nineteen wrought-iron rivets steel construction: trusses, decks - PowerPoint PPT Presentation

A RCHITECTURAL S TRUCTURES : Iron & Steel Trusses F ORM, B EHAVIOR, AND D ESIGN ARCH 331 • cast iron D R. A NNE N ICHOLS – 18 th century S PRING 2019 – chain links lecture nineteen • wrought-iron • rivets steel construction: trusses, decks & plate girders Steel Trusses 1 Architectural Structures F2009abn http:// nisee.berkeley.edu/godden Lecture 19 ARCH 331 Steel Trusses 2 Foundations Structures F2009abn Lecture 19 ARCH 331 Trusses Truss Connections http:// nisee.berkeley.edu/godden • gusset plates • require lateral bracing • consider buckling • bolts • indeterminate trusses • welds – extra members • diagonal tension counters – solvable with statics • cables can’t hold compression One Maritime Plaza, SOM 1964 5 lb – displacement methods F G E H 4  • elastic elongation http://courses.civil.ualberta.ca A D 6  B 6  C 6  – too few members, unstable 10 lb 20 lb (AISC - Steel Structures of the Everyday) Steel Trusses 4 Foundations Structures F2009abn Steel Trusses 3 Foundations Structures F2009abn Lecture 19 ARCH 331 Lecture 19 ARCH 331 1

Open Web Joists Manufactured Trusses • SJI: www.steeljoist.com • open web joists • Vulcraft: www.vulcraft.com • parallel chord – 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 Steel Trusses 6 Foundations Structures F2008abn Steel Trusses 5 Foundations Structures F2008abn Lecture 19 ARCH 331 Lecture 19 ARCH 331 Load Tables - w Decks • sheet steel • composite load for live load deflection limit (L/360) in RED total in BLACK Steel Trusses 7 Architectural Structures F2008abn Steel Trusses 8 Foundations Structures F2008abn Lecture 19 ARCH 331 Lecture 19 ARCH 331 2

Light-gage Steel Steel Decks • sheet metal • “ Texas ” style – shaped – corrugated – studs, panels, • common window frames – 1 – 3 spans – gage – can be • based on weight of insulated 41.82 lb/ft 2 / inch of thickness – composite • 24, 22, 18, 16, i.e. • with concrete • 0.0239, 0.0329, 0.0474, 0.0598 in • 0.6, 0.85, 1.0, 1.3, 1.6 mm Steel Trusses 9 Foundations Structures F2008abn Steel Trusses 10 Foundations Structures F2008abn Lecture 19 ARCH 331 Lecture 19 ARCH 331 Steel Decks Load Tables - w • common fire proofing • live load deflection limit – cementitious spray L/240 – composite concrete • non-composite – concrete is fill • lateral bracing • diaphragm action Steel Trusses 11 Foundations Structures Su2011abn Steel Trusses 12 Foundations Structures F2008abn Lecture 19 ARCH 331 Lecture 19 ARCH 331 3

Web Bearing Plate Girders • max loads • welds   • web stiffeners P ( N 2.5 ) k F t  n(max end) yw w   P ( N 5 ) k F t  n(max interior) yw w http:// nisee.berkeley.edu/godden Steel Trusses 14 Foundations Structures F2008abn Steel Trusses 13 Foundations Structures F2009abn Lecture 19 ARCH 331 Lecture 19 ARCH 331 Space Trusses Space Trusses • supports • connections • 3D with 2 force bodies and pins – pyramid – tetrahedron • “ frames ” have fixed joints • layers • 40 ’ s Steel Trusses 16 Foundations Structures F2008abn Steel Trusses 15 Foundations Structures F2008abn Lecture 19 ARCH 331 Lecture 19 ARCH 331 4

Space Trusses Space Trusses http:// nisee.berkeley.edu/godden http:// nisee.berkeley.edu/godden Steel Trusses 17 Foundations Structures F2009abn Steel Trusses 18 Foundations Structures F2009abn www.archdaily.com Lecture 19 ARCH 331 Lecture 19 ARCH 331 Tensegrities Method of Sections • 3D frame • relies on internal forces being in equilibrium on a section • discontinuous struts • cut to expose 3 or less members • continuous cables • coplanar forces   M = 0 too P P C AC F D A . E B AB A B y Free Ride Home – Kenneth Snelson Steel Trusses 19 Foundations Structures F2008abn Steel Trusses 20 Foundations Structures F2008abn Lecture 19 ARCH 331 Lecture 19 ARCH 331 5

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 P P . C AC F D A . E B B A AB B y Steel Trusses 21 Foundations Structures F2008abn Lecture 19 ARCH 331 6