Study On Seismic Behavior Of Reinforced Concrete Columns With Permanent Template Of Ultra-high Performance Concrete

In the early stage of this project,the static load tests were carried out on the slabs and beams with permanent template of ultra-high performance concrete(UHPC).The results show that the bonding performance between UHPC template and post-poured concrete is good.No bond-slip cracks were found between UHPC template and post-poured concrete before the peak load of beam and slab members.However,the performance of RC columns subjected to repeated loads still needs to be discussed through experimental study.Therefore,this paper intends to study the seismic behavior of RC columns with permanent template of UHPC.The main research contents and results are as follows.(1)In order to investigate the failure patterns,hysteretic behavior,deformation and energy dissipation capacity and strength and stiffness degradation,pseudo-static tests of six permanent template columns(PTC)and one RC column for comparison purpose were tested with varying shear span ratio,axial load ratio,concrete cover and stirrup spacing.Test results show that the permanent templates that perpendicular to the direction of loading debonded at about 70% of the peak load;the permanent templates that parallel to the direction of loading debonded at the final destruction of the specimen.Under the condition of the same shear span ratio,axial load ratio and the number of stirrup,the seismic behavior of the specimen with UHPC template and 10 mm concrete as cover is relatively better than others,and its bearing capacity and prophase stiffness are slightly decreased.(2)Based on ABAQUS software,the finite element model of RC column with the permanent UHPC template is established.The stress and failure process of the specimens are simulated numerically,and the accuracy of the finite element model is verified.Based on the finite element model in this paper,the seismic performance of this kind of column is deeply analyzed considering the variation of the design parameters of the tests.The results show that the trend of the simulated hysteretic curve is similar to that of the test hysteretic curve;the axial loadratio and shear span ratio have obvious influence on the bearing capacity,deformation capacity and energy dissipation capacity of of RC column with the permanent UHPC template.(3)According to the equilibrium equation of force,compatibility condition of deformation and material constitutive model,the formulas for calculating the load and displacement of the column at crack point,yield point and peak point are derived,and the load-displacement calculation model is established.The results show that the calculated values of load and displacement are close to the experimental values.It provides a basis for establishing the restoring force model of this kind of column.