Stability Analysis of Single and Double Steel Girders during Construction

Built-up steel I-girders are very commonly used in bridge construction. Their spans are typically very long, and they are susceptible to lateral torsional buckling if not enough lateral support is provided. This thesis includes guidelines for preventing lateral torsional buckling of steel I-girders under dead and wind load, accompanied with finite element analysis of double girder systems. The first portion includes capacity envelopes for single girders with single and double symmetric cross sections under various loading conditions and boundary conditions for double and single symmetric cross sections with double girders subjected to dead loads only. The second portion is dedicated to finite element analysis of double girders. Buckling analyses have been conducted on single symmetric double girders to verify their capacity equations and investigate the behavior of double girders subjected to wind load. The analyses focus on the weak axis bending of the double girder system as a whole and an evaluation of whether buckling of cross-bracing is an issue when lateral loads are present.