钢筋钢纤维混凝土梁弯矩-裂缝宽度计算方法

为了建立能够预测钢筋钢纤维混凝土梁受力过程中裂缝宽度的力学模型，首先考虑裂缝有效宽度和纤维有效拔出角度确定钢纤维混凝土拉应力-裂缝宽度本构关系，引入断裂力学概念建立了钢纤维混凝土梁截面弯矩-裂缝宽度的计算方法，在其基础上考虑钢筋作用提出一种分析钢筋钢纤维混凝土梁截面弯矩-裂缝宽度的计算方法，它可以模拟梁受弯破坏过程。采用本文方法、CECS 38—2004和RILEM TC 162-TDF中的最大裂缝宽度计算公式对收集到的12根钢筋钢纤维混凝土梁在正常使用条件下的裂缝宽度进行验算，结果表明：CECS 38—2004和RILEM TC 162-TDF的计算结果偏于保守且离散性较大，本文方法能够有效预测梁受力全过程裂缝宽度，计算精度高且变异系数小，为钢纤维混凝土结构裂缝控制提供理论依据。

Calculation method of bending moments and crack openings of steel fiber reinforced concrete beams with longitudinal reinforcement

The purpose of this paper is to establish a mechanical model that can predict the width of crack opening in steel fiber reinforced concrete(SFRC)beams with longitudinal steel bar reinforcement(RSFRC)under loading.We develop a tensile stress-crack width constitutive model of SFRC beams considering the effective width of cracks and the effective pull-out angle of steel fibers,and then a SFRC flexural strength model based on fracture mechanics.And we formulate a calculation model that,taking the effect of reinforcement into account,can be used to analyze the bending moments and crack widths of R-SFRC beams and simulate their bending failure process.This calculation model,along with the standard methods of CECS 38—2004 and RILEM TC 162-TDF,is used to calculate the crack width of the collected 12 R-SFRC beams at service loads.The results demonstrate that the calculation results of the two standard methods are conservative and discrete,while our method gives predictions in a good agreement with experimental measurements and can effectively predict the crack width of R-SFRC beams and its variation over the loading process with a good accuracy and small coefficients of variations.