## Example 01: Spacing of Screws in Box Beam

**Problem**

A concentrated load *P* is carried at midspan by a simply supported 4-m span beam. The beam is made of 40-mm by 150-mm timber screwed together, as shown. The maximum flexural stress developed is 8.3 MPa and each screw can resist 890 N of shear force.

- Determine the spacing of screws at
*A*. - Determine the spacing of screws at
*B*. - Determine the spacing of screws if screws at
*A*and*B*are equally spaced.

## Example 01: Maximum bending stress, shear stress, and deflection

**Problem**

A timber beam 4 m long is simply supported at both ends. It carries a uniform load of 10 kN/m including its own weight. The wooden section has a width of 200 mm and a depth of 260 mm and is made up of 80% grade Apitong. Use dressed dimension by reducing its dimensions by 10 mm.

Bending and tension parallel to grain = 16.5 MPa

Shear parallel to grain = 1.73 MPa

Modulus of elasticity in bending = 7.31 GPa

1. What is the maximum flexural stress of the beam?

2. What is the maximum shearing stress of the beam?

3. What is the maximum deflection of the beam?