Seismic Retrofit of Suspension Bridges in the Central and Eastern U.S. Using Distributed Supplemental Damping

美国中部和东部地区几乎所有的悬索桥都是在抗震设计概念被理解和广泛应用之前很久建造的。 这些桥梁通常在人口稠密的城市地区承载极高的交通量。 这些桥梁的抗震要求往往超过非延性构件的承载能力。 有必要对这些桥梁进行改造，以确保在地震事件期间和之后的生存。本研究的目的是评估在美国中部和东部地区的悬索桥改造中使用分布式附加阻尼。 附加阻尼是一种被动控制，其中阻尼装置被并入结构系统。 分布式阻尼是指这些设备在整个结构中均匀放置。 对该系统的初步调查表明，有可能大幅降低响应。 研究计划应包括旨在实现上述研究目标的许多活动：收集和评估CEUS中典型场地的强震记录。O重新处理已收集的纪录，以恢复长期的内容。典型悬索桥的广泛分析建模。O确定阻尼元件的最有效分布。O评估不同的阻尼器类型和特性。O加强桁架刚度降低或消除的研究 系统及其副作用。O建议的改善方法的可建造性及成本调查研究的影响可包括减少重大地震事件后的生命损失及经济损失、改善隔震系统的设计、建造更长及更轻的未来吊桥，以及提高对地震风险的认识。

Almost all of the suspension bridges in the central and eastern U.S. (CEUS) were built long before seismic design concepts were understood and widely practiced. These bridges carry extremely high volumes of traffic, often in densely populated urban areas. Seismic demands on these bridges often exceed the capacities of the nonductile members. There is a need to retrofit these brides to ensure survival during and after seismic events. The objective of this research is to evaluate the use of distributed supplemental damping in the retrofit of suspension bridges in the central and eastern portions of the United States. Supplemental damping is a type of passive control in which damping devices are incorporated into the structural system. Distributed damping refers to the placement of these devices evenly throughout the structure. Preliminary investigations of the system suggest that large reductions in response are possible. The program of research shall consist of numerous activities intended to fulfill the above mentioned research objective: O Collection and evaluation of strong motion records typical of sites in the CEUS. O Re-processing of collected records to recover long period content. O Extensive analytical modeling of typical suspension bridges. O Determination of most effective distribution of damping elements. O Evaluation of different damper types and characteristics. O Investigation into the reduction or elimination of stiffness from the stiffening truss system and its side effects. O Constructability and cost investigations of the proposed retrofit method.Impacts of the research could include reduction of loss of life and economic losses following a major seismic event, improved design of isolation systems, longer and lighter future suspension bridges, and greater awareness of the seismic risks in the CEUS.