Use of Performance-Based Methods to Evaluate Structural Response to Hurricane Loading

When executing major modernization of existing buildings besides the challenges of adapting new mechanical equipment and architectural elements, the greatest challenge can come from updating the structural frame to resist current code prescribed lateral forces. As research and testing results in the evolution of building codes, new design forces often exceed the limits of the lateral force resisting systems for older buildings. As great a challenge there is of upgrading the structural system, often the most expensive impacts are related to the time required, and impact to the existing occupants to remove and reconstruct architectural elements. This paper highlights a project where preliminary studies based on traditional methods of analysis indicated the need to perform major structural upgrading as part of the building modernization effort. Due to the requirement of maintaining full occupancy and the estimated costs for the effort, an alternative performance based analysis was performed. These included both simplified methods to prove the concept, and ultimately more advanced methods to verify the expected outcome. The analysis utilized non-linear push-over and time history analyses typical of those for high level earthquake loads for a structure exposed to hurricane forces. Loads were developed using wind tunnel analysis to simulate a one-hour event with a 0.2 sec time step. The result was that no structural upgrading was needed, thus saving the project approximately $20 million. This topic is of international interest. It advances the science of wind engineering beyond standard building code requirements. It demonstrates the resilience inherent in structures that is generally unaccounted for in day-to-day design.