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Outline

Seismic Hazard and Building Code Seismic Design in Kentucky

Outline Seismic hazard maps Seismic design maps Some problems in seismic design in KY Summary

Seismic Hazards Ground Motion (Primary-Basic Code Design) Causes >90 % damage USGS NEHRP ground motion hazard maps Fault rupture (Setback, 50 ft in CA) Secondary Hazards Ground motion amplification (soil classification) Liquefaction Slope failure

Seismic Hazards USGS NEHRP hazard maps Probabilistic Seismic Hazard Analysis (PSHA) maps Developed based on national/regional database may not reflect local variation Three return periods 500 years (10% PE in 50 years) 1000 years (5% PE in 50 years) 2,500 years (2% PE in 50 years)

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KBC-2002 and KRC-2002 KRC-2002: Using the probabilistic ground motion with 5% PE in 50 years for WKY Eliminate E zone KBC-2002: Cap of 0.4g for short period (UBC-97 zone 4) for WKY Some inconsistencies are still needed to be resolved

Summary Use of the probabilistic ground motion with 2% PE in 50 years is over-conservative for seismic design in areas surrounding the New Madrid seismic zone. However, it is not necessary conservative in other areas outside the New Madrid seismic zone. Local variations were not considered In IBC-2000 and IRC-2000 California: deterministic ground motion Current building code for CA: UBC-97 Maximum seismic design: 0.4g PGA Central and Eastern US: probabilistic ground motion Several counties: design PGA>1.0g

Summary