一种创新的基于阻尼的自适应Pushover方法及其在框架结构中的应用

An innovative adaptive Pushover method based on damping and its application to frame structure

以能力谱Pushover分析方法和自适应Pushover分析方法为基础,提出一种新的基于阻尼的自适应Pushover分析方法。这个方法运用了能力谱Pushover方法中等效阻尼比的概念来表示结构进入塑性的程度,通过每个振型独立加载所产生的能量计算出各自振型的等效阻尼比,利用通过阻尼比折减的反应谱来计算结构的地震作用力。同时,利用结构的振型相关系数对结构弹性阶段及塑性阶段的振型形状进行对比,分辨结构进入塑性前后各个振型的相关性以在自适应Pushover方法过程中对结构各自振型有效地独立加载。通过一榀框架算例,在EL-centro水平地震作用下初步验证了基于阻尼的自适应Pushover分析方法的适用性。算例表明,该方法可以有效地考虑结构高阶振型的影响,其比能力谱Pushover分析方法更接近于弹塑性时程分析的结果。

In this paper,a new adaptive Pushover analysis method based on equivalent damping is put forward.The method takes the concept of equivalent damping from capacity spectrum pushover analysis into consideration to simulate the nonlinear status of structures.The equivalent damping is obtained through the calculation of the energy in each Pushover case for each mode.Then the specific spectrum for particular damping ratio is adopted to calculate the seismic forces.In the meantime,the proposed method makes use of modal correlation coefficient to capture the mode shapes in plastic status most similar to the ones in elastic status to ensure every Pushover case for each mode can be carried through effectively.The proposed method is validated through the examples of one steel frame under the excitation of EL-centro earthquake.In the example,the proposed method gets a better result which is more similar to the nonlinear time history analysis comparing to the capacity pushover procedure due to the reason that the proposed method can consider the higher modes effects efficiently.