Experimental Study and Multiscale Finite-Element Analysis on the Flexural Behavior of Precast Bridge Slabs with Headed Bar Joints

Abstract

To reduce the construction complexity of concrete bridge slabs, a novel-headed bar joint with high-performance fiber reinforced mortar (HPFRM) was proposed. In this study, the flexural performance of connected precast bridge slabs under different joint configurations was investigated through structural-level experiments, with a focus on the overlapping length of headed bar and the strength of the HPFRM. Four-point flexural tests were conducted considering five different parameter combinations. Furthermore, three 3D numerical simulation approaches, namely, the normal multiscale model, refined multiscale model, and normal solid model, were proposed and validated against the tests. Based on the test and numerical results, the failure mechanisms and force transmission patterns of the headed bar joint connections were analyzed. The test results indicate that higher material strength improves the flexural performance of precast bridge slabs. Given joints with the same filling material strength, the improvement of joint flexural capacity is subjected to a threshold value of overlapping length. The recommended joint width for high-strength HPFRM joints should not be <100 mm in practical design, corresponding to an overlapping length of 45.6 mm. Similarly, for medium-strength HPFRM joints, the recommended joint width should be at least 150 mm, with a corresponding overlapping length of 95 mm. Compared with the test results, all the three proposed numerical simulation methods exhibited good reliability in simulating the failure modes of the precast bridge slabs with headed bar joint connections. Moreover, the refined multiscale model exhibited higher accuracy and generalizability in simulating the interaction behavior between deformed reinforcement and the HPFRM without assuming bond–slip relationships.