Research On U-RC Composite Pier Test Design

The sea-crossing bridge piers made of marine concrete are mainly placed by steel template.The engineering cost is high and there is a serious corrosion problem.The new structure of the bridge pier with Ultra-High Performance Concrete(UHPC)template is adopted,which not only has good corrosion resistance and permeability resistance,but also has the advantages of convenient construction,low cost and wide application prospect.This thesis promoted research of trial design about the new structure.The main research results are presented as follows:(1)Based on the actual engineering of Pingtan Strait Bridge,according to the original design of vase type bridge pier,the trial design change the vase type bridge pier into the diameter 280cm double column pier,and the outer nested 10cm thickness UHPC is used as the construction template,namely U-RC composite bridge piers.On the basis of the trial design,the three forms of the UHPC template joint are proposed,included epoxy resin joint,steel plate welded joint and bolt connection joint and compared the advantages and disadvantages of the three kinds of joints.(2)By using MIDAS/CIVIL software to make the calculation the internal force and resistance,the results show the control section can meet the requirements.And the safety of the joint in the process of the construction process is also checked.The results show that the design of the 10cm thickness UHPC template and the epoxy joint meet the construction requirements.Compared with the original design of the engineering quantity,the trial design of steel could save about 2410t,and total cost savings of nearly 30%.The above conclusion presented the application of UHPC in bridge pier template has advantages over the original design in construction and economy.(3)In order to explore the performance of U-RC composite columns,according to the trial design of U-RC composite structure,an experiment with ultimate bearing capacity includes 3 reinforced concrete column,3 UHPC casing,3 U-RC composite columns is reported.The longitudinal strain and transverse strain of concrete in the column were measured.The failure mode and the development of the crack were observed,and the test values of the ultimate bearing capacity were obtained.The test results show that the failure of U-RC composite column in axial compression test is due to the transverse deformation of concrete core to outer UHPC.UHPC did not reach the ultimate compressive strain and the its failure with cracks carrying out.It can be infer that UHCP layer has hooping effect with core concrete.Compared with the ordinary concrete column,the initial crack load of U-RC composite column is delayed,it is good for corrosion protection of bridge pier.The failure mode is tear,which leads to the separation of UHPC and core concrete.(4)By using the finite element analysis software ABAQUS to develop the FEM modeling to calculate the bearing capacity of the specimen are basically consistent with the experimental results,which shows that the finite element model can better simulate the performance of the test.