Moment modification factor of I-girder with trapezoidal-web-corrugations considering concentrated load height effects

Moment modification factors of the I-girder with trapezoidal web corrugations subjected to concentrated load, applied at different heights on the cross section and various end restraint conditions, are investigated. The moment modification factors are obtained by finite element buckling analyses. The new FEM program is developed by using beam elements and new general formulas of cross-section properties as well as a new warping constant of the I-girder with trapezoidal web corrugations. The theoretical results of moment modification factors are compared with commercial finite element software (ABAQUS) using shell elements. A series of finite element analyses with different corrugation profiles and lengths is performed. Through comparative numerical studies, the theoretical results are successfully verified. The moment modification factors from the SSRC Guide are compared with present FEM results. The new values of the variable Cb, the moment modification factor, in the SSRC Guide are proposed as the variable Cb,c to improve the accuracy of lateral–torsional buckling strength.

Research highlights
► I-girder with trapezoidal web corrugations is investigated by developing a FEM program.
► Four types of end restraint conditions and various load height effects are considered.
► The moment modification factors from present specification are non-conservative.
► New formulas to calculate moment modification factors are proposed for design.