Chapter 11 Shear Forces and Bending Moments Types

Chapter 11 Shear Forces and Bending Moments

Types of Loads on a Beam • Dead Loads: permanent loads (Equipment, Structural members, etc. ) • Live Loads: loads that vary and are hard to predict (People, Weather, etc. )

Types of Loads on a Beam (Cont’d) • Concentrated Loads • Uniformly Distributed Loads

Shear Along a Beam • Shear forces occur across the length of the beam, generally varying in magnitude • The shear force at any location on a beam is simply the sum of all the forces either to the right or to the left of a given location

Force Effects Along a Beam

Bending Moment Along a Beam • Bending moments that occur along the length of the beam cause the beam to rotate or deflect by some magnitude at each particular location • The bending moment at any location on a beam is simply the sum of the moments either to the left or to the right of that point

Shear Diagrams

Shear Diagrams (Cont’d)

Shear Diagrams (Cont’d)

Shear Diagrams (Cont’d)

Shear Diagrams (Cont’d)

Shear Diagrams (Cont’d)

Shear Diagrams (Cont’d)

Bending Moment Diagrams

Bending Moment Diagrams (Cont’d)

Bending Moment Diagrams (Cont’d)

Bending Moment Diagrams (Cont’d)

Bending Moment Diagrams (Cont’d)

Moving Loads • Assumed to be concentrated loads set at a fixed distance apart that move in unison across the beam • The maximum moment caused by a moving load will generally occur under one of the concentrated wheel or axle loads

Moving Loads (Cont’d)

Moving Loads (Cont’d)

Shear and Moment Diagrams for Continuous Beams • Beams that span over more than two supports are referred to as continuous beams • Frequently used in bridges and building • Because the bending moment is reduced in the middle of the span, a smaller beam section can be specified

Shear and Moment Diagrams for Continuous Beams (Cont’d)

Shear and Moment Diagrams for Continuous Beams (Cont’d)