Experimental Study On CFRP Ring-to-beam Concrete Columns Subjected To Low Velocity Impact

In recent years,with the increasing demand for urban building reinforcement and transformation,the reinforcement industry has been booming.Compared with the original reinforcement method,carbon fiber reinforcement has the advantages of light weight and high economic efficiency.More and more reinforcement projects choose carbon fiber reinforced composites(CFRP).However,due to the anisotropy and brittleness of CFRP materials,CFRP-reinforced buildings in engineering practice occurred due to the impact of collapse,such as the collapse of some of the bridge piers caused by the collision of vehicles and ships.However,in the actual engineering design,the impact load is rarely considered.In the existing reinforcement specifications,the problem is also a blank area.Therefore,considering the impact resistance of CFRP materials has a strong practical significance.In this paper,the low-speed impact test of CFRP-reinforced concrete columns was studied by the drop-weight device developed by the research group.The axial load of the residual bearing capacity of the impact-damaged specimens was studied by a 500 T four-column press.The research content of this paper is as follows:1.Introduced the design and production of the test piece,focusing on the components of the test piece including CFRP cloth,adhesive steel glue,adhesive glue and so on.The test device and data acquisition device are introduced in detail from the impact test and the static load test.2.In the low-speed impact test: the hammer of the same quality is used,and the initial kinetic energy of the ram is used as the research object.The drop hammer device developed by the research team at different heights respectively impacts the CFRP ring-shaped surrounding concrete column of one layer and two layers.Obtain the failure mode,contact time history curve,and support reaction time history curve.At the same time,use the camera to capture the whole impact process,and finally analyze all the test data.Finally,it is concluded that the failure modes of the CFRP concrete specimens are similar.The two-layer CFRP constraint can protect the concrete more effectively under impact load.3.Axial pressure test: The axial test of the damaged test piece obtained by the impact test was carried out by using a four-column press.The time-history curve and the stress-strain time-course curve of the residual bearing capacity were obtained by the data acquisition device,and the CFRP ring-shaped surrounding concrete column was observed.Destruction state,and finally collated and analyzed all the acquired data,and finally concluded that the final failure mode of CFRP-constrained concrete column is brittle failure,and the fracture section is inverted cone-shaped.The test ends with the damage at the weak position.