Experimental Research On Seismic Behaviors Of Concrete Column Restrengthened With Fiber Reinforced Polymer

Recently, the method of concrete structure restrengthened with fiber reinforced polymer sheet is widely used in civil engineering. The Aramid fiber reinforced polymer(AFRP) is a new material with excellent performance. Researching on it has very important significance for constructional engineering. This paper deals with the application of AFRP, AFRP and CFRP for seismic strengthening for concrete rectangle columns for the first time in our country.First, it studies the material performance of AFRP sheet. The process of making a material test member of AFRP and where should be paid attention have been particular introduced. The ultimate tensile stress and young's modulus of AFRP have gained. The experiment proves that the suggestion on CFRP also can be used on AFRP.Second, based on a common concrete column and ten columns restrengthed with fiber-reinforced plastic(FRP) which have been wrapped by AFRP or AFRP and CFRP sheets under low frequency alternate load, the paper has studied the questions such as characteristic of resilience, skeleton curve, energy consumption, degeneration of rigidity, the strain of steel hoop and FRP. The result indicates that strengthened with FRP not only increase columns' ultimate strength but also improve the performance such as energy consumption, ductility and so on. AFRP and CFRP can work well with each other has also been proved. This method has a great effect on the columns which have big axial compression ratio. An especial mode of wrapped FRP has been taken during the experiment that all the area from 0 to 30㎝ high has been reinforced. For this reason, the formula on the convert volume steel hoop ratio in Chinese "Technical Specification for Strengthening Concrete Structure with Carbon Fiber Reinforced Polymer" has been modified. Based on the existent stress-strain relationship for compressed members confined with FRP, a simple method to calculate the ultimate force and moment has been deduced. It can be used in engineering practice. Some suggestions are also made for the research in the future.