抗震能力曲线弹塑性双折线模型的确定方法

Determining method of elasto-plastic double broken line model for seismic capacity curve

抗震能力曲线弹塑性双折线模型对合理评估结构抗震性能具有重要作用。提出了抛物线法,以18个框架结构抗震能力曲线为例,运用抛物线法、修正割线(0.75Vu)法、通用屈服弯矩法和修正ATC-40法确定弹塑性双折线模型并进行相似性分析;研究顶点屈服位移角、延性比和双折线模型第二与第一刚度比的统计规律。研究表明,抛物线法是一种能反映抗震能力曲线弹塑性双折线模型屈服点本质力学特征的方法,与原抗震能力曲线相似度高;修正割线(0.75Vu)法和通用屈服弯矩法与抛物线法相似度高;修正ATC-40法计算的屈服位移明显偏小。

Elasto-plastic double broken line model for seismic capacity curve plays an important role in evaluating the seismic performance of structure reasonably. The parabolic method was proposed. Taking the seismic capacity curves of 18 frame structures for example,the elasto-plastic double broken line models were determined and the similarity analyses were carried out by using the parabolic method,modified secant( 0. 75Vu) method,universal yield moment method and modified ATC-40 method. The statistical regularities of top yield drift angle,ductility ratio and the ratio of second and first stiffness of the double broken line model were researched. The research results show that the parabolic method can reflect intrinsic mechanical characteristics of the yield point of double broken line model for seismic capacity curve,and has high similarities with actual seismic capacity curve. The modified secant( 0. 75Vu) method and universal yield moment method have high similarities with actual seismic capacity curve of parabolic method. The yield displacement of ATC-40 method is obviously smaller than those of others.