Answer to Question #330069 in Civil and Environmental Engineering for James

Question

A made up bridge has a span of 25 m between centers of end supports. Two logs of approximately

constant diameter are to be used. Each log must be capable of supporting a uniform load of 12 kN/m.

If the allowable stresses are 9.8 MPa in bending and 0.78 MPa in shear,

1) what diameter of the log must be used if

a. bending governs?

b. shear governs?

2) What is the safest diameter of log must be used?