考虑应力-挠度耦合效应的连续刚构体外束合理加固时机研究

Research on Reasonable Time of Continuous Rigid Frame Strengthened by External Tendon Based on Stress-Deflection Coupling Analysis

体外预应力加固时机的选择是否合理将对结构承载能力、使用性能的提升及全寿命周期成本产生显著影响。为解决以上问题,以某体外束加固连续刚构桥为依托工程,通过计算在不同初始挠度下体外束加固前、后结构最大主拉应力、挠度增量,确定主要控制参数取值范围。基于加固前后最大主拉应力-挠度耦合分析,以主拉应力限值为控制指标,从挠度控制的角度提出了体外束合理加固时机。结果表明,当体内预应力损失在10%以内,结构最大主拉应力、挠度增量变化较大,加固后最大主拉应力,挠度变化曲线趋于平缓,结构最大主拉应力、挠度近似呈正相关。以1.2 MPa为最大主拉应力控制指标,依托工程体外束合理加固时机为跨中挠度77 mm时,且体内预应力损失小于10%。

The reasonable selection of external tendon reinforcement timing will have a significant impact on the improvement of structural bearing capacity,service performance,and full life cycle cost.In order to study the reasonable time of continuous rigid frame strengthened by external tendon,a continuous rigid frame bridge reinforced with external tendons was taken as the background.By calculating the maximum principal tensile stress and deflection increment of the structure before and after external tendon reinforcement under different initial deflections,the range of main control parameters was determined.Based on the coupling analysis of maximum principal tensile stress and deflection before and after reinforcement,with the limit value of principal tensile stress as the control index,a reasonable reinforcement timing for external tendons was proposed from the perspective of deflection control.The results show that the maximum principal tensile stress and deflection of the structure change greatly when the internal prestress loss is within 10%.After reinforcement,the change curve of the maximum principal tensile stress and deflection tends to be flat,and the maximum principal tensile stress and deflection are approximately positively correlated.Taking the maximum principal tensile stress of 1.2 MPa as the control index,the reasonable strengthened time of the background project is that the mid-span deflection is 70 mm,and the internal prestress loss is less than 10%.