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基于实体退化单元,对钢筋混凝土(RC)梁和混杂碳/玻璃(C/G)纤维布采用分层壳元模型,对纵向受力钢筋采用组合壳元模型,模拟了混杂C/G纤维布的预应力作用,建立了预应力混杂C/G纤维布加固RC梁的非线性层壳组合单元模型,采用弥散裂缝模式、Ottosen屈服准则和Hinton压碎准则描述了加固梁的开裂、屈服和压碎的材料非线性效应,分析了破坏全过程中加固梁挠度变化规律、刚度折减规律、极限承载力与混杂C/G纤维布应力重分布。计算结果表明:非线性层壳组合单元分析方法可靠,加固梁的特征荷载计算值与试验值的相对误差不超过10%,且非线性层壳组合单元具有较好的收敛性和数值稳定性;在加固梁达到开裂荷载前,混杂C/G纤维布的应力重分布系数变化较小,开裂荷载时为1.3,其后应力重分布系数逐渐增大,屈服荷载时为4.1,极限荷载时为14.8;采用普通C/G纤维布加固时,纤维布高强性能未充分发挥,利用率约为83%,采用预应力C/G纤维布能改善梁的结构体系,能使得材料充分发挥作用,利用率超过90%。
Based on the physical degradation unit, a layered shell element model is adopted for the reinforced concrete (RC) beam and the mixed carbon / glass (C / G) fiber cloth and the composite shell element model is adopted for the longitudinal reinforced steel bar to simulate the hybrid C / G fiber cloth The nonlinear layered shell element model of prestressed hybrid C / G fiber reinforced plastic (CFRP) reinforced concrete girder is established, and the crack propagation, yielding and pressure of the reinforced beam are described by means of diffusion fracture mode, Ottosen yield criterion and Hinton crushing criterion The nonlinear effect of the broken material was analyzed. The variation law of deflection, stiffness reduction, ultimate bearing capacity and stress redistribution of the hybrid C / G fiber cloth were analyzed. The calculation results show that the analysis method of the nonlinear layered shell unit is reliable, the relative error between the calculated value and the experimental value of the reinforced beam is less than 10%, and the nonlinear layered shell unit has better convergence and numerical stability. Before the reinforcing beam reaches the cracking load, the stress redistribution coefficient of the hybrid C / G fiber cloth changes little, and the cracking stress is 1.3, and then the stress redistribution coefficient increases gradually, the yield stress is 4.1 and the ultimate load is 14.8 ; When ordinary C / G fiber cloth is used for reinforcement, the high strength performance of the fiber cloth is not fully utilized and the utilization rate is about 83%. The prestressed C / G fiber cloth can improve the structural system of the beam and make the material fully exert its effect. Over 90%.