Shear Flow in a Built-Up Beam
Shear Flow in a Built-Up Beam
Shear flow is the shear force per unit length that fasteners or welds must carry to keep a built-up section acting as one.
The shear flow is q = V·Q/I. where V is the shear force, Q the first moment of the connected area and I the section’s second moment of area.
Inputs
V := 50 kN=50000 N
Q := 1.2e6 mm^3=1.2e-03 m^3
I := 4.0e8 mm^4=4e-04 m^4
Apply the shear-flow formula.
q := V·Q/I=150000 kg/s^2
Results
The shear flow (force per length) sets the fastener spacing or weld size: divide a connector’s capacity by q to get the allowable spacing.
Assumptions & limitations
- Elastic shear distribution.
- Q for the connected area about the neutral axis.
- Prismatic section.