纤维缠绕角度对GFRP约束混凝土短柱轴压性能的影响

Influences of fiber angles on axial compressive behavior of GFRP-confined concrete stub column

为研究纤维缠绕角(即纤维缠绕方向与试件轴线的夹角)对GFRP约束混凝土柱轴压性能的影响,进行了纤维缠绕角为±45°,±60°以及±80°的GFRP约束混凝土短柱的轴压试验,主要分析了纤维缠绕角和GFRP管厚度对试件的破坏形态、承载力和应力-应变曲线的影响。研究结果表明:纤维缠绕角对于GFRP管的环向刚度和环向断裂应变有很大影响;纤维缠绕角绝对值越小,GFRP管对混凝土的约束作用越小;GFRP约束混凝土的峰值应力随纤维缠绕角绝对值的减小而减小,GFRP约束混凝土的极限应变随纤维缠绕角绝对值的减小而增大;Teng等的设计模型和Jiang等的分析模型均可较为准确地预测缠绕角±80°的GFRP约束混凝土的应力-应变关系,对缠绕角±60°的GFRP约束混凝土的应力-应变关系的预测偏不保守,而对缠绕角±45°的GFRP约束混凝土的应力-应变关系则无法预测。

In order to investigate the influences of fiber angles(i.e., the angle between the fiber direction and the longitudinal axis of the specimen) on the axial compressive behavior of GFRP-confined concrete, an experimental study on GFRP-confined concrete stub column with ±45°, ±60°and ±80° fiber angles was carried out under axial compression. The fiber angle and the GFRP tube thickness were considered as important parameters to investigate their influences on the failure mode, load capacity and axial stress-strain curves of GFRP-confined concrete. Experimental results show that the fiber angle has significant influence on the hoop stiffness and the hoop rupture strain of GFRP tube;the confinement effect of GFRP tube decreases with the decrease of the absolute fiber angle;the peak stress of the confined concrete decreases with the decrease of the absolute fiber angle, but the ultimate strain of the confined concrete increases with the decrease of the absolute fiber angle;Teng et al.’s design-oriented model and Jiang et al.’s analysis-oriented model can provide reasonably accurate predictions for specimens with ±80° GFRP tube, slightly unconservative predictions for specimens with ±45° GFRP tube, but inaccurate predictions for specimens with ±60° GFRP tube.