Question

For a pretensioned rectangular plank the uplift at centre on release of wires from anchors due to pretensioning only (force P, eccentricity e) will be

• A. $\frac{Pe{L}^2}{6EI}$
• B. $\frac{P{e}^{2}L}{6EI}$
• C. $\frac{Pe{L}^2}{8EI}$
• D. $\frac{P{e}^{2}L}{8EI}$

Answer 1

The correct option is C $\frac{Pe{L}^2}{8EI}$

Uplift due to pre-tensioning
= Moment of M/EI diagram about C
= $\frac{Pe}{EI}\times \frac{L}{2}\times \frac{L}{4}=\frac{Pe{L}^2}{8EI}$