钢筋高延性混凝土梁裂缝试验研究与计算方法

Experimental Research and Calculation Method of Cracks in Reinforced High Ductility Concrete Beams

为探究钢筋高延性混凝土(RHDC)梁裂缝开展机理,共设计四根钢筋高延性混凝土梁和一根普通钢筋混凝土(RC)梁,通过四点弯曲试验研究高延性混凝土极限拉应变和配筋率对构件裂缝宽度、裂缝间距以及裂缝发展高度的影响。研究表明:(1)与RC梁相比,RHDC梁的裂缝数量多且宽度小,加载过程中裂缝发展缓慢;(2)RHDC梁的裂缝宽度和裂缝高度随材料极限拉应变的增大而减小;(3)配筋率对RHDC梁裂缝宽度的影响与对RC梁的影响规律相同,随配筋率增大,RHDC梁裂缝宽度、裂缝高度以及平均裂缝间距均减小。基于试验和相关文献,考虑纤维桥联的贡献,建立RHDC梁的平均裂缝间距和最大裂缝宽度的计算公式,计算结果与试验结果吻合较好。

In order to explore the mechanism of crack development in reinforced high ductility concrete(RHDC)beams,a total of four reinforced high ductility concrete beams and one ordinary reinforced concrete(RC)beam were designed,and influence of the ultimate tensile strain and reinforcement ratio of high ductility concrete on component crack width,crack spacing and crack development height were studied through four-point bending tests.Research shows that(Ⅰ)compared with RC beams,RHDC beams have more cracks and smaller widths,and the cracks develop slowly during the loading process;(Ⅱ)the crack width and crack height of RHDC beams decrease with the increase of the ultimate tensile strain of the material;(Ⅲ)the influence of the reinforcement ratio on the crack width of RHDC beams is the same as that of RC beams.As the reinforcement ratio increases,the crack width,crack height and average crack spacing of RHDC beams all decrease.Based on experiments and related literature,considering the contribution of fiber bridges,the calculation formulas for the average crack spacing and maximum crack width of RHDC beams are established.The calculation results are in good agreement with the experimental results.