基于混凝土残余应变的CFRP布与钢板复合加固RC梁疲劳损伤研究

Fatigue Damage Study on RC Beams Strengthened with CFRP Sheets and Steel Plate Based on Residual Strain of Concrete

采用碳纤维增强复合材料(CFRP)与钢板复合加固钢筋混凝土(RC)梁,并对其开展疲劳性能试验,分析梁压区边缘混凝土的疲劳总应变和累积残余应变随循环次数的发展规律,根据实测数据提出梁压区边缘混凝土累积残余应变演化方程,最后利用压区边缘混凝土累积残余应变定义损伤变量,计算获得损伤变量演化曲线.结果表明:随着荷载幅的提高和疲劳循环次数的增加,复合加固的RC梁压区边缘混凝土疲劳总应变和累积残余应变增大,且其发展均呈现明显的三阶段规律;利用压区边缘混凝土累积残余应变所建立的损伤模型,可以较好地反映这种复合加固梁的疲劳累积损伤.研究结果为CFRP布与钢板复合加固梁的剩余疲劳寿命预测和损伤评价奠定了理论基础.

An experimental study on the fatigue behavior of reinforced concrete(RC)beamsstrengthened with carbon fiber reinforced polymer(CFRP)and steel plate wasconceived,designed and performed.The developing tendency of total fatigue strain andcumulative residual strain of concrete at the compressive edge with the increase offatigue loading cycles were observed and analyzed.Based on the experimental data,thecumulative residual strain evolution equation of concrete at the compressive edge waspresent.Finally,the damage evolution curve was obtained by calculating damage variabledefined with cumulative residual strain of concrete at the compressive edge.The resultsshow that,as fatigue load amplitude and fatigue cycles increase,total fatigue strain andcumulative residual strain of concrete at the compressive edge of CFRP-steel platecomposite strengthened RC beams increase and three-phase behavior is shown;damagemodel based on the cumulative residual strain of concrete at the compressive edge canexpress the fatigue cumulative damage well.The research results lay the theoreticalfoundation for the remaining fatigue life prediction and damage estimation of beamsstrengthened with CFRP sheets and steel plate.