NEESR-CR: Performance-Based Design for Cost-Effective Seismic Hazard Mitigation in New Buildings Using Supplemental Passive Damper Systems

Project Overview

The vision for the project is a validated multi-level, probabilistic, performance-based seismic design procedure for buildings with supplemental passive damping systems. In this procedure, the design of the damping system is integrated with the design of the associated seismic load resisting frames, and the uncertainties that influence the level of damage caused by ground motions at different seismic hazard (input) levels are treated explicitly. The procedure considers multiple performance objectives, with each objective associating a different level of damage with a different seismic hazard level. The project will design two steel-framed prototype buildings as the context for the research. Several types of dampers will be studied. Tests at the Lehigh NEES equipment site will characterize the dampers; analytical models for the dampers will be calibrated and validated. Extending previous work, a practical performance-based design procedure, and an associated design assessment procedure for buildings with passive dampers will be developed. These procedures treat inherent uncertainties using partial safety factors. The performance-based design procedure will be used to produce several design cases for each prototype building, by varying the strength of the steel frames and the damper type. Then, each design case will be assessed with a rigorous, probabilistic assessment procedure developed by the project. This assessment uses nonlinear dynamic analyses, and considers numerous damage states while rigorously treating uncertainties in building properties, damping systems, and ground motions. The procedure estimates the probabilities that these damage states are reached at different seismic hazard (input) levels. Large-scale real-time hybrid pseudo-dynamic simulations at the Lehigh NEES equipment site will validate the rigorous assessment procedure as well as the results of the practical design procedure. The hybrid simulations will have two phases: Phase 1 uses three individual large-scale dampers as the lab specimens, while the remainder of the building is modeled as analytical substructures; Phase 2 uses a large-scale 3-story steel frame with one damper at each story as the lab specimen, while the remainder of the building modeled as analytical substructures. Phase 1 simulations will be particularly efficient, by enabling numerous ground motions to be applied to the building, resulting in various levels of damage, without the need to repair the test specimens, since the damage will be within the analytical substructures. Phase 2 simulations will validate this approach.