Seismic Retrofit with Energy Dissipators

本项目由国家自然科学基金公告第90-23号“结构抗震修复与修复研究”资助。使用带贝尔维尔弹簧垫圈的槽孔螺栓进行的试点试验表明，在严重的循环加载期间，由于板表面之间的滑动，螺栓具有极好的能量耗散潜力。此类试验表明，在多次荷载反转期间，例如在严重地震期间，可能发生稳定的重复迟滞行为。连接处的滑移发生在螺栓上的滑移临界剪切力处。因此，可以精确地设计支撑和其他元件，使它们在地震事件引起的力下不会弯曲或屈服。这将消除在传统设计的钢支撑中出现的最不受欢迎的行为。在这个项目中，早期的研究将扩展到更大范围的螺栓尺寸和循环加载类型。几个螺栓在循环荷载作用下的连接行为也将被研究。在对这些结果进行分析后，将设计用于实验台的模型试验架。耗能连接的实际设计程序及其适用范围将通过对框架进行模拟地震荷载试验来制定。预计采用传统制造程序的拟议系统在实际应用中将具有极高的成本效益。

This project is supported under NSF Announcement No. 90-23 "Repair and Rehabilitation Research for Seismic Resistance of Structures." Pilot tests using bolts in slotted holes with Belleville spring washers show an excellent potential for energy dissipation during severe cyclic loading due to slip between faying plate surfaces. Such tests indicate stable repetitive hysteretic behavior during numerous load reversals such as may occur during a severe earthquake. The slip at a connection occurs at a slip-critical shear force on the bolts. Therefore it is possible to accurately design braces and other elements such that they would not buckle or yield under forces caused by a seismic event. This would eliminate the most undesirable behavior occurring in conventionally designed steel bracing. In this project the earlier studies will be extended to a larger range of bolt sizes and types of cyclic loading. The behavior of several bolts at a connection under cyclic loading will also be investigated. After analysis of these results, a model test frame for experiments on the table will be designed. Practical design procedures for energy dissipating connections and the range of their applicability will be developed by testing the frames with simulated earthquake loadings. It is expected that the proposed system utilizing conventional fabrication procedures will be exceptionally cost effective for practical applications.