Section 9 Members subjected to Combined Forces (Beam-Columns)

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Section 9 Members subjected toCombined Forces
(Beam-Columns)
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IS 800 2007
SECTION 9 MEMBER SUBJECTED TO COMBINED
FORCES 9.1 General 9.2 Combined Shear and
Bending 9.3 Combined Axial Force and Bending
Moment 9.3.1 Section Strength 9.3.2
Overall Member Strength
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9.2 Combined Shear and Bending
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9.2 Combined Shear and Bending
Sections subjected to HIGH shear force gt 0.6 Vd
a) Plastic or Compact Section b)
Semi-compact Section Mfd plastic design
strength of the area of c/s excluding the shear
area and considering partial safety factor V
factored applied shear force Vd design shear
strength
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9.3 Combined Axial Force and Bending Moment
DESIGN OF BEAM COLUMNS

• INTRODUCTION
• SHORT LONG BEAM-COLUMNS Modes of failure
• Ultimate strength
• BIAXIALLY BENT BEAM-COLUMNS
• DESIGN STRENGTH EQUATIONS
• Local Section Flexural Yielding
• Overall Member Flexural Buckling
• STEPS IN ANALYSING BEAM-COLUMNS
• SUMMARY

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INTRODUCTION

• Occurrence of Beam Columns

• Eccentric Compression
• Joint Moments in Braced Frames Rigid
• Sway Moments in Unbraced Frames
• Biaxial Moments in Corner Columns of Frames

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SHORT BEAM-COLUMNS
P
Py Agfy
Mp Zpfy
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SHORT BEAM-COLUMNS

M P e
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LONG BEAM COLUMNS
Non Sway Frame

Mmax Mo P?
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LONG BEAM-COLUMNS
Sway Frames

M Mo P?
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LONG BEAM-COLUMNS

B
Cm accounts for moment gradient effects
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LONG BEAM-COLUMNS

1.0
1.0
Mmax/Mp
Mo/Mp
M / MP
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SLENDER BEAM-COLUMNSModified Strength Curves for
Linear Analysis

Uniaxial Bending
Minor axis bending
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BEAM-COLUMNS / BIAXIAL BENDING

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IS 800 2007
9.3 Combined Axial Force and Bending
Moment 9.3.1 Section Strength 9.3.1.1
Plastic and Compact Sections
9.3.1.3 Semi-compact section fx. ? fy
/?m0 9.3.2 Overall Member Strength
9.3.2.1 Bending and Axial Tension ?
? Md
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9.3.2.2 Bending and Axial Compression

• Cmy, Cmz equivalent uniform moment factor as
  per table 18
• Also CmLT

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STEPS IN BEAM-COLUMN ANALYSIS

• Steps in Beam-Column Analysis
• Calculate section properties
• Evaluate the type of section
• Check using interaction equation for section
  yielding
• Check using interction equation for overall
  buckling

• Beam-Column Design
• using equivalent axial load

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SUMMARY

• Short Beam-Columns Fail by Section Plastification
• Slender Beam-Columns may Fail By
• Section Plstification
• Overall Flexural Yielding
• Overall Torsional-Flexural Buckling
• Intetaction Eqs. Conservatively Consider
• P-? and P-? Effects
• Advanced Analysis Methods Account for P- ? and P-
  ? Effects, directly more accuraely