twenty three lecture - texas a&m...
TRANSCRIPT
Connections 1Lecture 23
Architectural Structures IENDS 231
Su2006abn
ARCHITECTURAL STRUCTURES I:STATICS AND STRENGTH OF MATERIALS ENDS 231
DR. ANNE NICHOLS
SUMMER 2006
lecturetwenty threesteel connections:
bolts, welds &tension members
Connections 2Lecture 26
Architectural Structures IENDS 231
S2006abn
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
S2006abn
Bolts• bolted steel connections
Connections 4Lecture 26
Architectural Structures IENDS 231
S2006abn
Welds• welded steel connections
Connections 5Lecture 26
Architectural Structures IENDS 231
S2006abn
Fasteners• wood connections
Connections 6Lecture 26
Architectural Structures IENDS 231
S2006abn
Bolted Connection Design• considerations
– bearing stress• yielding
– shear stress• single & double
– member• rupture
Connections 7Lecture 26
Architectural Structures IENDS 231
S2006abn
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
S2006abn
Bolted Connection Design• ASD steel
– bearing:• bolts rarely
fail by bearing• other part fails first
Connections 9Lecture 26
Architectural Structures IENDS 231
S2006abn
Tension Members• steel members can have holes• reduced area• increased stress
Connections 10Lecture 26
Architectural Structures IENDS 231
S2006abn
Effective Net Area• likely path to “rip” across• bolts divide transferred force too
Connections 11Lecture 26
Architectural Structures IENDS 231
S2006abn
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
S2006abn
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
S2006abn
Welded Connection Design• considerations
– shear stress– yielding– rupture
Connections 14Lecture 26
Architectural Structures IENDS 231
S2006abn
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
S2006abn
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
S2006abn
Framed Beam Connections• angles
– bolted– welded
Connections 17Lecture 26
Architectural Structures IENDS 231
S2006abn
Framed Beam Connections• terms
– coping
Connections 18Lecture 26
Architectural Structures IENDS 231
S2006abn
Framed Beam Connections• tables for
standard bolt holes & spacings
• n = # bolts• angle leg
thickness• length needed
Connections 19Lecture 26
Architectural Structures IENDS 231
S2006abn
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
S2006abn
Beam Connections• block shear rupture • tension rupture