This study aims to analyze seismic damage of reinforced outlet piers of arch dams by the nonlinear finite element （FE） sub-model method. First, the dam-foundation system is modeled and analyzed, in which the effects...This study aims to analyze seismic damage of reinforced outlet piers of arch dams by the nonlinear finite element （FE） sub-model method. First, the dam-foundation system is modeled and analyzed, in which the effects of infinite foundation, contraction joints, and nonlinear concrete are taken into account. The detailed structures of the outlet pier are then simulated with a refined FE model in the sub-model analysis. In this way the damage mechanism of the plain （unreinforced） outlet pier is analyzed, and the effects of two reinforcement measures （i.e., post-tensioned anchor cables and reinforcing bar） on the dynamic damage to the outlet pier are investigated comprehensively. Results show that the plain pier is damaged severely by strong earthquakes while implementation of post-tensioned anchor cables strengthens the pier effectively. In addition, radiation damping strongly alleviates seismic damage to the piers.展开更多
系统级封装(system in package,SiP)作为后摩尔时代异构集成的关键技术,其内部多级互连结构的尺寸跨度达3个数量级,而互连尺寸的持续减小导致传统分析方法的成本与难度显著攀升.文中旨在建立一种快速准确的SiP器件评估方法,为器件可靠...系统级封装(system in package,SiP)作为后摩尔时代异构集成的关键技术,其内部多级互连结构的尺寸跨度达3个数量级,而互连尺寸的持续减小导致传统分析方法的成本与难度显著攀升.文中旨在建立一种快速准确的SiP器件评估方法,为器件可靠性设计提供支撑,首先对SiP器件的互连焊点形态进行精准预测,基于该结果构建等效简化的SiP整体模型及可控塌陷芯片互连(controlled collapsed chip connection,C4)、芯片互连(chip connection,C2)专用子模型,以降低仿真计算复杂度,随后采用子模型有限元分析方法,开展实际工况下的热循环有限元仿真,定位应力危险点并进行子模型计算,完成不同互连结构的寿命评估.结果表明,通过有限元仿真成功定位SiP器件的应力危险点,子模型计算有效反映了不同互连结构的力学性能差异,经寿命对比分析最终明确了兼具可靠性与经济性的最优互连结构,同时验证了所建立的等效简化模型及子模型分析方法的准确性与高效性.展开更多
基金National Natural Science Foundation of China under Grant Nos.51179093 and 91215301Specialized Research Fund for the Doctoral Program of Higher Education under Grant No.20130002110032
文摘This study aims to analyze seismic damage of reinforced outlet piers of arch dams by the nonlinear finite element （FE） sub-model method. First, the dam-foundation system is modeled and analyzed, in which the effects of infinite foundation, contraction joints, and nonlinear concrete are taken into account. The detailed structures of the outlet pier are then simulated with a refined FE model in the sub-model analysis. In this way the damage mechanism of the plain （unreinforced） outlet pier is analyzed, and the effects of two reinforcement measures （i.e., post-tensioned anchor cables and reinforcing bar） on the dynamic damage to the outlet pier are investigated comprehensively. Results show that the plain pier is damaged severely by strong earthquakes while implementation of post-tensioned anchor cables strengthens the pier effectively. In addition, radiation damping strongly alleviates seismic damage to the piers.
