spectrum analysis using staad
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24/03/2015 www.sefindia.org::ViewtopicSpectrumAnalysisUsingStaad.ProV8i
http://www.sefindia.org/forum/viewtopic.php?t=13615 1/10
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sharathknSEFIMember
Joined:10Jun2011Posts:17
Posted:MonFeb11,201312:37pmPostsubject:SpectrumAnalysisUsingStaad.ProV8i
Hi,
Ihaveafewurgentqueries,regardingthespectrumanalysisusingStaad.Prov8i,asfollows:
1.firstiwouldliketoknowwhileinloadcaseforSeismicSpectrum,whetherselfweightforyisonlyenough,orforalldirectionsitshouldbeapplied.Alsothemaximumforceasappliedonthenodesshallbeonlyapplyforonedirection,sayXtogetherwithresponsespectrum,oralsoithastobeagainapplyfordefiningresponsespectrumforzdirectionalso.
2.Alsoiwouldliketoknow,whetherdesigningcommandcanbefollowedaftertheanalysishasbeendoneinthesamestaadfile,oraseparatefilehastobecreatedwheretheseinterpretedforcesshouldbeappliedasanaxialforceforeachnodesforcarryingoutthedesignoftheframe
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nssenthilkumaranSEFIMember
Joined:27Oct2010Posts:2
Posted:TueFeb12,20137:53amPostsubject:SpectrumAnalysisUsingStaad.ProV8i
DearSefian,Hereismyreplytothequeries.Ifiamincorrect,othersmaycorrectme.1)InSTAADPro,wedonothaveanoptionofdefiningmasselementswhichareneddedfortheSpectrumanalysis.Sowhatwegenerallydois,firstapplytheDl+0.5LLonthestructure,Secondlyapplypinnedsupportstoallthenodes,analyseandgettheverticalforceineachnodeandapplytheforceinallthethreedirectionsforthecorrespondingnodeintheresponsespectrumloadcase.IfyourDLcasedoesnthaveselfweightinit,Youwillhavetoapplyitalongwiththeabovementionedforcesinallthethreedirections,i.e)selfweighty1,selfweightx1,selfweightz1.IfyourDLcasealreadyhasselfweightinit,youdontneedtoseperatelyspecifyselfweightcommandinthespectrumloadcase.Ihopeiamclear.Thereasonforapplyingallforcesinallthethreedirectionsisbecausethemasscalculatedatthenode(doneinternallyinSTAAD)mustbeappliedinallthreedirectionsinordertoprovideinertialforces.2)Asforyoursecondquery,itispossibletogivethedesigncommandaftertheresponsespectrumanalysisinSTAAD.Butiwouldnotrecommendit.Becauseincaseofspectrumanalysis,theforcesofallthemodesaresummedupusingtheSRSS(sumofsquarerootofsquares)method.andbecauseofthisthesignsofthebendingmomentswouldbelosti.e)ifyouseetheBendingmomentvaluesforthespectrumcase,allthevalueswouldbepositive.Thismayleadtooverdesignofsomesectionsandunfortunatelyunderdesignofsomesections.WhatiwouldrecommendisfindtheVb(Baseshear)valuesofdominantmodes(modesinwhichconsiderableamountofmassesparticipate),sumitupandthendistributeittoeachnodeusingtheformulainequivalentstaticmethod.Thenapplytheforces(nodalforcesstatic)ineachdirectionasa
-
24/03/2015 www.sefindia.org::ViewtopicSpectrumAnalysisUsingStaad.ProV8i
http://www.sefindia.org/forum/viewtopic.php?t=13615 2/10
seperateloadcaseandanalyseandobtaintheresults.Theforcesobtainedintheabovementionedmethodcanbeusedforthedesign.Regars,N.S.SenthilKumaran.StructuralEngineer,Tamilnadu,India
OnMon,Feb11,2013at6:07PM,sharathknwrote:
Quote:
Hi,
Ihaveafewurgentqueries,regardingthespectrumanalysisusingStaad.Prov8i,asfollows:
1.firstiwouldliketoknowwhileinloadcaseforSeismicSpectrum,whetherselfweightforyisonlyenough,orforalldirectionsitshouldbeapplied.Alsothemaximumforceasappliedonthenodesshallbeonlyapplyforonedirection,sayXtogetherwithresponsespectrum,oralsoithastobeagainapplyfordefiningresponsespectrumforzdirectionalso.
2.Alsoiwouldliketoknow,whetherdesigningcommandcanbefollowedaftertheanalysishasbeendoneinthesamestaadfile,oraseparatefilehastobecreatedwheretheseinterpretedforcesshouldbeappliedasanaxialforceforeachnodesforcarryingoutthedesignoftheframe
PostedviaEmail
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nrupenyadahalliSEFIMember
Joined:09Sep2009Posts:17
Posted:WedFeb13,20135:57amPostsubject:SpectrumAnalysisUsingStaad.ProV8i
Hi,
IfyouareusingSRSSmethodforthisinSTAADthenSW&othermasshastobedefinedinall3orthogonaldirections.Sinceonecantunderstandcompletebehavourofmodeshapeswithmassparticipatinginall3directions...
MaybeIS1893part1&4mayhelpuonmassparticipationinXY&Znmodeshape.
Nrupen
OnMon,Feb11,2013at6:07PM,sharathknwrote:Quote:
Hi,
Ihaveafewurgentqueries,regardingthespectrumanalysisusingStaad.Prov8i,asfollows:
1.firstiwouldliketoknowwhileinloadcaseforSeismicSpectrum,whetherselfweightforyisonlyenough,orforalldirectionsitshouldbeapplied.Alsothemaximumforceasappliedonthenodesshallbeonlyapplyforonedirection,sayXtogetherwithresponsespectrum,oralsoithastobeagainapplyfordefiningresponsespectrumforzdirectionalso.
2.Alsoiwouldliketoknow,whetherdesigningcommandcanbefollowedaftertheanalysishasbeendoneinthesamestaadfile,oraseparatefilehastobecreatedwheretheseinterpretedforcesshouldbeappliedasanaxialforceforeachnodesforcarryingoutthedesignoftheframe
-
24/03/2015 www.sefindia.org::ViewtopicSpectrumAnalysisUsingStaad.ProV8i
http://www.sefindia.org/forum/viewtopic.php?t=13615 3/10
PostedviaEmail
Backtotop
va...
Joined:26Jan2003Posts:59
Posted:WedFeb13,201310:30amPostsubject:SpectrumAnalysisUsingStaad.ProV8i
DearAll,1)InthelatestversionofSTAADproV8iselectseries4thereisaprovisiontoprovideareferencemassloadcase.Thismasswillbeusedduringdynamicanalysis.2)Secondly,thereisafacilitytoattachasignofdominantmodetotheresultsofresponsespectrumanalysiswhichareotherwiseabsolutevalues.Regards.HemantVadalkar,ConsultingEngineerSTADDEngineersMumbaiFrom:nssenthilkumaran[mailto:forum@sefindia.org]Sent:Wednesday,February13,20133:40PMTo:general@sefindia.orgSubject:[SEFI]Re:SpectrumAnalysisUsingStaad.ProV8i
DearSefian,
Hereismyreplytothequeries.Ifiamincorrect,othersmaycorrectme.
1)InSTAADPro,wedonothaveanoptionofdefiningmasselementswhichareneddedfortheSpectrumanalysis.Sowhatwegenerallydois,firstapplytheDl+0.5LLonthestructure,Secondlyapplypinnedsupportstoallthenodes,analyseandgettheverticalforceineachnodeandapplytheforceinallthethreedirectionsforthecorrespondingnodeintheresponsespectrumloadcase.
IfyourDLcasedoesnthaveselfweightinit,Youwillhavetoapplyitalongwiththeabovementionedforcesinallthethreedirections,i.e)selfweighty1,selfweightx1,selfweightz1.
IfyourDLcasealreadyhasselfweightinit,youdontneedtoseperatelyspecifyselfweightcommandinthespectrumloadcase.Ihopeiamclear.Thereasonforapplyingallforcesinallthethreedirectionsisbecausethemasscalculatedatthenode(doneinternallyinSTAAD)mustbeappliedinallthreedirectionsinordertoprovideinertialforces.
2)Asforyoursecondquery,itispossibletogivethedesigncommandaftertheresponsespectrumanalysisinSTAAD.Butiwouldnotrecommendit.Becauseincaseofspectrumanalysis,theforcesofallthemodesaresummedupusingtheSRSS(sumofsquarerootofsquares)method.andbecauseofthisthesignsofthebendingmomentswouldbelosti.e)ifyouseetheBendingmomentvaluesforthespectrumcase,allthevalueswouldbepositive.
Thismayleadtooverdesignofsomesectionsandunfortunatelyunderdesignofsomesections.WhatiwouldrecommendisfindtheVb(Baseshear)valuesofdominantmodes(modesinwhichconsiderableamountofmassesparticipate),sumitupandthendistributeittoeachnodeusingtheformulainequivalentstaticmethod.Thenapplytheforces(nodalforcesstatic)ineachdirectionasaseperateloadcaseandanalyseandobtaintheresults.
Theforcesobtainedintheabovementionedmethodcanbeusedforthedesign.
Regars,
N.S.SenthilKumaran.StructuralEngineer,Tamilnadu,India
OnMon,Feb11,2013at6:07PM,sharathknforum@sefindia.org(forum@sefindia.org))>wrote:autoremoved
PostedviaEmail
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24/03/2015 www.sefindia.org::ViewtopicSpectrumAnalysisUsingStaad.ProV8i
http://www.sefindia.org/forum/viewtopic.php?t=13615 4/10
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sharathknSEFIMember
Joined:10Jun2011Posts:17
Posted:ThuFeb14,201311:45amPostsubject:
Hi,earlierIaskedafewqueriesonresponsespectrumanalysisinstaad.pro.thankyouforresponse.Keepinginmind,Ifollowedthebelowmentionedsteps,kindlycorrectitwhereeverIwentwrong,asImdoingitfirsttime.
1)TakingacombinationofDL+0.5LLinstaad.proandassigningeverybeamcolumnjunctionnodeasFixedSupport,Ifoundoutthejointweights.
2)Inanotherstaadfileofthesamemodel,Ifirstassignedthesejointweightsunderseismicdefinition.AfterthatIcreated1stloadcasesasspectrumXinwhichItookthemaximumwhichistheFyjointloadandassigneditforX,Y&ZdirectiontogetherwiththeresponsespectrumloadUsingIS1893andCQCmethodforXdirection.
Thenafter,Icreated2ndloadcaseasspectrumZinwhichIonlyassignedtheresponsespectrumloadforZdirection.
AfterthisIcreatedloadcasesforDeadLoadinwhichselfweightiny(1)hasbeenassigned,LiveloadsandLoadCombinations.
3)AfterthisIneedtoknow,howtointerpretthePeakstoryshear,modalbaseactionandparticipationfactorsfromtheoutputofthestaadanalysissoastocalculatethenassignthelateralforcesoneachnodeoneachstoreyinXandZdirectionina3rdstaadfileofthesamemodel,tocarryouttheequivalentstaticearthquakeanalysis._________________KNSharath
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shivrajekadamGeneralSponsor
Joined:30Dec2012Posts:8Location:Mumbai.
Posted:ThuFeb14,20133:06pmPostsubject:SpectrumAnalysisUsingStaad.ProV8i
DearSenthil,
Ihavegonethroughurreply,iagreedwithuropinionasfarasfirstpointisconsideredbutnotwiththesecondcase.
2)Ifurdoingdynamicanalysisofbuildinganduraddingalltheresponsesusinganyoneofmodalcombinationmethodi.eCQC,SRSSorABS,allmemberforcessignedisgettinglostduetosquarerootandsquaringoperationbuttosatisfythisconditionweareconsideringallloadcombinationsgivenin1893:2002(24numbers),Sourstructuralmemberdesignisalwaysonaconservativeside.Butifurfoundationisraftfoundationorcombinedfoundattionthenuneedtobringbackthesignesofreactionsforaccurateanalysisotherwiseurfdndesignmaybeeitherconseravativeorunderdesign.Secondlyasfarasmyknowledgeitisnotpossibletodistributetheloadateachandeverynodebyusingformulegiveninequivalentstaticmethodbecauseudonotknowthemassparticipationatthatnodeinthatmode.
Regards,ShivrajKadam.
On2/13/13,nssenthilkumaranwrote:Quote:
DearSefian,
Hereismyreplytothequeries.Ifiamincorrect,othersmaycorrectme.
1)InSTAADPro,wedonothaveanoptionofdefiningmasselementswhichareneddedfortheSpectrumanalysis.Sowhatwegenerallydois,firstapplytheDl+0.5LLonthestructure,Secondlyapplypinnedsupportstoallthenodes,analyseandgettheverticalforceineachnodeandapplytheforceinallthethreedirectionsforthecorrespondingnodeintheresponsespectrumloadcase.
IfyourDLcasedoesnthaveselfweightinit,Youwillhavetoapplyitalongwiththeabovementionedforcesinallthethreedirections,i.e)selfweighty1,selfweightx1,selfweightz1.
-
24/03/2015 www.sefindia.org::ViewtopicSpectrumAnalysisUsingStaad.ProV8i
http://www.sefindia.org/forum/viewtopic.php?t=13615 5/10
IfyourDLcasealreadyhasselfweightinit,youdontneedtoseperatelyspecifyselfweightcommandinthespectrumloadcase.Ihopeiamclear.Thereasonforapplyingallforcesinallthethreedirectionsisbecausethemasscalculatedatthenode(doneinternallyinSTAAD)mustbeappliedinallthreedirectionsinordertoprovideinertialforces.
2)Asforyoursecondquery,itispossibletogivethedesigncommandaftertheresponsespectrumanalysisinSTAAD.Butiwouldnotrecommendit.Becauseincaseofspectrumanalysis,theforcesofallthemodesaresummedupusingtheSRSS(sumofsquarerootofsquares)method.andbecauseofthisthesignsofthebendingmomentswouldbelosti.e)ifyouseetheBendingmomentvaluesforthespectrumcase,allthevalueswouldbepositive.
Thismayleadtooverdesignofsomesectionsandunfortunatelyunderdesignofsomesections.WhatiwouldrecommendisfindtheVb(Baseshear)valuesofdominantmodes(modesinwhichconsiderableamountofmassesparticipate),sumitupandthendistributeittoeachnodeusingtheformulainequivalentstaticmethod.Thenapplytheforces(nodalforcesstatic)ineachdirectionasaseperateloadcaseandanalyseandobtaintheresults.
Theforcesobtainedintheabovementionedmethodcanbeusedforthedesign.
Regars,
N.S.SenthilKumaran.StructuralEngineer,Tamilnadu,India
OnMon,Feb11,2013at6:07PM,sharathknwrote:
Quote:
Hi,
Ihaveafewurgentqueries,regardingthespectrumanalysisusingStaad.Prov8i,asfollows:
1.firstiwouldliketoknowwhileinloadcaseforSeismicSpectrum,whetherselfweightforyisonlyenough,orforalldirectionsitshouldbeapplied.Alsothemaximumforceasappliedonthenodesshallbeonlyapplyforonedirection,sayXtogetherwithresponsespectrum,oralsoithastobeagainapplyfordefiningresponsespectrumforzdirectionalso.
2.Alsoiwouldliketoknow,whetherdesigningcommandcanbefollowedaftertheanalysishasbeendoneinthesamestaadfile,oraseparatefilehastobecreatedwheretheseinterpretedforcesshouldbeappliedasanaxialforceforeachnodesforcarryingoutthedesignoftheframe
PostedviaEmail
Backtotop
arvind_kumar49SEFIMember
Joined:13Mar2011Posts:17
Posted:FriFeb15,20136:20pmPostsubject:SpectrumAnalysisUsingStaad.ProV8i
Thereisneedtoclarifythatmassinallthethreedirectionsshouldnotbeappliedsimultaneously.e.g.forseismicinXdirectionapplymassinXdirection..
OnWed,Feb13,2013at3:39PM,nssenthilkumaranwrote:[quote]DearSefian,
-
24/03/2015 www.sefindia.org::ViewtopicSpectrumAnalysisUsingStaad.ProV8i
http://www.sefindia.org/forum/viewtopic.php?t=13615 6/10
Hereismyreplytothequeries.Ifiamincorrect,othersmaycorrectme.1)InSTAADPro,wedonothaveanoptionofdefiningmasselementswhichareneddedfortheSpectrumanalysis.Sowhatwegenerallydois,firstapplytheDl+0.5LLonthestructure,Secondlyapplypinnedsupportstoallthenodes,analyseandgettheverticalforceineachnodeandapplytheforceinallthethreedirectionsforthecorrespondingnodeintheresponsespectrumloadcase.IfyourDLcasedoesnthaveselfweightinit,Youwillhavetoapplyitalongwiththeabovementionedforcesinallthethreedirections,i.e)selfweighty1,selfweightx1,selfweightz1.IfyourDLcasealreadyhasselfweightinit,youdontneedtoseperatelyspecifyselfweightcommandinthespectrumloadcase.Ihopeiamclear.Thereasonforapplyingallforcesinallthethreedirectionsisbecausethemasscalculatedatthenode(doneinternallyinSTAAD)mustbeappliedinallthreedirectionsinordertoprovideinertialforces.2)Asforyoursecondquery,itispossibletogivethedesigncommandaftertheresponsespectrumanalysisinSTAAD.Butiwouldnotrecommendit.Becauseincaseofspectrumanalysis,theforcesofallthemodesaresummedupusingtheSRSS(sumofsquarerootofsquares)method.andbecauseofthisthesignsofthebendingmomentswouldbelosti.e)ifyouseetheBendingmomentvaluesforthespectrumcase,allthevalueswouldbepositive.Thismayleadtooverdesignofsomesectionsandunfortunatelyunderdesignofsomesections.WhatiwouldrecommendisfindtheVb(Baseshear)valuesofdominantmodes(modesinwhichconsiderableamountofmassesparticipate),sumitupandthendistributeittoeachnodeusingtheformulainequivalentstaticmethod.Thenapplytheforces(nodalforcesstatic)ineachdirectionasaseperateloadcaseandanalyseandobtaintheresults.Theforcesobtainedintheabovementionedmethodcanbeusedforthedesign.Regars,N.S.SenthilKumaran.StructuralEngineer,Tamilnadu,India
OnMon,Feb11,2013at6:07PM,sharathknforum@sefindia.org(forum@sefindia.org))>wrote:autoremoved
PostedviaEmail
Backtotop
prof.arc...
Joined:26Jan2003Posts:648
Posted:SatFeb16,201312:46amPostsubject:SpectrumAnalysisUsingStaad.ProV8i
Iamnotcommentingontheuseofcommercialsoftwareasitisthepracticenowadaystousethemratherthantowriteapplicationsoftwarebytheuseritself.
useofSRSShaspitfallsbecausethe"sign"islostifyourefertoBISHandbookonIS:1893,theproblemisexplainedinthechapteronstacklikestructurestwodifferentshapesaregivenforshearforceandbendingmomentalongtheheight.inmodalcombinations,NEVERUSESRSSforcombinationofmodalstressesalsodonotuseSRSStofirstobtainLOADSandthenderiveshears&bendingmomentsfromthatcombinedLoaddiagramLesserevilistocombinemodalshearsandmodalmomentsseparately
ihadalwayspreferredtodotimehistoryanalysiswherethe"SIGN"ispreserved
Protectiontotheanalystliesinfollowingthecodalprovisionseventhoughsuchprovisionsmaybetheoreticallywrong!!
ARC
-
24/03/2015 www.sefindia.org::ViewtopicSpectrumAnalysisUsingStaad.ProV8i
http://www.sefindia.org/forum/viewtopic.php?t=13615 7/10
On2/15/13,shivrajekadamwrote:Quote:
DearSenthil,
Ihavegonethroughurreply,iagreedwithuropinionasfarasfirstpointisconsideredbutnotwiththesecondcase.
2)Ifurdoingdynamicanalysisofbuildinganduraddingalltheresponsesusinganyoneofmodalcombinationmethodi.eCQC,SRSSorABS,allmemberforcessignedisgettinglostduetosquarerootandsquaringoperationbuttosatisfythisconditionweareconsideringallloadcombinationsgivenin1893:2002(24numbers),Sourstructuralmemberdesignisalwaysonaconservativeside.Butifurfoundationisraftfoundationorcombinedfoundattionthenuneedtobringbackthesignesofreactionsforaccurateanalysisotherwiseurfdndesignmaybeeitherconseravativeorunderdesign.Secondlyasfarasmyknowledgeitisnotpossibletodistributetheloadateachandeverynodebyusingformulegiveninequivalentstaticmethodbecauseudonotknowthemassparticipationatthatnodeinthatmode.
Regards,ShivrajKadam.
On2/13/13,nssenthilkumaranwrote:
Quote:
DearSefian,
Hereismyreplytothequeries.Ifiamincorrect,othersmaycorrectme.
1)InSTAADPro,wedonothaveanoptionofdefiningmasselementswhichareneddedfortheSpectrumanalysis.Sowhatwegenerallydois,firstapplytheDl+0.5LLonthestructure,Secondlyapplypinnedsupportstoallthenodes,analyseandgettheverticalforceineachnodeandapplytheforceinallthethreedirectionsforthecorrespondingnodeintheresponsespectrumloadcase.
IfyourDLcasedoesnthaveselfweightinit,Youwillhavetoapplyitalongwiththeabovementionedforcesinallthethreedirections,i.e)selfweighty1,selfweightx1,selfweightz1.
IfyourDLcasealreadyhasselfweightinit,youdontneedtoseperatelyspecifyselfweightcommandinthespectrumloadcase.Ihopeiamclear.Thereasonforapplyingallforcesinallthethreedirectionsisbecausethemasscalculatedatthenode(doneinternallyinSTAAD)mustbeappliedinallthreedirectionsinordertoprovideinertialforces.
2)Asforyoursecondquery,itispossibletogivethedesigncommandaftertheresponsespectrumanalysisinSTAAD.Butiwouldnotrecommendit.Becauseincaseofspectrumanalysis,theforcesofallthemodesaresummedupusingtheSRSS(sumofsquarerootofsquares)method.andbecauseofthisthesignsofthebendingmomentswouldbelosti.e)ifyouseetheBendingmomentvaluesforthespectrumcase,allthevalueswouldbepositive.
Thismayleadtooverdesignofsomesectionsandunfortunatelyunderdesignofsomesections.WhatiwouldrecommendisfindtheVb(Baseshear)valuesofdominantmodes(modesinwhichconsiderableamountofmassesparticipate),sumitupandthendistributeittoeachnodeusingtheformulainequivalentstaticmethod.Thenapplytheforces(nodalforcesstatic)ineachdirectionasaseperateloadcaseandanalyseandobtaintheresults.
Theforcesobtainedintheabovementionedmethodcanbeusedforthedesign.
Regars,
N.S.SenthilKumaran.StructuralEngineer,Tamilnadu,India
-
24/03/2015 www.sefindia.org::ViewtopicSpectrumAnalysisUsingStaad.ProV8i
http://www.sefindia.org/forum/viewtopic.php?t=13615 8/10
OnMon,Feb11,2013at6:07PM,sharathknwrote:
Quote:
Hi,
Ihaveafewurgentqueries,regardingthespectrumanalysisusingStaad.Prov8i,asfollows:
1.firstiwouldliketoknowwhileinloadcaseforSeismicSpectrum,whetherselfweightforyisonlyenough,orforalldirectionsitshouldbeapplied.Alsothemaximumforceasappliedonthenodesshallbeonlyapplyforonedirection,sayXtogetherwithresponsespectrum,oralsoithastobeagainapplyfordefiningresponsespectrumforzdirectionalso.
2.Alsoiwouldliketoknow,whetherdesigningcommandcanbefollowedaftertheanalysishasbeendoneinthesamestaadfile,oraseparatefilehastobecreatedwheretheseinterpretedforcesshouldbeappliedasanaxialforceforeachnodesforcarryingoutthedesignoftheframe
PostedviaEmail
Backtotop
sudippaulSEFIMember
Joined:17Jun2010Posts:1
Posted:SatFeb16,20134:39pmPostsubject:SpectrumAnalysisUsingStaad.ProV8i
DearSefians,
Pls.gothroughthe"SIGN"and"DOMINANT"commandin"STAAD".Itwillprovidetheresponsesoutofamodalcombinationwithsignofthedominantmodeorwithsigngovernedbythesignofthedominantmodes.
Further,somewhereinSTAAD,IreadthatbydefaultthemodalcombinationruleautomaticallychangesinternallyfromSRSStoCSMandfromCSMtoCQC,dependingontheclosenessofthemodes,somaybeknowinglyorunknowingly,thebestcombinationrulewillbefollowed..butthesameshallbechecked...
Timehistoryanalysisisnotalwaysrequiredfornormalcivilengineeringstructures.....afrequencydomainapproachwitheitherfewmodesorafullfledgedresponsespectrumanalysisismorethanenough....
Regards
Dr.S.Paul,Manager,Struc.Engg.Dept.,EngineersIndiaLtd.,1BCP,ND66
Ihadalwayspreferredtodotimehistoryanalysiswherethe"SIGN"ispreservedFurther,
On16February201312:11,prof.arcwrote:[quote]Iamnotcommentingontheuseofcommercialsoftwareasitisthepracticenowadaystousethemratherthantowriteapplicationsoftwarebytheuseritself.
-
24/03/2015 www.sefindia.org::ViewtopicSpectrumAnalysisUsingStaad.ProV8i
http://www.sefindia.org/forum/viewtopic.php?t=13615 9/10
useofSRSShaspitfallsbecausethe"sign"islostifyourefertoBISHandbookonIS:1893,theproblemisexplainedinthechapteronstacklikestructurestwodifferentshapesaregivenforshearforceandbendingmomentalongtheheight.inmodalcombinations,NEVERUSESRSSforcombinationofmodalstressesalsodonotuseSRSStofirstobtainLOADSandthenderiveshears&bendingmomentsfromthatcombinedLoaddiagramLesserevilistocombinemodalshearsandmodalmomentsseparately
ihadalwayspreferredtodotimehistoryanalysiswherethe"SIGN"ispreserved
Protectiontotheanalystliesinfollowingthecodalprovisionseventhoughsuchprovisionsmaybetheoreticallywrong!!
ARC
On2/15/13,shivrajekadamwrote:autoremoved
PostedviaEmail
Backtotop
nssenthilkumaranSEFIMember
Joined:27Oct2010Posts:2
Posted:MonFeb18,20136:42amPostsubject:SpectrumAnalysisUsingStaad.ProV8i
Dearshivraj,Iconcurwithprof.arc'sreply.Whatimeantby'signswouldbelost'isthatthebendingmomentvariation,shearforcevariationetcacrossthespanofthememberwouldbelost.I.e,therewouldnotbenegativemomentsatsupportsorpositivemomentsatthespan.Allthemomentvalueswouldbepositiveforthemember.Sotherealvariationwillnotbecapturedifweusesrss.Andthereisaformulafordistributingthebasesheartodifferentfloorsineq.Staticmethodin1893code.Wehavetosubstitutetheahwiththeresponsespectrumsaccelerationcoeffecientcorrespondingtothefrequencyofthemodeconsideredandtheweightateachfloorlevelcanbereplacedbyweightateachnode.OnFeb16,201312:39PM,"prof.arc"wrote:[quote]Iamnotcommentingontheuseofcommercialsoftwareasitisthepracticenowadaystousethemratherthantowriteapplicationsoftwarebytheuseritself.
useofSRSShaspitfallsbecausethe"sign"islostifyourefertoBISHandbookonIS:1893,theproblemisexplainedinthechapteronstacklikestructurestwodifferentshapesaregivenforshearforceandbendingmomentalongtheheight.inmodalcombinations,NEVERUSESRSSforcombinationofmodalstressesalsodonotuseSRSStofirstobtainLOADSandthenderiveshears&bendingmomentsfromthatcombinedLoaddiagramLesserevilistocombinemodalshearsandmodalmomentsseparately
ihadalwayspreferredtodotimehistoryanalysiswherethe"SIGN"ispreserved
Protectiontotheanalystliesinfollowingthecodalprovisionseventhoughsuchprovisionsmaybetheoreticallywrong!!
ARC
On2/15/13,shivrajekadamwrote:autoremoved
PostedviaEmail
Backtotop
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24/03/2015 www.sefindia.org::ViewtopicSpectrumAnalysisUsingStaad.ProV8i
http://www.sefindia.org/forum/viewtopic.php?t=13615 10/10
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