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The design request described on this page[bridge modeler|kb:Bridge modeler] substructure seismic-design process is availabledocumented in CSiBridge. It was also available in the bridge[Bridge modeler in SAP2000, up to version 14 of SAP2000.
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The procedure used by SAP2000 for the bridge substructure seismic design is documented in [Automated seismic design of bridges based on AASHTO guide specifications for LRFD seismic bridge design|doc:Bridge seismic analysis and design] manual. The structure displacement demand is calculatedSeismic Design|doc:Bridge seismic analysis and design] manual. This manual, based on AASHTO specifications for LRFD bridge seismic design, describes the automated seismic-design procedure for bridges. Displacement-demand formulation is based on Article 4.8 of the AASHTO Guide Specifications for LRFD Seismicbridge Bridgeseismic Designdesign.

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h1. Applicability

TheDesign designprocedures implemented in SAP2000 is the [bridge modeler|kb:Bridge modeler] are applicable forto *reinforced -concrete columns*.

{related-incident:no=23273|comment=hidden-content}
*Related incident:*
* Incident 23273 - Discussion that the automatic seismic bridge design is not available for steel columns
as of V14.2.0{hidden-content}

h1. Seismic Designdesign category
Category
The Seismicseismic design category, is determined in accordance withthrough AASHTO Article 3.5, is based on the design spectral valueacceleration of a one -second period. design spectral acceleration.

h1. Hinges

Caltrans Thehinges programare createsassigned Caltransaccording hingesto forthe bridge -seismic -design request,. butBecause Caltrans hinges are onlyspecific availableto forcertain Sectiontypes Designer section, regular rectangular sections or circular section. Therefore, the column sectionof cross section, users should beensure onethat ofcolumn thesections sectionsare forrectangular, whichcircular, Caltransor hingesfrom canthe beSection generatedDesigner. 

h1. Pushover Analysisanalysis

Sometimes,During the pushover analysis may not get completed, becausewhen thea structure is being pushed beyond its displacement capacity, andnumerical itproblems becomesarise unstable,due thusto causinginstability. numericalUnder problems and thesuch conditions, analysis being terminatedterminates prior to reaching the full target displacement. HoweverIn spite of termination, the calculated pushover capacity displacements are still correct, becausesince they are automatically identified from the pushover curve just before the strength loss.

h2. Pushover Analysisanalysis for Integralintegral Substructuresubstructure

IfFor your bridge modelmodels containswith integral substructure, youusers should evaluate whether thereconsider pushover analysis offor individual bents is appropriate for your situation. Sincesince the integral connection between the bents and the superstructure will results incause frame action,. youUsers may considerchoose alsoto investigatinginvestigate pushover analysisresponse for the entire bridge (including the deck) along inthe longitudinal directionaxis. This type of pushover analysis would need to be setup manually, outside ofmay be done outside the bridge modeler.

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*Related Incident:*
* Incident 23572 - (outgoing email 4/23/2010)
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h2. Pushover target displacement ratio

The pushoverPushover target displacement ratio generates istarget useddisplacement as follows: The
program* firstDemand determinesdisplacement theis demand displacementderived from the [response-spectrum analysis|kb:Response-spectrum analysis.]
This* demandTarget displacement for pushover analysis is thenderived multipliedas bythe theproduct specifiedof targetdemand displacement ratio to obtainand target displacement forratio
the
pushoverDuring analysis.implementation, a Forpushover example,target settingdisplacement thisratio parameterequal to 1 would result inpushes the structure being pushed exactly to the demand displacement,. while settingSetting this parameter equal to 2 would result inpushes the structure being pushed to twice the demand displacement. The bent failure is determined from theSince pushover -curve drop, soindicates itbent mayfailure, be a good idea tousers should review the pushover curves to determine whether or not the structure is being pushed to full failureachieves failure, and increase the valuetarget ofdisplacement thisratio parameter ifas necessary.

{hidden-content}
*Related IncidentsIncident:*
* *Incident {incident:no=32307|comment=32307 - Explanation of pushover displacement ratio}
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h1. See Also

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*Related IncidentsIncident:*
* *Incident {incident:no=37517|comment=37517 - Number of modes for seismic design request}
** {email:from=ok|to=kl|date=8/23/2011|subject=Number of modes for seismic design request|comment=|id=7636559}
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* [Bridge Seismic Design manual|doc:Bridge seismic analysis and design] manual
* [Bridge seismic design request tutorial|tutorials:Bridge seismic design request] tutorial \- additionalfurther discussion foron the model developed in the "Bridge Seismic Design" manual. model
* [Caltrans hinge|kb:Caltrans hinge]