Analytical investigation of pre-stressed, pre-cast beams with steel pipe sleeves

This paper presents an analytical investigation of the structural performance of a pre-stressed, pre-cast concrete beam with steel pipe sleeves. The hybrid pre-cast beam consists of reinforcing steel, a pre-stressing tendon, pre-cast concrete and cast-in-place concrete. Steel sections are installed at both ends of the beam, and steel pipe sleeves are installed at the locations of pipes. The steel pipe sleeves in the pre-cast, pre-stressed beam allow the installation of piping and facility equipment. A strain-compatibility approach was used to predict the influence of the sleeves and pre-stressing on the structural behavior of the hybrid pre-cast beams. It was found that reinforcing rebar, used to reinforce the sleeve openings for circular steel pipes with a diameter of 125 mm, contribute 20% to the flexural load resisting capacity, suggesting that rebar reinforcement can be considered one of the structural components of the beam. The pre-stressed, pre-cast beam with steel pipe sleeve openings exhibited performance similar to that of beams without openings when the reinforcements placed for the sleeve opening were considered part of the flexural stiffness of the beam.