Optimization of Pretensioned Steel Fiber Reinforced Concrete Beam

Abstract

Pretensioned concrete beams are used as a main load bearing member for composite bridges with a span to 30 m. The advantage of longitudinal prefabrication technology of beams for small span bridges is quick installation, savings of straight supporting scaffolding of centers and formwork. The amount of labour with formwork, reinforcement and concrete including work with scaffolding of centers on site is reduced at a minimum. During searching applications of steel fiber reinforced concrete (SFRC) suitable for this kind of structure a pretensioned concrete beam suitable for a bridge bay with a span from 12 to 15 m has been chosen for an investigation. Three types of beam were manufactured for experimental tests. The beams were supposed to be a part of a bridge bay with a composite slab. These pretensioned beams were made of SFRC. In case of the experimental tests, a cast-in place concrete cover from plain concrete was casted on the top of the beams. The cast-in place concrete cover simulated a top composite slab. The bearing capacity of the beams with the cast-in place concrete cover was tested until their destruction. The tested beams showed higher bearing capacity than it was determined by a theoretical calculation. The beams also demonstrated high safety against collapse during structure overloading. The process of the experimental testing was also simulated on a numerical nonlinear model and then the results were compared. The result comparison of the both types of tests did not show any significant irregularities.