BFRP螺旋条带内约束海水海砂混凝土圆柱的轴压性能

Axial Compression Test of Seawater Sea-Sand Concrete Circular Column Inner-Confined by BFRP Spiral Strip

为研究以BFRP筋作为纵向增强筋、连续BFRP螺旋条带作为约束元件且带保护层的新型海水海砂混凝土圆柱的轴心受压性能,对8根短柱试件进行轴压试验,研究了BFRP纵筋配筋率和BFRP条带的宽度、间距对其轴压性能的影响;并基于试验数据推导了该类受压构件轴压承载力的计算表达式。研究结果表明:有条带约束试件的破坏过程和机理为试件高度中部混凝土保护层先剥落,然后螺旋条带断裂,随后核心混凝土压碎、纵筋屈曲,保护层剥落范围小于无条带约束试件;BFRP螺旋条带能对核心混凝土和BFRP纵筋有一定约束效应,可提高BFRP纵筋抗压强度利用率;试件抗压承载力随BFRP纵筋配筋率增大而提高;条带约束可使试件承载力提高0.9%~10.4%,极限位移增大16.39%~130.82%;减小条带间距或增大条带宽度均能提高试件承载力;试件位移延性系数总体不高;采用文中推导的轴压承载力计算表达式得到的计算值与试验值吻合较好。

In order to study the axial compression behavior of a new type of sea water sea-sand concrete circular column reinforced by BFRP longitudinal bars and confined by continuous BFRP spiral strip,also with concrete cover,8 short columns were test under axial compressive load.The influence of reinforcement ratio of BFRP longitu-dinal bars and the width and spacing of BFRP spiral strip on the axial compression performance of the columns was studied.According to the study results,the failure process and mechanism of such new type of column are that the concrete cover cracks and fell off first at middle of its height,then the spiral strips were fractured,finally the core concrete was crushes and the BFRP longitudinal bars are buckling;the damage ranges of concrete covers of the specimens confined by strips are smaller than that of the specimen without strip confining;the BFRP spiral strips can provide some constraint effect on the core concrete and BFRP longitudinal bars and improve the utilization rate of the compressive strength of BFRP bars;the bearing capacity of the new type of column increases with the increase of reinforcement ratio of BFRP longitudinal bars;under the restraint of the strips,the bearing capacity of the specimens is increased by 0.9%~10.4%,and the ultimate displacements is increased by 16.39%~130.82%;reducing the spacing or increasing the width of strips can improve the bearing capacity of the column;the displacement ductility coefficients of the specimens are generally not high.The calculated values from the expression for predicting the axial compression bearing capacity of such column derived in this paper are in good agreement with the experimental values.