nineteen steel construction: trusses, decks & plate girders - - PowerPoint PPT Presentation

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nineteen steel construction: trusses, decks & plate girders - - PowerPoint PPT Presentation

Aug 27, 2023 153 likes •373 views

A RCHITECTURAL S TRUCTURES : F ORM, B EHAVIOR, AND D ESIGN A RCH 331 D R. A NNE N ICHOLS S PRING 2019 lecture nineteen steel construction: trusses, decks & plate girders Steel Trusses 1 Architectural Structures S2019abn Lecture 19 ARCH

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SLIDE 1

S2019abn Steel Trusses 1 Lecture 19 Architectural Structures ARCH 331

lecture

nineteen

steel construction:

trusses, decks & plate girders

ARCHITECTURAL STRUCTURES: FORM, BEHAVIOR, AND DESIGN ARCH 331

  • DR. ANNE NICHOLS

SPRING 2019

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SLIDE 2

S2019abn Steel Trusses 2 Lecture 19 Architectural Structures ARCH 331

Iron & Steel Trusses

  • cast iron

– 18th century – chain links

  • wrought-iron
  • rivets

http:// nisee.berkeley.edu/godden

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SLIDE 3

S2019abn Steel Trusses 3 Lecture 19 Architectural Structures ARCH 331

Truss Connections

  • gusset plates
  • bolts
  • welds

(AISC - Steel Structures of the Everyday) http://courses.civil.ualberta.ca

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SLIDE 4

S2019abn Steel Trusses 4 Lecture 19 Architectural Structures ARCH 331

Trusses

  • require lateral bracing
  • consider buckling
  • indeterminate trusses

– extra members

  • diagonal tension counters

– solvable with statics

  • cables can’t hold compression

– displacement methods

  • elastic elongation

– too few members, unstable

C B H D 4 G A E F 5lb 6 6 6 10lb 20lb http:// nisee.berkeley.edu/godden One Maritime Plaza, SOM 1964

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SLIDE 5

S2019abn Steel Trusses 5 Lecture 19 Architectural Structures ARCH 331

Manufactured Trusses

  • open web joists
  • parallel chord
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SLIDE 6

S2019abn Steel Trusses 6 Lecture 19 Architectural Structures ARCH 331

Open Web Joists

  • SJI: www.steeljoist.com
  • Vulcraft: www.vulcraft.com

– K Series (Standard)

  • 8-30” deep, spans 8-50 ft

– LH Series (Long span)

  • 18-48” deep, spans 25-96 ft

– DLH (Deep Long Spans)

  • 52-72” deep, spans 89-144 ft

– SLH (Long spans with high strength steel)

  • pitched top chord
  • 80-120” deep, spans 111-240 ft
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SLIDE 7

S2019abn Steel Trusses 7 Lecture 19 Architectural Structures ARCH 331

Load Tables - w

load for live load deflection limit (L/360) in RED total in BLACK

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SLIDE 8

S2019abn Steel Trusses 8 Lecture 19 Architectural Structures ARCH 331

Decks

  • sheet steel
  • composite
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SLIDE 9

S2019abn Steel Trusses 9 Lecture 19 Architectural Structures ARCH 331

Light-gage Steel

  • sheet metal

– shaped – studs, panels, window frames – gage

  • based on weight of

41.82 lb/ft2 / inch of thickness

  • 24, 22, 18, 16, i.e.
  • 0.0239, 0.0329, 0.0474, 0.0598 in
  • 0.6, 0.85, 1.0, 1.3, 1.6 mm

http:// nisee.berkeley.edu/godden

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SLIDE 10

S2019abn Steel Trusses 10 Lecture 19 Architectural Structures ARCH 331

Steel Decks

  • “Texas” style

– corrugated

  • common

– 1 – 3 spans – can be insulated – composite

  • with concrete
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SLIDE 11

S2019abn Steel Trusses 11 Lecture 19 Architectural Structures ARCH 331

Steel Decks

  • common fire proofing

– cementitious spray – composite concrete

  • non-composite

– concrete is fill

  • lateral bracing
  • diaphragm

action

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SLIDE 12

S2019abn Steel Trusses 12 Lecture 19 Architectural Structures ARCH 331

Load Tables - w

  • live load

deflection limit L/240

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SLIDE 13

S2019abn Steel Trusses 13 Lecture 19 Architectural Structures ARCH 331

Plate Girders

  • welds
  • web stiffeners

http:// nisee.berkeley.edu/godden

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SLIDE 14

S2019abn

  • max loads

( 2.5 )

n(max end) yw w

P N k F t

  ( 5 )

n(max interior) yw w

P N k F t

 

Steel Trusses 14 Lecture 19 Architectural Structures ARCH 331

Web Bearing

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SLIDE 15

S2019abn Steel Trusses 15 Lecture 19 Architectural Structures ARCH 331

Space Trusses

  • 3D with 2 force bodies and pins

– pyramid – tetrahedron

  • “frames”

have fixed joints

  • layers
  • 40’s
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SLIDE 16

S2019abn Steel Trusses 16 Lecture 19 Architectural Structures ARCH 331

Space Trusses

  • connections
  • supports
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SLIDE 17

S2019abn Steel Trusses 17 Lecture 19 Architectural Structures ARCH 331

Space Trusses

http:// nisee.berkeley.edu/godden www.archdaily.com

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SLIDE 18

S2019abn Steel Trusses 18 Lecture 19 Architectural Structures ARCH 331

Space Trusses

http:// nisee.berkeley.edu/godden

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SLIDE 19

S2019abn Steel Trusses 19 Lecture 19 Architectural Structures ARCH 331

Tensegrities

  • 3D frame
  • discontinuous struts
  • continuous cables

Free Ride Home – Kenneth Snelson

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SLIDE 20

S2019abn Steel Trusses 20 Lecture 19 Architectural Structures ARCH 331

Method of Sections

  • relies on internal forces being in

equilibrium on a section

  • cut to expose 3 or less members
  • coplanar forces  M = 0 too

A B C P F E D P . A By AC AB

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SLIDE 21

S2019abn Steel Trusses 21 Lecture 19 Architectural Structures ARCH 331

Method of Sections

  • joints on or off the section are good to

sum moments

  • quick for few members
  • not always obvious where to cut or sum

A B C P F E D P . A By AC AB B .