STUDY ON FACTORS AFFECTING THE LIMIT STATE OF POSITIVE BENDING SECTIONS IN CONTINUOUS COMPOSITE GIRDERS

Abstract

 Recently, it is thought to be possible to use plastic moment M_p as the bending capacity of girders in conjunction with the revision of the specifications for highway bridges in 2017. Overseas specifications, such as LRFD and EC, permit to design the simple girders based on M_p as the bending capacity. However, in the design of continuous girders by LRFD and EC, there are cases in that the bending capacity has to be reduced under M_p considering the effects of moment redistribution due to non-linear behavior of negative bending sections. By contrast, the design method which utilize M_p as the bending capacity of girders has not been clarified in the specifications for highway bridges in Japan. Therefore, it is important to clarify the limit states of continuous composite girders in order to spread design of continuous composite girders considering M_p as the bending capacity. In this study, bending behaviors of three-span continuous composite with variation in span-ratio and distribution of bending stiffness are investigated theoretically. As a result, it is found that the bending capacity does not need to be reduced under M_p for all cases investigated in this study.