][ STEEL
STRUCTURES ][
][ STEEL
STRUCTURES ][
TENSION CONNECTIONS WITH BOLTS
================================
P&A 347
Two stress investigations:
==================
reduced section through the hole
load capacity of bolt
Net Section:
=========
allowable tension stress = 0.50 Fu
Fu = ultimate tensile strength of steel
PA 266 & 267 Table 8.1 Fu=58=29ksi
Unreduced Section:
==============
allowable tension stress = 0.60 Fy
PA 266 & 267 Table 8.1 Fy=36 = 22ksi
Threaded Rods:
===========
allowable tension stress = 0.33 Fu
PA 266 & 267 Table 8.1 Fu=58=19ksi
Effective Net Area:
==============
Ae = Ct x An
Ae = reduced effective net area
An = actual net area
Ct = reduction coefficient
Ct = 0.90
for W, M, or S shapes with flange widths
not less than 2/3 the depth of structural tees
cut from such shapes,
when the connection is to the flanges and has
at least 3 fasteners per line in the direction of
the stress
Ct = 0.85
for W, M, or S shapes not meeting the above
conditions and for tees cut from such shapes,
provided the connection has no fewer than
3 fasteners per line in the direction of the stress
Ct = 0.75
For all members with connections that have only
2 fasteners per line in the direction of stress.
Larger Ct reduction coefficients may be justified by testing.
Punched Holes:
===========
for Rivets
and Bolts
punching damages
net section is 1/8 inch larger
than nominal diameter of fastener
Single Row of Fasteners:
==================
O O O O
Net area = net width x plate thickness
Staggered Row of Fasteners:
=====================
O O O O
O O O
In the case of a chain of holes extending across a part in any diagonal or zigzag line, the net width of the part shall be obtained by deducting from the gross width the sum of the diameters of all the holes in the chain and adding, for each gage space in the chain, the quantity.
s x s / 4 g
s = longitudinal spacing (pitch) in inches
for any 2 successive holes.
g = transverse spacing (gage) in inches
for the same 2 holes
width
- sum( O......O)
+ s x s / 4 g
-----------------------
Net Width
TEARING IN BOLTED CONNECTIONS ============================== P&A 350 Shear & Tension Forces ================= tearing out the edge of one of the attached members shear = horizontal tension = vertically TEARING IN BOLTED CONNECTIONS
Net Tension Area ============= shear = 0.30 Fu PA 266 & 267 Table 8.1 Fu=58=17.4ksi tension = 0.50 Fu PA 266 & 267 Table 8.1 Fu=58=29ksi Known: ====== Edge Distance Hole Spacing Diameter of Hole Determine: ======== Net Width Shear Tension Stresses Total Tearing Load
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©Dr. Gruenwald 1996, 1997
