huangyhg

lrfd vs. lfd temperature load
we are working on a three span deck truss design which has hollow stem piers. these piers were designed using the lrfd design specs. after the design was complete we decided to cross check it with the group v loading of lfd and found that the hollow stem pier would require approx. 25% more reinforcing steel with the lfd design. it appears that the 0.5 multiplier for temperature forces in the lrfd strength checks is the reason why there is such a difference between the two codes. could you provide any insight into the use of the 0.5 multiplier for lrfd as compared with the group v lfd loadings. at present, there is quite a disconnect between the two situations. the disconnect disappears if the 1.2 factor for displacements is used for the lrfd situation. did the aashto committee make a conscious decision to reduce force effects due to temperature changes from the lfd specifications?

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