Experimental Study On Seismic Performance Of New Prefabricated Retaining Block For The Pier Bent Cap Of Bridges

Seismic damages,such as transverse displacement and beam falling of the main girders,are very common in the bridge seismic damage investigation at home and abroad.The transverse anti-seismic retaining block is one of the important components to prevent the main beam from over transverse displacement and falling.In China,there is no clear design provision for the anti-seismic retaining block in the current bridge seismic design code.The damage probability of the retaining block composed of normal concrete(NC)under earthquake is very high.However,it is very difficult to repair the damaged retaining blocks after the huge earthquake.The existing test and theoretical research mainly focus on the integral common retaining block structure which were widely used in practical bridge engineering.However,these researches ignored the reliability of the retaining block repair or replacement after the earthquake.Therefore,this paper proposed a new prefabricated ultra-high-performance-concrete(UHPC)retaining block with clear loading transfer path,convenient repair and replacement after the earthquake.Four retaining block specimens were designed for low cycle quasi-static test,and the seismic performance of the new UHPC retaining block were investigated.The main contents and conclusions are as follows:(1)According to the different structure and material of the retaining block,four different retaining block specimens were designed and the one-way reciprocating loading test scheme was formulated.The quasi-static failure test was carried out.The failure process and phenomenon of four groups of block structures were studied.The results show that:(1)the horizontal bearing capacity of the lateral retaining block can be greatly enhanced by using the UHPC material.In the test,the damage of UHPC retaining block is very small,but the NC retaining block is destroyed basically;(2)the horizontal displacement capacity and self-resetting function of the lateral retaining block are greatly improved by using the prefabricated retaining block structure,and the damage degree of the prefabricated retaining block to the bent cap is far less than that of the integral retaining block;(3)the UHPC prefabricated retaining block can meet the requirements of bearing capacity,displacement capacity and self-resetting capacity at the same time.It is more convenient to replace and repair after the earthquake.Therefore,the proposed retaining blocks can be used as a beneficial alternative form of bridge anti-seismic retaining block design in China.(2)The three-dimensional finite element analysis models of four different block specimens were established by the ABAQUS software.Based on the test loading process,the finite element numerical simulation analysis was carried out and the numerical analysis results were compared with the test results.The results show that: the failure phenomena and force displacement hysteresis curves of different retaining blocks obtained by finite element analysis are basically consistent with the test results,which verifies the reliability and rationality of the four groups of finite element analysis models of the block,which can provide a theoretical basis for the further finite element parameter analysis of the assembled block.