BEAM-COLUMNSPROF. V. KALYANARAMAN

Department of Civil EngineeringIndian Institute of Technology MadrasChennai 600036email: kalyan@civil.iitm.ernet.in

DESIGN OF BEAM COLUMNSINTRODUCTION

SHORT & LONG BEAM-COLUMNS Modes of failure Ultimate strengthBIAXIALLY BENT BEAM-COLUMNS

DESIGN STRENGTH EQUATIONS Local Section Flexural YieldingOverall MemberFlexural Buckling

STEPS IN ANALYSING BEAM-COLUMNS

ANALYSIS EXAMPLE

SUMMARY

INTRODUCTIONCauses Of Bending In Beam ColumnsxyzEccentric CompressionJoint Moments in Braced Frames Rigid Sway Moments in Unbraced FramesBiaxial Moments in Corner Columns of Frames

SHORT BEAM-COLUMNS

Pcs = Ag * fyMP = Z * fy

P

SHORT BEAM-COLUMNS Failure envelope 1.0

LONG BEAM COLUMNS Non Sway Frame

LONG BEAM-COLUMNS Sway Frames

LONG BEAM-COLUMNS B

LONG BEAM-COLUMNS Long columnsloading curveShort columnloading curveFcl /PcsF0/PcsFc/PcsEqn. 3Mo/MpMmax/MpM / MP1.01.0

SLENDER BEAM-COLUMNS AAfter correction for (P-) effectFc/PcsFcl/PcsMy/Mpy

Short column failure envelopeAfter correcting for sway and bow (P- and P-)1.01.0P*P* Minor axis bendingUniaxial Bending

SLENDER BEAM-COLUMNS AMxMpxP/Py < 0.25P/Py >0.5Short ColumnSlender ColumnFig. 7 Beam-column Moment Rotation BehaviourOBCCFFFED

BEAM-COLUMNS / BIAXIAL BENDING

DESIGN STRENGTH EQUATIONSLocal Section Failure

Overall Member failure

STEPS IN BEAM-COLUMN ANALYSISSteps in Beam-Column AnalysisCalculate section propertiesEvaluate the type of sectionCheck using interaction equation for section yieldingCheck using interction equation for overall buckling

SUMMARYShort Beam-Columns Fail by Section PlastificationSlender Beam-Columns may Fail BySection PlstificationOverall Flexural YieldingOverall Torsional-Flexural BucklingIntetaction Eqs. Conservatively ConsiderP- and P- EffectsAdvanced Analysis Methods Account for P- and P- Effects, directly & more accuraely