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Thornton Tomasetti 19 of 234 <br />UPPER AND LOWER BOUND DAMPER ANALYSIS <br />NOTES: <br />1 - FOR ASCE41-13 SECTION 14.3.2.4 UPPER- AND LOWER-BOUND ANALYSES WITH +/-15% VARIATION IN <br />DAMPERS' COEFFICIENT OF DAMPING (C-VALUE), SEPARATE PARALLEL MODELS WERE RUN FOR ALL <br />DAMPERS AT 0.85*C, C, AND 1.15*C. COLUMN PMM RATIOS FROM THE THREE MODELS ARE PRESENTED. <br />2 - MAXIMUM DCRs FOR EACH COLUMN ARE ENVELOPED FROM ALL GROUND MOTIONS. DCRs ARE <br />PRESENTED FOR Ll-L3 AND L3-L4 ONLY. BY INSPECTION COLUMN DCRs ABOVE LEVEL 4 WILL BE LOW FOR <br />ALL VARIATIONS IN DAMPER PROPERTIES. <br />3 - TWO COLUMNS SHOW HIGH DCRs FROM NET TENSION IN A SINGLE TIME STEP IN ONLY THE NORTHRIDGE <br />EVENT. IF NET TENSION PLUS FLEXURE LED TO REBAR YIELD, OTHER COLUMNS WOULD ACT STIFFER AND <br />HAVE RESERVE CAPACITY TO RESIST GREATER LATERAL DEMANDS. <br />MEAN OF PMM DCRs FOR THESE TWO COLUMNS FOR ALL GROUND MOTIONS IS 0.71. WHILE FOUR GROUND <br />MOTIONS DO NOT SATISFY ASCE 41-13 USE OF MEAN RATHER THAN MAXIMUM VALUES (AT LEAST 7 GROUND <br />MOTIONS ARE NEEDED), THIS RESULT PROVIDES SOME PERSPECTIVE. <br />4 - THE MEAN OF ALL L3-L4 COLUMN MAXIMUM PMM DCRs (NOT ALL OCCURING SIMULTANEOUSLY) IS 0.52 <br />WITH A STANDARD DEVIATION OF 0.13. THIS SUGGESTS COLUMNS OVERALL ARE ABLE TO RESIST PMM <br />DEMAND EVEN IF A CORNER COLUMN YIELDS IN A RARE EVENT.