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Connections 1Lecture 26
Architectural Structures IENDS 231
F2007abn
ARCHITECTURAL STRUCTURES I:STATICS AND STRENGTH OF MATERIALS ENDS 231
DR. ANNE NICHOLS
FALL 2007
lecturetwenty sixsteel connections:
bolts, welds &tension members
Connections 2Lecture 26
Architectural Structures IENDS 231
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Connections• needed to:
– support beams by columns– connect truss members– splice beams or columns
• transfer load• subjected to
– tension or compression– shear– bending
Connections 3Lecture 26
Architectural Structures IENDS 231
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Bolts• bolted steel connections
Connections 4Lecture 26
Architectural Structures IENDS 231
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Welds• welded steel connections
Connections 5Lecture 26
Architectural Structures IENDS 231
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Fasteners• wood connections
Connections 6Lecture 26
Architectural Structures IENDS 231
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Bolted Connection Design• considerations
– bearing stress• yielding
– shear stress• single & double
– member• rupture
Connections 7Lecture 26
Architectural Structures IENDS 231
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Bolted Connection Design• ASD steel
– shear:
• bolt strengths• single & double
– bolt types• A325-SC, A490-SC• A325-N, A490-N• A325-X, A490-X
vv Ff ≤
Connections 8Lecture 26
Architectural Structures IENDS 231
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Bolted Connection Design• ASD steel
– bearing:• bolts rarely
fail by bearing• other part fails first
Connections 9Lecture 26
Architectural Structures IENDS 231
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Tension Members• steel members can have holes• reduced area• increased stress
Connections 10Lecture 26
Architectural Structures IENDS 231
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Effective Net Area• likely path to “rip” across• bolts divide transferred force too
Connections 11Lecture 26
Architectural Structures IENDS 231
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ASD – Tension Members• non-pin connected members:
– Ft = 0.60Fy on gross area– Ft = 0.50Fu on net area
• pin connected members: – Ft = 0.45Fy on net area
• threaded rods of approved steel: – Ft = 0.33Fu on major diameter – (for static loading only)
Connections 12Lecture 26
Architectural Structures IENDS 231
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LRFD - Tension Members• limit states for failure1. yielding
2. rupture*
Ag - gross area Ae - effective net area Fu - tensile strengthof the steel (ultimate)
ntu PP φ≤
gynt AFP == 9.0φ
eunt AFP == 75.0φ
Connections 13Lecture 26
Architectural Structures IENDS 231
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Welded Connection Design• considerations
– shear stress– yielding– rupture
Connections 14Lecture 26
Architectural Structures IENDS 231
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Welded Connection Design• weld terms
– butt weld– fillet weld– plug weld– throat
• weld materials– E60XX– E70XX
FEXX = 70 ksi
Connections 15Lecture 26
Architectural Structures IENDS 231
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Welded Connection Design• ASD
– shear• Fv = 0.30Fweld
– throat• T =0.707 x weld size
– area• A = T x length of weld
– weld metal generally stronger than base metal (ex. Fy = 50 ksi)
vv Ff ≤
Connections 16Lecture 26
Architectural Structures IENDS 231
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Framed Beam Connections• angles
– bolted– welded
Connections 17Lecture 26
Architectural Structures IENDS 231
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Framed Beam Connections• terms
– coping
Connections 18Lecture 26
Architectural Structures IENDS 231
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Framed Beam Connections• tables for
standard bolt holes & spacings
• n = # bolts• angle leg
thickness• length needed
Connections 19Lecture 26
Architectural Structures IENDS 231
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Beam Connections• LRFD provisions
– shear yielding– shear rupture– block shear rupture– tension yielding– tension rupture– local web buckling– lateral torsional buckling
Connections 20Lecture 26
Architectural Structures IENDS 231
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Beam Connections• block shear rupture • tension rupture
