Shelby County Seismic Hazard Analysis
Shelby County, Tennessee
Shelby County, and its county seat of Memphis, TN, is home to nearly one million residents. It lies within the New Madrid Seismic Zone, a major seismic zone with the potential to produce large, damaging earthquakes to the densely populated urban area. Despite the high risk of earthquakes, only recently have buildings in Memphis been designed to perform under such conditions.
In 2011, SSR, along with two other consulting firms, was asked to perform a Seismic Hazard Analysis for Regional One Health’s Regional Medical Center (The MED) and the Shelby County Administrative Office Building, specifically looking at standards ASCE-31, Seismic Evaluation of Existing Buildings, and ASCE- 41, Seismic Rehabilitation of Existing Buildings. The Seismic Evaluation of Existing Buildings included a seismic assessment of four buildings on the campus of The MED and the county building. The evaluation qualified elements of the buildings’ lateral and gravity structural systems, highlighting potential deficiencies.
After identifying the deficiencies of the buildings, SSR performed the more detailed Seismic Rehabilitation of Existing Buildings and provided preliminary retrofit designs for two buildings at The MED, the Routh Center for Women & Newborns and the Chandler Tower. The Rout Center for Women & Newborns is a seven-story reinforced concrete moment frame structure built in 1956 as five independent structures that have since been combined under one roof. The Chandler Tower, a seven-story moment frame structure with three concrete stories and four steel stories, was built in 1961. A Seismic Rehabilitation of Existing Buildings was also performed at the Shelby County Administration Building, a 12-story concrete shear wall structure built in 1966. All three buildings were designed before any seismic design was required in Memphis.
As a result of the hazard analysis, new lateral force resisting systems were designed to bring the three buildings up to modern code. The lateral system consisted of high strength concrete shear walls and a system of collectors to deliver the seismic forces into the new shear walls and protect the integrity of the buildings should an earthquake hit the area.