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Thornton Tomasetti 232 of 234 <br />ITEM #4 - ORIGINAL DESIGN CODE COMPARISON - FOUNDATION <br />BEYOND COMPARING THE BASE SHEARS AND BASE OVERTURNING MOMENTS, A MORE APPROPRIATE <br />STUDY IS TO ASSESS THE LIKELY LEVEL OF AXIAL COMPRESSION IN BASE COLUMNS DUE TO SEISMIC <br />FORCES FROM UBC1961 AND CURRENT GROUND MOTIONS. THESE WOULD BE MORE IN LINE WITH THE <br />ORIGINAL FOUNDATION DEMANDS. <br />GRAVITY LOADING ASSUMPTIONS: <br />ASSUMED LOADS <br />UBC 1961 (Office) <br />SELF-WEIGHT No change <br />SUPER-IMPOSED DEAD LOAD --- <br />PARTITIONS 20 psf <br />LIVE LOAD 50 psf <br />REDUCED (Full 60%)20 psf <br />Note: Reduced LL used in both models <br />ASCE7-10 (Residential) <br />No change <br />3 psf <br />10 psf <br />40 psf <br />16 psf <br />UBC 1961 SEISMIC LOAD APPLICATION: <br />TWO ETABS MODELS ARE ANALYZED IN PARALLEL: A MODEL WITH UBC1961 GRAVITY/SEISMIC LOADS AND <br />A CURRENT MODEL WITH GRAVITY LOADS WITH 50%/50YR GROUND MOTIONS. <br />AS A BEST-GUESS AS TO HOW SEISMIC LOADS WERE APPLIED IN THE ORIGINAL DESIGN USING UBC 1961, <br />AN EQUIVALENT-LATERAL FORCE (ELF) PROCEDURE IS ASSUMED. AN ELF LOAD CASE IN ETABS IS <br />SCALED TO MATCH THE SAME BASE SHEAR LISTED ON THE PREVIOUS PAGE (1198k). LOADING IS <br />CONSIDERED IN ALL FOUR DIRECTIONS (X,Y,+VE, -VE) <br />ELF SCALE FACTORS: <br />Name Stiffness From Mass Source Load Type Load Name Scale Fador <br />EL Preset P-dela DISS,Cl Load Pattern ELF*021 3 <br />ELFy 1 Preset P delta M:Sm 1 Load Pauem ELFy 021 <br />1 <br />RESULTING BASE SHEARS: <br />Load FX FY FZ 14*MY MZ <br />1 Case Combo kip kip kip kip'Ft kip-ft k,pft <br />1 - <br />ELEK 1 -1198 023*733E-06 0 43 -13504211 --5384.8816 <br />ELFy 1 0 -1197.97 0 135621.7433 -4.716E-05 |41497.4868 <br />AN AXIAL LOAD COMPARISON BY COLUMN FOR THE UBC 1961 AND CURRENT ANALYSIS IS SHOWN ON THE <br />FOLLOWING SHEET.