预应力碳纤维布加固混凝土方形截面短柱轴心受压试验

EXPERIMENT OF AXIAL COMPRESSION OF REINFORCED CONCRETE SHORT SQUARE-COLUMNS STRENGTHENED WITH PRESTRESSED CFRP SHEETS

为了研究预应力碳纤维(CFRP)布加固混凝土方形截面短柱轴心受压力学性能,根据配筋率的不同设计了3组共计12根混凝土方形截面短柱,每组包括3根预应力CFRP布加固的混凝土柱和1根普通混凝土柱。通过静载试验获得了各试件受压极限承载力、位移和预应力CFRP布应力增量等试验数据,得到了荷载作用下试件变形曲线及破坏形态,分析了预应力CFRP布应力水平和纵筋配筋率对混凝土方形截面短柱加固后的力学性能的影响。研究结果表明:采用预应力CFRP布约束混凝土柱一方面能够限制混凝土横向变形,使柱中混凝土从加固时刻起即受到环向应力,提高了混凝土极限压应变,从而显著提高柱的极限承载力,承载力提高幅度在60%以上;另一方面,由于受压柱的延性与截面配筋率有关,加固柱配筋率较低时,延性较好;反之则延性较差。

In order to study the mechanical properties of reinforced concrete short square-columns strengthened with prestressed CFRP sheets under axial compression,3 groups of RC square-columns,total of 12,were designed according to reinforcement ratio,each group including 3 RC columns strengthened with prestressed CFRP sheets and 1 RC column.The experimental data such as ultimate compressive bearing capacity,displacement and stress increment of prestressed CFRP sheets were obtained from the static load test.Load deformation curve and failure mode of specimens were also achieved.The effect of stress level of prestressed CFRP sheets and reinforcement ratio on the mechanical properties of strengthened RC short square-columns was analyzed.The experimental results indicated that strengthening with prestressed CFRP sheets could limit concrete lateral deformation,confine concrete by hoop stress from strengthening moment,as well as improve the ultimate compression strain of concrete,thus remarkably enhancing column ultimate bearing capacity by more than 60%.What＇s more,the ductility of compression columns strengthened with prestressed CFRP sheets was influenced by reinforcement ratio.When reinforcement ratio of the strengthened column was lower,ductility was better,otherwise worse.