Experimental Study On Interfacial Tensile Properties Of Prefabricated UHPC Wet Joint

The reason why segmental prefabrication can be widely used as the structural form of bridge engineering in China is mainly because the prefabricated bridge can guarantee the engineering quality,the construction speed is fast,the impact on the surrounding environment and traffic is small,and the span of the bridge can be widely used a series of advantages.Because the joints are the weak links of segmental prefabricated and assembled Bridges,the mechanical properties of segmental prefabricated and assembled Bridges are deeply affected by the mechanical properties of joints,whether in the limit state of normal use or in the limit state of bearing capacity.Therefore,it is of great practical significance to study the new type of wet joint structure and its mechanical properties of prefabricated concrete Bridges for accelerating construction speed,enhancing bridge quality and improving bridge durability.In order to study the mechanical properties of prefabricated UHPC wet joint interface under tensile action,the following researches are mainly carried out in this paper.Firstly,in view of the wet joints of concrete material type(C50 and UHPC),wet joints reinforced structure parameters,carried out three sets of a total of nine precast box girder assembled roof longitudinal tensile test of wet joint model,through the test and analysis of different load level joint of steel and concrete strain and displacement,found mainly due to the large interface place tensile strain of concrete specimen damage caused is often happened in precast segments and wet joint interface.Secondly,the finite element model of prefabricated UHPC wet joint under tensile load was established by comprehensively considering the strain rate effect and contact relationship of reinforcement and concrete under tensile load.The results of the finite element calculation were analyzed and compared with the previous tests to draw a data conclusion and verify the accuracy of the finite element model calculation.Finally,the finite element model after the above verification was used to analyze the influence of lap length and bar spacing on the tensile properties of the wet joint of prefabricated UHPC.Due to the relatively short lap length of the reinforcement at the joint,when the model reached the failure bearing capacity,the stress of the reinforcement did not reach its yield strength.Even if the steel bar spacing and the steel bar lap length in the joints are different,there is no significant difference in cracking load,but the resistance to deformation of wet joints changes after cracking.The deformation resistance of wet joints is enhanced with the decrease of the bar spacing and the increase of the section reinforcement ratio.