低体积含量的钢纤维混凝土三折线拉应变软化曲线的确定

Determination of the Trilinear Tension Softening Curve of Reinforced Concrete with Steel Fiber in Low Volumn-ratio

以带切口的钢纤维混凝土三点弯曲梁为研究对象,假定钢纤维混凝土的拉应变软化曲线为三折线形式,根据材料基本力学性能指标和初始裂纹失稳时实测的应变分布,建立韧带所在截面的力平衡方程,通过联立方程求解,得到钢纤维混凝土的拉应变软化曲线系数,并可以直接通过韧带上距裂尖第二道应变片拉断时的应变分布和对应荷载,利用弯矩平衡方程验证计算系数的正确性;最后以一低体积含量的钢纤维混凝土试验梁为计算实例,验证了这种方法的可行性。

A notched three-point bent beam is researched about the tension strain softening curve that is made from reinforced concrete with steel fiber. The trilinear model is assumed for the tension softening curve. According to the tested typical value of material performance and strain distribution when the initial crack is instable, the balance equation is set up on the ligament section, and then the undetermined coefficient is solved and the strain softening curve is gotten. The result can be verified by the bent balance equation and tested strain distribution when the second strain gauge is broken. As an example, a test beam with low volume-ratio steel fiber is analyzed and the method is verified.