High-Order Nonlinear Analysis and Soil-Structure Interaction: Application to Seismic Evaluation and Retrofit

摘要

Performance-based earthquake engineering was utilized to ascertain the seismic performance of an existing two-story non-ductile reinforced concrete building with a proposed new third floor steel-framed addition. The structure, hereafter referred to as the Capital Unity Center, is located in downtown Sacramento, California, and was designed and constructed in early 1940s per the applicable building codes at the time of construction. Capitol Unity Center is a remodel and addition to an existing warehouse structure and is an integral part of the city's attempt to renovate the older downtown buildings. The new center will house a museum with space for exhibits, performing area, and workshops. Since the renovation constitutes major structural changes, the structure in the new configuration must comply with the current seismic provisions of the California Building Code [3]. In addition, since the facility and will be used by the California Department of Education, it must comply with the more stringent requirements of the California Division of State Architecture (DSA). Provisions of FEMA 356 [1], ACI 318 [2] and CBC 2001 [3] were used for a detailed investigation. Comprehensive material testing, detailed geotechnical investigations, site-specific seismic hazards, and state-of-the-art nonlinear structural analysis were performed to assess the seismic performance of the building, identify deficiencies, and evaluate efficacy of seismic retrofit techniques. Analysis showed that the existing structural elements with the architectural renovations did not meet the required performance goals. To obtain satisfactory behavior, both the superstructure and substructure require retrofit. In its retrofitted configuration, the building would then meet the performance objectives.