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 3) Delivery 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 Built up members 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 Erection of Steel Joists 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