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

美国中部和东部几乎所有的悬索桥（CEUS）都是在抗震设计概念被理解和广泛应用之前建造的。这些桥梁承载着极高的交通量，通常位于人口稠密的城市地区。对这些桥梁的抗震要求往往超过了非延性构件的承受能力。有必要改造这些新娘，以确保在地震期间和之后的生存。本研究的目的是评估分布式附加阻尼在美国中部和东部悬索桥改造中的应用。补充阻尼是一种被动控制，其中阻尼装置被纳入结构系统。分布阻尼是指在整个结构中均匀地放置这些装置。对该系统的初步调查表明，大幅度降低响应是可能的。研究计划应包括许多旨在实现上述研究目标的活动：O收集和评估CEUS中典型站点的强震记录。O重新处理已收集的记录，以恢复较长时期的内容。O对典型悬索桥进行广泛的分析建模。O确定阻尼元件的最有效分布。O不同阻尼器类型和特性的评估。O研究降低或消除加劲桁架系统的刚度及其副作用。提出的改造方法的可建造性和成本调查。该研究的影响可能包括减少重大地震事件后的生命损失和经济损失，改进隔离系统的设计，未来更长更轻的悬索桥，以及提高对CEUS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.