Axial Loads

1
Bending in Beams, II
Structural Engineering Laboratory 560.208 Spring
2000
2
Overview

• Shear force and bending moment diagrams
• Normal strains and stresses
• Shear stresses
• Deflections
• Combined strains/stresses
• normal and shear strains in web

3
Normal Stresses

• From Hookes law
• As expected introduces
• material parameter E (Youngs modulus)
• geometric parameter, I (2nd moment of area)

4
Shear Stresses

• Shear stress at location in section
• V Shear at section I 2nd moment of area
• Q 1st moment of area about point where stress
  required
• b Width of section

5
Laboratory Exercise

• You will be provided a simply-supported beam
• Load with test rig
• central load on simple beam
• mid-span load on 2-span continuous beam
• Record (3 increments of load) in each case
• strain gauge outputs
• LVDT output and
• load cell outputs.
• Compute applied load, deflection and stresses

6
Summary Report Requirements

• Outline equipment used and procedures
• Compute expected moments/shears/stresses in
  members using load beam dimensions
• Compute stresses from measurements and compare
• Plot deflection vs. load and compare with
  expected
• Make sure all group members names are indicated
  and signed off.