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1136 GEOENV1RONMENT 2000 <br />a •• -· $;.olo "',,.., '"' = ss-2 = --! ss-' Refu3oe <br />I = .· <~·::-.: = <br />~ ~ ~-,~~· <br />= :'-;-., ·,, ,, .'\: '·.'-..."'.:: ·,;;: = <br />FIG. 4 Orr Plan and Longitudinal Section (Hushmand Associates, 1994) <br />::§: 0.1 .,----,---------, <br />z <br />0 <br />~ 0.0 <br />~ <br />tJ ~ -0.1 'j..;c:;;;:.,::;:;c~~~~~·~··~·~~~·.'·,".~..,..j <br />20 40 60 80 100 120 <br />TlME (sec) <br />3 0.1 ,-----------....., <br />Us,..,. IW~ Lal>donlq. <br />OUTCROP "•· r..q,, 1.77 !Ia <br />20 40 60 80 100 120 <br />TIME (sec) <br />3 0.3 ,..------------, <br />1:: ... ~~~~ <br /><-0.3 <br />12 16 20 24 28 32 <br />TIME (sec) <br />:§ o.o Tj ----------, I::J~:-:::1 <br />< -0.3 .f,=;:;.;:;:;;~~~~~~,.;.~.,..J <br />0 8 12 16 20 u ~ u <br />TlME (sec) <br />FIG. 5 Orr Strong Motion Records, Northridge and Landers Earthquakes <br />MSW PROPERTIES <br />-MSW' (Kavazanjian & Matasovic', 19941 <br />.•.•• PEAT (Seed & !driss. 1970a <br />___ CLAY (Seed & Idrisa, Hl70b) <br />0.001 0.01 0.1 <br />CYCLIC SHEAR STRAIN (51>) <br />10 <br />~30y---~---~-~~~--, <br />-MSW (l<o'l'n:>:Rnjian & MntnsoviO, 1994) <br />...... PEAT (Seed & ldriss, 1970al / S 25 ___ CLAY (Seed & Idriss, 1970b <br />'< " ~ 20 l <br />0: <br />!1. <br />0.0001 0.001 <br />CYCLIC <br />i Lilllll <br />. . . . <br />I I iiilioj <br />0.01 0.1 1 <br />SHEAR STRAIN (%) <br />I <br />' j <br />10 <br />FIG 6. Modulus Reduction and Damping Curves For MSW <br />1137 <br />The MSW unit weight and shear wave velocity profiles presented in Figures <br />1 and 3 were used in the trial and error analysis to obtain the best-fit equivalent- <br />linear soil parameters. The upper 1.5 m of the MSW unit weight and shear wave <br />velocity profiles were deleted and replaced with values representative of compacted <br />cover soil to simulate field conditions. The effective strain factor used to compute <br />the representative shear strain from the calculated peak cyclic shear strain for <br />evaluation of modulus reduction and damping factors was varied to achieve the best <br />fit with the observed acceleration response. Both the Northridge and Landers records <br />for Oil were used in the analysis. <br />When comparing the equivalent-linear analysis results to the observed <br />behavior in the Northridge earthquake, it was observed that when the parameters <br />were adjusted to match the peak acceleration, a poor fit was obtained with the rest <br />of the response spectra. Therefore, matching the· peak acceleration was discarded <br />as a basis of comparison and the analyses focused on achieving a good fit with the <br />observed response spectra over the broadest possible range of periods, with emphasis <br />placed on the longer periods which contribute the most to seismic deformation