Time-Dependent Analysis of Long-Span, Concrete-Filled Steel Tubular Arch Bridges

Concrete-filled steel tubular (CFST) arch bridges have gained popularity over the last decades for use in long-span applications. At service conditions, these bridges are influenced significantly by the time-dependent behavior of the concrete. This paper presents a finite-element model that was developed using commercial finite-element software and is capable of describing the time-dependent behavior. The proposed approach can account for the construction process, time effects, and geometric nonlinearity. The time-dependent behavior of the core concrete in the arch ribs was modeled using European guidelines and the integral-type creep law, implemented with the finite-element model with a user-defined subroutine. The accuracy of the proposed method was validated against real site measurements recorded for a representative arch bridge. As part of this work, the necessity of considering the variation of the time of first loading and the geometric nonlinearity has been discussed. Finally, a simplified method was developed based on the results of the refined finite-element model and is recommended for possible use in day-to-day routine design.