预应力UHPC梁弯曲性能分析与合理设计

摘要

In order to study the basic mechanical performance and rational design method of prestressed ultra-high performance concrete(U HPC)beam,the full process flexural loading test of a large-scale prestressed UHPC-T beam was completed.Nonlinear finite element model of prestressed UHPC beam based on concrete damage plasticity(CDP)model was established,the test process was carefully simulated and the analysis results were compared with the test results. Based on the simulation model,the influences of number of prestressed tendons,tensile stress, compressive and tensile strength of U HPC materials on the flexural properties of U HPC beams were studied.The formula for calculating the prestressed reinforcement ratio of UHPC beam was put forward,and its reasonable range was suggested.The rational design method of UHPC beam w as preliminarily discussed.T he results show that the finite element model based on the CDP model can better simulate the flexural performance of prestressed U HPC beam.The analysis results are in good agreement with the test results.Increasing the prestress can effectively improve the bearing capacity,but reduce the ductility.Increasing the compressive strength of U HPC material has little effect on the mechanical properties at elastic and cracking stages,but can effectively improve the ductility of component.Increasing the tensile strength can effectively improve the crack resistance and ductility of component,and improve the ultimate bearing capacity.%为研究预应力超高性能混凝土(U H PC)梁的基本受力性能和合理设计方法,完成了一片大比例预应力U HPC-T形梁的弯曲全过程加载试验;基于混凝土损伤塑性(CDP)模型建立预应力U H PC梁的非线性有限元模型,对试验过程进行了细致模拟,将分析结果与试验结果进行对比;以仿真模型为基础深入研究了预应力筋数量、张拉应力、U H PC 材料抗压和抗拉强度等参数对U H PC梁弯曲性能的影响规律;提出了U H PC梁的预应力配筋率计算公式,并建议了其合理范围,初步探讨了U HPC梁的合理设计方法.结果表明:基于CDP模型的有限元模型能较好模拟预应力U H PC梁的弯曲受力性能,分析结果与试验结果吻合良好;提高预应力能有效提高构件承载力,但延性降低;提高U H PC材料的抗压强度对构件弹性阶段和开裂阶段受力性能影响不大,但能有效提高构件延性,提高抗拉强度能有效提高构件的抗裂性能和延性,并使极限承载力有所提高.