FRP筋混凝土梁挠度与裂缝宽度计算模型分析

收集国内外218组纤维增强复合材料(FRP)筋混凝土梁受弯性能试验结果，重点研究了正常使用阶段和极限状态下梁挠度和裂缝宽度的发展规律，基于试验数据修正了FRP筋应变不均匀系数ψ与强度配筋影响系数的关系，建立了该类梁受弯挠度计算模型；深入分析了FRP筋混凝土梁受弯截面内力臂系数η、构件受力特征系数α_cr对构件裂缝宽度计算精度的影响，确定η，α_cr的合理取值，优化计算模型，并与规范GB 50608—2010建议模型计算值进行对比分析。结果表明:根据建立的ψ与强度配筋影响系数关系，选取η=0.88，α_cr=1.5得到的建议模型能够较好预测FRP筋混凝土梁受弯挠度和裂缝宽度，比规范计算结果吻合好，验证了建议模型的准确性和合理性。

Calculation Model of Deflection and Crack Width of Concrete Beam Reinforced with FRP Bars

The 218 groups of flexural test results at home and abroad of concrete beams reinforced with fiber reinforced polymer (FRP) were collected, and the development laws of beam deflection and crack width under serviceability limit state and ultimate limit state were studied emphatically. On the basis of test data, the relationship between the non uniformity coefficient of FRP strain and influence coefficient of strength reinforcement was corrected, and the deflection calculation model of flexural member was established. The influences of coefficient of internal force arm and force characteristic coefficient of component of the FRP reinforced concrete beam bending section on the calculation accuracy of crack width were deeply analyzed. The reasonable values of η?and α_cr?were determined, and the calculation model was optimized. The calculated values were compared with that of the model proposed by technical code GB 50608—2010 for infrastructure application of FRP composites. The results show that the suggested model by selecting η=0.88, α_cr=1.5 based on the relationship between ψ?and influence coefficient of strength reinforcement can predict the deflection and the crack width of concrete beams reinforced with FRP bars better than GB 50608—2010, and the calculation results of modified model are in good agreement with experimental results, the accuracy and rationality of the proposed model is verified.