Study on flexural behavior of built-in thin-walled H-steel timber composite beam

In order to achieve efficient combination of steel and timber, and improve the flexural behavior of the steel timber composite beam, a novel built-in thin-walled H-steel timber composite beam was proposed. To investigate the failure process, failure modes and composite bearing capacity mechanism of the proposed steel timber composite beam, bending tests were carried out with considered parameters including width of timber flange, spacing of flange shear connection screws, thickness of thin-walled H-steel, thickness of timber flange, height of timber web and thickness of timber web. In addition, the simplified predicted formulas of deflection and flexural capacity were also proposed for the built-in thin-walled H-steel timber composite beam, and the 3D finite element numerical simulation was developed as well. The results show that the failure modes can be divided into three types according to failure process and characteristics, including cracking in tension of tension flange board, cracking in tensile area of web board, and compression failure of compression flange board, or servere buckling of compression flange and servere adhesive peeling. The built-in thin-walled H-steel timber composite beam, with section area ratio about 3.5% of thin-walled H-steel, can significantly increase the flexural capacity, flexural stiffness, energy dissipation and ductility compared with pure timber beams. The flexural behavior of the built-in thin-walled H-steel timber composite beam is significantly influenced by the height of timber web, the width of timber flange, the thickness of timber flange and the spacing of flange shear connection screws. With the increasing of the height of the timber web, the width of the timber flange, the thickness of the timber flange and the decreasing of the spacing of flange shear connection screws, the flexural capacity of the built-in thin-walled H-steel timber composite beam is significantly improved. Increasing the thickness of the thin-walled H-steel can improve the flexural capacity and stiffness of the steel timber composite beam to a certain extent. While the influence of the thickness of the timber web on the flexural capacity is not obvious. The predicted formulas of deflection and flexural capacity and the FE model are rational and verified through a comparison with experimental results, showing reasonable agreement. © 2022, Editorial Office of Journal of Building Structures. All right reserved.