高强钢管超高强混凝土短柱偏压性能试验研究

Experimental study on compression performance of ultra-high-strength concrete (UHSC) filled high-strength steel tube stub columns subjected to eccentric load

为研究高强钢管超高强混凝土构件的压弯性能,以偏心率为参数,进行了10根高强钢管超高强混凝土短柱的偏压试验,得到不同偏心率下短柱的破坏模式、荷载-柱中侧移曲线和荷载-柱中应变曲线。研究结果表明,随偏心率的增加,短柱弯曲变形伴随的受压强度破坏特征不明显,偏压承载力减小,受拉、压侧外缘的截面塑性程度提高,延性改善更为显著;高强钢管超高强混凝土短柱达到偏压承载力前,组合截面可较好地满足平截面假定;当偏心率不大于1.6时,高强钢管超高强混凝土短柱发生小偏压破坏;截面塑性不断发展,受压侧外缘高强钢管对核心超高强混凝土的套箍作用发挥比较充分。对比承载力试验值与采用GB 50936—2014《钢管混凝土结构技术规范》计算的承载力值发现,现有规范中小偏压的折减系数计算方法并不完全适用高强钢管超高强混凝土偏压短柱。基于试验结果,提出了偏压折减系数的修正计算方法。

In order to study the compresion-bending performance of ultra-high-strength concrete-filled high-strength steel tube short columns,ten spcimens subjected to different eccentric loads were carried out.The failure modes,load-deflection curves,and load-strain curves of the short columns were investigated.The results show that with the increase of eccentricity,the compressive failure characteristics associated with bending deformation tend to be less obvious,the bearing capacity decreases,the plasticity level at the edge of the tension and compression zone increases,and the ductility is improved more significantly.Before the ultra-high-strength concrete-filled high-strength steel tube short column reaches the eccentric bearing capacity,the composite section satisfies the plane section assumption.When the eccentricity is less than 1.6,small eccentric failure occurs in ultra-high-strength concrete-filled high-strength steel tube.With the development of section plasticity,the hoop effect of high-strength steel tube on UHSC at the edge of the compression zone is brought into play.By comparing the bearing capacity obtained from the test and the predicted values of GB 50936—2014‘Technical code for concrete steel tubular structures’,it is found that the reduction coefficient considering the influence of eccentricity on bearing capacity is not applicable to ultra-high-strength concrete-filled high-strength steel tube short column occurred in small eccentric failure.Therefore,a modified calculation method of reduction coefficient was proposed based on the test results.