带预应力约束拉杆R-CFT短柱轴压性能试验研究

为了解约束拉杆预拉力对矩形钢管混凝土短柱受力性能的影响,进行了3个带预应力约束拉杆短柱轴压试验和另外2个对比试验,对比试验试件中1个不带约束拉杆,1个带普通约束拉杆。预应力约束拉杆和普通约束拉杆均由M20高强度螺栓组成,作为普通约束拉杆的高强度螺栓,在构件受轴向压力前与钢管壁焊接成一体;作为预应力约束拉杆的高强度螺栓,在构件受轴向压力前通过扭紧螺帽产生预拉力,然后与钢管壁焊接成一体,由拉杆预拉力对钢管壁和核心混凝土进行预压。试验结果表明,设置约束拉杆后,构件的承载力提高,轴向变形能力增强;与普通约束拉杆相比,预应力约束拉杆能减小构件最大荷载时的变形,但对构件承载能力和后期变形能力影响不大;减小预应力约束拉杆的横向间距,可有效减小构件最大荷载时的轴向变形,提高构件前期刚度,但对构件承载力影响不明显;在截面宽度和拉杆数量不变的情况下,随着截面长宽比的增加,构件后期变形能力减小。

Experimental Analysis on Axial Compressive Behavior of R- CFTStub Columns with Prestressed Binding Bars

In order to investigate the effect of prestressed binding bars on axial compressive behavior of rectangular concrete-filled tubular（CFT） short columns,five rectangular CFT short columns,three with prestressed binding bars,one with ordinary binding bars,the other with no binding bars,were constructed and tested under axial compressive loads.The binding bars were made up with high-strength bolts.As used for ordinary binding bars,the high-strength bolts were welded to the steel tube before the column was loaded to axial compressive force.As used for prestressed binding bars,the high-strength bolts were first tensed by screwed screw cap down to bring force to prestress the steel tube and its core concrete,then welded to the steel tube before the column was loaded to axial compressive force.Test results indicate that the bearing capacity and ductility of rectangular CFT short columns are increased by setting binding bars.Compared to ordinary binding bars,the prestressed binding bars can decrease the longitudinal displacements corresponding to ultimate strength,but have little effect on the ultimate strength and displacement capacity after ultimate strength of the columns.The longitudinal displacements corresponding to ultimate strength of the columns decrease with the decreasing of space between binding bars.With the same section width and amount of binding bars,the bearing capacity of the columns improves with the increase of section long-broad-ratio,while displacement capacity after ultimate strength decreases with the increase of section long-broad-ratio.