Seismic Behavior Of FRP-ECC Reinforced Concrete Columns With Ductile Hinges

As the largest deformation and energy consuming area in concrete structure,plastic hinge area is often damaged due to low ductility and poor energy consumption.For column structure,plastic hinge area often occurs at the end of column.How to improve the deformation capacity and energy dissipation of column ends is the key to improve the seismic performance of the whole structure.In recent years,with the rapid development of new materials,Engineered Cementitious Composites(ECC)have entered the public field of vision.ECC has the characteristics that different from concrete which shows significant ductility.The uniaxial tension shows strain hardening characteristics as well as ultimate tensile strain can stable reach more than 3% which is more 150 times than concrete;Under uniaxial compression,the ultimate compressive strain is about 0.4%~0.5%,which is more 2~2.5 times than concrete;Due to fiber tensile effect,ECC has good control effect on the crack development.In the saturated state,the average crack width is less than 0.1mm and energy consumption is 3 times that of concrete.These features of the ECC clearly make up for the defects of the concrete material.It is because of the excellent performance of ECC,this paper argues that the use of ECC to replace the concrete on the plastic hinge zone of column is a very effective way to improve the seismic performance;In addition,in order to more fully improve the seismic performance of the columns,the paper studies on different types of FRP package and constraints on ECC.The main research work includes three parts in this paper as follows:(1)The basic mechanical properties test of the test materials.The paper will measure the stress-strain relationship of ECC,the ultimate tensile strength and fracture strain of FRP,the compressive strength of concrete and the stress-strain relationship of the reinforced bar.(2)FRP-ECC column axial compression test.The paper will use CFRP,PET constraints on ECC column respective to study on uniaxial mechanical performance,and considers the impact of different cross-section chamfer radius,FRP layers on the strength and the ductility of ECC.(3)Seismic performance test of FRP-ECC column.The paper will use ECC instead of concrete in the plastic zone.At the same time,by using a combination of CFRP,PET and considering the variation of the test ratio,then studies the above parameters on the performance of the column hysteresis,bearing capacity,energy consumption,ductility and stiffness degradation.