复合配筋ECC/混凝土组合梁受弯性能研究

Flexural behaviors of reinforced with hybrid FRP and steels ECC/concrete composite beams

为了进一步研究对高延性纤维水泥基复合材料与混凝土共同作用下的力学性能,提出新型FRP筋-钢筋复合增强ECC/混凝土组合梁构件,将FRP筋配制在梁构件边角处,而ECC仅用于梁构件易于开裂的受拉区。旨在有效提高梁的延性和耐久性。首先,提出ECC简化应力-应变关系模型,采用截面条带法对构件的受弯性能进行分析;结果表明:试验结果与模拟结果吻合较好,验证了模型的可靠性。在此基础上进行参数分析,分析了不同配筋率、ECC层厚度、FRP筋种类等参数对构件受弯性能的影响。结果表明配筋率可大大提高构件的受弯性能;ECC层厚度对梁构件弯矩-曲率曲线影响不大;三种FRP筋中CFRP筋梁的承载力最高而GFRP筋梁的变形性能最好;最后通过对试验数据的拟合,得出曲率-裂缝宽度关系曲线,并分析三种不同因素对梁裂缝宽度的影响。

In order to further study the mechanical properties of engineered cementitious composites and concrete,ECC/concrete composite beam reinforced with FRP and steel bars is proposed.The composite beam is designed to improve the ductility and durability of the flexural members,where FRP bars are arranged at the corners of the beam members,while ECC is only employed in the tension zone,designed to effectively improve the ductility and durability of the beam.Firstly,the simplified stress-strain model of ECC was proposed,and the flexural behaviors of the composite beams were analyzed by section layer method.The results show that the experimental results are in good agreement with the simulation results,which verifies the reliability of the proposed model.After that,parametric studies with regards to reinforcement ratio,ECC layer thickness and FRP bar types were carried out.The results show that the flexural performances are greatly improved with increasing reinforcement ratio.The thickness of the ECC layer has little effect on the moment-curvature curve of the beam members.Among the three types FRP bars,CFRP bars lead to the highest flexural strength while GFRP bars result in highest deformation capacity.Finally,the curvature-crack width relationship was obtained by the regression of test data and the effects of three factors on the crack width of composite beams were carried out.