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

P E R Framework for Performance-Based Engineering {Loss analysis}{Damage analysis}{Dynamic analysis}{Hazard analysis} 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

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

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

EFFICIENCY STIFF SLOPE

EFFICIENCY RESULTS STIFF SLOPE DUCTILE SLOPE Ts < 0.5 s Ts > 0.5 s Period Independent Arias Intensity Spectral 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)

SUFFICIENCY ln(D) = f(IM) + d M+e ln(R) 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 WON’T SPEND A LOT OF TIME ON THIS B/C NOT MUCH PEER RESEARCH Need to identify where sources are: -easy for major strike slip faults such as those shown here -more difficult for reverse slip faults (common in so. Cal), especially blind thrusts -must allow background seismicity for uknown faults SEGMENTS: likely future earthquake sources along fault – e.g., we might think SH is one likely source, NH is another, or both at once (assign weights to each scenario) - relate fault size to magnitude using empircal relations (m-A scaling relns) F(m): we discuss in report several models (exponential, characteristic, maximum magnitude), and what was recommended by a CDMG-USGS working group for CA RATE: need separate rate for large (characteristic) event on major sources, and small eqks, which is assumed to follow G-R. Source: WGCEP, 1999

SURFACE FAULT RUPTURE

Seismic Site Effects Local ground conditions Basin response 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

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

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

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