Response spectra for differential motion of structures supports during earthquakes in Egypt

الملخص EN

Differential motionsofgroundsupportsofstiffstructureswithlargeplandimensions and separatefoundationsunderearthquakeswerestudiedbyresearchersduringthelastfewdec- ades.

Suchatypeofstructuralresponsewaspreviouslyunderestimated.Theimportanceofstudying such aresponsecomesupfromthefactthatusuallythestructuresaffectedareofstrategicimpor- tance suchasbridges.Duringtheirexpectedlife,structuresmayexperiencevibrationsexcitedby ground wavesofshortwavelengthsduringnear-sourceearthquakes,orduringamplifiedearthquake signals, duringexplosions,orduringvibrationsinducedfromnearbystrongvibrationsources.This is thecasewhenthedifferentialmotionofsupportsbecomesconsiderable.Thispaperaimsto review theeffectsofseismicsignalvariationsalongthestructuresdimensionswithemphasison Egypt asacasestudy.Thepapershowssomepatternsofthedamageimposedbysuchdifferential motion.

Areplicationofthedifferentialmotioninthelongitudinaldirectionisappliedonaframe bridge model.Theresultingstrainingactionsshowthenecessityforconsideringthedifferential motion ofsupportsinthedesignofspecialstructuresinEgypt.Finally,responsespectraforthedif- ferential motionofsupports,basedontheavailabledatafrompreviousearthquakesinEgypt,is derived andproposedfordesignerstoincludeinthedesignprocedurewhenaccountingforsuch type ofstructuralresponse,andespeciallyinlong-spanbridges