隔震结构多向动力耦合激励作用下连续倒塌力学行为及支承位移场异变监测研究

Progressive collapse of structures, which is caused by the local damage, will generally result in serious consequences, and thus have become a focusing topic in the field of civil engineering worldwide. However, the study on the progressive collapse of isolated structures is still left blank. In fact, no matter what type of isolation devices are employed, the isolation system takes effect though a reduced horizontal stiffness, and the capacity of rotational restriction for the super structure are reduced compared with those in the fixed-base structures. This will, in turn, reduces the redundancy of progressive collapse resistance of the isolation layer. This project selects the effect of both the disturbing of isolator supporting structure, such as the collapse of the collapsible loess foundation, excavation of foundation pit of a neighboring building, and the accidental destroying of rubber isolator due to intentional or unintentional impaction, shock or earthquake induced fire disaster as the initial failure scenario, the progressive collapse mechanism of the remaining isolated system will be analyzed using FEM numerical simulation, subjected to the separate action of sudden impacting of the vertical unbalanced loading caused by the dead weight of the super structure or the horizontal seismic excitation, or subjected to the coupled action of vertical unbalanced loading and horizontal seismic excitation, or horizontal-vertical seismic excitation coupled with vertical unbalanced loading. The structural robustness for progressive collapse resistance will be analyzed subjected to the coupled action of multi- directional dynamic excitation. The extraordinary change of the supporting displacement field of the isolation system due to support disturbing and the damaging displacement filed and stress filed of the critical positions of the remaining isolated structure will be monitored using structural health monitoring technique, and the algorithm for identifying the invisible damage of isolated system will be worked out. With scale model specimen fabricated, model test will be carried out for several loading cases such as the separate action of vertical unbalanced loading or the coupled action of vertical unbalanced loading with either horizontal seismic excitation, or horizontal-vertical seismic excitation.

由结构局部破坏而引发连续倒塌一般都会带来严重后果，因而成为土木工程领域的国际热点。然而，对隔震结构连续倒塌的研究目前尚属空白。事实上，无论采用哪种隔震装置，隔震系统水平刚度及其对上部结构转动约束能力均较小，这就降低了隔震层抗连续倒塌的冗余度。本项目分别选取黄土地基湿陷或临近建筑基坑开挖等诱发隔震支座支承扰动，以及碰撞、火灾等因素诱发隔震支座意外缺失作为初始损伤，对剩余隔震体系在竖向不平衡荷载突加冲击和水平地震激励分别作用，及水平-竖向多向地震与竖向不平衡荷载耦合激励作用下的连续倒塌机制进行数值模拟，对隔震结构在多向动力耦合激励作用下的抗连续倒塌鲁棒性进行分析，并对隔震系统支承扰动时的位移场异常变化、结构危险部位的位移和应力进行监测，建立隔震支座隐性损伤的识别算法。制作缩尺模型试件，对隔震模型在竖向不平衡荷载单独作用或与水平地震、水平-竖向地震耦合作用等几种情形的动力连续倒塌进行试验研究。

倒塌是结构破坏的终极表现形式，而结构的连续倒塌往往会带来严重经济损失和恶劣社会影响，因而成为土木工程领域着力解决的热点研究议题。在本项目立项之前，国内外对隔震结构连续倒塌的研究鲜有报道。对隔震结构连续倒塌机理的探索，有助于在隔震技术推广应用过程中识别对结构安全有重大风险的一些因素，从而有助于研发相应的结构体系或构造措施对这些可能的风险加以预防。隔震结构连续倒塌力学行为与传统抗震结构有很大不同。叠层橡胶支座隔震结构的全部竖向及水平荷载均由数量非常有限的若干个隔震支座承担，结构竖向稳定性和抗倾覆能力也皆依赖于隔震支座。加上隔震层水平刚度及其对上部结构转动约束能力均较小，这就降低了隔震层抗连续倒塌的冗余度。本项目首先利用理论分析与数值模拟相结合的方法，对隔震结构在多向动力耦合激励下的受力状态及损伤发展进行推演，得出隔震结构在火灾、爆炸、相邻结构深基坑开挖或黄土场地湿陷等因素诱发的连续倒塌基本规律，建立了多向动力激励下隔震结构抗连续倒塌的鲁棒性指标，提出相应的理论表达式。其次，利用结构健康监测技术，对支承系统水平和竖向位移场异常变化、隔震层及上部结构关键构件破坏应力场进行监测，探索了监测系统配置方法及隔震系统隐性损伤识别算法。最后，结合缩尺模型对隔震结构不同部件失效后的剩余隔震体系在不同激励方向、不同激励强度的动力耦合激励作用下的连续倒塌特点进行试验研究，将隔震支座缺失的动力试验结果与数值模拟、理论分析及现场监测结果相对比，验证隔震结构动力连续倒塌判别准则。本项目的研究揭示了隔震层比较难以形成抗连续倒塌的悬链线机制、隔震结构抗连续倒塌的薄弱环节、隔震系统隐性损伤诱发的竖向不平衡荷载与水平地震作用耦合是隔震结构极端不利工况等隔震结构连续倒塌相关的一些重要规律，对深化理解隔震结构的损伤和连续倒塌机理提供了重要的定量参考，为隔震技术推广应用、人才培养和国际学术交流提供了理论支撑。