16.3 Definition of a beam

Beam of arbitrary cross section

• Assumptions that underlie beam theory
  • A beam is much longer than its characteristic cross section
  • A beam carries:
    • Axial forces (P)
    • Shear forces (S)
    • Distributed loads (p)
    • Torques (T)
    • Bending moments (M)
  • The reference line for a beam is the line of the centroids
  • The reference line is often assumed to be straight