Passive Energy Dissipation Devices for Upgrading of Steel Structures

9416516 Betereo北岭地震对大量多层钢框架建筑造成了重大破坏。 对这种损坏有许多不同的解释，包括焊接问题、钢的材料特性、一般设计理念、结构系统中缺乏冗余和多个抗侧力荷载路径。 再加上这些观察结果的事实是，最近的几个实验研究强调了潜在的非弹性循环荷载下的大型焊接钢连接性能差。 提高钢结构建筑抗震性能的一种方法是通过引入特殊装置来提高结构系统的耗能能力，从而降低主要结构系统关键区域的能量需求。 本文对钢框架结构的被动耗能减震进行了理论分析和试验研究。 对四种不同的被动耗能减震体系进行了研究。 这些器械代表了无源器械的主要类别：摩擦、金属、纯粘性和粘弹性。 两个设备进行了实验研究（摩擦和纯粘性），和测试的结果被用来开发两种类型的设备的数值模型。 这些数值模型，然后在分析研究中使用。 另外两种类型的被动阻尼器（形状记忆合金和粘弹性）也包括在研究中，但在本项目中没有进行实验研究。 在前人研究成果的基础上，建立了阻尼器的数值模型。 一个实际的钢结构建筑，典型的那些在北岭地震中遭受破坏的确定和使用作为分析研究的基础。 选择了一组地震地面运动，代表服务水平，中等和严重的地震震动。 首先分析所选建筑的现有（未升级）状况。 升级方案的基础上的四种类型的阻尼装置设计的建筑物和他们的好处进行了仔细比较的响应参数。 通过考虑主要结构系统的延性和能量需求，以及通过使用适当的响应参数评估非结构部件和内容的损坏，来评估性能效益。最后，评估了升级方案对建筑物因地震摇晃而遭受经济损失的脆弱性的影响。 被动消能技术是一种对现有结构进行抗震升级的方法，与传统方法相比，该方法具有性能和经济效益。 该研究项目旨在进一步发展和完善利用这些技术进行升级的方法。 这是北岭地震项目。 ***

9416516 Betereo The Northridge earthquake caused significant damage to a large number of multistory steel framed buildings. A number of different explanations for the damage have been proposed, including problems with welding, the material properties of the steel, and the general design philosophy and lack of redundancy and multiple lateral-resisting load paths in the structural systems. Coupled with these observations is the fact that several recent experimental investigations have highlighted the potential poor performance of large welded steel connections under inelastic cyclic loading. One approach for improving the seismic performance of the types of steel buildings is to increase the capability of the structural system to dissipate energy by introducing special devices for this purpose, and thus decreasing the energy demands on critical regions of the primary structural system. A combined analytical and experimental study focusing on the benefits of passive energy dissipation for steel frame structures is undertaken in this project. Four different passive energy dissipation systems are investigated. These devices are representative of the main classes of passive devices: friction, metallic, pure viscous, and viscoelastic. Two devices are studied experimentally (friction and pure viscous), and the results of the testing are used to develop numerical models of the two types of devices. These numerical models are then utilized in the analytical study. Two other types of passive dampers (shape memory alloy and viscoelastic) are also included in the study, but not investigated experimentally in the present project. Numerical models are developed for these dampers based on the results of other pervious and current research. An actual steel building, typical of those that suffered damage in the Northridge earthquake is identified and used as the basis of the analytical study. A set of earthquake ground motions are chosen, representing service-le vel, moderate and severe earthquake shaking. The selected building is first analyzed in its existing (non-upgraded) condition. Upgrade schemes based on each of the four types of damping devices are designed for the building and their benefits investigated by a careful comparison of response parameters. The performance benefits are assessed by considering ductility and energy demands on the primary structural system, and also by evaluating damage to nonstructural components and contents using appropriate response parameters. The impact of the upgrade schemes on the vulnerability of the building to economic loss due to earthquake shaking is finally assessed. Passive energy dissipation techniques represent a method for seismic upgrading of existing structures that offers performance and economic benefits over conventional approaches. This research project is designed to further develop and refine the methodologies for upgrading using these techniques. This is a Northridge earthquake project. ***