Mickey Leland Federal Building
Built in the early 1980s, the George Thomas “Mickey” Leland Federal Building is a 22-story office tower in downtown Houston. The GSA purchased the building and in 2009 sought proposals to update and re-skin the structure. Since the original construction, new wind load provisions had been added to the code. Additionally, the new skin design included a larger “wind sail” area which required that the existing lateral load system be checked for compliance with current requirements.
The initial static analysis of the existing lateral force resisting system showed many members were significantly overstressed by the higher current code wind loads and new cladding configuration. Instead of strengthening all of these members, Walter P Moore used an innovative analysis approach to better model the building’s structural behavior. This performance-based analysis accounted for the non-linear behavior of material using state-of-the-art methods as opposed to the approximate methods used in conventional industry practice. While this had been used in seismic design, it had never before been applied to wind loads.
This alternative design approach made it economically feasible to save the entire existing structure by significantly reducing the quantity of members requiring strengthening, saving on the demolition and new materials. The savings were approximately 1,500 tons of concrete, 175 tons of reinforcing steel, and 350 tons of cradle-to-grave CO2 emissions that would have been generated as a result of producing this quantity of structural metals. The design team applied for and achieved a LEED Innovation in Design (ID) credit for demonstrating that by using this approach, a 30% reduction in material quantities in the lateral load resisting system had been achieved.