Experimental Study On Seismic Performance Of RPC Box Piers

RPC (Reactive Powder Concrete) has high strength and excellent durability, which is very suitable for long-span bridges with high piers in the harsh natural environment. Given the structural characteristics of box piers and the properties of RPC, this paper suggests build box piers with RPC instead of normal concrete. Up to now, seismic performance of RPC box piers has been rarely studied, while most of studies in China and abroad are limited to normal concrete piers and high-strength concrete box piers. In this paper, such seismic performance as ductility, hysteresis curve, skeleton curve, etc. of RPC box piers is studied by pseudo-static test on three RPC box piers. This dissertation involves mainly the following investigations and corresponding results:1. The background of the subject selected is introduced by summarizing the progress and conclusions of previous studies on seismic performance of RPC box piers in China and abroad, and thus purpose of this paper is brought up.2. RPC properties are tested, and the strength and stress-strain curves are drawn.3. With pseudo-static test on three RPC box piers subjected to constant axial force and reversed horizontal load finished in this paper, influence of horizontal load on the seismic performance of RPC box piers is studied, the characteristics of the hysteresis curve, skeleton curve, load degradation curve, stiffness degradation curve and moment-curvature curve of pier bottom are analyzed, and displacement ductility factor and dissipative coefficient are solved.It has proved that RPC box piers shows good seismic performance,and the loading direction of the horizontal load has a impressive effect on seismic performance of RPC box piers, and the members undertaking forward horizontal load has better seismic performance than the ones undertaking skewed horizontal load.4.Based on the experimental study on the seismic performance of RPC box piers, appropriate constitutive relations of both RPC and reinforced concrete, together with the section layer method, are adopted so as for non-linear analysis programming, by which moment-curvature-axial force relation of pier section and horizontal load-displacement relation of pier top are drawn. Thus the correctness of the program is verified by comparing the results of both calculation and experiment. 5. Parameters of axial compression ratio and longitudinal reinforcement ratio of RPC box piers are analyzed with non-linear analysis program, which indicates:within the selected range of axial compression ratio and longitudinal reinforcement ratio(1.9%-3.7%), the ultimate horizontal bearing capacity increases first and then decreases while the component displacement ductility factor decreases, as the axial compression ratio increases; and the higher the longitudinal reinforcement ratio is, the lower the component displacement ductility coefficient will be. With the loading angle decreasing, the ultimate horizontal bearing capacity increases while the ductility index increases first and then decreases.