CFRP筋体外预应力加固T形截面混凝土梁短期挠度计算方法

CALCULATION METHOD ON SHORT-TERM DEFLECTION OF CONCRETE T-BEAMS STRENGTHENED WITH EXTERNALLY PRESTRESSED CFRP TENDONS

通过静力试验和理论分析,研究CFRP筋体外预应力加固T形截面混凝土梁在短期荷载作用下的使用性能,探讨短期挠度计算方法。结果表明,CFRP筋体外预应力加固梁的荷载-跨中挠度曲线呈三折线变化;跨中截面混凝土和CFRP筋的平均应变在梁体开裂之前沿截面高度基本呈线性变化,开裂后,CFRP筋的平均应变明显小于梁底混凝土的应变。基于试验结果,计算开裂刚度折减系数和CFRP筋粘结特征系数,考虑二次效应的影响,运用有效惯性矩法建立了CFRP筋体外预应力加固T形截面混凝土梁的短期挠度计算公式,可供实际工程设计参考。

A static test and theoretical analysis were conducted to investigate the service performance of concrete T-shaped beams strengthened with externally CFRP tendons under short-term loading, and the calculation method of short-term deflection was explored. The test results indicate that the load-midspan deflection curves of strengthened beams can be simplified as a tri-segmentsegment line. The average strains of concrete and CFRP tendon of strengthened beams basically vary linearly over the depth of the beams at the midspan section before cracking. The average strain of CFRP tendon is obviously less than the strain of bottom concrete after cracking. Based on the test results, the reduction coefficient of cracking stiffness and the bonding characteristic coefficient of CFRP tendons were calculated, and the calculation formula for the short-term deflection on beams strengthened with externally prestressed CFRP tendons was proposed in term of an effective inertia moment method considering the influence of second order effects, and it can provide a reference for practical engineering design.