预应力混杂碳/玻璃(C/G)纤维布加固RC梁的应力重分布

Stress redistribution of RC beams strengthened with prestressed hybrid carbon/glass(C/G)fiber cloth

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 solid degraded shell element,the layered shell element model was adopted for reinforced concrete（RC）beam and hybrid carbon/glass（C/G）fiber cloth,the combined shell element model was used for longitudinal reinforcement,and the prestress effect of hybrid C/G fiber cloth was simulated.A kind of nonlinear layered shell combined element for RC beam strengthened with prestressed hybrid C/G fiber cloth was established.The nonlinear effects of cracking,yielding and crushing of RC beam were described by cracking mode,Ottosen yielding criterion and Hinton crushing criterion.The changing rule of deflection,the reduction rule of stiffness and the ultimate bearing capacity of strengthened beam were analyzed,and the stress redistribution of hybrid C/G fiber cloth was studied.Calculation result shows that the nonlinearlayer shell combined element analysis method is reliable,the relative error between the calculated value of characteristic load of strengthened beam and its experimental value is not more than10%,and the nonlinear layered shell combined element has good convergence and numerical stability.Before the strengthened beam reaches cracking load,the stress redistribution coefficient of hybrid C/G fiber cloth changes little and is equal to 1.3at cracking load.Then it increases gradually,is equal to 4.1at yielding load and is equal to 14.8at ultimate loads.When the beam is strengthened with common hybrid C/G fiber cloth,the high-strength property of fiber cloth cannot be fully used,and the utility degree is about 83%.When the beam is strengthened with prestressed hybrid C/G fiber cloth,the structural system of beam be improved,the high-strength property of fiber cloth can be well used,and the utility degree exceeds to 90%.