Structural Engineering · Engineering Glossary
A seismic retrofit is a structural modification of an existing building to improve its ability to resist earthquake forces, reducing the risk of damage or collapse during a seismic event. Retrofit measures typically add new lateral force resisting elements — shear walls, braced frames, moment frames — or strengthen existing connections and foundations.
Seismic retrofits are triggered by mandatory programs (such as Los Angeles's soft-story ordinance requiring retrofit of pre-1978 wood-frame apartments), voluntary upgrades, change-of-occupancy reviews, or building assessments following an earthquake. Common retrofit strategies include adding plywood shear walls, installing steel moment frames or braced frames, strengthening soft-story columns with steel jackets, and improving foundation connections. The structural engineer performs a seismic evaluation following ASCE 41 (Seismic Evaluation and Retrofit of Existing Buildings) to quantify the deficiencies and design the retrofit scope. Apex Grid provides seismic evaluation and retrofit engineering for commercial, industrial, multifamily, and government buildings.
Apex Grid Engineering maintains this glossary as a resource for architects, contractors, developers, and property owners who encounter unfamiliar engineering terminology on their projects.
View All Engineering TermsApex Grid's licensed PEs provide structural engineering services across multiple jurisdictions — with fast quote turnaround and permit-ready documents.
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