Steel Construction

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Steel Construction
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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

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3 components

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

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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

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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

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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

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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

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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, F14-56
• Light weight, strong
• Used extensively on roofs and floors
• Castellated beams F14-7

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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

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Lifting Equipment

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

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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

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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

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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

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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

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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