Influence of construction process on long-term responses of CFST trussed arch bridges

As the span of concrete-filled steel tubular (CFST) arch bridge increases, time effects has a considerable influence on the static behavior of the arches. A refined finite element model was brought up to predict the long-term response of concrete-filled steel tubular (CFST) arch bridge accounting for the construction process, aging of concrete, time effects under both axial forces and moments, and geometric and material nonlinearities. The creep and shrinkage of concrete core for CFST arches was modelled using the Eurocode 2 (EC2) model. The time-dependent behavior of concrete core under various stress history was simulated with the step-by-step method. The EC2 model and the step-by-step method were implemented in ABAQUS with the UMAT subroutine. The reliability of the model was benchmarked against site-measured data of real bridge application. With this model, the influence of the construction process on the long-term response of CFST arch bridges was investigated. It is noted that the construction process can significantly increase the long-term displacement of the arches, the stresses in the steel tubes, and the bending moment along the arch ribs. When discussing the time effects of the concrete core on the static response of the CFST arch bridges, construction process needs to be considered, otherwise considerable underestimation will be resulted.