Answer Happy

A bridge was designed with a rigid road deck which is supported by a concrete pillar and rigid footing. Safety standards require a minimum factor of safety of 10, but an overloaded truck has asked for permission to cross the bridge.... Your boss has suggested adding 2 temporary pillars made of equal length steel pipe (as shown below) to accommodate the higher 430 kip load from the overloaded truck. The 2 steel pillars are equal distance from the existing concrete pillar. Concrete has a Young's Modulus of 6.5 x 106 psi and a compressive strength of 2500 psi. The steel pipe has a 35 ksi yteld strength. Will the concrete pillar have a factor of safety of at least 10 -- with the 2 temporary pillars installed? Quantitatively justify your answer. Ignore buckling. 430 KIA 430 KID Rigid Road Deck Rigid Road Deck 3.5 ft Concrete Pillar 8 ft (Added) 24 inch schedule 40 steel pipes Rigid Footing Rigid Footing 430KIA 430K1P Cross-Sectional Schematic Diagram - Not to Scale. Schedule 40 Nominal Pipe Size O.D. inches I.D., inches 24" 24.00 22.54