The rise in performance-based engineering, in which a structure is proportioned to meet certain predictable performance requirements, necessitates reasonable estimates of component behavior during earthquakes. It is customary to determine component properties via physical lab tests. For components such as concrete anchors, verification of the ultimate strength is required and quasi-static pull tests are sufficient. The situation is more involved for other components, such as beam-to-column assemblies, since an earthquake produces dynamic back-and-forth cyclic actions and the component is often expected to deform inelastically. …
Author Archives : Bruce F. Maison P.E., S.E.
Bruce F. Maison is a Consulting Engineer practicing in El Cerrito, California. He is an active member of the Existing Buildings Committee of the Structural Engineers Association of Northern California (SEAONC). He is also a member of the ASCE/SEI Committee responsible for the performance-based engineering standard ASCE 41, Seismic Evaluation and Retrofit of Existing Buildings. (maison@netscape.com)
Technical Considerations for Engineers
Prescriptive Performance-Based Design: An Innovative Approach to Retrofitting Soft/Weak-Story Buildings (STRUCTURE, September 2019) describes the approach contained in the Federal Emergency Management Agency (FEMA) P-807 guideline. P-807 is a method to retrofit a weak first story of wood buildings to mitigate side-sway pancake-type collapse, as depicted in the Figure. The hazard posed by such buildings was underscored by their damage in the 1989 Loma Prieta earthquake affecting the San Francisco Bay area, as well as in the 1994 Northridge earthquake in the Los Angeles region. Some cities in California have enacted ordinances mandating retrofit of soft-story buildings. …