Beams

BEAMS A structural member loaded in the transverse direction to the longitudinal axis. Internal Forces: Bending Moments and Shear

Stability

Stability

Stability

Stability

Stability

Stability

Stability

Stability

Stability

Stability

Stability

Stability

Stability

Stability

Stability

Stability

Stability

Structural Steel - Characteristics Buckling: Instability due to slenderness

Stability

Elastic Buckling

Limit States

Limit States

Limit States

Limit States

Classification of Shapes Compact Section Non-Compact Section Web Local Buckling Flange Local Buckling

Bending Strength of Compact Shapes Lateral Torsional Buckling

Bending Strength of Compact Shapes

Bending Strength of Compact Shapes Laterally Supported Compact Beams

Bending Strength of Compact Shapes

Bending Strength of Compact Shapes Elastic Buckling

Elastic Buckling Cb = factor to account for non-uniform bending within the unbraced length See AISC table 3-1 p 3.10 Mmax A B C L/4 L/4 L/4 L/4

Elastic Buckling

Elastic Buckling

Elastic Buckling Cb = factor to account for non-uniform bending within the unbraced length Rm= 1 for doubly symmetric cross sections and singly symmetric subject to single curvature See textbook p 190 for other cases

Elastic Buckling Cb = factor to account for non-uniform bending within the unbraced length

Elastic Buckling Cb = factor to account for non-uniform bending within the unbraced length ho = distance between flange centroids = d-tf

Bending Strength of Compact Shapes

Bending Strength of Compact Shapes Inelastic Buckling Linear variation between Mp and Mr

Nominal Flexural Strength – Compact Shapes

Nominal Flexural Strength – NON-Compact Shapes Most W- M- S- and C- shapes are compact A few are NON-compact NONE is slender Webs of ALL hot rolled shapes in the manual are compact FLB and LTB Built-Up welded shapes can have non-compact or slender webs FLB, WLB, LTB (AISC F4 and F5)

Nominal Flexural Strength – NON-Compact Shapes WLB