Steel Designers Manual - TheBestFriend.org

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Steel Designers' Manual - 6th Edition (2003)
JOISTS
Dimensions and properties 1177
REDUCED PLASTIC MODULUS UNDER AXIAL LOAD
xx
Section Plastic Major Axis Reduced Modulus Plastic Minor Axis Reduced Modulus
Designation Modulus
Modulus
Axis
x-x
Lower Values
Of n
Change
Formula
Higher Values
Of n
Axis
y-y
Lower Values
Of n
Change
Formula
At n =
Higher Values
Of n
cm 3
K1 K2 At n1 = At n2 = K3 K4 cm K1 K2 K3 K4
254 ¥ 203 ¥ 82 # 1080 1080 2680 0.195 0.504 134 8.88 371 371 107 0.248 597 0.548
254 ¥ 114 ¥ 37 ‡ 459 459 737 0.354 0.576 49.0 11.3 79.1 79.1 22.1 0.408 190 0.236
203 ¥ 152 ¥ 52 # 541 541 1250 0.213 0.490 72.7 8.30 176 176 54.5 0.272 292 0.511
152 ¥ 127 ¥ 37 # 279 279 542 0.256 0.533 44.4 7.15 99.8 99.8 37.0 0.334 186 0.412
127 ¥ 114 ¥ 29 # 181 181 342 0.262 0.542 30.5 6.77 70.8 70.8 27.5 0.347 132 0.407
127 ¥ 114 ¥ 27 # 172 172 396 0.208 0.507 25.6 7.48 68.2 68.2 23.1 0.275 112 0.523
127 ¥ 76 ¥ 16 ‡ 104 104 198 0.272 0.500 14.6 8.18 26.4 26.4 8.75 0.337 50.3 0.388
114 ¥ 114 ¥ 27 ‡ 151 151 313 0.234 0.557 26.0 6.58 65.8 65.8 26.0 0.315 121 0.420
102 ¥ 102 ¥ 23 # 113 113 226 0.239 0.534 21.2 6.04 50.6 50.6 21.2 0.329 90.8 0.428
102 ¥ 44 ¥ 7 # 35.4 35.4 52.5 0.391 0.575 5.07 8.52 6.03 6.03 2.22 0.460 16.1 0.143
89 ¥ 89 ¥ 19 # 82.7 82.7 163 0.240 0.515 17.4 5.36 38.0 38.0 17.4 0.340 67.9 0.416
76 ¥ 76 ¥ 15 ‡ 54.2 54.2 103 0.250 0.533 11.4 5.37 25.8 25.8 12.0 0.354 47.4 0.404
76 ¥ 76 ¥ 13 # 48.7 48.7 129 0.170 0.463 8.66 6.15 22.4 22.4 8.66 0.239 34.2 0.576
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n = F/(A py), where F is the factored axial load, A is the gross cross sectional area and py is the design strength of the section.
For values of n lower than n1, the reduced plastic modulus, Srx = Srx1 = K1 - K2.n 2 , for major axis bending.
For values of n higher than n2, the reduced plastic modulus, Srx = Srx2 = K3(1 - n)(K4 + n), for major axis bending.
For values of n between n1 and n2, the reduced plastic modulus, Srx = Srx1 + (Srx2 - Srx1)(n - n1)/(n2 - n1), for major axis bending.
For lower values of n, the reduced plastic modulus, Sry = K1 - K2.n 2 , for minor axis bending.
For higher values of n, the reduced plastic modulus, Sry = K3(1 - n)(K4 + n), for minor axis bending.