速度脉冲激励作用下混凝土框架柱抗剪性能研究

Shear-resistant behavior of concrete frame columns subjected to velocity pulse-like excitations

研究等效速度脉冲地震作用下混凝土框架柱最不利抗剪性能。以混凝土框架结构底层柱为分析对象,采用等效正弦速度脉冲激励作为地震动输入,通过非线性动力时程分析,研究竖直和水平向联合速度脉冲地震作用对框架柱抗剪性能的影响,分析速度脉冲地震作用与竖向和水平向加速度峰值比、峰值输入时差、剪跨比以及基本振动周期等对抗剪需求和抗剪承载力的交互影响规律。结果表明:脉冲速度强度增大,框架柱抗剪需求增大;竖向与水平向峰值比增大,柱抗剪承载力减小。加速度峰值输入时差对柱的最不利抗剪性能有重要影响;剪跨比越大,速度脉冲的影响越显著。基于分析结果的非线性回归,建立了考虑速度脉冲及其交互因素影响的最不利剪力作用效应修正系数。

The shear-resistant behavior of concrete frame columns subjected to velocity pulse-like excitations was studied.The first floor columns of reinforced concrete frame structures were used to investigate the effects of vertical and horizontal velocity pulse-like excitations on shear-resistant behavior of concrete columns.Three equivalent sine velocity pulses were taken as earthquake import to execute nonlinear dynamic time history analysis.Combined effects of vertical-to-horizontal peak acceleration ratio,import time difference of peak values between vertical and horizontal excitations,shear-span ratio,and fundamental period on shear-resistant demand and shear-resistant capacity were analyzed with the assessment of the effect of velocity pulse action.The results demonstrated that shear-resistant demand of concrete columns increases with increase in intensity of velocity pulse,and shear-resistant capacity decreases with increase in vertical-to-horizontal peak values ratio;import time difference between vertical and horizontal excitations has an important influence on the most unfavorable shear-resistant behavior of concrete frame columns;the higher the values of shear-span ratio,the more significant the influence of velocity pulse excitations;the nonlinear regression analysis for the above results is conducted,and an empirical approach considering different effect of these factors is proposed.