A large sign is to be supported on two steel poles, each of which will be supported by a 500 mm diameter drilled shaft embedded into a stiff silty clay. The lateral wind load will be 5.4 kN and will act at a height of 8 m above the ground surface. This load will be equally distributed to the two poles. Using a rigid analysis, compute the required depth of embedment and the maximum moment in each drilled shaft. Use a factor of safety of 3.0.

2. Solve the following problem Determine the maximum torque T that can be resisted by two shafts with a circular section of outer diameter of 100 mm. For the first shaft, the section is solid (no holes). For the second shaft, the section is hollow with an inner diameter of 75 mm. Use an allowable shear stress Tallow = 100 MPa and provide a drawing of the shear stress distribution on both sections. Rug'd max T for solid shaft Tallow = 100MP₂ diameter d loomm T hole diameter dinner = 75mm max T for hollow shaft 2D stress distribution

The design specifications of a 1.2-m-long solid circular transmission shaft require that the angle of twist of the shaft not exceed 4° when a torque of 750 N-m is applied. Determine the required diameter of the shaft, knowing that the shaft is made of a steel with an allowable shearing stress of 90 MPa and a modulus of rigidity of 77.2 GPa. The required diameter of the shaft is mm.