Seismic Safety Study

Abstract

During the past three decades, the Laboratory has been proactive in providing a seismically safe working environment for its employees and the general public. Completed seismic upgrades during this period have exceeded $30M with over 24 buildings structurally upgraded. Nevertheless, seismic questions still frequently arise regarding the safety of existing buildings. To address these issues, a comprehensive study was undertaken to develop an improved understanding of the seismic integrity of the Laboratory's entire building inventory at the Livermore Main Site and Site 300. The completed study of February 2005 extended the results from the 1998 seismic safety study per Presidential Executive Order 12941, which required each federal agency to develop an inventory of its buildings and to estimate the cost of mitigating unacceptable seismic risks. Degenkolb Engineers, who performed the first study, was recontracted to perform structural evaluations, rank order the buildings based on their level of seismic deficiencies, and to develop conceptual rehabilitation schemes for the most seriously deficient buildings. Their evaluation is based on screening procedures and guidelines as established by the Interagency Committee on Seismic Safety in Construction (ICSSC). Currently, there is an inventory of 635 buildings in the Laboratory's Facility Information Management System's (FIMS's) database, out of which 58 buildings were identified by Degenkolb Engineers that require seismic rehabilitation. The remaining 577 buildings were judged to be adequate from a seismic safety viewpoint. The basis for these evaluations followed the seismic safety performance objectives of DOE standard (DOE STD 1020) Performance Category 1 (PC1). The 58 buildings were ranked according to three risk-based priority classifications (A, B, and C) as shown in Figure 1-1 (all 58 buildings have structural deficiencies). Table 1-1 provides a brief description of their expected performance and damage state following a major earthquake, rating the seismic vulnerability (1-10) where the number 10 represents the highest and worst. Buildings in classifications A and B were judged to require the Laboratory's highest attention towards rehabilitation, classification C buildings could defer rehabilitation until a major remodel is undertaken. Strengthening schemes were developed by Degenkolb Engineers for the most seriously deficient A and B classifications (15 total), which the Laboratory's Plant Engineering Department used as its basis for rehabilitation construction cost estimates. A detailed evaluation of Building 2580, a strengthening scheme, and a construction cost estimate are pending. Specific details of the total estimated rehabilitation costs, a proposed 10-year seismic rehabilitation plan, exemption categories by building, DOE performance guidelines, cost comparisons for rehabilitation, and LLNL reports by Degenkolb Engineers are provided in Appendix A. Based on the results of Degenkolb Engineers evaluations, along with the prevailing practice for the disposition of seismically deficient buildings and risk-based evaluations, it is concluded that there is no need to evacuate occupants from these 58 buildings prior to their rehabilitation.