Research On Seismic Performance Of Prestressed Fabricated UHPC Retaining Block For Bridge Structures

With the rapid development of China’s traffic infrastructure,bridge engineering is playing such an increasingly important role in the traffic network.Therefore,it is of great engineering significance to reduce the damage probability of bridge s and improve the recoverable function of traffic network after the unpredictable earthquake event.Based on the concept of functionally recoverable seismic design,this paper proposes a new prestressed prefabricated UHPC retaining block that used in bridg e structure.The seismic performance of the new block was studied by combining with the model load test and theoretical analysis.The main research content and work are as follows:(1)The ABAQUS finite element(FE)model of the normal concrete(NC)prefabricated retaining block with the under pedestal is established,and the FE model is verified based on the existing test results.Then the influence of friction coefficient,material strength and prestressing on the mechanical properties of the new block ar e analyzed.The existing problems of the prefabricated NC block are summarized and put forward the solution of using UHPC instead of NC.The results show that the friction between the retaining block and the side of the cap beam affects the energy dissipation performance of the prefabricated block.The critical rotational load and bearing capacity increase with the increase of lateral prestressing load.Due to the limitation of material strength,it is difficult to improve the bearing capacity of the NC retaining block fundamentally only by increasing the number of steel tendons.(2)The prestressed prefabricated UHPC retaining block structure without the under pedestal is studied experimentally.The failure process of the UHPC retaining block under one-way cyclic load are analyzed corresponding to different design parameters.The effects of the height of loading position,the thickness and the initial tension on the bearing capacity,stiffness and self-resetting performance of the UHPC retaining block are discussed.The results show that increasing the height of loading position will reduce the bearing capacity,critical rotational load and stiffness of the block,while increasing the initial tension and the thickness of the block can effectively improve the bearing capacity of the block.(3)The ABAQUS FE model of the UHPC prefabricated retaining block without the under pedestal is established and the accuracy and applicability of the FE model are verified.The influences of the friction coefficient,initial tension,prestressing duct and the thickness of the block on the mechanical properties of the new prefabricated UHPC retaining block are analyzed.The results show that the influence of friction on the mechanical properties of the new prefabricated UHPC b lock is negligible,and the initial tension will affect the critical rotational load of the block.The larger the prestressing duct is,the lower the bearing capacity of the block will be.The thicker the block,the greater the bearing capacity.(4)Based on the research results from both of experiment and finite element numerical simulation,the formula derivation process of the theoretical mechanics analysis model for two types of prestressed prefabricated UHPC retaining block is applied and calculation formula of this model is obtained.Then,these formulas are verified by using the FE analysis method.