Deflections in Simply Supported Beams | Area-Moment Method
The deflection δ at some point B of a simply supported beam can be obtained by the following steps:
1. Compute $t_{C/A} = \dfrac{1}{EI}(Area_{AC}) \, \bar{X}_C$
2. Compute $t_{B/A} = \dfrac{1}{EI}(Area_{AB}) \, \bar{X}_B$
3. Solve δ by ratio and proportion (see figure above).
$\dfrac{\delta + t_{B/A}}{x} = \dfrac{t_{C/A}}{L}$