Steel Construction

3 components

• 1) Advanced Planning– Divisioning – dividing structure into units used

to schedule fabrication and delivery• Determined by order in which structure is erected• Joint effort between fabricator and erection

manager

– Must check size and weight of members against plant capacity, transportation size, wt limits, erection equipment capacity

3 components

• 2) Fabrication– Shop drawings, steel type, built up or rolled

section, connection method, camber

• 3) Delivery

Field Operations

• Receiving and unloading– Sorting – shake out – id members with code

• By size or by placement on structure• Want all material for a unit in one place

– Inspecting• Welds, rust, warped or torqued

– Storing – store off ground, protect from dirt, grease, corrosion

• Large members stored on truck until erection• Need a large enough storage area• Yarding – storing in a temp area and then moving to erection

area– Erecting

Field Operations

• Must be careful unloading steel– Can damage surface coating, bend or torque

members– Use double slings to avoid bending members– Must inspect for damage and conformance to

shop drawings and tolerances– T14-1

Structural Steel

• Types of Steel– A36 carbon structural steel – most common– A572 High Strength – Low Alloy Structural

Steel– A 588 Corrosion resistant High Strength –

Low Alloy Structural Steel– Weathering steel – develops protective

coating – no painting required

Structural Steel

– Camber and sweep• Camber – looks like frown allows for beam to

return to level position once load is applied• Sweep – curve in beam

Structural Steel

– Standard Rolled Shapes• F 14-2, T 14-2

– Built up members• F14-3• Used when common rolled shape is not available• Open web joists and joist girders, F14-5&6

– Light weight, strong– Used extensively on roofs and floors

• Castellated beams – F14-7

Erection

• Usual process uses three crews– Raising crew – lifts member into position and temp

bolts it into position (safely)– OSHA regs – structural integrity – ability of structure

to safely stand during erection• Safety regs - erection floor cannot be more than 8 floors

above highest completed permanent floor, Not more than 4 floors of unfinished connections above highest permanently secured floor

– Fitting crew – brings member into proper alignment and tightens enough bolts to hold it in place

– Fastening crew – final connections

Lifting Equipment

• Cranes, tower cranes

• Small jobs may see F 14-9 ( old stuff)

Alignment of Steel

• Within tolerances of AISC Code of Standard of Practice

• Vertical or plumb error +/- 1 unit in 500 units of height

• Outside columns cannot be more than 1” towards or 2” away from building line in 20 stories

• Minimum clearance between members• Coping or blocking – notching beams to provide

clearance when connecting beams to columns• Electrical and plumbing notches need to be

designed

Alignment of Steel

• Guys– Cables used to align members– Do not overstress

• Erection of Steel Joists– Require lateral bracing

• Cannot release joist from crane until braced

Field Connections

• Fastening systems– Bolting

• Two types of bolt systems– Interference-body or interference-fit bolts

» Oversized bolt driven into hole – holds bolt in place while tightened

– Tension Control or tension set bolts» Bolt stem breaks when specified torque hit

– In both cases need to make sure that bolts are tightened to specified torque

– F14-11, 14-12

– Riveting – not used much today

Field Connections

• Fastening systems– Welding

• All welders should be certified by American Welding Society

• F 14-14 standard welding symbols• Welds must be tested & inspected for quality

– Visual – quickest must be highly trained– Destructive – used when questionable quality– radiographic, ultrasonic provide image of weld– magnetic particle, liquid penetrant inspection - show

flaws

Safety

• Hard hats, gloves• Eye protection for welders, cutters, chipping ops• Harnesses if off ground level

– And scaffolding– Over 25’ – safety nets– Tag lines on all hoisted beams to handle swing– Surfaces of beams must be dry and suitable for

walking