Experimental study on long-term performance of steel-concrete composite bridge with an assembled concrete deck

Due to the new-old concrete age difference, the long-term behavior of steel-concrete composite bridge with an assembled concrete deck is different from that of a monolithic concrete deck. In order to address this issue, a 1/6 scale mock-up for the segmental beam of one practical cable-stayed composite bridge was precast and assembled. Long-term performance test of 390 days was performed on the assembled mock-up subjected to sustained loads. Moreover, shrinkage and creep tests were also conducted on concrete prisms for precast slabs and post-pouring joint of the assembled mock-up. Meanwhile, two types of finite element (FE) models were established by using Midas FEA. The first one adopted the proposed analysis strategy considering the influence of concrete age difference between the post-pouring joint and the precast slabs, and the other one adopted the traditional analysis strategy ignoring the influence of the new-old concrete age difference. The experimental results were compared with the numerical results calculated by these two FE models. The FEM results calculated by the proposed model agreed well with the experimental observations, while the traditional model severely underestimated the effect of creep and shrinkage of the post-pouring joint concrete. The effect of the long-term performance of the new-old concrete reduced the value of normal stress in the post-pouring joint, and tensile stress led by the shrinkage difference of the new-old concrete could appear the position adjacent to the post-pouring joint under the condition of insufficient axial force of the assembled concrete deck. Moreover, water curing of the whole concrete deck of the assembled composite beam after casting the concrete of post-pouring joint can reduce the tensile stress of the concrete deck. Much attention should be paid to the influence of concrete age difference between post-pouring joint and precast slabs, during the serviceability behavior analysis of the assembled steel-concrete composite bridge.