柱脚设角钢的高强钢棒混凝土方柱抗震性能研究

Study on seismic behavior of concrete square columns reinforced by ultra-high strength steel bar and partially confined by angle steel

以低粘高强钢棒作为主筋的混凝土柱,能在直至大变形阶段均具有稳定增长的承载力和较小的残余变形,有良好的自复位性能,但耗能能力较延性柱弱。该研究在高强钢棒混凝土方柱的柱脚配置角钢,在保证高强钢棒混凝土柱良好自复位性能的基础上提高其水平承载力和耗能能力。设计并制作了4根柱脚配置角钢和1根无角钢的高强钢棒混凝土方柱,进行低周往复加载试验,研究柱脚有无角钢、角钢厚度和轴压比、剪跨比对柱水平承载力、残余变形和耗能能力的影响。试验结果表明:所有高强钢棒柱加载直至位移角4%仍保持持续增长的承载力,加载位移角为2%和4%时的残余位移角分别在0.5%和1%以内,构件可修复概率分别能达100%和50%;与无角钢柱相比,相同轴压比的柱脚配置角钢的混凝土柱受弯承载力提升率达47%,单循环耗能提升最大达94%,累积耗能提升达24%;随着剪跨比的增加,试验柱的承载力下降;随角钢厚度的增大,承载力提升率增大,而耗能提升率减小。

The concrete square columns reinforced by ultra-high strength steel bars with low bond-strength(referred to as RC columns)possess a drift-hardening capability up to large drift with small residual drifts,but of which the energy dissipation capacity is unsatisfactory.In order to improve the lateral strength and energy dissipation capacity of the RC columns with self-centering capability,a strengthening method was proposed to partially confine the RC columns by angle steel.Four RC columns partially confined by angle steel with one counterpart RC columns without angle steel were fabricated and tested under reversed cyclic lateral load while subjected to constant axial load.The effects of the presence or absence of angles,angle thickness and axial compression ratio and shear span ratio on the seismic behavior of RC columns were discussed.The test results show that the lateral force of all the test columns continued to increase until drift ratio of 4%.The residual drifts were within 0.5%and 1%with the drift ratio of 2%and 4%,respectively.That is,the corresponding repairable probability of the specimens were 100%and up to 50%.Compared with the non-angle steel specimen under the same axial compression ratio,the flexural strength of specimens with angle steel increased by up to 47%,the single-cycle energy consumption increased by up to 94%,and the cumulative energy consumption increased by 24%.With the shear span ratio increases,the load capacity of the test column decreases significantly.With increasing thickness of the angle steel,the increasing rate of the lateral strength of the columns increased,while the increasing rate of the energy consumption decreased.