钢筋增强混凝土-ECC组合梁抗弯性能理论与试验研究

为探讨ECC在结构新建、加固等领域的应用,开展钢筋增强混凝土-ECC组合梁的抗弯性能全过程理论研究,分析组合梁在弹性阶段、带裂缝工作阶段、破坏阶段的破坏现象,结合平截面假定和本构关系分析各阶段截面的应力-应变关系,依据力和力矩平衡原则建立抗弯承载力计算公式,通过组合梁和RC梁的抗弯试验验证理论的正确性,进一步理论分析不同ECC厚度对组合梁的抗弯承载力和延性性能的影响。研究表明:与RC梁相比,用ECC替代部分受拉区混凝土承载力可提高60%以上,位移延性可提高46%以上;ECC厚度在19%~38%梁高范围内可获得较为优越的抗弯承载力和延性;为发挥ECC材料的高延性应将其与高强混凝土和高强钢筋结合使用,并着眼于提高构件的阻裂、限裂、增韧等性能。

Theoretical and experimental study on flexural behavior of steel reinforced concrete-ECC composite beams

In order to discuss the application of ECC in the field of new construction and reinforcement of structures, the whole process theoretical study of flexural behavior of steel reinforced concrete-ECC composite beams was carried out. The failure phenomena of composite beams in the elastic stage, the working stage with cracks and the failure stage were analyzed. The stress-strain relationship of sections in each stage was analyzed based on the assumption of plane section and the constitutive relationship, and the flexural resistance was established according to the principle of force and moment balance. The correctness of the theory was verified by the flexural tests of composite beams and RC beams, and the effect of different ECC thickness on the flexural capacity and ductility of composite beams was further analyzed theoretically. The results show that, compared with RC beams, the bearing capacity of beams with ECC in partial tension zone can be increased by more than 60% and the displacement ductility can be increased by more than 46%. When the ECC thickness ranges from 19% to 38% of beam height, the beams can obtain better flexural bearing capacity and ductility. In order to give full play to the high ductility of ECC materials, ECC should be combined with high strength concrete and high strength steel bars, and focus on improving the crack resistance, crack limitation and ductility behaviors of members.