Work out shear force diagram instantly with clear inputs, formula shown and shareable results.
For an off-centre point load, taking moments about each support splits the load in inverse proportion to the distances: the near support takes more. A 9 kN load 2 m along a 5 m span puts 5.4 kN on the left support and 3.6 kN on the right. The shear diagram is constant at each reaction value and jumps by the load at its position, so peak shear is the larger reaction.
Support reactions
R(right) = P a / L, R(left) = P - R(right)
Moment under the load
M = R(left) x a
Immediately beside the support with the larger reaction, which is the support nearer the load.
Because a point load is an abrupt change in the internal force. Distributed loads give sloping shear diagrams instead of steps.