钢纤维混凝土增强增韧机理和力学分析

Strengthening and Toughening Mechanism and Mechanical Analysis of Steel Fiber-reinforced Concrete

针对钢纤维混凝土材料的力学性能,以试验结果为基础,对强度增强效应和变形增韧机理作了相应的理论分析。利用岩石三轴应力试验机,开展材料力学试验,得到较低应变率下不同钢纤维体积率的混凝土应力-应变关系曲线。基于唯象学理论并由试验结果可知:在同一应变率10-4s-1下,钢纤维体积率为0.75%的混凝土的峰值应力相对于素混凝土的峰值应力提高了23%,钢纤维体积率为3%时,其峰值应力提高了55%。且随着钢纤维体积率的增加,钢纤维混凝土材料的峰值应变和极限应变都随之提高。并在峰值应力之后出现应力的应变软化现象。钢纤维体积率对混凝土基体有明显的增强和增韧效应,而且提高了峰值应力后的韧度,由此得到裂后韧度与钢纤维体积率的具体函数表达式。

According to the mechanical properties of steel fiber concrete materials,the strength enhancement effect and deformation toughening mechanism are analyzed theoretically based on the test results.The stress-strain curves of concrete with different steel fiber volume ratios under low strain rate were obtained by rock tri-axial stress testing machine.Based on the phenomenological theory and the test results,under the same strain rate of 10 -4 s -1 ,the peak stress of concrete with the volume rate of 0.75% of steel fiber was 23% higher than that of plain concrete,and the peak stress 55% higher with 3% volume rate of steel fiber.With the increase of steel fiber volume ratio,the peak strain and the ultimate strain of steel fiber reinforced concrete materials increased correspondingly,and the strain softening phenomenon of stress occured after the peak stress.The steel fiber volume ratio has obvious strengthening and toughening effect on concrete matrix,and it increases the toughness after peak stress.The specific functional expressions of post-fracture toughness and the volume ratio of steel fiber are obtained.