高强钢绞线网增强ECC加固无损RC梁截面刚度计算

Calculation of section rigidity of non-damaged RC beams strengthened by high-strength steel wire strand meshes reinforced ECC

高强钢绞线网增强ECC(Engineered Cementitious Composites)是一种新型高性能复合材料,具有优异的延性、韧性及裂缝控制能力。为了进一步将该复合材料用于混凝土结构加固,以显著提高加固后结构的整体性能,进行该复合材料加固无损钢筋混凝土(Reinforced Concrete,RC)梁的抗弯刚度的试验和理论研究。考虑纵向高强钢绞线配筋率、工程用水泥基复合材料(Engineered Cementitious Composites,ECC)配方及高强钢绞线直径的影响,设计制作6根高强钢绞线网增强ECC加固无损RC梁和1根未加固的对比RC梁,进行受弯性能试验,并采用刚度比法对加固梁的受弯刚度进行分析。研究结果表明:采用高强钢绞线网增强ECC加固无损RC梁,可显著提升RC梁的受弯刚度、承载能力、控裂及变形能力,加固梁的受弯刚度随着纵向高强钢绞线配筋率或ECC弹性模量的增大而提高,纵向钢绞线配筋率接近的情况下,改变钢绞线公称直径,对加固梁的受弯刚度的影响不大。基于试验结果分析,采用相关力学理论和混凝土结构基本原理,推导建立了高强钢绞线网增强ECC加固无损RC梁的受弯刚度计算公式,该公式计算结果与试验结果吻合较好。

High-strength steel wire meshes reinforced ECC(engineered cementitious composites)is a new type of high-performance composite material with excellent ductility,toughness and crack-control ability.In order to apply this composite material to strengthen concrete structures to significantly improve the overall performance of concrete structures,the flexural stiffness of non-damaged reinforced concrete(RC)beams strengthened by this composite material was studied experimentally and theoretically in this paper.Considering the influences of reinforcement ratios of longitudinal high-strength steel wire strands,formulas of engineered cementitious composites(ECC)and high-strength steel strand diameter,six non-damaged RC beams strengthened by high-strength steel wire strand meshes reinforced ECC and one unstrengthened contrast RC beam were designed,manufactured and subjected to bending performance tests.The stiffness ratio method was used to analyze the bending stiffness of the strengthened beam.The results indicate that the use of high-strength steel wire strand meshes reinforced ECC to strengthen RC beams can significantly improve the bending rigidity,bearing capacity,crack-control capacity and deformation capacity.Besides,the bending stiffness of the strengthened beam grows as the reinforcement ratio of longitudinal high-strength steel wire strands or the elastic modulus of ECC increases.Moreover,changing the nominal diameter of the high-strength steel wire has little effect on the bending stiffness of the strengthened beam when the reinforcement ratios of longitudinal high-strength steel wire strands are close.Based on the analysis of test results,a formula for calculating the stiffness of the non-damaged RC beams strengthened by high-strength steel wire strand meshes reinforced ECC is deduced and established by using the relevant mechanical theory and the basic principles of concrete structures.The calculated results using this formula are in good agreement with the test results.