Experimental study on assembled monolithic steel-concrete composite beam in positive moment

摘要

This study aims to investigate the static behavior of a simply-supported assembled monolithic steel-concrete composite beam (SCCB). A total of ten composite beams were tested considering the parameters of shear connection degree, reserved hole shape, concrete deck width, and deck casting method. Based on the test results, failure mode, stiffness, ductility, and moment capacity were obtained and are discussed in this paper. Compared to the conventional SCCBs with wide flange beams and headed shear connectors, the composite beam considered in this study has favorable flexural performance, while reducing the excessive cost and potential construction challenge due to the use of precast concrete (PC) deck. The flexural behavior of the new assembled monolithic SCCBs was investigated through the one-point bending tests on the ten specimens. The study results indicate that: (1) The assembled monolithic SCCB with shear stud group (SSG) or steel block shear connector (SBSC) has higher moment capacity and ductility, with the ductility factor ranging from 3.4 to 6.8; (2) the higher the degree of shear connection, the greater the moment capacity; (3) the SBSC has higher moment capacity and stiffness and is suggested for practical use for better welding quality and convenient construction; (4) the nonlinear calculation formula specified in GB50017-2017 (Code for Design of Steel Structures) predicts more accurate ultimate moment strength for the composite beams with partial shear connection than Eurocode 4, in comparison with the experimental results; (5) the SCCB with PC deck shows respective 50% and 174% higher elastic stiffness when using SSG and SBSC, compared to the SCCB with cast-in-place concrete (CIPC) deck.