Investigation of equal strength mild steel tenons as displacement restraining devices for long-span railway arch bridges

Abstract

In this paper, Equal Strength Mild Steel Tenons (ESMSTs) have been developed as a candidate for displacement restraining device of long-span railway arch bridges. They are made of a cheap and easily fabricated material, low carbon mild steel. The geometry is designed according to the principle of equal strength beam to make full use of the ductile deformation of mild steel, increase the energy dissipation capacity and alleviate damage concentration. To begin, the design concept of ESMST is given followed by the derivation of the theoretical formula of the mechanical properties with the vertical free mechanism which is of no vertical load to guide the design. A pseudo-static experiment program is then presented for two full-scale 2.5 m tall ESMSTs. Besides, a rigorous 3D numerical model was developed in ABAQUS to reproduce the behavior of ESMSTs to guide the design of ESMST in future application. Finally, a case study is presented for the application of ESMST in one of typical long-span railway arch bridges to evaluate its efficiency and effectiveness. The test results indicate that the tested ESMSTs can meet the demands of the long-span railway arch bridges for high initial stiffness, energy dissipation and deformability under strong earthquake action. It was also found that the ESMST had good fatigue performance. In addition, the developed numerical model in ABAQUS can accurately reproduce hysteretic behavior of the ESMST and hence can be used with confidence in the future to guide the design of ESMSTs. Results from the case study show the ESMSTs can work effectively and efficiently in reducing the response of long-span railway arch bridges without imposing much additional demand on the substructure. Findings of this study can provide guidance on the design of ESMSTs as well as support for the application of the ESMSTs in long-span railway arch bridges.