Comparison of detailing methods for straight skewed steel I-girder bridges

Abstract

The effects of support in steel bridges can present significant challenges during construction. The tendency of the girder to twist or layover during the placement of the deck can present a particularly challenging problem regarding detailing the cross-frames that provide bracing to the steel girders. There are generally three alternatives regarding the detailing for the cross-frames to achieve an approximate plumb condition of the webs: 1) detailing for no load fit, 2) detailing for steel dead load fit, or 3) detailing for total dead load fit. In the past, different detailing methods have been investigated to identify and compare structural responses affected by the detailing methods. However, the use of wrong camber diagrams in these studies lead to erroneous calculations of structural responses for total dead load fit.The objectives of this paper are: 1) to identify structural responses that are affected by different detailing methods, and 2) to compare different detailing methods for straight skewed I-girder bridges using correct cambers.Different structural responses affected by detailing methods, henceforth called lack-of-fit effects, are discussed for each method. It has been shown that line girder analysis cambers should be used instead of 2D grid analysis cambers to simulate lack-of-fit for the final fit detailing method. It has been found that lack-of-fit effects for the final fit detailing method at steel dead load stage are equal and opposite to the lack-of-fit effects for the erected fit detailing method at total dead load stage.