2 bars bent upAnchor/hanger bars= 2-10 mm diameterStirrups = 6 mm diameter @ 300 mm c/c.Materials : HYSD bars and M20 grade concrete

30

PROBLEM No. 3

31

PROBLEM No. 4A rectangular beam of cross section 300 x 450 mm is supported on 4 columns which are equally spaced at 3m c/c. The columns are of 300 mm x 300 mm in section. The reinforcement consists of 4 bars of a6 mm diameter (+ve reinforcement) at mid span and 4 bars of 16 mm diameter at all supports (-ve reinforcement). Anchor bars consists of a 2-16 mm diameter. Stirrups are of 8 mm diameter 2 legged vertical at 200 c/c throughout. Grade of concrete is M20 and type of steel is Fe 415. Draw longitudinal section and important cross sections.

32

PROBLEM No. 4

33

PROBLEM No. 5Draw to scale of 1:20 the Longitudinal section and two cross-

section of a cantilever beam projecting 3.2 from a support using following dataClear span =3.2mOverall depth at free end = 150 mmOverall depth at fixed end = 450 mmWidth of cantilever beam = 300 mm

Main steel = 4-28 mm dia with two bars curtailed at 1.5m from supportAnchor bars = 2 Nos. 16 mm diaNominal stirrups = 6mm dia at 40 mm c/cBearing at fixed end = 300 mmUse M20 concrete and Fe 415 steel

35

PROBLEM No. 5

36

PROBLEM No. 6A cantilever beam with 3.2m length is resting over a masonry wall and supporting a slab over it. Draw to a suitable scale Longitudinal section, two cross-sections and sectional plan with the following data:Size of beam = 300 mm x 350 mm at free end and 300 mm x 450 mm at fixed end and in the wall up to a length of 4.8m Main steel: 4 nos. of 25 mm dia bars, two bars curtailed at 1.2m from free endHanger bars: 2 nos. 16mm.Stirrups: 6mm dia 2 legged stirrups @ 200 mm c/c the support length and @100 mm c/c from fixed end up to length of 1m @ 150mm c/c up to curtailed bars and remaining @ 200 c/c.

Use M20 concrete and Fe 415 steel

37

PROBLEM No. 2

38

PROBLEM No. 7A beam has following data

Clear span = 4mSupport width = 300mmSize of web = 350 x 400 Size of flange = 1200 x 120mmMain reinforcement in two layers : 3-20 tor + 3-16 tor and to be curtailed at a distance 400 mm from inner face of support Hanger bars: 3- 20 torStirrups: 2L-8 tor @ 200 c/cUse M20 concrete and Fe 415 steel

Draw longitudinal and cross section if the beam is1. T-beam2. Inverted T-beam3. L-Beam

40

PROBLEM No. 5

41

PROBLEM No. 5

43

PROBLEM No. 5

44

Do it Yourself

1. Draw the longitudinal section and typical cross sections ( at centreand support), and show the reinforcement details in a simply supportedrectangular beam of size 300 mm x 500 mm, clear span 5m supportedon walls of 0.3m, use a suitable scale

Reinforcements:Main: 4 No. 16mm dia with 2 No. cranked at 1m from centre of

support. Stirrup holders 2 Nos. of 12 mm diaStirrups: 2 legged 8 mm dia stirrups at 250 mm c/c in the central 2m

span and 2 legged 8 mm dia stirrups at 150 mm c/c in the remainingportion. Assume concrete M 20 grade and steel Fe 415, and suitablecover. Prepare the bar bending schedule and calculate quantity of steeland concrete required.

45

Do it Yourself

2. Prepare the bar bending schedule and estimate quantity of steel andconcrete after drawing the longitudinal and cross section. Other detailsare

Span of beam = 4.2 mCross section at support end 300 x 600 mm and cross section at

free end 300 x 150 mmReinforcements:Main tension steel: 4-20 mm dia, 2 bars are curtailed at a distance

of 2m from free endHanger bars: 1-12 mm diaTwo legged stirrups 8mm dia @ 140 mm c/c for full length.

46

Dr. G.S.Suresh

Civil Engineering Department

The National Institute of Engineering

Mysore-570 008

Mob: 9342188467 Email: [email protected]

47

Design and drawing of RC StructuresCV61DETAILING OF BEAMSLearning out ComeIntroductionIntroductionSlide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40Slide Number 41Slide Number 42Slide Number 43Slide Number 44Slide Number 45Slide Number 46Slide Number 47

Reinforcement Detailing

Documents

Transcript of Reinforcement Detailing