The 4.5 ft long concrete post is reinforced with six steel bars,each with a ¾” diameter. Determine the maximum allowable axialload, P, which can be applied to the post if the allowable normalstresses in the steel and concrete are 24 ksi and 2.1 ksi,respectively.Es = 29000 ksiEc = 4200 ksi P3: The 4.5 ft long concrete post is reinforced with six steel bars,each with a %" diameter. Determine the maximum allowable axialload, P, which can be applied to the post if the allowable normalstresses in the steel and concrete are 24 ksi and 2.1 ksi,respectively.18 in.Es = 29000 ksi4 ftEc = 4200 ksi

Given Data: The length of the concrete post is L=4.5 ft. The diameter of the steel bars is d=3/4 in. The diameter of the concrete post is D=18 in. The number of steel bars is n=6. The allowable normal stress in steel is σs=24 ksi. The allowable normal stress in concrete is σn=2.1 ksi. The modulus of elasticity of steel is Es=29000 ksi. The modulus of elasticity of concrete is Ec=4200 ksi.Calculate the cross-sectional area of steel rods and concrete portion. The cross sectional area of the steel rods is As As=π4d2=π40.75 in2=0.441 in2 The cross-sectional area of the concrete is Ac Ac=π4D2-As=π418 in2-0.441 in2=254.34-0.441=253.899 in2Calculate the load in concrete and steel. Consider the maximum allowable axial load for the concrete post as P. The load in the steel rods due to the applied load is Ps δs=PsLAsEsPs=δsAsEsL=δs0.441 in229000 ksiL=12789δsL The load in the concrete due to the applied load is Pc δc=PcLAcEcPc=δcAcEcL=δc253.899 in24200 ksiL=1066375.8δcL The total load is P P=Ps+Pc=12789δsL+1066375.8δcL Since the member is composite, the deflection in each member is same. P=Ps+Pc=12789δsL+1066375.8δcL=12789δL+1066375.8δL=1079164.8δLδL=P1079164.8Calculate the allowable strain in concrete and steel. The maximum allowable strain in steel is εs εs=σsEs=24 ksi29000 ksi=0.0008275 The maximum allowable strain in concrete is εc εc=σcEc=2.1 ksi4200 ksi=0.0005 The maximum allowable strain in the member is 0.0005Calculate the maximum allowable axial load on the post. The maximum allowable strain in the member and the strain due to applied load must be equal. δL=P1079164.80.0005=P1079164.8P=0.0005×1079164.8=539.582 lb≈539 lb The maximum allowable axial load for the reinforced concrete post is 539 lb.