287plf 335plf Page 4 UNIVERSITY OF CALIFORNIA BERKELEY Department of Civil

# 287plf 335plf page 4 university of california

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Page 4 UNIVERSITY OF CALIFORNIA, BERKELEY Department of Civil Engineering CE 120 - Instructor: J. P. Moehle - Spring 201 5 To solve for Lc: 1)Set |+Mmax|=|-Mmax| or 2)Iterate. 1) Setting |+Mmax|=|-Mmax: +Mmax and –Mmax varies inversely with change of Lc. Therefore, minimum value for design moment will be obtained when |+Mmax|=|-Mmax|. w/8*(50-Lc) 2 = 25wLc (50-Lc) 2 = 200Lc (Note: does not depend on w) Lc=8.58ft. 2) Alternatively Lc can be found by Iteration: Lc (ft) Mb (k-ft) Mc (k-ft) Me(k-ft) Maximum Absolute Design Moment (k-ft) 0.00 233.44 0.00 233.44 233.44 1.00 224.19 -18.68 224.19 224.19 2.00 215.14 -37.35 215.14 215.14 3.00 206.27 -56.03 206.27 206.27 4.00 197.58 -74.70 197.58 197.58 5.00 189.08 -93.38 189.08 189.08 6.00 180.77 -112.05 180.77 180.77 7.00 172.65 -130.73 172.65 172.65 8.00 164.71 -149.40 164.71 164.71 9.00 156.96 -168.08 156.96 168.08 8.10 163.93 -151.27 163.93 163.93 8.20 163.15 -153.14 163.15 163.15 8.30 162.37 -155.00 162.37 162.37 8.40 161.59 -156.87 161.59 161.59 8.50 160.82 -158.74 160.82 160.82 8.60 160.04 -160.61 160.04 160.61 8.70 159.27 -162.47 159.27 162.47 Lc= 8.6ft gives minimum design moment of 160.6k-ft. [158.1k-ft]
UNIVERSITY OF CALIFORNIA, BERKELEY Page 5 Department of Civil Engineering CE 120 - Instructor: J. P. Moehle - Spring 2013

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