预应力高强钢丝绳抗弯加固钢筋混凝土梁的理论分析

预应力高强钢丝绳加固是一种新型高效加固方法(简称P-SWR加固技术)。首先对试验用钢丝绳抗拉强度、拉伸极限应变和松弛等力学性能进行试验研究;然后给出预应力高强钢丝绳加固后混凝土梁开裂荷载、最大承载力计算方法;结合预应力高强钢丝绳加固混凝土梁的荷载-挠度关系曲线,分析了预应力度、配筋率、钢丝绳与混凝土黏结性能等各种参数对P-SWR加固梁截面短期刚度的影响,提出了相应的计算公式;基于高强钢丝绳抗弯加固对混凝土梁裂缝平均间距和钢筋应力影响的分析,建议了计算P-SWR加固后混凝土梁最大裂缝宽度的修正规范方法、名义拉应力方法和实用简化方法。建议的各计算方法简单,与相应试验值的比较表明具有较高的精度,可用于P-SWR抗弯加固混凝土结构的理论分析和简化设计。

Theoretical analysis of the flexural behavior of RC beams strengthened with prestressed high strength steel wire ropes

A recently developed flexural strengthening method for RC beams by using prestressed high strength steel wire ropes(P-SWR strengthening technique)was presented.The mechanical properties of the steel wire ropes,such as the ultimate tensile strength,ultimate tensile strain and relaxation,were studied.Based on the experimental results, a theoretical method was proposed to predict the cracking load and flexural capacity of RC beams strengthened with P-SWR.According to the loading-deflection curves obtained in the present study,several factors such as prestressing level of P-SWR,ratio of reinforcement,and bond strength between P-SWR and concrete were also studied.Those factors are believed to be related to the short-term section stiffness of RC beams.Prediction equations were suggested. A set of theoretical evaluation methods was proposed for the P-SWR strengthening technique.This evaluation system includes a modification to the current code,a calculation for nominal tensile stress,and a simplified method for predicting the maximum crack width.The results from using the proposed theoretical evaluation methods agree well with the experimental ones.