Axial Compression Of Circular Concrete Hollow Pier Columns Of Frp Confined Effect Study

Many bridges, incorporating hollow piers, have been constructed throughout the world, particularly high-pier bridges. Hollow columns have a better seismic performance by reducing the self weight and improving the self stiffness. Due to the human factors, the natural factors, disaster damage, design specification improvement, security reserve enhancement and so on, more and more reinforced concrete (RC) columns need to be strengthened, a variety of reinforcement materials and technologies have been developed and improved also. Among them, fiber reinforced polymers/plastics (FRP) have been widely used in structure reinforcement for their well-known advantages, including their less workload, short construction period, good durable performance and simplicity in use. Few foreign studies investigated the performance of FRP-confinement of hollow-core RC columns, and it's an almost unknown field in China. Through the axial compression tests of 6 hollow concrete cylinders researching the effectiveness of confined concrete with CFRP, the main works and achievements are as follows:1. The results showed that, concrete columns wrapped with CFRP stripe showed a significant increase the strength and deformation property, even changed the failure mode. Observation, collapse of hollow concrete columns was due to concrete crush, and ruin of CFRP-wrapped columns was on account of fibers rupture.2. Test results show that the paste scheme influences to the reinforcement effect, such as fiber amount, fiber stripe width, stripe space and so on. Reinforcement effect more obvious with the fiber amount increased, but don't increase linearly. When fiber stripe width was certain, bearing capacity and ductility improved less with the increase of space between fiber stripes. Based on the existing research at home and abroad, consider paste plan, whether hollow section and hollow rate, put forward the formula of corresponding confined concrete strength calculation and the model of stress-strain relationship, compared with test results available, the proposed equations gave good agreement.3. The whole nonlinear analysis through ANSYS program was work out to analyze the reinforcement effect of hollow concrete cylinders confined with CFRP stripes, analysis results and experimental results were in good conformity.