基于倒角处拉应变的玄武岩纤维约束矩形截面混凝土轴压峰值应力计算模型

Axial ultimate compressive stress model of BFRP-confined rectangular concrete based on tensile strain at rounded corners

对54个玄武岩纤维增强树脂基复合材料(BFRP)约束的矩形截面混凝土试件进行了轴压试验,探究了BFRP约束层数、倒角半径和截面长宽比对BFRP拉应变折减系数的影响规律。试验结果表明,依据矩形截面侧边拉应变和环向平均拉应变确定的BFRP拉应变折减系数会高估BFRP的约束效率。基于BFRP约束矩形截面混凝土时倒角处的纤维拉应变,建议了BFRP拉应变折减系数的计算方法,同时依据该计算方法和试验数据,通过构建柱状膜结构静水压力平衡模型建立了BFRP约束矩形截面混凝土轴压峰值应力计算模型。基于收集的大量试验数据,对比分析了本文建议的纤维增强树脂基复合材料(FRP)约束矩形截面混凝土轴压峰值应力计算模型和典型轴压峰值应力计算模型的预测结果,验证了典型计算模型的合理性,发现本文建议的FRP约束矩形截面混凝土轴压峰值应力计算模型的预测精度较高。

This paper presents an experimental study on the axial compressive behavior of 54 rectangular prisms confined with basalt fiber-reinforced polymer(BFRP).The influences of the BFRP layers,corner radius and aspect ratio on the tensile strain reduction factors of BFRP were investigated.The test results show that the tensile strain reduction factors calculated based on tensile strains in sides and average tensile strain of lateral BFRP sheets will overestimate confinement efficiency.Based on tensile strains at the corners,a computing method of tensile strain reduction factors of BFRP sheets was proposed.According to the proposed computing method of tensile strain reduction factors and experimental data in this paper,the hydrostatic pressure balance equation of the cylindrical BFRP membrane was used to build an axial ultimate compressive stress model of BFRP-confined rectangular concrete.Based on a large collection of test data,predicted results of the proposed model and the existing typical models were compared and analyzed.The rationality of the existing typical models was verified.The prediction accuracy of the proposed axial ultimate compressive stress model is higher than the existing typical models.