Report - PEER - University of California, Berkeley

4. EXPERIMENTAL PROGRAMFigures 3a and 3b consider Taiwan seismic code draft updated in 2002. It stipulates,for a hard rock site, the S a (T=1 sec) values for earthquake hazard of 10% chance ofexceedance in 50 years (10/50 Design Earthquake, DE) and 2/50 (MaximumConsidered Earthquake, MCE) earthquakes as 0.68g and 0.91g, respectively. The 5%damped S a values for TCU082EW records are also shown on Figs. 3a and 3b. Thecorresponding PGA values for the 10/50 and 2/50 levels of excitations are 0.46g and0.62g, respectively, for the TCU082EW record. Similarly, for the LP89g04NS record,the corresponding PGA values for the 10/50 and 2/50 levels of excitations are 0.40gand 0.54g, respectively.Sa(T=1)=0.68g0.4 DE,10 / 500.5MCE, 2 / 50ξ=5%ξ=5%000 1 2 3(b)Period (sec)Period (sec)Figure 3. Design acceleration spectra (a)10/50 (b)2/50 hazard level.As shown in Fig. 4, the two earthquake records are TCU082EW (from the 1999ChiChi earthquake) and LP89g04NS (from the 1989 Loma Prieta earthquake), both ofwhich are considered to represent general motions without near-field directivityeffects. The original test plan was to scale these two records in acceleration amplitudeto represent four separate pseudo-dynamic loading events, which were sequenced asfollow: (1) TCU082 scaled to represent a 50/50 hazard intensity, i.e., with a 50%chance of exceeding in 50 years, (2) LP89g04 scaled to a 10/50 hazard intensity,which represents the design basis earthquake, (3) TCU082 scaled to a 2/50 hazard,and (4) LP89g04 scaled to a 10/50 hazard — identical to loading (2). The recordsscaling is based on matching the spectral acceleration at one second period to thespecified earthquake hazard levels.Acceleration(m/sec 2 )Sa (g)2.21.10-1.121.61.20.8Taiwan's Code 2002TCU082 EWLP89g04NS(PGA) LP89g04NS=0.40g(PGA) TCU082=0.46gTCU082, PGA=0.217g-2.20 15 30 45Time (sec)(a) 0 1 2 3Acceleration(m/sec 2 )2.21.10-1.1LP89g04, PGA=0.212g-2.20 10 20 30 40Time (sec)Figure 4. Original ground accelerations used in test (before scaling).Sa (g)2.521.51Taiwan's Code 2002TCU082 EWLP89g04NS(PGA) LP89g04NS=0.54g(PGA) TCU082=0.62gSa(T=1)=0.91g249