Rolling Isolation Systems to Protect Building Contents from Earthquakes

易碎物品和关键任务的建筑内容，如医院设备，可以放置在滚动隔离系统上，以保护它们免受地震事件的破坏。滚动隔离系统由一对匹配的水平矩形框架和固定在其角落的刚性浅盘组成。下框的盘子上凹，上框的盘子下凹。位于这些盘子之间的一个大钢球允许上部框架在下部框架上滚动。滚动隔震系统所能抵御的震动强度在很大程度上取决于钢盘的直径。目前滚动系统的一个限制因素是它们只能保护物体免受水平振动。此外，对于特定应用而言，最佳的碗形和适当的能量阻尼量仍然是一个悬而未决的问题。该奖项支持研究开发滚动隔离系统，可以保护脆弱的建筑内容物免受严重的水平和垂直运动。由此产生的系统将包含用于垂直隔离和多层隔离的专用组件。在开发这些系统并评估其减轻地震危害的前景的过程中，这项研究将使人们更好地了解地震地面运动的真正三维方面及其对脆弱物体和结构的影响。最终，滚动隔离的适当设计和实施将确保不可替代的物体、关键的医院和电信设备以及数字基础设施在严重地震期间和之后保持运行，从而减轻这些潜在灾难性事件的成本。为本科生和高中生提供的研究机会将扩大本研究的参与范围。一项工业外联方案将加强结果的实际传播。滚动隔离系统固有的非完整约束导致横向和旋转动力学之间的非线性耦合。因此单轴和线性化模型不足以预测这些系统的响应。因此，该项目的目标是提高受三维地面运动影响的设备和部件的高容量隔离系统的性能和实施。本文将推导三维隔震系统非线性动力学的新数学模型，并在六自由度振动台上进行实验验证。这些经过验证的模型将加速设计新的碗状拓扑结构，以最大限度地提高这些系统的有效驱替能力。新的地震危害分析方法将被开发出来，以识别地面运动的三维性质和建筑物和内容物的阈值敏感行为。

Fragile objects and mission-critical building contents such as hospital equipment may be placed on rolling isolation systems in order to protect them from damage during earthquake event. Rolling isolation systems consist of a matched pair of horizontal rectangular frames with rigid shallow dishes fixed to their corners. The dishes in the lower frame are concave up, and those in the upper frame are concave down. A large steel ball located between these dishes allows the upper frame to roll over the lower frame. The intensity of shaking that rolling isolation systems can protect against is determined largely by the diameter of the steel dishes. Currently one of the limiting factors for rolling systems is that they can protect objects only from horizontal shaking. Further, the best bowl shape and the proper amount of energy-damping for a particular application remain open questions. This award supports research to develop rolling isolation systems that can protect fragile building contents from severe horizontal and vertical motions. The resulting systems will incorporate specialized components for vertical isolation and multiple isolation layers. In developing these systems and assessing their promise for earthquake hazard mitigation, this research will lead to a better understanding of the true three-dimensional aspect of earthquake ground motions and their impact on fragile objects and structures. Ultimately, the proper design and implementation of rolling isolation will ensure that irreplaceable objects, critical hospital and telecommunications equipment, and digital infrastructure will remain operational during and after severe earthquakes, thereby mitigating the costs of these potentially disastrous events. Research opportunities for undergraduate and high school students will broaden the participation in this research. An industrial-outreach program will enhance the practical dissemination of the results. The non-holonomic constraints inherent to rolling isolation systems result in nonlinear coupling between lateral and rotational dynamics. Uniaxial and linearized models are therefore not sufficient to predict the response of these systems. The objective of this project is therefore to advance the performance and implementation of high-capacity isolation systems for equipment and components subjected to three-dimensional ground-motions. New mathematical models for the nonlinear dynamics of three-dimensional isolation systems will be derived and validated with experiments on a six degree of freedom shake table. These validated models will accelerate the design of new bowl topologies in order to maximize the effective displacement capacities of these systems. New methods of seismic hazard analysis will be developed that recognize the three-dimensional nature of ground motions and the threshold-sensitive behavior of buildings and contents.