Seismic retrofit

Seismic retrofitting is the modification of buildings that already exist to make them resistant to earthquakes.^[1] Seismic retrofitting techniques can be applied to other kinds of natural disasters such as tornadoes and strong winds from thunderstorms.

Municipal Services Building in Glendale, California retrofitted with base isolation.

Seismic retrofit performance objectives

Main levels of retrofitted building structure performance ^[2] objectives may vary, namely:

Infill shear trusses — University of California dormitory, Berkeley
External bracing of an existing reinforced concrete parking garage (Berkeley)
Port Authority Bus Terminal in New York City
One of many "earthquake bolts" found throughout period houses in the city of Charleston subsequent to the Charleston earthquake of 1886. They could be tightened and loosened to support the house without having to otherwise demolish the house due to instability. The bolts were directly loosely connected to the supporting frame of the house.
Infill shear trusses — University of California dormitory, Berkeley, California
Massive exterior structure — Parking garage over ground level shops, Berkeley, California
Pleasing use of detail – note "waist" effect and integrated bench in base. Pedestrians exiting shops are protected from collision with bench by railings behind original footing
Exterior steel infill shear truss seismic retrofit of reinforced concrete dormitory, University of California, Berkeley.
Exterior general reenforcement of an existing garage structure with street level shops. Located in Berkeley near the Hayward Fault. Image by User:Leonard G. for the seismic retrofit
Partial failure due to inadequate shear structure at garage level. Damage in San Francisco due to the Loma Prieta event.