基于构形度的强震下单层球壳结构倒塌模式优化研究

COLLAPSE SCENARIO OPTIMIZATION OF SINGLE-LAYER SPHERICAL SHELLS UNDER SEVERE EARTHQUAKE EXCITATIONS BASED ON WELL-FORMATION

基于杆系结构构形易损性理论,以构形度标准差最小为目标函数,以构件截面尺寸为优化变量,并考虑长细比、挠度、杆件强度及稳定约束条件,建立了单层球壳结构构形度优化模型。将遗传算法和模拟退火算法作为子算法,基于混合策略构造出遗传-模拟退火算法(GASA),并采用自适应策略降低算法对优化参数的依赖性。以跨度70m的单层球壳结构为例,通过凝聚过程分析识别结构存在的构形度不均匀区域。采用GASA算法对该区域的杆件截面进行构形度优化。通过对优化后结构凝聚过程分析和地震动力时程分析,表明优化模型和优化算法可以有效的解决优化变量繁多的大型单层球壳结构地震作用下倒塌模式的优化问题。

Based on the form vulnerability theory of skeletal structures, a well-formation optimal model of single-layer spherical shells is established by taking the minimization of the standard deviation of the well-formation as the optimization objective and the cross-sectional dimensions of members as the optimization variables. This optimal model takes into account the constraints of a slender ratio, a deflection, bar strength and stability. Taking genetic algorithm and simulated annealing as sub algorithms, a genetic-simulated annealing algorithm(GASA) is put forward using a mixed strategy. Meanwhile, adaptive strategies are adopted to reduce the dependency of the algorithm upon the optimization parameters. Taking an example of a 70 m span single-layer spherical shell, the uneven well-formation regions are identified through a clustering process. The cross-sectional dimensions optimization of members located in those regions is carried out using GASA. By the clustering process analysis and the seismic time history analysis, it is indicated that the optimized model and algorithm can effectively solve the collapse scenario optimization of large-scale single-layer spherical shells with several optimization variables under earthquake excitations.