Torsional Behavior of Hybrid Reinforced Concrete Box Girders Composed of Conventional Concrete and Modified Reactive Powder Concrete

Abstract

This paper investigates experimentally the torsional behavior of hybrid reinforced concrete box beams composed of conventional concrete at side walls and modified reactive powder concrete at top and bottom flanges. Hybrid reinforced concrete members is used extensively to deal with the members strength requirements related to flexural, shear and torsion in structural systems. The torsion failure is an undesirable failure because it's occurred in a brittle nature, it is necessary to avoid this type of failure in the earthquake areas. Three reinforced concrete box beams with dimensions (300x300x1200) mm of (width x height x length) respectively and interior hollow dimensions (140x140)mm were cast and tested to failure by using two opposite cantilevers arms which contribute in transferring the torque to the central part of the box beam. One of the beams was poured with conventional concrete, second beam with modified reactive powder concrete and third beam was poured as a hybrid member. Experimental data on ultimate capacity, cracking torsional loads, failure pattern and twisting angle for each of the box beams were gained. The experimental results show that the ultimate torsional strength value of hybrid box beam higher than conventional concrete beam by about (58) % and lower than modified reactive powder concrete specimen by about (40.75)%.

Keywords: Hybrid reinforced concrete, conventional concrete, modified reactive powder concrete and torsion.