竖向不规则钢-混凝土混合框架静力非线性分析

根据高阶振型对结构位移的贡献,提出基于多振型侧向力分布形式用于竖向不规则结构的静力非线性分析。通过静力非线性分析和动力时程分析结果的对比,验证了侧向力分布形式的准确性。为研究不规则程度对混合结构非线性行为和破坏模式的影响,改变混凝土框架的刚度和强度形成6个竖向不规则混合结构。通过对不规则混合结构层间能力系数的计算,初步判断混合结构刚度和强度的竖向不规则分布特征,评估可能存在的薄弱层和结构破坏模式。采用所提出的侧向力分布形式分别对结构模型进行静力非线性分析,得到混合结构模型的塑性铰开展特征和层间位移角分布,结果表明:混合结构刚度和强度的不规则程度直接影响结构非线性行为和破坏模式,较均匀的层间能力系数分布能够避免结构中出现明显的薄弱层,使结构破坏模式更加合理。

Static Pushover Analysis on Vertically Irregular Steel-RC Composite Frames

According to the contribution of high vibration modes to the displacement of structures, a lateral load pattern method based on multi-modes was proposed in static pushover analysis on vertically irregular structures. The accuracy of the proposed method was verified by comparatively analyzing the results of static pushover analysis and dynamic time-history analysis. In order to evaluate the influence of the degree of stiffness and strength irregularity on the nonlinear behavior and failure modes of composite frames, six vertically irregular composite frame structures were prepared by changing the strength and stiffness of the pre-existing RC (Reinforced Concrete) frames. Inter-story capacity factors of composite frame structures were calculated to quantify the stiffness and strength irregularity along the frame height, and consequently predict the weak story and the failure mode of the structures. The formation of plastic hinges and the distribution of story drift ratios were obtained from the static pushover analyses with the proposed lateral load pattern method. Results indicate that the degree of stiffness and strength irregularity directly affects the nonlinear behavior and failure mode of composite frame structures. A more uniform distribution of story capacity factor can avoid obvious weak stories in the structure, and give a more reasonable structural failure mode.