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在结构连续倒塌分析中,可通过荷载动力放大系数将静力荷载进行放大,从而间接模拟结构的动力响应。目前国内外相关文献中关于动力放大系数取值的观点不同。对于空间结构,杆件失效后剩余结构容易出现塑性;塑性程度对动力放大系数影响较大,使得动力放大系数具有不确定性。提出采用应力比值法研究张弦结构的动力放大系数,其过程为:在设计荷载组合下控制结构不同的平均应力比值,得到不同构件截面大小的结构模型,然后对这些模型进行动力放大系数的分析。为了充分研究动力放大响应,分别定义了弹性位移动力放大系数、弹塑性动力放大系数和荷载动力放大系数。分析结果表明:对于张弦结构,弹性动力放大系数最大不超过2.0;由于塑性的发展,弹塑性动力放大系数有可能超过2.0。荷载动力放大系数取2.0比较保守;建议索破坏时荷载动力放大系数取1.6~1.8,其他重要构件破坏时荷载动力放大系数取1.3~1.5。
In the continuous collapse analysis of structure, the static load can be amplified by the dynamic amplification factor of load to indirectly simulate the dynamic response of the structure. At present, there are different views on the value of dynamic amplification factor in relevant literature at home and abroad. For the spatial structure, the remaining structure after the failure of the rod is prone to plasticity; the degree of plasticity greatly affects the power amplification coefficient, making the power amplification coefficient uncertain. Proposed the stress ratio method to study the dynamic amplification coefficient of the string structure, the process is: under the design of load combinations control the structure of different average stress ratio, the cross-sectional structure of different components of the structure model, and then analyze the model of the power amplification factor . In order to fully study the dynamic amplification response, the elastic displacement power amplification coefficient, the elastic-plastic power amplification coefficient and the load power amplification coefficient are respectively defined. The analysis results show that for the string structure, the elastic power amplification factor does not exceed 2.0. Due to the plasticity, the elastic-plastic power amplification factor may exceed 2.0. Load power amplification factor of 2.0 is more conservative; Proposed cable damage load amplification factor of 1.6 to 1.8, the other important component damage load amplification factor of 1.3 to 1.5.