Concrete Centre - Scheme Manual to EC2

cement concrete

Since its publication in 2006, the Concrete building scheme design manual has proved a popular publication and this update is intended to assist the transition to Eurocode 2 for the design of concrete structures by showing how to carry out initial design to the Code. As before it will greatly assist candidates for the Institution of Structural Engineers chartered membership examination by drawing together in one place useful information including design aids that are specifically prepared for Eurocodes.

Andrew Minson was the originator of the concept for this book, but the final format and content have evolved over time with input gratefully received by the author, Owen Brooker, from a number of people. The book contains some new material but many of the ideas and much of the data have been developed from many sources over several years. It is not possible to credit every source; indeed many are unknown, but wherever possible, references have been made to relevant documents.

Particular thanks are due to Jenny Burridge and Bob Wilson who have spent considerable time reviewing and commenting on drafts and providing useful guidance on what the examiners are expecting. Thanks are also due John Brazier, Andrew Cotter, Bryan Magee and Matt Obst, who have commented or made useful contributions in more specialised areas.

Gillian Bond, Issy Harvey, Sally Huish and Michael Burbridge Ltd have also made essential contributions to the production of this handbook.

All advice or information from MPA –The Concrete Centre is intended only for use in the UK by those who will evaluate the significance and limitations of its contents and take responsibility for its use and application. No liability (including that for negligence) for any loss resulting from such advice or information is accepted by MPA –The Concrete Centre or its subcontractors, suppliers or advisors. Readers should note that MPA –The Concrete Centre publications are subject to revision from time to time and should therefore ensure that they are in possession of the latest version.

Printed by Michael Burbridge Ltd, Maidenhead, UK.

i

Contents

ii

Symbols used in this handbook

Symbol Definition

D

iii

without

iv

a

a a

b

b

b b

b b

g

g

g

g

g

d

d

y

l

l

m

r

r

r

r

r r

s

s

s

f

f

f

c

1

Introduction

How to use this handbook

Text on a pale blue background provides information to help candidates prepare for

the examination and is not intended for use in the examination itself.

Assumptions

2

The examination

Timing

Further information

3

Development of solutions (section 1)

Viable structural solutions

two

■ ■

■ ■

■ ■

■ ■

■ ■

■ ■

■ ■

■ ■

■

Functional framing

Load transfer

■

■

■

4

Pilecap

Pile

Tie/strut

Long-span roof

Stiff floor Load-bearingconcreteblock wall

Upstandbeam

Column

Column

Raft

Shearwall

Transfer beam

b) Gable shear wall

c) Reservoir

Retainingwall

Flat slab (min. 3 bays)

Slendercolumns

Floor slab ‘on grade’

d) Precast concrete terracing

GLGL

a) Building section

5

Partition load

Uniform load

Wall reaction

Load from beam= load on wall

Foundation reaction

Foundation load

column

Deflection, bendingand shear in beamleads to reactionsat the end of thebeam

Foundation reaction

Pile cap

Pile reaction

Pile load

Friction reaction

End reaction

Pile

Stress =LoadArea

Load on pilecap

Ground reaction

Load onto ground

B

1.5B

sBulb of pressurefor /5

Load on rock

Brickwork wall

s = bearingpressure

a) Vertical loads

Reinforced concrete

6

Bearing pressures

W2

W1Soil at rest

GWL

Water load

Surcharge

Passiveresistance

GL

GL

Hogging

TensionExtra compressionwith bending

Supportremoved

Wallsdisplaced

Tieac

tion

Floor sag

c) Effect of accidental impact

d) Retaining wall

Wind

b) Plan view of diaphragm action

Tension

7

Stability

Lateral stability

■

■

■

■

■

■

■

Movementjoint

a) Walls resist bending in one plane, frame action in other plane. Good tortional stiffness.

b) Walls resist bending in both planes. Good tortional stiffness.

c) Core resists bending in both planes. Poor tortional behaviour due to eccentricity.

d) Cores resist bending in both planes. Good tortional stiffness.

e) Cores resist bending on each section of the building independently. Relative shear displacement at movement joint.

8

■

■

■

Uplift

Concrete frame options

Foundations and retaining structures

Ground-bearing slabs

■

■

■

■

■

Foundation solutions

■

■

9

One-way slab

P/T flat slab Hybrid hollowcore and topping

Key

a) Imposed load Qk = 2.5 kN/m2

b) Imposed load Qk = 5.0 kN/m2

c) Imposed load Qk = 7.5 kN/m2

100

300

400

500

4 5 6 7 8 9 10 11 12 13 14 15Span in m

Dep

th in

mm

200

Troughed slab Flat slab

600

100

300

400

500

4 5 6 7 8 9 10 11 12 13 14 15Span in m

Dep

th in

mm

200

600

100

300

400

500

4 5 6 7 8 9 10 11 12 13 14 15Span in m

Dep

th in

mm

200

600

10

✓ ✓

✓

✗

Solid flat slab (Continuity improves economy) ✓✓ ✓✓ ✓✓ ✓✓ ✓✓ ✓✓ ✓✓ ✓✓ ✓✓ ✗

Solid flat slab with drops ✓ ✓ ✓ ✓ ✓✓ ✓ ✓ ✓ ✓✓ ✓✓ ✓✓ ✗

Solid flat slab with column heads (Forming column head

disrupts cycle times and interferes with holes adjacent to

columns)

✓ ✓ ✓ ✓✓ ✓✓ ✓ ✓✓ ✓✓ ✓✓ ✓✓ ✗

Waffle slab ✓✓ ✓ ✓ ✓ ✓✓ ✓✓ ✓✓ ✓✓ ✓✓ ✓✓ ✗

Biaxial voided slab (Can be used with in-situ or with

precast soffit slab, which would act as permanent

formwork)

✓✓ ✓ ✓✓ ✓✓ ✓✓ ✓✓ ✓✓ ✓✓ ✓✓ ✓✓ ✓

Solid one-way slab with beams ✓ ✓✓ ✗ ✓✓ ✓✓ ✓✓ ✓✓ ✓✓ ✗

Solid slab with band beams ✓✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓✓ ✓✓ ✓✓ ✗

Ribbed slab with beams ✓ ✓ ✓ ✗ ✓✓ ✓✓ ✓ ✓✓ ✓✓ ✓✓ ✗

Ribbed slab with integral band beams ✓ ✓✓ ✓ ✓ ✓ ✓ ✓ ✓✓ ✓✓ ✓✓ ✓✓ ✗

Tunnel form (One-way slab on walls) a ✗ ✗ ✓✓ ✓✓ ✓✓ ✓✓ ✗ ✓✓ ✗ ✓✓ ✓✓ ✓✓ ✗ ✓✓ ✓✓ ✗

Composite lattice girder soffit slab b ✗ ✗ ✓✓ ✓ ✓✓ ✓ ✗ ✓ ✓✓ ✓✓ ✓✓ ✓ ✓

Precast hollowcore slab ✗ ✗ ✓✓ ✓ ✓✓ ✓ ✗ ✓✓ ✓✓ ✓✓ ✓✓

Composite precast slab ✗ ✗ ✓✓ ✓ ✓✓ ✓ ✗ ✓ ✓✓ ✓✓ ✓ ✓

Precast double ‘T’ units ✗ ✗ ✓✓ ✓ ✓ ✗ ✓✓ ✓✓ ✓ ✓✓ ✓✓

Precast crosswall and solid prestressed slab ✗ ✗ ✓✓ ✓ ✓✓ ✓✓ ✗ ✓ ✗ ✓✓ ✓ ✓✓ ✗ ✓✓ ✓✓ ∏

Solid two-way slab with beams ✗ ✗ ✓ ✓ ✓ ✗ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✗

Two-way waffle slab with beams ✗ ✗ ✓ ✗ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✗

Waffle slab with integral beams ✗ ✗ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✗

Precast twin wall and lattic girder soffit slab with

in-situ infill and topping

✗ ✗ ✓✓ ✓ ✓✓ ✓✓ ✓✓ ✓✓ ✗ ✓✓ ✓ ✓✓ ✗ ✓✓ ✓✓ ✓

Precast columns and edge beams with in-situ floor

slab✓✓ ✓✓ ✓✓ ✓✓ ✓✓ ✓ ✓✓ ✓ ✓✓ ✓✓ ✓

Precast columns and floor units with in-situ beams b ✗ ✗ ✓✓ ✓ ✓✓ ✓✓ ✓✓ ✓ ✗ ✓✓ ✓✓ ✓✓ ✓ ✓ ✓✓

In-situ columns and beams with precast floor units b ✗ ✗ ✓✓ ✓ ✓✓ ✓✓ ✓✓ ✓ ✗ ✓✓ ✓✓ ✓ ✓ ✓✓

In-situ columns and floor topping with precast

beams and floor units

✗ ✗ ✓✓ ✓ ✓ ✓ ✗ ✓✓ ✓✓ ✓ ✓ ✓

13

Piling options

Retaining walls

15

Ground improvement

■

■

■

■

■

■

16

Remediation using soil stabilisation/solidification

Stabilisation

Solidification

l

l

l

l

l

l

l

l

l

l

l

l

l

l l

17

Design appraisal

Safety

■

■

■

■

■

18

■

■

■

■

■

■

■

■

■

■

■

Economy

Foundations ■

Cladding ■

Partitions ■

Airtightness ■

Services ■

19

Buildability

Using flat soffits ■

Repetition of design elements ■

Simplification ■

Standardisation ■

Rationalisation of reinforcement ■

■ precast prefabricated

Using in-situ concrete ■

Robustness

Durability

Site constraints

■

■

■

■

■

■

■

20

Speed of construction

Aesthetics

Acoustics

Footfall-induced vibration

21

mm % change mm % change mm % change mm % change

kg/m2 % change kg/m2 % change kg/m2 % change kg/m2 % change

Thermal mass

Sustainability

23

210020902080207020602050204020302020201020000

20

40

60

80

100

120

140

160

180

200Cumulative CO emissions2

Cpr

oduc

ed(t

onne

s)O

2

Embodied CO2

COin

use

2

Year

NoteThis graph assumes solar shading used and air-conditioning will be installed in homes whentemperatures become uncomfortable, but will be used with natural ventilation whenever possible.

Heavy (cavity walls, precast concrete floors, dense block partitions)Medium-heavy (cavity walls, precast concrete floors, block partitions)Medium (cavity walls, timber floors,Light (timber frame & floors,

Key

lightweight partitions) lightweight partitions)

Building movements

■

■

■

■

■

24

■

■

■

■

me me

me me

me me

me me

me me

me me

me

Fire resistance

25

Typical loads

a) Favourable layout of restraining walls (low restraint)

b) Unfavourable layout of restraining walls (high restraint)

28

Total 4.0 Total 3.6

Total 2.8

Total 0.4

Total 2.4

Total 1.8

Total 0.9

Total 0.5

Total 2.40

Total 0.5

Total 4.0

Total 0.4

Total 0.8

30

Typical spatial requirements

Car parks

6.0 m 4.8 m

Bin width

4.8 m

3 x 2.4 mbays3

bins

reco

mm

ende

dm

inim

um

BA

A: 0.46 m minimum0.8 m to 1.0 mpreferred range

B: 3.3 m minimum3.6 m desirable

Acceptablesupport positions

Typical baydimensions

*

*

Interbin support zone

Services

Preliminary sizing

31

Duct leaving riser / coreconsider universalcolumns as beams

H

Below deep beamsfinal terminal device only

Main duct run-outsbelow normalmaximum beam size

FFL

FFL

AB

CD

E

F

G

VAV terminal box

400 500

A Structural zoneB 50 mm deflection and toleranceC Approx. 500 mm HVAC duct or terminal deviceD 50 mm support and toleranceE 5 150 mm sprinkler zone (if required)F 150 mm lighting and ceiling zoneG Floor to ceiling heightH Raised floor

a) Flat soffit

Raisedfloor

Floor toceilingheight

Serviceszone

Structuralzone A

BC

D E

F

G

H

b) Downstand beams

Key

32

Beams

Simply supported

End-bay

Cantilever

Transfer beams

One-way spanning slabs

Two-way spanning slabs

33

Flat slabs

Ribbed slabs

a

Waffle slabs

34

1

2

3

4

Squarecolumn

Imposed load

h

Superimposed deadload =1.5 kN/m2

Post-tensioned slabs and beams

35

Precast concrete floor units

300

200

1003.0 4.0 5.0 6.0 7.0 8.0 9.0

Span (m)

Slab

dept

h(m

m)

KeyCharacteristic imposed load (IL)

2.5 kN/m2

5.0 kN/m2

7.5 kN/m2

10.0 kN/m2

36

Columns

■

■

■

■

■

■

■

Shear walls

37

Depth

Tension

Compression

Span

The letter

not

■

■

■

■

■

38

Engineering Consultants99 High StreetNewtownNW9 9AA

Your ref:Our ref: 1099/OB/1.01/21-11-06 21 November 2006

FAO Mr J Client

Dear Mr ClientCall Centre – Implications of Recent Minor Seismic Activity

As we are sure you are aware there has recently been a minor earthquake in the region of the recently completed Call Centre. We would like to address the concerns you may have regarding the strength of your building if faced with a similar event.

Initially we would like to confirm that the structure has been designed to the latest Building Regulations and Codes of Practice. There is no requirement to explicitly consider the effects of seismic activity because historically the most significant horizontal forces on structures in this region are wind forces, rather than forces arising from seismic activity.

We would suggest that, before making any decisions about strengthening the structure, we wait for a consensus amongst the experts as to whether this type of event is likely to occur more frequently in the area and what they recommend as the design requirements. We would expect that, if changes are necessary, the Building Regulations will be revised and that clear guidance will emerge on whether existing buildings should be strengthened. The Call Centre is just one of many buildings that could be affected by a similar earthquake in this region.

In the meantime, we would like to reassure you that the building as it stands will have reasonable strength to resist to a minor seismic event. It has been designed with ties to ensure that ‘progressive collapse’ does not occur and these will act to strengthen the building in the event of an earthquake. There are, however, a number of specific areas where localised damage could occur as a result of a small earthquake; these are detailed below.

precast units and topping screed are designed to act as a stiff diaphragm. However, depending on the intensity of the earthquake, this system may have insufficient strength to carry the forces. A design check can be carried out when there is agreement on the design forces that should be used for an earthquake in this region.

earthquake the structures will move laterally and the width of the joint is unlikely to be sufficient to prevent the two structures from making contact. We think there are two options for overcoming this; either the joint could be made wider by making alterations to the existing structure, or the lateral stiffness of the building could be increased by incorporating more stability walls. The latter would reduce the sideways sway during a seismic event. It may also be the preferred solution if the floor diaphragm requires strengthening. We will need to have a discussion so we can find an acceptable solution that provides minimal disruption to your business and the minimum effect on the architecture.

we will need to review the strength of the foundations to resist lateral forces, for which they were not designed. The building has a suspended ground floor, which means that there are beams tying the foundations together. This is beneficial in the event of an earthquake, because it prevents the foundations moving apart possibly causing major damage to the frame.

generally left to the precast manufacturer to design. This is usually beneficial because he can carry out the work more efficiently and to suit his working methods. On this project the manufacturer has used a ‘billet’ type connection, which is perfectly adequate for the job it was designed to do. However, it offers less spare capacity to resist the forces from an earthquake and strengthening may be required.

during an earthquake is almost certain to damage the glazing. The current glazing is laminated glass, which means that it will not break into small pieces. However, there is a risk that whole panes will come away from their fixings with the potential to cause loss of life. To overcome this, strengthening of the column–to-roof beam connections will be necessary to reduce lateral sway.

We cannot be certain about how design guidance will change as a result of the earthquake, but the above comments should give you an appreciation of the preventive measures that are likely to be necessary. If you would like to discuss the situation further then please contact us.

Yours sincerely

39

Design calculations (section 2c)

Expectations of the examiners

sufficient

principal

Principal elements

■

■

■

■

■

■

■

■

■

■

■

■

■

■

■

40

Durability and fire resistance

■

■

■

X0

XC1

XC2 AC-1

XC3 XC4

XF1

XF3

XF3

XD1

XD3

XF2

XF4

XF4

XS1 XF1

XF3 or XF4

a

b

c

d D

e

41

D D D D D D D D

f

g

h

j

42

a

b

c

d

e

f

43

Assessing the design moments

Flexure

d d

d

d

44

Shear

Slabs

r

r

r

r

45

Beams

START

No

Yes (cot y = 2.5)

Determine y from:

y = 0.5 sin-1vEd

0.20 fck (1 – fck/250)

Yes

No

Determine vEd where:

vEd = design shear stress [vEd = VEd/(bwz) = VEd/(0.9 bwd)]

IsvEd < vRd,max cot y = 2.5? Redesign

section

IsvEd < vRd,max cot y = 1.0?

(see Table 3.7)

Determine the concrete strut capacity vRd,max cot y = 2.5from Table 3. 7

Calculate area of shear reinforcement:

Check maximum spacing for vertical shear reinforcement: sl,max = 0.75 d

Asw

s=

vEd bw

fywd cot y

Procedure for determining vertical shear reinforcement

y y

46

Deflection

Notes

1 For two-way spanning slabs, the check

should be carried out on the basis of the

shorter span.

2 This graph assumes simply supported span condition (K = 1.0).K = 1.5 for interior span conditionK = 1.3 for end span conditionK = 1.2 for flat slabsK = 0.4 for cantilevers

3 Compression reinforcement, r',has been taken as 0.

4 Curves based on the following expressions:

where r ≤ r0

and

where r > r0

11 + + 3.2 –1= Kr

fck

r01.5

d

l fck

r

r0[ ( ) ]

11 + += K( r – r ')

fck

r01.5

d

l12

fck

r0

r '[ ]

1.5

Percentage of tension reinforcement (As,req/bd)

12

0.40% 0.60% 0.80% 1.00% 1.20% 1.40% 1.60% 1.30% 2.00%

14

16

18

20

22

24

26

28

30

32

34

36Sp

an t

o d

epth

rat

io (

l/d)

fck = 50

fck = 45

fck = 40

fck = 35

fck = 32

fck = 30

fck = 28

fck = 25

fck = 20

Basic span-to-effective-depth ratios

■

■

s s

47

600

750

900

1200

1500

2000

Beams and slabs

Flat slabs

4.03.02.01.0

Ratio Gk/Qk

c2 = 0.8, gG = 1.35

c2 = 0.6, gG = 1.35

c2 = 0.3, gG = 1.35

c2 = 0.6, gG = 1.25

c2 = 0.3, gG = 1.25

c2 = 0.2, gG = 1.25

c2 = 0.2, gG = 1.35

App

roxi

mat

e st

eel s

tres

s at

SLS

for

A s,re

q, s

su

180

200

220

240

260

280

300

320

To determine stress in the provided reinforcement (ss), calculate the ratio Gk/Qk,

read up the graph to the appropriate curve and read across to determine ssu.

ss can be calculated from the expression: ss = ssu f

As,req pf

1p

As,prov d

Determination of steel stress

48

Estimating reinforcement quantities

■

■

■

■

Detailing

Maximum and minimum areas of reinforcement

Minimum spacing of bars

&f

f

49

f f

f

300

350

400

450

500

550

600

650

700

750

800

900

1000

1100

1200

1300

1400

1500

Maximum spacing of bars

Design of beams

Governing criteria

50

Analysis

Flanged beams

Fire resistance

f f

51

OB CCIP - 018

MS TB1

TCC Aug 09

Gk = 1500 kN, Qk = 1000 kN

1.5 m 9.0 m

Initial sizing Shear stress not to exceed 4 N/mm2 (to avoid reinforcement congestion).

Ultimate load = 1.35 x 1500 + 1.5 x 1000 = 3525 kN (ignoring self-weight)

Take b = 600

d = VEd

vEdb

Take overall depth as 1650 mm (d = 1550)

Bending Mmax = 3525 x 1.5 = 5288 kNm For Mmax = 5288, b = 600, d = 1550, fck = 32 N/mm2

K = 0.115, As = 8858 mm2 (z = 1297 mm)

Use 8 H40 (10100 mm2) in 2 layers.

Shear vEd = 3525 x 103/(0.9 x 600 x 1550) = 4.21 MPa

Assuming the strut is at 45°

Asw ≥ 4.21 x 600s 435 x cot 45°

≥ 5.81 mm

Try H12 linkss = 452/5.81 = 78 mm

Say 4 H12 links @ 75 mm ctrs

Comments Remember to check headroom beneath the beam

H40 bars will be heavy; if there is no reasonable alternative, ensure that the contractor is aware so he may take steps to safeguard the health and safety of the steel fi xers.

= 3525 x 103 = 1469 mm 4 x 600

8H40barsSlab

reinforcement

1650

600

4 H12 links@ 75 ctrs

Section 2.10.2

Figure 3.1

Figure 3.1

Table 3.7

Worked example 1Transfer beam

52

One-way spanning slabs

Governing criteria

Analysis

1

2

3

4

5

1

2

Fire resistance

f f

REI 60

REI 90

REI 120

REI 240

1

2

53

OB CCIP - 018

MS OW1

TCC Aug 09

Worked example 2One-way slab

6000 6000 6000 6000

Initial sizing From Economic concrete frame elements – 167 Section 2.10 or 6000/32 = 187.5, say 200 mm

Loading ULS = 1.35 (0.2 x 25 + 1.5) + 1.5 x 2.5 = 12.5 kN/m2

Bending Check first support from end M = – 0.086Fl Table 3.14 = – 0.086 x 12.5 x 62

= – 38.7 kNm

For b = 1000, d = 200 − 25 − 10 = 165, fck = 28 Then K = 0.051, As, req = 567 mm2 (z = 157 mm) Use H12 @ 175 ctrs (As,prov = 646 mm2)

Shear VEd = 0.6F = 0.6 x 12.5 x 6 = 45.0 kN Table 3.14

vEd = VEd = 45.0 x 103 bd 1000 x 165

= 0.27 N/mm2

100 As = 100 x 646 = 0.39 bd 1000 x 165

vRd,c = 0.57 Table 3.6 vEd < vRd,c no shear links required

Deflection Maximum sagging moment = 0.075 Fl Table 3.14 = 0.075 x 12.5 x 62 = 33.75 kNm

For fck = 28, d = 165, b = 1000 Then K = 0.044, As,req = 494 mm2 (z = 157 mm)

r = As,req/bd = 494 x 100/(1000 x 165) = 0.30%Basic l/d = 35.2 x 1.3 = 45.8 (K = 1.3 for end span condition) Figure 3.2actual l/d = 6000/165 = 36.4 OK

Use H16 @ 200 ctrs As,prov = 566 mm2

Imposed load = 2.5 kN/m2

Superimposed dead load = 1.5 kN/m2

Concrete class C28/35cnom = 25 mm

Two-way spanning slabs

Governing criteria

Analysis

54

a

a

a

a

b

b

■

■

55

bb

b b

56

b

b

b b

Fire resistance

f f

REI 60

REI 90

REI 120

REI 240

Flat slabs

Governing criteria

Analysis

■

■

■

■

■

57

OB CCIP - 018

MS TW1

TCC Aug 09

Worked example 3Two-way slab

l x =7200 7200 72007200

l y=

900

090

00

Initial sizing From Economic concrete frame elements: 213 mm Section 2.10 or 9000/36 = 250 mm say 250 mm

Loads n = 1.35 (1.5 + 6.25) + 1.5 x 5 = 18.0 kN/m2 (ULS)

Check short span d = 250 − 25 − 8 = 217 mm

ly = 9.0

= 1.3 lx 7.2

bsx = – 0.069 and bsx = 0.051 Table 3.17

Support moment msx = bsx n lx2 = – 0.069 x 18.0 x 7.22 = – 64.4 kNm/mcritical in bending For msx = 64.4, b = 1000, d = 217, fck = 28

Then As = 718 mm2/m (K = 0.049 & z = 206 mm) Use H12s @ 150 ctrs (As,prov = 754 mm2/m)

Shear bvx = 0.50 Table 3.18 Vsx = bvx n lx = 0.5 x 18.0 x 7.2 = 64.8 kN/m width vEd =

VEd = 64.8 x 103 = 0.30 N/mm2 bd 1000 x 217

100 As = 100 x 754 = 0.35 bd 1000 x 217

vRd.c = 0.57 N/mm2 > 0.30 no shear links required Table 3.6

Deflection Maximum sagging moment = 0.051 x 18.0 x 7.22 = 47.6 kN/m For b = 1000, d = 217, fck = 28 Then K = 0.036, As req = 531 mm2 (z = 206 mm)

r = As,req/bd = 531 x 100/(1000 x 217) = 0.24%Basic l/d = 35.2 x 1.3 = 45.8 (K = 1.3 for end span condition) Figure 3.2actual l/d = 7200/217 = 33.2 OK



Imposed load = 5 kN/m2

cnom = 25 mm

Concrete class C28/35

58

1

2

Negative

Positive

Punching shear reinforcement

b

b

b = 1.5

b = 1.4 b = 1.15

Internal column

Corner column

Edge column

b

59

lx (longerspan)

Columnstrip

Co

lum

nst

rip

Middlestrip = lx -

Mid

dle

str

ip

ly

ly

lyly

ly

ly

2

2

44

4

4

l y (s

ho

rter

span

)

Middlestrip = lx – dropsizeDrop

Dro

p

Ignore drop if

dimension < ly/3

Ignore drop if

dimension < ly/3

ly

Co

lum

n s

trip

=

lx

Column strip =dropsize

dro

psi

ze

a) Slab without drops

b) Slab with drops

rr r

p

60

Transfer moments

61

Fire protection

f f

d d

Ribbed slabs

Governing criteria

Geometry

T

R

W

bc

xa

Self-weight = cRy ( + ) + + ( + ) kN/mW Z T H a b

225x

Z

y

H

62

OB CCIP - 018

MS FS1

TCC Aug 09

Worked example 4Flat slab

9000 9000 9000 9000

700

070

00

Initial sizing Using Economic concrete frame elements: 284 mm

Or 8000/26 = 307 mm, say 300 mm Section 2.1

Loading ULS = 1.35 (1.5 + 0.3 x 25) + 1.5 x 5 = 19.65 kN/m2

Bending Check long span end bay condition

M = – 0.086Fl = – 0.086 x 19.65 x 7 x 92 = – 958 kNm Table 3.20

Centre strip Design moment = 0.75 x 958 = 718 kNm Table 3.21critical

For b = 3500, d = 300 − 30 − 10 = 260 mm, fck = 28

Then K = 0.108, As = 7110 mm2

Centre column strip = 4740 mm2 (2708 mm2/m)

Use T20 @ 100 ctrs (As,prov = 3140 mm2/m)

Outer column strip = 2370 mm2 (1354 mm2/m)

Use T20 @ 200 ctrs (As,prov = 1570 mm2/m)

Punching shear VEd = 19.65 x 7.0 x 9.0 = 1238 kN

At column face, vEd = b VEd

= 1.15 x 1238 x 103

= 4.07 < 4.98 uideff 4 x 350 x 250Table 3.22

Shear resistance without links: 100 As

= 100 x 3140

= 1.26% bd 1000 x 250

vRd,c = 0.75 MPaArea of steel at first control perimeter, 2d = 2 x 250 = 500 mm from column face.Length of perimeter = 4 x 350 + 2 x 500 = 4542 mmRadial spacing sr = 0.75 x 250 = 188 mmAsw = (vEd – 0.75 vRd,c)sr u1/(1.5 fywd,ef)

= d1.15 x 1238 x 103 – 0.75 × 0.75m x 188 x 4542 /(1.5 x 313)

4542 x 250 = 1257 mm2/perimeter

Using 10 mm dia. links, no of links = 1257/78.5 = 16, spacing = 4542/16 = 284 < 1.5d

Deflection Maximum sagging moment = 0.075 Fl = 0.075 x 19.65 x 7 x 92

= 836 kNm




cnom = 30 mm

Supported by 350 mm square columns

63

Analysis

2

3

Bending reinforcement

Reinforcement in the topping

Centre strip Design moment = 0.55 x 836 = 460 kNmcritical

For b = 3500, d = 260 and fck = 28

K = 0.069, As = 4351 mm2 Or As = 1243 mm2/m

r = As,req/bd = 1243 x 100/(1000 x 260) = 0.48%Basic l/d = 20.3 x 1.2 = 24.4 (K = 1.2 for flat slab condition) Figure 3.2actual l/d = 9000 / 260 = 34.6Increase area of steel to reduce steel stress, assume H20 @ 225 ctrs (1400 mm2)Approximate steel stress at SLS = 236 MPa Figure 3.3Therefore approximate steel stress, ss, when As,prov = 1400 mm2

ss = 236 x 1243/1400 = 210 MPaIncreased basic l/d = 24.4 x 310/210 = 36 > 34.6 OK


Comments 1. The design in the orthogonal direction has not been included.2. For the design of the strips across two panels only, coefficients from Table 3.20 are not appropriate.

64

20

25

28

30

32

35

40

45

50

Fire protection

f f

REI 60

REI 90

REI 120

REI 240

65

OB CCIP - 018

MS RS1

TCC Aug 09

Worked example 5Ribbed slab

750

7200

1000

Initial sizing Using Economic concrete frame elements: 255 mm

or 7200/29 = 248 mm, say 250 mm

Assume self-weight = 4.0 kN/m2 Table 2.9c

Loading ULS = 1.35 (4.0 + 1.5) + 1.5 (2.5) = 11.2 kN/m2

Bending Check sagging moment in end bay

d = 250 – 26 – 6 – 8 = 210 mm

Effective length = 6.2 + 2 x 1/2 x 0.210 = 6.41 m

M = 0.075Fl = 0.075 x 11.2 x 6.412 x 0.75 = 25.9 kN/m per rib Table 3.20

For b = 750, d = 210, fck = 28

K = 0.030, As,req = 291 mm2 (z = 200 mm)

x = 2.5 (210 – 200) = 25 mm

N.A. in flange – design as rectangular section

Deflection r = As,req/Ac = 291 x 100/(125 x 110 + 750 x 100) = 0.33%Reduction factor for flanged section = 1 – 0.1 x ((750/125) – 1) = 0.5 use 0.8. Table 3.25Basic l/d = 0.8 x 33 x 1.3 = 34.3 (K = 1.3 for end span condition)actual l/d = 7200 / 210 = 34.3 OK


Superimposed load = 1.5 kN/m2

Concrete class: C28/35

cnom = 26 mm

Topping thickness = 100 mm

A142 mesh

100

150

H16

10 125 10

H6

BS EN 1992-1-1: Fig 5.4

66

Waffle slabs

Governing criteria

Geometry

x

y

b

a

c H

N = number of waffles Self-weight = - + +xyH N a b a b2 2 2 225xy

c3 kNm2,

Analysis

Bending reinforcement

67

Reinforcement in the topping

Fire protection

f f

a a a a

a a

Precast flooring systems

68

■

■

■

Post-tensioning

12.9 ‘Super’

15.7 ‘Super’

15.7 ‘Euro’

15.2 ‘Drawn’

Restraint

Load balancing

69

OB CCIP - 018

MS WS1

TCC Aug 09

Worked example 6Waffl e slab

9000

720

0

Initial sizing Using Economic concrete frame elements: 425 mm thick (i.e. 325 moulds + 100 topping)

or 9000/20 = 450, say 425 thick Section 2.9

Assume self-weight = 7.3 kN/m2 Table 2.9c

Ultimate load n = 1.35 (7.3 + 1.5) + 1.5 (2.5) = 15.6 kN/ m2

There is a substantial beam along the column strips, which can therefore resist torsion at the corners. Design as a two-way spanning slab.

ly = 9.0 = 1.25 lx 7.2 Interpolating for a corner panel

Hogging moments bsx = − 0.066, Sagging moments bsx = 0.049 Table 3.17

Bending at support Msx = bsx nlx2 = − 0.066 x 15.6 x 7.22 = − 53.4 kN/m width

For ribs @ 900 ctrs

M = 53.4 x 0.9 = 48.0 kNm/rib

For d = 425 − 26 − 6 − 8 = 385 mm, b = 900, fck = 28

Then As,req = 299 mm2 (Taking z = 0.95d and therefore N.A. is in fl ange)

Defl ection r = As,req/Ac = 299 x 100/(180 x 285 + 900 x 100) = 0.21%Defl ection not critical by inspection Figure 3.2

Use 2 x H16 per rib (As,prov = 402)




cnom = 26 mm

Stresses

s

s

70

Unstressed

slab

Prestressed

slab

Proposed

loading

Final

condition

a)

b)

c)

d)

Cover

Cover

70 x 19 mm ductLongitudinal duct

a) Transverse directionCover

Transverse duct

b) Longitudinal direction

70 x 19 mm duct

71

Stress limits

b

Initial design

72

OB CCIP - 018

MS PT1

TCC Aug 09

Worked example 7Post-tensioned slab

9000 9000 9000 9000

700

070

00

Initial sizing 9000/36 = 250 mm thick (Economic concrete frame elements: 249 mm)

Geometry Area of concrete, Ac = 7000 x 250 = 1750 x 103 mm2

Second moment of area, Ic = 7000 x 2503/12 = 9.11 x 109 mm4

Distance to extreme fibres from neutral axis, yb = yt = 125 mmSection modulus, Zb = Zt = 9.11 x 109/125 = 72.9 x 106

Strand diameter = 12.9 mmMinimum cover = 20 mmDistance to centre of strand = 60 mmTendon profile for end span (most critical):

Number of Characteristic value of maximum force, 186 kNstrands required Initial prestress = 0.8 x 186 = 149 kN (allow for 80% of characteristic force)

Prestress in service condition = 0.7 x 149 = 104 kN (allow for 10% loss at transfer and 20% loss at service, check in detailed design)Balance dead loads with prestressingP = ws2/(8a) = 7 x 6 x 92/(8 x 0.098) = 4339 kN

No. of tendons required = 4339/104 = 41.7, try 9 x 5 strands per duct Total force = 4680 kN

Moments (SLS) Applied loads wa = 7 x (6.25 + 1.25 + 5) = 87.5 kN/mBalancing load wb = 8aP/s2 = 8 x 0.098 x 4160 / 92 = 40.2 kN/mBalanced moment M ≈ (wa – wb) l

2/10 = (87.5 – 40.2) x 92/10 = 383.1 kNm

Mid-span stresses st = P + M = 4680 x 103 + 383.1 x 106 = 2.7 + 5.3 = 8.0 N/mm2

Act Zt 1750 x 103 72.9 x 106

For class C32/40 allowable compressive stress is 12.8 N/mm2 OK

sb = P – M = 4680 x 103 – 383.1 x 106 = 2.7 – 5.3 = – 2.6 N/mm2

Act Zb 1750 x 103 72.9 x 106

For class C32/40 allowable tensile stress is 2.7 N/mm2 OK

Comments Stresses at the support and punching shear should also be checked at this stage for a flat slab (see 3.12.3)It is assumed that deflection, the ULS requirements and transfer requirements can be met with passive reinforcement in detailed design, as is usually the case.




Idealised tendonshape a = 250 – 60– 60– = 98

125a

125

60

60

652 for initial

design only

Table 2.22

Table 3.29

Section 3.16.2

Section 3.16.3

Table 3.30

Section 3.16.3

Table 3.30

73

Columns

Design

b

b

Condition 1 ■

Condition 2 ■

Condition 3 ■

ll

l

l

l

l l

74

Detailing

75

OB CCIP - 018

MS C1

TCC Aug 09

Worked example 8Column

300

Column

9000 9000

750

075

00

Loads Column supports 4 storeys

Ultimate load per floor = 1.35 (0.3 x 25 + 1.5) + 1.5 x 5 = 19.7 kN/m2

Total ultimate axial load = 4 x 19.7 x 7 x 9

N = 4952 kN

Initial sizing Using Economic concrete frame elements – 450 mm square

Column design NEd/bhfck = 4952 x 103/(4502 x 32) = 0.76

Take minimum moment as 4952 x 0.02 = 99 kNm (assume column is not slender)MEd/bh2fck = 99 x 106/(4503 x 32) = 0.03d2 = 35 + 8 +16 = 59 mmd2/h = 59/450 = 0.13

Use column graph for d2/h = 0.15Asfyk/bhfck = 0.35

As = 0.35 x 4502 x 32/500 = 4536 mm2

Use 6 H32 (As,prov = 4830 mm2)




cnom = 35 mm

H25

H8 links@ 300 ctrs

450

450

76

Fire resistance

f f

Shear walls

Design issues

s

77

s

Walls with unequal stiffness

e Lateral load

Shearcentre

y

78

Detailing

Fire resistance

f f

OB CCIP - 018

MS SW1

TCC Aug 09

Worked example 9Shear walls

40 kN

75 kN

75 kN

75 kN

gk = 35kN/m

gk = 35kN/m

gk = 35kN/m

gk = 35kN/m

2.5

200 mmthick wall

3.0 m

3.0 m

3.0 m

3.0 m

m

Q k,w

Comment This design assumes that the base is sufficient to resist overturning. When designing the base for overturning the EQU category should be used rather than STR as used here.

Assume critical combination is 1.0 Gk + 1.5 Qk,w where Qk,w is wind load.

Assuming the floor load is 4000 kN supported on 8 columns, the horizontal action due to imperfections = 0.25% x 4000 = 10 kN

ft = N − M Lt (tL2/6)

N = 1.0 x 35 x 4 x 2.5 + 0.200 x 12 x 2.5 x 25 = 500 kN

MEd = 1.5((40 + 10) x 12 + (75 + 10)(9 + 6 + 3)) = 3195 kNm

ft = 500 x 103 − 3195 x 106 2500 x 200 (200 x 25002/6)

= 1.0 − 15.3

= − 14.3 N/mm2

Assume that the tension is resisted by 1 m at the end of the wall.

As = 0.5 ft Lt t

fyd

= 0.5 x 14.3 x 1000 x 200 = 3287 mm2 or 1644 mm2/face 435

Use T20s @ 175 ctrs (1800 mm2/face)

79

OB CCIP - 018

JB SW2

TCC Dec 06

Worked example 10Shear walls with varying stiffness

60.0y 5.0

8.0

25.0

Shearcentre

W 4W 2

10.0

5.0 e

W 1

W 3

Wind force, take as 1.0 kN/m2

The relative stiffness of the walls can be calculated as follows (note as the walls are rectangular and the same thickness we can use the depth only)

W1 = 103 = 1000 m3

W2 = 83 = 512 m3

Total = 1512 m3

y = 0.1 x 1000 + 59.9 x 512 = 20.3 m 1512

Eccentricity, e = 30 – 20.3 = 9.7 m

Twisting moment, Mt = 9.7 x 1.0 x 60 x 3.6 = 2095 kNm per floor

In the worst case this moment can be resisted by the walls W3 and W4 only, the force (F) in each wall is:

F = 2095/24.8 = 84.5 kN per floor

To check for the critical case the direct design force on the walls W3 and W4 from the wind parallel to these walls = 1.0 x 3.6 x 25/2 = 45 kN, and therefore the forces imposed by the twisting action are more onerous and should be used for design.

Comments This layout is not particularly eccentric and yet still imposes large torsional forces.

Floor-to-floor height = 3.6 m

80

Ground-bearing slabs

1

2

■

■

■

■

■

Shallow foundations

Key considerations

■

■

■

■

Allowable bearing pressure

81

Fully weathered

Partially

weathered

Unweathered

82

700

600

500

400

300

200

100

00 1 2 3 4 5 6

Very dense

Dense

Medium dense

Loose

Foundation width (m)

Allo

wab

lebe

arin

gpr

essu

re(k

N/m

)2

tolim

itse

ttle

men

tto

25m

m

N = 10

N = 20

N = 30

N = 40

N = 50

Piled foundations

Pilecap design

■

■

83

ya

whereN = number of pi le s in g roupP = total load appli ed M = bendi ng moment a ppli edy = local di stance of the pi l e

fr om the neutral axis of the groupy = loc al di stance of pi l e ‘a’

from the neutral axis of the g roup

The force in pil e ‘a’ is given by :

±

a

a

aa

2 l

2 l

2l

A B

C D

2 l

2 l

Piles in cohesive material

a

g g gg

84

a

p ggg

p g

Sand orsandygravel

L Stiff clayB

Soft clay

Stiff clayLB

L < 10B

L = 20B

L > 40B

1.00

1.00

1.00

0.75

0.75

0.75

0.50

0.50

0.50

0.25

0.25

0.25

0

0

0

0

0

0

50

50

50

100

100

100

150

150

150

200

200

200

Adhe

sion

fact

orAd

hesi

onfa

ctor

Adhe

sio n

fact

or

Undrained shear strength, (kN/m )cu2



L > 20B

L = 10B

L > 40B

L = 10B

Stiff clayL

B

85

g

g

Group action – bored piles in clay

_ i

86

Piles in granular soil

d

ggg

ddggg

ffff

OB CCIP - 018

JB BP1

TCC Dec 06

Worked example 11Bored pile in clay

10 m

0 m c = 70 kN/mu2

c = 170 kN/mu2

Find safe working load of a 450 mm diameter bored pile in clay

Qf = ac As + cu Nc Ab gs gb

Qf = 0.45 (70 + 170)/2 p x 0.45 x 10 + 170 x 9 x p x 0.2252

3.0 2.5

= 254 + 97.3

= 351 kN

87

dddd

ffffdddd

a dd

ff

Piles in chalk

88

gggg gggg

Piles into rock

a

Basement construction

89

■

■

■

■

OB CCIP - 018

JB BP2

TCC Dec 06

Worked example 12Bored pile in sand

0 m

10 m

Mediumdensesand

Find safe working load of a 450 mm diameter bored pile in sand

Qa = Nq* Ab qo´ + As qo´,mean ks tand

gf

Take h´ = 33°, l/d = 10000/450 = 22.2

Nq* ≈ 41

Qa = 41 x p x 0.2252 x 18 x 10 + p x 0.45 x 10 x 18 x 5 x 0.387 x tan 33

3

Qa = 1174 + 320

3

= 498 kN

91

Plans, sections, elevations and critical

details (section 2d)

■

■

■

■

Plans, sections and elevations

■

■

■

■

■

■

■

■

■

Critical details

92

600150

300600

SFL = 112.150

600

FLOOR LAYOUT

SECTION X - X

All columns 300 x 300, centred on grid unless noted otherwise

150

150150

600 dp x 300

600

dpx

300

600

dpx

300

600

dpx

300

400 dp x 300

Up Down

1100

150

300

dpx

250

1501650

3450

400 dp x 300

200wall

150

150

600 dp x 300150

7000

150 3750 4250 150

B CA30

00

X

Column500 x 300

2

3

X

SFL = 112.150

1

200

500 250

93

Foundations

B

L

L

L

Y

X

L

Z

B

75 mm Blinding

L-bars to provide anchorage,attached to pile reinforcementwith couplers

Pile cut down tocut-off level

Pile reinforcement

75 mm

Damp-proofmembrane

b) Pile and pilecap connection forlarge diameter bars

Top ofpilecap

a) Pile and pilecap connection

94

Resin-anchored starter bars

b) Perimeter strip foundation

Facade

Damp-proofcourse

Blinding

Blinding

Concrete strip foundation

Precast hollowcore unit

In-situ screed

100 mm

d) Strip foundation supporting pre-cast unit

450min 75

f) Connection of column to pad foundation

Internal wall

FFL

Well compactedsub-base

Screed

In-situ RCslab

Insulation

Blinding

Blinding

Damp-proofmembrane

Mesh reinforcement

a) Internal strip foundation

Insulation

Well compactedsub-base

Blinding

Damp-proofmembrane

Damp-proofcourse

Façade

Top of pilecap

In-situ RC slab on sub-base

TOC

Blinding Well compactedsub-base

Insulation

Damp-proofmembrane

Blinding

Damp-proofcourse

c) Typical perimeter pile cap and ground bearingslab interface

Existingcolumn

New RC column

Sub-base

Resin-anchored dowelbars

New concretefoundation

Existingconcretefoundation

Damp-proofmembrane

Blinding

RC slab

e) Strengthening existing foundation

In-situ concrete

Reinforcement

95

Sub-base

Compressiblematerial

Mass concreteDamp-proofmembrane

Foundation

20 mm soft jointExistingmasonry wall

Mass concrete

Assumed foundationto existing wall

50 mm soft jointfilled withcompressiblematerial

Blinding

f) New structure isolated from existing buildingfoundations

Damp-proofmembrane

Damp-proofmembrane

RC wall

Concrete foundation

Blinding

Mass concreteAssumed foundationto existing wall

Existingmasonrywall

Longitudinal joint

Outline of columnbase below slab

a) Isolation joint around concrete column: plan

Reinforcedconcrete column

Transverse joint(where provided)

Isolation joint(See SectionA A below)

d) Wall isolation joint

Proprietary joint sealant 20 mm wide

Compressible filler board 20 mm wide

Longitudinal joint

Outline of basebelow slab

b) Isolation joint at steel stanchion: plan

Transverse joint(where provided)

Compressible filler board20 mm wide, joint sealedwith proprietary sealant

Sub-base

c) Section A A

A A

Blinding

Isolation joint

Concrete surround tostanchion baseplateconstructed to finishedfloor level

e) New structure allowed to load existing buildingfoundations

Reinforced concrete

DPC

96

Retaining walls

c) Precast concrete crib wall d) Mass concrete gravity wall

a) Reinforced concrete cantilever wall

Mass concrete

b) Reinforced concrete basement wall

Precast concrete

In-situ concretebase

Large radius bendif required

300 mm widegranular backfill

Weep hole

Drainage pipe

Large radius bendif required

Water-bar

y

d

x

z

y

97

Basement walls

Pile

Pile

Superstructure

Ground floor slabReinforcedconcretecapping beam

Reinforced concretecolumn

Z Z

Contiguouspile wall

Reinforcedconcretebasement wall

Waterproofing to internalor external surface ofbasement wall asrequired

Basement slabIn-situconcreteinfill

Section Z Z

Section Y Y

b) Temporary contiguous pile wall

Superstructure

Ground floor slab

Reinforced concretecolumn

King post

YYReinforced concretebasement wall

Waterproofing to internal orexternal surface of basementwall as required

Basement slab

Precast concretelagging panels

c) Temporary king post wall

Section X X

In-situ concreteSecant pilewall

Connection between basement slaband secant wall if required

a) Secant pile wall used as part of permanent structure

Basement slab

Secant pilewall

In-situ concrete to giveflush surface forwaterproofing system

XX

Superstructure

Ground floor slab

Reinforcedconcreteground beam

98

Waterproofing

150 min sealedoverlap

225 min

Drainage pipe

Concretebase

Sub-base

Fillet

c) Externally applied bitumen sheet tanking

Gradeddrainagematerial

40 space flushedup with mortar

Outerwall

Asphalt

Fillet

50 protective screedon insulating layer

d) Internally applied asphalt tanking:vertical loading with masonry

50 protectivescreedof selected

600 mm zone

Bitumen sheeting

Masonry wall or protectiveboard

In-situconcretewall

Graded drainagematerial

Sub-base

Drainagepipe

Fillet

Blindingconcrete

Externalconcretewall

300 mmzone ofselectedbackfill

DPM applied to innerface of external wall

Concrete floor

Horizontal DPM protectedwith 50 screed

200min

Gradeddrainagematerial

a) Internal damp proof membrane

b) Example of damp proof membrane applied externally

Drainage pipe

600 mm zonebackfilled withselected fill

20 min render mortar

In-situ concrete wall

Masonry wallor protectiveboard

DPM applied tomortar render

In-situ concrete floor

Horizontal DPMprotected with50 screed

Blinding concrete

Sub-base

backfill

DPM

Structural walland floor

Fillet

99

Protection

Fillet

Tanking

Fillet

Isolated pile groups

Stabilising beam

Pile cap

150

Slab reinforcement

Cavity drain formerColumn

Cavity former cutaround columns

Pile

SSLTOC

50

Laid to falls

Drainage gulley

Foundation

Reinforcedconcretewall

b)Junction of floor and wall cavitiy systems

Blockwork wall

ScreedCavity drainage former

a)Cavity system at column position

Screed

100 mm min.

Drainage channel

Reinforced in-situconcrete

Floor finishes

Waterproofrender

Tanked waterproofingsystem

Chamfer at internaland external corners

Blinding

Selected backfill

Graded drainage material

Drainage pipeBlinding

100

Cladding

f) Fixing detail to allow movement

Horizontal restraintbrackets

Horizontal restraintbracket

Steel angle supporting claddingpanel fixed to RC frame

Shims for verticaltolerance

Claddingpanel

Fixing between bracketand RC frame

a) Cladding panel fixed to reinforced concrete upstand b) Precast concrete cladding supported by concrete beam

Precast concretecladding panels

Cladding bracket allowsfor vertical and horizontaladjustment

Cast-in socketwith cross pin(or vertical cast-in channel)

c) Horizontal fixing for precast concrete claddingpanel

RC concrete

e) Cladding bracket with three degrees of adjustment

Cladding bracket

Precast concretecladding panels

Range ofmovement

Serrated face for verticaladjustment

d) Load bearing and horizontal restraint fixingfor precast cladding panels

Expansion anchor or cast-inchannel and serrated cleat,and plate washer for lateraladjustment

RC frame

Precastconcretepanel

Precast concretecladding panel

In-situ concrete frame

Soft joint

Shims

In-situ concrete frame

CladdingpanelCladding bracket

Adjustment

Note: any steel connected to external elements should be galvanised or, more durably, stainless steel.

101

Insulation

Fixing toRC frame

Soft joint

Cavity tray

a) Brickwork supported at floor level

Continuous formedangle brickworksupport system

b) Retained façade

Insulation

Retainedfaçade

Soft joint

In-situ concrete

In-situ concrete

Fixing to frame allowsvertical movement

Tie

(stainless steel)

Lateralrestraintfixing

Tie intobrickwork

Lateralrestraint fixing

Waterstops

Blinding

a) Construction floor jointwith external waterstop

b) Construction wall jointwith external waterstop

c) Construction joint withhydrophilic strip

d) Floor-to-wall joint withexternal waterstop

Recess cast inconcrete

Hydrophilicstrip

InsideOutside

102

Movement joints

Soft joint

Sealant

Sealant

Expansion joint suitablefor traffic

Waterstop

f) Movement joint suitable for trafficc) Partial contraction joint

Waterstop

Joint sealingcompound

Steelcontinuity50%

No concrete continuityand no initial gap

Sealant

e) Movement joint at column location

Soft joint

Reinforcedconcretecolumn

d) Movement joint in a suspended slab with shear transfer

Shear connector

b) Complete contraction joint

Waterstop

Joint sealingcompound

No steelcontinuity

No concrete continuityand no initial gap

Expansion typewaterstop

a) Expansion joint

Initial gap forexpansion

No steelcontinuity

Non-absorbentjoint filterSealing compound

103

Superstructure

New RC slab

Existing column

15 mm soft joint

10 mm steel plate

Plan Section X X

c) Detailing to avoid new slab loading existing column

a) Reinforced beam to column connection b) Transfer beam connection

X X

d) Precast unit supported on in-situ beam (hybrid construction)

Hollowcore unitReinforcement projecting fromin-situ beam bent down intostructural topping

Reinforcement to2 cores per unit

Minimum 100 mmbearing

In-situ beam

Structural topping

New reinforcedconcrete slab

Screed

104

Method statement and programme

(section 2e)

Method statement

General contents of the method statement

■

■

■

■

■

■

■

■

■

■

Detailed considerations

■ work at height

■ excavations confined spaces

■ difficult to handle

■ stability requirements

■ noise

■ vibration

■ groundwater

■ contaminants

■ utility services

■ buoyancy

105

■ adjacent properties

Refurbishment ■

Weight of elements ■

■ lifting equipment

Temporary propping ■

Programme

not

Starton site

Flat slab

Ribbed slab

Waffle slab

One-way slab and band beam

Two-way beam and slab

P/T flat slab

Hybrid beam and slab

Hybrid twin wall

Column/slab construction

Wall/slab construction

Precast crosswall

Tunnel form

Lead-in time (weeks) Speed on site (weeks/1000 m2/crane) 1 1 2 3 423456789101112

If designed by P/T contractor

106

Example programmes

6

5

4

3

2

1

A B C D

E F G H I

7500

750075007500

75007500

750 07500

7500

7500 7500 7500 7500

87654321 161514131211109 20191817 2221

Substructure 8 weeks

Remove topsoil and reduced level dig 2 weeks

Pad foundations 4 weeks

Underslab drainage 3 weeks

Ground floor slab 3 weeks

Site set up 2 weeks

Activity Duration

Superstructure 10 weeks

Walls/columns grd to 1st 3 weeks

1st floor slab 4 weeks

Walls/columns 1st to 2nd 3 weeks

2nd floor slab 4 weeks

Walls/columns 2nd to 3rd 3 weeks

3rd floor slab 3 weeks

Roof upstands and bases 2 weeks

107

Substructure 8 weeks

Remove topsoil and reduced level dig 2 weeks

Pad foundations 4 weeks

Underslab drainage 3 weeks

Ground floor slab 3 weeks

Site set up 2 weeks

Activity Duration

Superstructure 13 weeks

Walls/columns grd to 1st 2 weeks

1st floor RC beams 2 weeks

Walls/columns 1st to 2nd 2 weeks

2nd floor RC beams 2 weeks

Walls/columns 2nd to 3rd 2 weeks

3rd floor RC beams 2 weeks

Roof upstands and bases 2 weeks

87654321 161514131211109 20191817

1st floor PC planks 1 week

2nd floor PC planks 1 week

3rd floor PC planks 1 week

2221

108

Robustness requirements

for precast concrete frames

■

■

■

■

■

Internal ties

Perimeter floor ties(everywhere)

Continuousperipheraltie(s)

Floor ties either uniformalydistributed or collectedat columns

Continuousperipheralgable tie

Continuity tie

Ties anchored intocolumns wherecontinuity cannotbe provided

h

Horizontal ties

■

■

Vertical ties

109

NoteNot suitable for Class 2B and Class 3 buildings in accordancewith Approved Document A [36]

Concrete topping

Precast hollowcoreunit

Support

In-situ concrete

In-situconcrete

110

Gablebeam

In-situconcrete

Floor

slabTie bar

Edge beam

Reinforcement anchoredinto precast columnusing alternatives shownin Figure A.9

Tie bar diameter

In-situ concrete Minimum + 2 + 10 mmHagg

b) Sectiona) Plan

In-situinfill

Projecting barsGable beam

At least one (often two) core(s)opened for approximately 300 m m

Plug in open cores

111

Slot formed in column

Site-placed bars positionedinside projecting loops

Grouted sleeve

Fully anchoredcast-in-socket

Anchor plate

112

Design aids

d

s

s g d

g

d

113

r

r

R r

r

y y

114

r

115

r

116

r

117

0.1250.070 0.070

0.100 0.1000.080 0.025 0.080

0.107 0.071 0.1070.077 0.036 0.036 0.077

0.105 0.079 0.079 0.1050.078 0.033 0.046 0.033 0.078

0.1560.095 0.095

0.125 0.1250.108 0.042 0.108

0.134 0.089 0.1340.104 0.056 0.056 0.104

0.132 0.099 0.099 0.132

0.105 0.051 0.068 0.051 0.105

0.1880.156 0.156

0.150 0.1500.175 0.100 0.175

0.161 0.107 0.161

0.170 0.116 0.116 0.170

0.158 0.118 0.118 0.1580.171 0.112 0.132 0.112 0.171

0.1670.111 0.111

0.133 0.1330.122 0.033 0.122

0.143 0.095 0.1430.119 0.056 0.056 0.119

0.140 0.105 0.105 0.1400.120 0.050 0.061 0.050 0.120 0.144 0.108 0.115 0.108 0.144

0.159 0.148 0.148 0.159

0.143 0.111 0.111 0.1430.160 0.144 0.160

0.144 0.100 0.1440.156 0.156

0.139 0.139

0.167

0.211 0.181 0.191 0.181 0.2110.179 0.167 0.167 0.179

0.210 0.183 0.183 0.2100.181 0.161 0.181

0.213 0.175 0.2130.175 0.175

0.203 0.2030.188

0.135 0.109 0.117 0.109 0.1350.150 0.139 0.139 0.150

0.134 0.111 0.111 0.1340.151 0.134 0.151

0.136 0.104 0.1360.146 0.146

0.129 0.1290.156

0.100 0.079 0.086 0.079 0.1000.120 0.111 0.111 0.120

0.099 0.081 0.081 0.0990.121 0.107 0.121

0.101 0.075 0.1010.117 0.117

0.096 0.0960.125

Uni

form

lydi

stri

bute

d0.

5l0.

5lCo

ncen

trat

edat

mid

span

Conc

entr

ated

atth

ird

poin

ts

118

0.4060.406

0.3750.375

0.6250.625

0.4000.400

0.5000.500

0.6000.600

0.3930.393

0.5360.536

0.4640.464

0.6070.607

0.3950.395

0.5260.526

0.5000.500

0.4740.474

0.6050.605

0.3440.344

0.6560.656

0.3750.375

0.5000.500

0.6250.625

0.3660.366

0.5450.545

0.4550.455

0.6340.634

0.3690.369

0.5320.532

0.5000.500

0.4680.468

0.6310.631

0.3130.313

0.6880.688

0.3500.350

0.5000.500

0.6500.650

0.3390.339

0.5540.554

0.4460.446

0.6610.661

0.3420.342

0.5400.540

0.5000.500

0.4600.460

0.6580.658

0.3330.333

0.6670.667

0.367 0.500 0.6330.633 0.500 0.367

0.357 0.548 0.452 0.6430.643 0.452 0.548 0.357

0.6400.3600.535

0.4650.500

0.5000.465

0.5350.3600.640 0.659 0.602 0.621

0.6210.6310.430 0.6020.631

0.6590.480

0.4290.661

0.6370.595

0.433

0.433

0.5950.6610.429 0.637

0.611

0.611

0.656

0.656

0.4170.417

0.6670.667

0.421 0.647 0.6360.679 0.615 0.636

0.6150.647

0.6790.421

0.4200.681

0.654 0.6070.607 0.654

0.6810.420

0.4250.675

0.6250.625

0.6750.425

0.6880.688

0.6490.649

0.5950.595

0.6140.614

0.6220.622

0.4340.434

0.4330.433

0.6280.628

0.5890.589

0.6510.651

0.4370.437

0.6050.605

0.6460.646

0.4220.422

0.6560.656

0.447 0.598 0.591 0.576 0.6200.620 0.576 0.591 0.598 0.447

0.6210.621

0.571 0.603 0.4460.446 0.5710.603

0.617 0.583 0.4500.6170.5830.450

0.6250.4380.625

0.438

Uni

form

lydi

stri

bute

dTr

iang

ular

lydi

stri

bute

dCo

ncen

trat

edat

mid

span

Conc

entr

ated

atth

ird

poin

ts

119

Moment

Moment

0.277 0.277

0.025 0.223 0.025

2l ll

Shear

0.2230.777 1.000

1.000 0.7770.223

0.311 0.311

0.357 0.186 0.357

2l l 2l

Shear

0.845

1.155

1.1550.5000.500 0.845

0.277 0.2770.109 0.257 0.109

2l ll

0.466 1.000 0.5340.534 1.000 0.466

0.311 0.311

0.373 0.273 0373

2l l 2l

0.864 0.500 1.1361.136 0.500 0.864

Uni

form

lydi

stri

bute

dU

nifo

rmly

dist

ribu

ted

120

c) Beam overhanging one support - concentrated load at end of overhang

R VA A= =Pal

R V VB A B= + = Pl( + )l a

V PB =

M Pamax =

Pa2

3EI( + )l a

Moment

Shear

VA

VB

Mmax

l a

P

CBA

b) Beam overhanging one support - uniformly distributed load on overhang

l a

A BC

VBVA

Shear

Moment

Mmax

R VA A= =

VB= + =

V waB =

Mmax =

wa2

wa3

wa2

wa2l

2

2l(2 )l + a

24EI(4 + 3 )l a

l a

A B C

VB2

VB1

V1

Mhog,max

Msag, max

Moment

Shear

a) Beam overhanging one support - uniformly distributed load

R VA A= = ( )l a2 2

2l

2l

2l

R V VB B 1 B2= + =

w

w

w

( + )l a2

V w aB1 =

VB2 = ( + )l a2 2

Msag, max =

wa2

2

8l2 ( + ) ( )l a l a

2 2

Mhog, max=

dC =

dC =

dC =

wa

24EI(4a l l3 + 3a3)

2 3 3

Loading

Loading

Loading

R VB A

w

121

MA

MA

MB

MB = /4F h1

MB MA

MAMA

MA= /8F h1MA

MA

MD= (2 + ) /8F F h1 2

MDMD

MDMD

MC = ( + ) /4F F h1 2

MC

MCMCMC

MCMC

ME = ( + + ) /4F F F h1 2 3

ME

ME

ME

M F F F hF 1 2 3 = (2 + 2 + ) /8

MFMF

MFMF

2

2

2

2

2

2

b b

h

h

h

F1

F1 + F2

4

4

F1 + F2

4

F1

4

F1

2F1

2

F1 + F2

2

F1

4

b) Forces

F1

F2

F3

F1

4

F1 + F2

4

F1 + F2

4 F1 + F2

2

F1 + +F2 F3

2F1 + +F2 F3

4

4

(3 +2 + )hF1 F2 F3

2b

4

2

c) Moments

0

2

F1 + +F2 F3

4

F4

(3 +2 + )hF1 F2 F3

2b

4

Deflectedshape

Assumed pinconnection

a) Frame and deflections

NoteColumns and beams have equal stiffness

/

F/

F/

F/F/

F/

122

Compression reinforcement required

Key

–– 25 fck

–– 30 fck

–– 35 fck

–– 40 fck

–– 50 fck

0.25

0.20

0.15

0.10

0.05

0.00

0.0 0.5 1.0 1.5 2.0

Compression reinforcement often advised (x/d > 0.45)

z < 0.95d

MEd

/bd2

f ck

100 As/bd

As

b

x

d

125

1.2

1.1

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

00 0.005 0.010 0.015 0.020 0.025 0.030 0.035 0.040 0.045 0.050

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

Kr = 1

Ratio = 0.5d/h

dh

As fyk/h2fck

NEd

/h2

f ck

MEd /h3fck

128

References

129

Further reading

■

■

■

■

■

■

■

■

■

■

■

130

Index

8

10

12

16

20

25

32

40

8

10

12

16

20

25

32

40

8

10

12

16

20

25

32

40

8

10

12

16

20

25

32

40

Concrete Centre - Scheme Manual to EC2

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Transcript of Concrete Centre - Scheme Manual to EC2