Parameters Affecting Your Structure (Own or use):
Distance to Known Faults:
Expected EQ Magnitude:
Fault Rupture Return Interval:
Soil Conditions at site:
Seismic intensity grows exponentially with proximity to EQ fault.
Determines expected Energy Release and intensity of seismic event.
How often the fault section is expected to break, according to historical records. For example, 1650 year EQ history of the Hayward Fault showns a Mean Ocurrence Interval of 151 +/- 23 years (last event in 1868, next expected event in 2018 +/- 23 years).
Please Note:
"Good soils" at site will transmit higher accelerations of nearby EQ events, but will not settle differentially within the structures footprint. "Bad soils" could deform substantially when shaking and cause differential settlement, thus potentially damaging the foundation and compromising the structure while it is resisting the earthquake.
Building Characteristics:
Buildings which are Regular (box shaped) in plan and elevation have good structural response, while Irregular buildings (L-shaped, vertical offsets, soft story, etc) behave poorly and sustain substantially more damage.
For existing structures, year structure built provides indication of lateral resistance provisions probably implemented during construction, significantly less than current requirements.
In new structures, redundancy, ductility, and robustness of structure beyond minimum code requirements will improve survivability of structure and minimize effort to repair structure after a strong seismic event.
Earthquake Issues of Concern
Code Intent:
No Collapse Criteria - The purpose of earthquake code provisions is primarily to safeguard against major structural failures and loss of life, not to limit structural damage or maintain function; this is true for both bridge and building structures, although the methodologies are different at present.
In the event of a major seismic event, if your structure was designed according to current minimum code requirements, your structure would probably not collapse but could result in damage that is not repairable.