Steel Framing System 15%

Framing methods

Connection

1. Rigid –

fully welded (site welded) Bolted

weld type : FSBW

Web stiffener

Portal frame

2. Semi rigid (not common)

3. Simple connection – doesn’t provide bending moment

Building Stability

One way rigid, one way braced ‘

Rigid frame by portal ,because it is a shop front for clear opening

Blockwork braced by shear wall – fire rating

Features ADV DIS Application

2way rigid Resist lateral forces in both

planes by frame

Column to beam connection

must be rigid

Column approximately equal

stiffness

Larger bending moment in

columns

Beam continuity reduce

deflection?

1. 1. No Stablising elements

required for lateral forces

in any plane

2. 2. Freedom in planning

3. 3. Continuous beam

design lead to reduced

beam size

1. Costly as it req

rigid connection

2. Fabricated box

column needed

3. Large column

moment

Multi storey frame

Low rise rectangular

frame – architectural

requirement

restriction

Heavy industrial

structures

2 way

brace

Beams are simply supported (LARGE

size)

Column are axially loaded members

Beam encountered small eccentricity

Therefore required rigid floor system

to prevent distortion

Shear wall, braced panel

1. Simple connection –

less cost

2. I column

3. Beams assumed

simply supported for

design

1. Restricted in

planning due to

stablising element

2. Heavier beam size

low to medium

density rise building

Using core. Steel

framed or slip

formed concrete

1 way

brace

High bending resistance at x axis ,

low at y axis

Reinforced concrete floor slab resting

1. Simple connection

2. Can use I column

3. Continuous beam

design method in

rigid connections

1. Some restriction

in planning

2. Rigid connection

used unbraced

plane

Low rise industrial

frames

Industrial structure

Connection

Bolting

Snug tight4.6/S or 8.8/S pin connection by hand tools / spanners/standard wrench

Shear force transfer depends on the shear capacity of bolts M16 8.8/4.6S

Full Tension 8.8 TF fiction , 8.8 TB bearing rigid connection by pneumatic impact wrench. fully tension provided by torque – shear

force or friction

8.8 TF – no slippage

Part turn method -> torque control method, load indicator method

Simple Semi-rigid Rigid

Minimal rotational restraint Control deformation Max rotation restraint (no rotation)

Flexible end plate

True bolts

14mm

Web 8mm thick

Less BM, no tolerance

Angle cleat plate

Web and flange cleat plate

Bolted beam to column end plate

Bolts placed as far as possible for tension in beam

Welded stiffener

Combination bolted and welded flange splice

6mm fillet weld high strength bolts -> N16 4.6

/N16 8.8S bolts

High eccentricity

Web side plate

Pin type

Welding

Features ADV DIS Application

Butt weld

Stronger

Required bevel preparation

tested and design

Load penetrate through the

finish weld, occupy the

depth of the section

Simplicity of joint

Minimal change of

stress path

Req expensive edge

preparation

Need greater care of

correct welding

procedure

Rigid connection

End plate portal rafter

End Plate to Flanges

Subjected to large

bending moment

Subjected to dead

load, live load &

uplift force

Fillet weld

No surface preparation req

Weaker

Less material used

Less time needed

No need beveling

Weaker Web cleat plate

Each side of web

Continous fillet weld to

column

Web stiffener

Directly opposite to

the flange

Pin (grouted) to get

stability at pin Splice connection

Apex connection

Rigid prefabricated

webstiffener high load

transfer

8.8 TB N 28 bolt

50 of them

Cross braced

Joining column

Transfer load from flange to the other flange via bolt thick plate

Fully rigid joint floor to another

Universal column – pin connection why?

Portal Framing 5 %

Rafter to column connection

Holding down bolt

Purlins /metal deck connected to top flange – prevent rafter & column from buckling

Zed : can be overlapped

Cee: provide continuity

Rafter – top flange in compression (use purlins stop buckling)

Bottom in compression (use fly bracing to stop buckling)

Fly bracing prevent flange from buckling

Web stiffener – prevent buckling

Bracing to resist longitudinal wind load

3 internal column no take bending moment, only take vertical load, it is design as three continuous rafter with 3 internal column

support

4 pin – semi rigid – to hold it temporary during erection

It will then be remove and fix with 2 pin

Better erection for the pin

Eaves tie – transfer wind load from the end frame into braced frame

End frame –critical: high bending moment & high deflection due to uniform load

bracing resist wind load

only applicable when wind force on the opposite end to transfer through via metal deck/ eaves struct

Pin base – no moment transfer … only shear and axial force

Ground Slab 20%

1. Long Strip 30 x 6-9m

Pour with vibrating screed

Pour joint used to allow shrinkage to occur

Introduce saw cut to reduce random cracks

No saw cut – random cracks in slab occur to shrinkage

2. Wide Strip – big contractor

Single /Double strips to allow pour twice floor area and twice as much concrete

Increase speed of constrcution

Require better equipment -Vibrate , trowl

Use trussed vibrating screed – level the concrete

12m wide

3. . Large Area Construction

More labour and req better equipment to vibrate, trowel and finish

Methods to keep slab level 1spot levels2. Removable rails 3. Large screed .

Industrial Slab

1. Base

2. Vapour barrier -> slip membrane prevent water rising through subgrade

3.subbase – selected material (pour material) provide load bearing capacity

A. Compacted – reduce drag in subgrade (less chance of random cracking)

reduce the drag and reduce the tension in the slab

B. Rolled/ consolidated to get uniform CBR, get flat hard surface

C. Bound subbase or equivalent to reduced material being washed away due to pumping

Quarry dust and crushed fine

D. Uniform CBR (subgrade reaction) to determine the strength load capacity 10-50-> determine slab thickness

By improving the CBR - slab thickness can be reduced

4.Subgrade natural formation =load bearing capacity

Saw Cut

contraction

Pour Joint

Construction

Joint are used for minimise the risk of shrinkage, cracking, to avoid conflict with other structures and penetration

Dowel may be used as a load transfer mechanism across a joint to adjacent pavement panels- > low flexural stresses in the panel,

serve to prevent vertical movements of adjacent panels and to avoid stepping

@ Pour Joint

1. Round Dowel bar probs- restrain sideway movement perpendicular to the bars and parallel to the joints

I. Reinforcement does not go through the pour joint as pour joint needs to be used as a shrinkage inducer

II. Stop differential movement at the joint

III. Allow horizontal movement ..greasing/putting a plastic sleeve on the other side allow the slab to slide side way but stop vertical

movement

Diamond Flat Plate Dowel – allow slab horizontal movement parallel to the joint

IV. Stop differential movement at the joint

V. Allow horizontal movement ..greasing/putting a plastic sleeve on the other side allow the slab to slide side way but stop vertical

movement

VI. Allow longitudinal shrinkage to occur

2 Keyway --not use very often

VII. Construction keyway joints, create a rebate on one side

VIII. formed with timber moulds attached to the formwork,

IX. , provide load transfer and allow for concrete shrinkage and rotation at joints. >150mm thick slab to be effective

X.

The max pour 10x10

850 ummicro strain -> 8.5mm .. project

specify 550 micro strain+ reinforcement

400=4mm

Crack due to shrinkage likely to occur at saw

cut (contraction joint area)

Reinforcement on that slab

control the shrinkage

Reinforcement on that slab

control the shrinkage Debonding on the right Bonding

@Contraction Joint (Saw cut0.25mm) 25% deep of the slab

I. Dowels to prevent differential vertical movement under the saw cut

II. Aggregate interlock can be used to prevent differential vertical movement as long as < cracks 1.5mm –

III. Allow longitudinal movement (shrinkage )to occur sideway

Dowel 4cm in a duct at the saw cut

To allow longitudinal difference occurring from1 pour to another

To allow different shrinkage rate from 1 pour to another pour

IV. dowel(MECHANICAL LOAD TRANSFER device) design to allow the joint to open and close buthold the slab on each side of

the joint, they transfer load from adjacent slab across the joint, critical corner andedge loading stresses and permitting thinner

slabs to be used (SQUAREallow vertical shear load to be fullytransferred from one slab to the other

V.

Armoured Edges

1. isolation joints compressive foam

occurs at column

Permit horizontal vertical movement + rotation between abutting elements

provided between pavement panel and fixed parts of the building ( such as column, walls) to prevent the development of stresses

that may result from differential movements

Debonding on the right

Reduce Joint Maintenance

Concrete in place at that side and lock the steel plate on

Straightness provide good surface finish

Armoured edge instead of having concrete at the edge --- both side have got steel

edges protect the edge of the slab

10mm wide 1020mm

Shear studs welded to it, lock the steel plate to prevent it from felling off. ..provi

de permanent formwork, built in diamond dowel, when concrete shrink, it strips it

s thread on the

Nylon plastic bolts to allow it to shrink back, strip the thread at the bolt at the po

ur joint .. 3mm move -> expect 10mm Armor edge protect the edge … serviceab

le floor start to shrink- > crack ( $3000)