Precast 2 Mixed PDF

7/26/2019 Precast 2 Mixed PDF

1/79

Precast Concrete in

Mixed Construction

The Design and Construction of

Precast Concrete Structures


2/79


3/79

International Airport Oslo -

5 structural materials


4/79

Helsinki precast concrete, steel and timber


5/79

Houston Art Gallery precast

f e r r o c r e t e and integrated steel truss


6/79


7/79

Contents

What is

mixed &

composite

construction

Hybrid

precast &

insitu

Precast

with

timber and

masonry


8/79

Contents

What is

mixed &

composite?

Precast

concrete

with

steelwork

Hybrid

precast &

insitu

Precast

with

timber and

masonry


9/79

Contents

What is

mixed &

composite?

Precast

concrete

with

steelwork

Hybrid

precast &

insitu

concrete

Precast

with

timber and

masonry


10/79

Contents

What is

mixed &

composite?

Precast

concrete

with

steelwork

Hybrid

precast &

insitu

Precast

with

timber and

masonry


11/79

CONSTRUCTION TECHNIQUES

MONO single material

HYBRID precast and insitu concrete

MIXED concrete with other materialsCOMPOSITE structural interaction


12/79

Precast floorunits on steel

beams

Mixed or composite?


13/79

Mixed or composite?


14/79

19 mm dia. x 125 mm @ 150 c/c

= 70 kN per stud


15/79

200 mm deep prestressed hollow core floor


16/79

40-100 mm gap

Tie bars in slots = 1200 mm long

Cast insitu concrete


17/79

1200-1500 mm wide

150 300 mm

depth


grade 25

Full scale testswithout studsLoad

Deflection



18/79

1200-1500 mm wide

150 300 mm

depth


grade 25

Load

Deflection



19/79

1200-1500 mm wide

150 300 mm

depth


grade 25

Full scale testswith studsLoad

Deflection



20/79

1200-1500 mm wide

150 300 mm

depth


grade 25

Load

Deflection


21/79

Precast Insitu infi ll

Small cracks at interface

Tie bars, say T12 or T16 @ 400 c/c


22/79

30 to 40% more moment capacity:

shallow beams, or greater spans?


23/79

BENEFITS of MIXED

CONSTRUCTION ?

- material performance suits structural and

architectural needs

- elements are optimised

- fewer elements & more prefabrication

- less scaffolding & site labour problems

- less wet concrete & reinforcement on site

- less risk of bad weather delays


24/79

POTENTIAL DIFFICULTIES ?


25/79



26/79


- too many suppliers

- split design responsibilities

- inadequate design information

- no codes of practice for the interfaces

- early design information

- tolerances

- mistimed deliveries

- construction sequence

- temporary stability and safety


27/79

Contents

What is

mixed &

composite?

Precast

concrete

withsteelwork

Hybrid

precast &

insitu

Precast

with

timber and

masonry

PRECAST ADDED TO STEELWORK


28/79


pretensioned floors onto beams and rafters

pretensioned beams to columns

faade panels to steel frames

hollow core wall panels to steel frames


29/79

PRECASTADDEDTO

STEELW

ORK



30/79


Offices for Ericsson Sweden


31/79

Offices for Ericsson, Sweden

resulting in a flat-slab ?


32/79

resulting in a flat slab ?

The Big Apple car park & shopping mall, Finland


33/79

The Big Apple car park & shopping mall, Finland

16 m span x 400 deep + 20 mm steel soffit


34/79

Prefabricated Delta beam + composite slab


35/79

p


36/79

Steel columns and head fixing + precast


37/79

g p

soffit units 16 m long x 3.6 m wide

Bracken House in London insitu columns,


38/79

prestressed beams and metal decking

753 million (RM 5000m) new soccer stadium .


39/79

Steel frame, precast terraces (SCC) and


40/79

composite steel beam + hollow core floors

Temporary steel roof to 6 storey precast car park


41/79

Hollow core wall panel + steel frame


42/79

Hollow core wall panel + steel frame


43/79


44/79

BENEFITS

rapid steelwork erection

long span precast floors

composite floor + beam

thermal efficiency in facade

PROBLEMS


45/79

BENEFITS

rapid steelwork erection

long span precast floors

composite floor + beam

thermal efficiency in facade

steel beam deformations

under temporary conditions

add steel ties whilst f ixing

precast

torsional instability of steel

beams

tolerances

PROBLEMS


46/79

Contents

What is

mixed &

composite?

Precast

concrete

withsteelwork

Hybrid

precast &

insitu

concrete

Precast

with

timber and

masonry

PRECAST WITH CAST INSITU CONCRETE


47/79

pretensioned floors onto/within beams

precast shell beams with insitu continuity

pretensioned beams onto columns

precast frames onto insitu foundations

precast facades on insitu frames

Precast for speed + insitu for diff icult access.

Eastern Pretech Kepong Malaysia


48/79

Eastern Pretech, Kepong, Malaysia.

London Gatwick airport precast floor units

span 16 m onto insitu beams and columns


49/79

span 16 m onto insitu beams and columns

20 m long post-tensioned beam with hollow

core slabs, used compositely?


50/79

core slabs, used compositely?


51/79

No composite

action usedbetween insitu

beam and

precast floors.

Composite cast insitu beams

and prestressed floor units


52/79

p

Tie steel in 1500

mm long slots

Composite slab with shallow post-tensioned

beams possible in a 150 m long car park.


53/79

Underground car park, Italy.

Floor x beam span = 80 sq.m

T l d h 2 0


54/79

Total depth = 250 mm

Precast composite slab

= 250 mm deep hollow core + 75 mm


55/79

insitu topping to span about 10 m.


56/79

VNOTower,TheH

ague,Nethe

rlands

Stability =

cast insitu

columns,

steeldiagonals,

precast +

insitu floordiaphragm

Cast insitu = precast progress


57/79

BENEFITS


58/79

BENEFITS

PROBLEMS

horizontal elements prefabricated

minimise formwork

continuity at beam-column

connections giving greater

span/depth ratio

immediate working platform

BENEFITS


59/79

BENEFITS

PROBLEMS


minimise formwork

continuity at beam-column

connections giving greaterspan/depth ratio


tolerances

mistimed deliveries

formwork removal

relative shrinkage and

creep movements


60/79

Contents

What is

mixed &

composite?

Precast

concrete

withsteelwork

Hybridprecast &

insitu

Precast

with

timber and

masonry

PRECAST CONCRETE MIXED

WITH TIMBER


61/79

pitched roof rafters

exposed face beams, e.g. Glulam

timber frames with precast f loor planks

timber housing with precast concrete

walls and floors

PRECAST CONCRETE MIXED WITH TIMBER


62/79

Supermarket in Belgium.

Who designs the precast-to-timber connection?


63/79

Total precast concrete car park in Sweden ?


64/79

. with glue-laminated timber roof


65/79

Timber frame with .


66/79

Timber frame with two-way spanning

precast f loor units


67/79

BENEFITS


68/79

BENEFITS

PROBLEMS

long span, lightweight, rafters

provide clear open office space

Glulam beams are both

architectural and structural

can be integrated with precast

and steelwork

speed of erection

BENEFITS


69/79

BENEFITS

PROBLEMS

long span, lightweight, rafters

provide clear open office space

Glulam beams are both

architectural and structural

can be integrated with precast

and steelwork

speed of erection

no design information

unfamiliar details

connection design

end rotations greater than

precast

more expensive than steelrafters

The Dutch House; precast masonry walls, psc

or rc hollow core, prefab masonry panels


70/79

Same idea in many European countries


71/79

Prefabricated brickwork fascia spandrel beams

Insitu brickwork infill shear walls


72/79

PRECAST CONCRETE MIXED WITH MASONRY

Michael Hopkins Inland Revenue, Nott ingham


73/79

600 prefabricated brick pillars 3 variants

305 precast f loors 15 variants


74/79

Precast f loors 14 m x 3.6 m with exposed soffi t


75/79

The rotunda and air con control tower


76/79

BENEFITS


77/79

PROBLEMS

accurate prefab masonry


lightweight floors in hollow core

or beam and block

infill shear walls possible


BENEFITS


78/79

PROBLEMS

accurate prefab masonry


lightweight floors in hollow core

or beam and block

Infil l shear walls possible


bearings

delays due to strength ofmasonry during precast f ixing

tolerances

floor shrinkage/creep effects

CONCLUSIONS


79/79

mixed construction used in 75% new buildings

mixed does not always mean composite

to replace one material element with another forthe benefit of the whole building process

precast concrete has central role both asprimary and secondary elements

some architectural demands only satisfiedusing mixed construction

Documents

Precast 2 Mixed PDF