500 mm FIGURE 1.46 Composite bar system for Problem 1.12. PROBLEM 1.13 The concrete composite post in Figure 1.47 is 1.2 m long with a 0.3 m x 0.3 m square cross section. The post is reinforced by four vertical steel rods of the same length having a cross-sectional area of A, = 0.00125 m² each, and is loaded by a single vertical load P = 500 kN applied on the rigid cover plate as shown below. The modulus of elasticity for concrete is E. = 17 GPa, whereas the modulus of elasticity of steel is E, = 200 GPa. Determine the stresses in the steel rods and concrete. PROBLEM 1.14 The composite bar system in Figure 1.48 consists of a steel bar and a bronze bar that are both securely attached to a rigid block and rigid supports. The system is loaded with a total load P at the rigid block. If the total applied load is P=42,000 lb, determine the stresses in the two bars. PROBLEM 1.15 The composite post in Figure 1.49 has the same properties and dimensions as in Problem 1.13, except that there is a gap A = 0.1 mm between the top of the Rigid cover plate 1.2 m FIGURE 1.47 Concrete composite post for Problem 1.13. P=500 kN Steel rods (4) A, -0.00125 m² each Concrete 0.3 mx 0.3 m Postcross section 0.3 m 0.3 m