Approximations of Lateral Displacements of Reinforced Concrete Frames with Symmetric Haunched Beams in the Elastic Range of Response Using Commercial Software

Abstract

Commercial software for structural analysis and design has significantly evolved in recent years. Nowadays, they are more user- friendly, in addition to providing engineers with more modeling options to solve complex problems and geometries. Tapered elements in gen- eralandhaunchedbeamsinparticularweretraditionallydifficulttomodelinthepast;therefore,mostcommercialsoftwaredidnotincludethem in their element libraries. Recently, leading commercial software worldwide for structural analysis such as ETABS or STAAD-Pro allow engineerstomodelhaunchedbeamsintheelasticrangeofresponse.However,thetechnicalinformationprovidedwithinthesoftware'smanual does not always describe the details of the numerical modeling; i.e., whether it is based on rigorous traditional methods or is just an approximationbaseduponthecalculusofvariations.InthispapertheapproximationsobtainedwithcommercialsoftwareforasetofRCframes with symmetric haunched beams under lateral loading in the elastic range of response are reported when compared with those obtained with a traditional beam theory in which shear deformations are included. It is shown that the modeling used in commercial software is in general reasonable;however,itleadstoanunderestimationofthelateraldisplacements.Dependingonthesoftwareandthemodelingoptionused,lateral displacementsvaryfrom62toalmost100%ofthosecalculatedusingtraditionalbeamtheory.DOI:10.1061/(ASCE)SC.1943-5576.0000143. © 2013 American Society of Civil Engineers. CE Database subject headings: Beams; Lateral displacement; Computer software; Elasticity. Author keywords: Tapered elements; Haunched beams; Nonprismatic beams.