反分析法确定钢纤维水泥砂浆拉应力与裂缝张开位移关系
DETERMINING THE STRESS-CRACK OPENING RELATIONSHIP OF SFRM BY INVERSE ANALYSIS
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摘要: 在数值模拟钢纤维混凝土结构或构件和用基于断裂力学理论的设计方法设计钢纤维混凝土结构或构件时，钢纤维混凝土材料 -w关系是一个重要的材料参数。该文根据三点弯曲缺口梁的荷载与裂缝张开位移(CMOD)曲线用反分析法确定了钢纤维水泥砂浆的 -w关系。试验制作了五种不同体积含量的钢纤维水泥砂浆单轴拉伸试件、圆柱体压缩试件和梁试件，钢纤维体积含量分别为0.5%、1.0%、1.5%、2.0%和2.5%。试验发现，当钢纤维体积含量较小时，三点弯曲缺口梁的荷载与裂缝张开位移曲线呈现CMOD软化特性；而当钢纤维体积含量较大时，三点弯曲缺口梁的荷载与裂缝张开位移曲线呈现CMOD强化特性。对有CMOD软化特性的钢纤维水泥砂浆，可用三折线软化模型来模拟钢纤维水泥砂浆的 -w关系；对有CMOD强化特性的钢纤维水泥砂浆，可用应力跌落-常残余强度模型来拟合。Abstract: The stress-crack opening relationship is a basic material input in fracture mechanics-based design methodology and numerical simulation for fiber reinforced cementitious composites. In the present study, the tensile stress-crack opening relationship of steel fiber reinforced mortar (SFRM) is determined by inverse analysis using load versus crack mouth opening displacement (CMOD) curve from notched beam tests. Five series of SFRM with different steel fiber volume fractions (from 0.5% to 2.5%) were tested. Direct tension tests were performed to obtain the tensile strength of SFRM. Behavior of the SFRM is classified into two types: CMOD-softening and CMOD-hardening. The results show that the tri-linear model can be used to model the stress-crack opening relationship of SFRM with CMOD-softening behavior, and the drop-constant model can be used to simulate the stress-crack opening relationship of SFRM with CMOD-hardening behavior.
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