Resolution No. 4814 - Laserfiche WebLink

Home Browse Search

1.0 INTRODUCTION 1.1 Eugene City Hall The Eugene City Hall is a two-story structure designed in 1962 and built in 1964. The lower level includes a parking structure, mechanical equipment rooms and a fire station, with about 87,608 square feet. The upper level includes office space and City Council Chambers, with about 74,777 square feet (excluding the open plaza area). The building footprint is rectangular (323' x 323'). The structural systems for this building are a combination of moment-resisting non-ductile reinforced concrete frames coupled with some reinforced concrete shear walls. As discussed below, the building was built well before current seismic design standards were established for western Oregon. The building has significant structural and non-structural seismic deficiencies, with a significant probability of extensive damage and/or possible collapse at levels of ground shaking likely in major earthquakes. The building includes police headquarters, a major downtown fire station, the Fire Marshal's office, City Manager's office, Human Resources and Risk Management department, and the municipal courts and court offices. 2.0 MITIGATION PROJECT A preliminary seismic vulnerability assessment has been conducted for the Eugene City Hall. Full details of the seismic vulnerability engineering evaluation (including seismic capacity calculations), along with synopses of previous seismic vulnerability evaluations, are given in Chapters 2, 3 and 5 of the Technical Appendix. These chapters include engineering analyses and numerous photographs of structural building elements (where exposed) and non- structural elements (including critical equipment) with extensive commentary on the specific seismic deficiencies identified in this building. These chapters also include discussion of necessary mitigation actions (seismic retrofits) and engineering costs estimates for these structural and non-structural retrofits. This seismic vulnerability assessment has clearly identified specific structural and non-structural deficiencies. The building was designed in 1962 and completed in 1964. Overall, the amount of steel reinforcing in structural concrete members and the extent of confinement provided by the steel is much lower than current design requirements. A major structural deficiency is inadequate shear walls to provide necessary lateral capacity for earthquake ground motions. Major structural deficiencies also include "short column" deficiencies on the perimeter of the first level (retaining walls adjacent to the columns do not have expansion joints at the column); such deficiencies are known to result in load concentrations with resulting structural failures to the short columns, leading to partial collapse.