Abstract

This paper presents comparative study of design procedure for steel moment resisting frames with supplemental damping using performance-based design constraints under earthquake ground motions. The first design example is based on a 4-story steel moment frame building with velocity dependent dampers; the second design example is based on the same building with displacement dependent dampers. The primary seismic-resistant frames, without dampers, were designed to meet the Uniform Building Code of 1997. The amount of supplemental damping for velocity-dependent devices was proportioned based on the first mode of the structural motion. The design of supplemental damping for displacement dependent devices was based on the stiffness of the structure. The seismic resistant frames, with dampers, were designed to remain elastic under a Design Basis Earthquake. The design goal is to limit the lateral drift to 1% of the story height and the Demand-to-Capacity ratio of the moment connections within 1 for a Design Basis Earthquake event. In the event of a larger earthquake, such as Maximum Credible Earthquake, plastic hinge formations and some structural damage would be expected. In that case, the post-Northridge moment connections will provide the ductility to minimize the damage. Lessons learned and suggestions for design guidelines are presented.

Key words: Earthquake analysis, steel, moment-resisting frames, damping devices, displacement-dependent, velocity-dependent