Experimental study on prestressing method of tension string structure of long span emergency bridge

Abstract In order to develop a suitable method for applying prestress in large‐span emergency bridges with a tensegrity beam structure, this paper proposes a prestress application method based on diamond strut mechanism. The 92 meters long span emergency bridge is taken as the research background. The bridge is a lightweight and high‐load emergency bridge equipment, which can quickly restore traffic after traffic interruption caused by natural disasters or sudden emergency rescue situations. Compared with the existing tensioning method and strut rotation method, this method can save 97% and 74% of the external force requirements, respectively, while providing the same top bracing force. Only a 3t lever hoist can complete the application of prestress. And existing methods require heavy hydraulic equipment or traction machine. Therefore, this method is more convenient and labor‐saving than the traditional method of prestressing. A 1:1 scale strut mechanism test piece was designed and made. Prestress application tests and strut mechanism loading tests were conducted. The test results show that: the prestressing application method based on the top brace of diamond strut is simple and fast, and can meet the demand of 160kN pre‐top brace force; from the load‐displacement curve from zero to the maximum internal force of 620KN of the struts under the full bridge through‐loaded condition. The bracing structure has consistently remained within the linear elastic phase, and the structural safety requirements are met.