预应力筋松弛变异对PC梁桥长期性能影响研究

Study on Influence of Relaxation Variation of Prestressed Tendons on Long-Term Performance of PC Beam Bridge

PC梁桥开裂和下挠与预应力筋长期预应力损失过大密切相关。针对环境温度和预应力不均匀性对预应力筋松弛和结构挠度的影响进行研究,提出一种考虑温度和预应力不均性的松弛损失计算公式。研究表明:高温作用会加快预应力松弛速率;预应力分布不均匀也会增加预应力损失。综合考虑这2个不利因素对PC梁桥长期挠度和结构应力影响是较大的。

The cracking&down deflection of PC beam bridge are closely related to the excessive long-term prestress loss of prestressed reinforcement.The effects of ambient temperature&prestress heterogeneity on the relaxation of prestressed reinforcement&structural deflection are studied,and a calculation formula of relaxation loss considering temperature&prestress heterogeneity is proposed.The results show that high temperature will accelerate the relaxation rate of prestress;uneven distribution of prestress will also increase prestress loss.Comprehensive consideration of these two adverse factors has a great impact on the long-term deflection&structural stress of PC beam bridge.