基于多层框架结构的楼层阻尼比修正的仿真研究

Simulation research on story damping ratio modification based on a multistory frame structure

摘要:

附加有效阻尼比的确定是消能减震结构设计的关键。为探究布置消能器楼层数的不同对结构设计安全性的影响,以新疆地区某多层钢筋混凝土框架结构为研究对象,采用非线性时程分析方法和等效结构模型的振型分解反应谱分析方法,基于各楼层剪力计算结果,引入楼层阻尼比修正系数k_mn,对等效结构模型的附加有效阻尼比进行迭代修正。结果表明:采用小震时程分析阻尼比的等效结构模型,其楼层阻尼比修正系数随着阻尼器布置楼层数的逐渐增加呈现出先增后减的趋势,当阻尼器布置层数为楼层总数的3/5时折减率最低;采用中震时程分析阻尼比的等效结构模型,当阻尼器布置楼层数不少于2/5时,可满足设防要求;对于多层框架结构,考虑综合成本,黏滞阻尼器的布置楼层数可不采用满布的形式。

Abstract:

Determining an additional effective damping ratio is key to designing energy dissipation structures. To explore the influence of the number of floors with dampers on the safety of structure design, this study used a multistory reinforced concrete frame structure in Xinjiang as the research object. Nonlinear time-history analysis and mode decomposition response spectrum analysis of the equivalent structure model were performed. Based on shear force calculation results for each floor, the story damping ratio modification factor was introduced to promote iterative correction of additional effective damping ratio of equivalent structure model. The results show that the story damping ratio modification factor of the equivalent structure model first increases and then decreases with an increasing number of floors with dampers when using the time-history analysis under small earthquakes. Moreover, the reduction rate is the lowest when the number of floors with dampers is three-fifths of the total number of floors. However, an equivalent structure model where no less than two-fifths of the floors have dampers can meet fortification requirements when using the time-history analysis under intermediate earthquakes. Considering the comprehensive cost, the viscous dampers do not need to cover all floors.