Hybrid Steel I‐girders: Cross‐section Behaviour and Moment Redistribution Capacity

Abstract Hybrid steel I‐girders, incorporating varying strength grades for constituent plates, present a versatile solution to accommodate different bending loading conditions. This study examined experimentally and numerically the performance of hybrid I‐girders with high strength flange plates and lower strength webs. The impact of lower strength webs on the moment‐rotation characteristics of hybrid steel I‐girders with diverse section geometries was analysed. The findings suggest that lower strength webs could enhance the rotation capacity of I‐girders, but Class 1 and compact sections with high strength flanges fail to meet the rotation capacity requirement of 3. Moreover, based on an extensive database established in this study, the design methodologies for cross‐section resistance, as well as moment redistribution calculation methods specified in American bridge standards were evaluated. The assessment results indicates that the prescribed methods in the AASHTO bridge specification and Eurocode 3, along with the continuous strength method and direct strength method, could offer safe predictions for cross‐section resistance. Furthermore, the investigated I‐girders were shown to possess adequate moment redistribution capacity as outlined in the AASHTO bridge specification.