978-1337094740 Chapter 6 Part 2

subject Type Homework Help
subject Pages 14
subject Words 4047
subject Authors William T. Segui

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page-pf1
Pe1y2EIy
K1L22EIy
KyL2229000116
12 1221601 kips
B1yCmy
page-pf2
6.6-13
(a) LRFD solution:
page-pf3
2. 5Mmax 3MA4MB3MC
12. 54Q
2. 54Q3044Q301. 923
For Cb1. 923,
bMn1. 923331636. 5 ft-kips bMp600 ft-kips
use bMnbMp600 ft-kips
Pu
8
Mux
Muy
0. 7769 8
4. 096Q
Let 0. 7769 8
9
600 01, Solution is: 36. 77 kips
Maximum Q36. 8 kips
page-pf4
2. 5Mmax 3MA4MB3MC
12. 52. 5Q
2. 52. 5Q3042. 5Q301. 923
For Cb1. 923,
Mn
b
1. 923220423. 1 ft-kips Mp
b
399 ft-kips
page-pf5
Pa
8
Max
May
0. 7803 8
2. 563Q
Let 0. 7803 8
2. 563Q
6.7-1
Determine the axial compressive design strength. Use LcKxLfor the unbraced
page-pf6
2. 5Mmax 3MA4MB3MC
12. 5135. 7
2. 5135. 7335. 11421. 83378. 772. 208
For Cb2. 208, bMn2. 2084791058 ft-kips
Pu
8
Mux
Muy
0. 5182 8
135. 7
6.7-2
(a) LRFD solution
M2
98. 4 0. 266 7
For the braced case,
Pe12EIx
page-pf7
2. 598. 4336. 948. 20353. 32. 239
For Cb2. 239, bMn2. 239415929. 2 ft-kips
Since 929.2 ft-kips bMp,usebMnbMp473 ft-kips
Pu
528
Pu
cPn
8
9
Mux
bMnx
Muy
bMny
0. 8341 8
9
98. 4
473 0
page-pf8
b
Since 618.0 ft-kips Mp
b
,use Mn
b
Mp
b
314 ft-kips
Pa
360
6.8-1
(a) LRFD solution
The factored axial load is
Pu1. 20. 30 2361. 60. 70 236349. 3 kips
page-pf9
Pu
cPn
8
9
Mux
bMnx
Muy
bMny
0. 7308 8
9
248. 6
258 0
Pu
cPn
8
9
Mux
bMnx
Muy
bMny
0. 4318 8
9
248. 6
422 00. 955 4
0. 955 1. 0 (OK)
Calculate B1:
is not needed.)
UseaW1279
selection.
page-pfa
Mnx
281 ft-kips and Pn
538 kips
Pn/c
538 0. 438 7 0. 2 use Equation 6.5 (AISC Eq. H1-1a):
Pa
Pn/c
8
9
Max
Mnx/b
May
Mny/b
0. 4387 8
9
168
281 0
0. 970 1. 0 (OK)
6.8-2
Mux (top) 182 ft-kips
page-pfb
Pu
400
6.8-3
(a) LRFD Solution
Mntx 1
As a preliminary check (remember that Cbhas not been accounted for)
Pu
Mux
Muy
0. 1918 135
page-pfc
Cb
bMn1. 14157179. 0 ft-kips bMp176 ft-kip
use bMn176 ft-kips
Pu
2cPn
Mux
bMnx
Muy
bMny
0. 1918 138. 2
176 0
Pn/c234 kips Mnx/b104 ft-kips
As a preliminary check (remember that B1has not yet been computed and Cbhas not
been accounted for),
Pa
Pn/c
45
234 0. 192 3 0. 2 use Equation 6.6 (AISC Equation H1-1b)
Pa
Max
May
45
page-pfd
Pe1x
2885
Max B1xMntx 1. 0269092. 34 ft-kips
From Figure 5.15 in the textbook, Cb1. 14. Modify Mnx/bto account for Cb.
6.8-4
Pu140 kips
The factored moments at the top are
Mntx Mnty 150 ft-kips
The factored moments at the bottom are
As a preliminary check (remember that Cbhas not been accounted for)
Pu
2cPn
Mux
bMnx
Muy
bMny
140
21020150
525 150
260 0. 931
0. 931 1. 0 (OK)
[6-33]
© 2018 Cengage Learning®. All Rights Reserved. May not be scanned, copied or duplicated,
or posted to a publicly accessible website, in whole or in part.
page-pfe
bMnx 568 ft-kips, cPn979 kips, and bMny 273 ft-kips
Determine which interaction equation to use:
Pu
cPn
140
979 0. 143 0. 2 use Equation 6.4 (AISC Eq. H1-1b):
As a preliminary check,
Pu
Mux
Muy
140
B1xCmx
1Pu
Pe1x
0. 4
1140
7756
0. 407 1.0 B1x1. 0 as assumed
Pe1y2EIy
page-pff
6.8-5
(a) LRFD Solution
Pu1. 21351. 6415826. 0 kips
The factored moments are
Mntx (top) 1. 2901. 6270540. 0 ft-kips
Pu
cPn
8
9
Mux
bMnx
Muy
bMny
826
1620 8
9
540
1030 0
0. 976 1/0 (OK)
Calculate B1for the axis of bending:
[6-35]
© 2018 Cengage Learning®. All Rights Reserved. May not be scanned, copied or duplicated,
or posted to a publicly accessible website, in whole or in part.
page-pf10
(Since this shape is adequate for Cb1.0, computation of the actual value of Cbis not
necessary.)
UseaW14159
(b) ASD Solution
been accounted for),
Pa
Pn/c
550
1070 0. 514 0. 2 use Equation 6.5 (AISC Equation H1-1a)
Pa
8
Max
May
0. 514 8
360
Pn/c
9
Mnx/b
Mny/b
9
618 01. 08
Calculate B1:
[6-36]
© 2018 Cengage Learning®. All Rights Reserved. May not be scanned, copied or duplicated,
or posted to a publicly accessible website, in whole or in part.
page-pf11
Cmx 0. 6 0. 4 M1
M2
0. 6 0. 4 120
360 0. 466 7
2. 536030412032402. 143
CbMnx/b2. 1436181324 ft-kips Mpx/b649 ft-kips
use Mnx/b649 ft-kips
6.8-6
(a) LRFD Solution
Mntx 1. 2160/21. 6160/2224. 0 ft-kips
page-pf12
bMnx 461 ft-kips cPn898 kips bMny 229 ft-kips
Determine which interaction equation to use:
Pu
cPn
128. 8
898 0. 143 4 0. 2 use Equation 6.4 (AISC Eq. H1-1b):
As a preliminary check (remember that Cbhas not been accounted for)
Pu
Mux
Muy
128. 8
Check the W14s. Try a W14 82. From Table 6-2,
bMnx 462 ft-kips cPn697 kips bMny 168 ft-kips
Pu
cPn
128. 8
697 0. 184 8 0. 2 use Equation 6.4 (AISC Eq. H1-1b):
Pu
Mux
Muy
128. 8
M2
299. 6 0. 300 9
Cmy 0. 6 0. 4 M1
M2
0. 6 0. 4 33. 6
43. 4 0. 290 3
Pe1x2EIx
Lcx22EIx
KxL2229000662
0. 8 16 1228031 kips
page-pf13
2. 5299. 6393. 1437. 83168. 72. 222
use bMn446 ft-kips
Pu
128. 8
The service-load moments at the bottom are
Mntx 214 ft-kips, Mnty 31 ft-kips
selection. For the two axes,
Max B1xMntx 1. 0214214 ft-kips
page-pf14
Check the W12s. Try a W12 79. From Table 6-2,
Mnx/b277 ft-kips Pn/c520 kips Mny/b135 ft-kips
As a preliminary check (remember that B1has not yet been computed and Cbhas not
been accounted for),
Pa
92
Cmx 0. 6 0. 4 M1
M2
0. 6 0. 4 160
214 0. 300 9
Cmy 0. 6 0. 4 M1
M2
0. 6 0. 4 24
31 0. 290 3
Pe1x2EIx

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