CFRP加固混凝土梁抗弯极限承载力的计算分析

Calculation and Analysis of Limit Flexural Loading of CFRP Strengthened Concrete Beams

分析碳纤维加固梁的受力特征、确定其极限承载力 ,是加固工程的首要问题 .通过对已承载结构的分析 ,发现其存在二次受力问题 ,即CFRP滞后现象 .为此 ,在计算加固梁的抗弯极限承载力时 ,引入了CFRP强度发挥系数概念 ,并在确定加固梁极限弯矩的基础上 ,建立了极限弯矩与CFRP厚度的关系式 .研究结果表明 :对已承载结构 ,为提高加固效率 ,在加固前应尽量卸载 ;加固用CFRP厚度存在临界值t0 ,当CFRP厚度超过临界值t0 时 ,对加固结构不但无益 。

Preloaded structures demonstrate a second-loading phenomenon that produces the hysteresis of CFRP. Therefore the concept of effective CFRP strength coefficient is introduced for calculation of limit flexural loading of strengthened beams, and on the basis of limit bending moment determination, the relationship of CFRP thickness and limit bending moment is established. It is concluded from the results of analysis that in order to improve the strengthening efficiency of preloaded structures, service load should be removed before strengthening; strengthening CFRP thickness displays a critical value t0. But it does harm rather than good to the strengthened structures if CFRP thickness surpasses the critical value t0. Preloaded structures demonstrate a second-loading phenomenon that produces the hysteresis of CFRP. Therefore the concept of effective CFRP strength coefficient is introduced for calculation of limit flexural loading of strengthened beams, and on the basis of limit bending moment determination, the relationship of CFRP thickness and limit bending moment is established. It is concluded from the results of analysis that in order to improve the strengthening efficiency of preloaded structures, service load should be removed before strengthening; strengthening CFRP thickness displays a critical value t0. But it does harm rather than good to the strengthened structures if CFRP thickness surpasses the critical value t0.