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Steel Construction

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

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Steel Construction

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  1. Steel Construction

  2. 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. 3 components • 2) Fabrication • Shop drawings, steel type, built up or rolled section, connection method, camber • 3) Delivery

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. Lifting Equipment • Cranes, tower cranes • Small jobs may see F 14-9 ( old stuff)

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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

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