Performance-Based Geotechnical Earthquake Engineering for Seismic Design Prediction

NEEDS FOR PERFORMANCE-BASED GEOTECHNICAL EARTHQUAKE ENGINEERING Jonathan Bray University of California, Berkeley Pacific Earthquake Engineering Research Center

SHAKING-INDUCED DAMAGE to Bridges and Buildings Moehle

Seismic Displacement LIQUEFACTION-INDUCED DAMAGE EERC Slide Collection EERC Slide Collection

P E E R Framework for Performance-Based Engineering DV = Decision variable (e.g., down-time, costs)DM = Damage Measure (e.g. damage state, cracking)EDP = Engineering Demand Parameter (e.g., peak story drift, drift ratio, seismic displacement)IM = Intensity measure (e.g., Sa, Arias intensity)(IM) = Rate of exceedance of IM {Loss analysis}{Damage analysis}{Dynamic analysis}{Hazard analysis}

D IM IM: characterizes the strong ground motion M, R, Site, Fault Example Objective: predict seismic Displacements Decouple the HAZARD analysis from the DYNAMIC RESPONSE Minimize the dispersion around the predicted displacements

1.SLOPE MODEL equiv-linear, SDOF, coupled stiffness (Ts) - strength (ky) 2. EARTHQUAKE DATABASE 45 EQ - 1447 records Ts ky D 3. INTENSITY MEASURES amplitude: PGA, PGV, PGD, SA, SV frequency content: Tp, Tm duration: D5_95, Dbracketed other: Arias Intensity Housner Spectral Intensity EXAMPLE

EFFICIENCY STIFF SLOPE

EFFICIENCY RESULTS STIFF SLOPEDUCTILE SLOPE Ts < 0.5 s Ts > 0.5 s Period IndependentArias IntensitySpectral Intensity Period Dependent Spectral Acceleration at Ts

SHORT BUILDING OR BRIDGE • Intensity Measures (IM): • Sa(T1), PGV, Ia, Sa(T1)[Sa(2T1)/Sa(T1)]0.5 Longitudinal drift ratio Longitudinal drift ratio (Mackie and Stojadinovic, 2002)

ln(D) = f(IM) + d M+e ln(R) SUFFICIENCY Stiff Slope NO INTENSITY MEASURE IS SUFFICIENT FOR ALL TS and ky

VECTORS OF IM’s: D = f( SA(Ts), IM2) MORE DUCTILE STRONGER

PERIOD-INDEPENDENT INTENSITY MEASURES Peak Ground Acceleration PGA Peak Ground Displacement PGD Arias Intensity (Arias, 1970) Cumulative Absolute Velocity (Kramer 2002; 5 cm/sec2 threshold) Response Spectrum Intensity (Housner, 1959) Peak Ground Velocity PGV & Pulse Period Tv

PERIOD-DEPENDENT INTENSITY MEASURES Spectral Acceleration at Fundamental Period Spectral Combination (Cordova et al. 2000) Spectral Vector (Conte, 2002) Spectral Combination IM1I&2E (Luco and Cornell, 2001) Sa(T1) Sa(T1)

Factors Affecting (IM): •  (m): Rate of earthquakes with magnitude m • f(m): relative likelihood of earthquakes with different magnitudes • f(IM|m,r): distribution of IM conditioned on m and r Stewart et al. PEER Report-2001/09

Source Characterization • Source locations • Segmentation • m-A relations • f(m) models • Rate • Large events (characteristic) • Small events Source: WGCEP, 1999

SURFACE FAULT RUPTURE

Seismic Site Effects • Local ground conditions • Response of horizontal sediment layers • Accounts for resonance, impedance contrasts, soil non-linearity • Basin response • Accounts for 2-D/3-D sediment geometry • Surface topographic effects Combined Influence on Ground Motions

Simplified Geotechnical Site (SGS) Categories (Rodríguez-Marek et al. 2001)

Northridge EQ Loma Prieta T = 0.3 s T = 1.0 s T = 0.3 s T = 1.0 s Site SGS UBC SGS UBC SGS UBC SGS UBC B .40 (.08) .46 (.07) .45 (.11) .52 (.09) .51 (.10) .52 (.10) .58 (.11) .61 (.11) C .54 (.05) .54 (.06) .60 (.05) .54 (.06) .38 (.05) .36 (.05) .53 (.08) .52 (.07) D .41 (.04) .42 (.03) .36 (.03) .41 (.03) .39 (.07) .39 (.06) .59 (.11) .64 (.10)

10 17 17 31 GROUND MOTION DATABASE Simplified Geotechnical System Rodriguez-Marek et al. 2001 Rock 15% Soft Rock / Stiff Shallow Soil Deep Stiff Soil 27% 58% Fault Types Reverse Oblique Normal 1208 records from 75 Earthquakes Active Plate Margins Magnitudes 4.7 – 7.6 Distances 0.1 – 250 km Reverse Strike Slip

Near Fault Ground MotionsNorthridge EQ: Rinaldi Receiving Station Newhall - Pico Canyon

Performance-Based Geotechnical Earthquake Engineering for Seismic Design Prediction