Structural Behavior of Reinforced Concrete Hybrid Wide Beams under Shear Effect

Abstract

The present work contains experimental study for the structural performance of reinforced concrete wide beams made from two grades of concrete (32.6 and 63.7 MPa) subjected to shear effect. The specimens involve ten wide beams of dimensions 1200×220×110 mm. The wide beams were divided into two groups according (a/d) ratio, the first group are of (a/d) ratio (2.5) and the second group are of (a/d) ratio (3.5). The first wide beam in each group is normal strength concrete, the second sample is high strength concrete while the third beam is made from normal strength concrete at top and high strength concrete at bottom, the fourth sample is made from high strength concrete at top and normal strength concrete at bottom, the last beam is divided in to three sections, the mid section from normal strength concrete while the sides from high strength concrete. All the tested wide beams were reinforced with 4φ8mm longitudinal bars in bottom and 2φ5mm in top without web reinforcement. In both groups, comparing to first beam, the second beam exhibits greater ultimate load by about (42.8% and 41%) respectively, the third beam show increasing in ultimate load by (8.5% and 5.26%) while the fourth beam denote increasing in ultimate load by (19% and 15.8%), finally, the increasing in ultimate load of the fifth beam is about (33.3% and 32.6%). Wide beams made totally or partially from high strength concrete show larger deflection values than the reference beams. Crack width values at service and final stages were recorded. All the tested wide beams were failed in shear. Keywords: wide beams; shear effect; High Strength Concrete; hybrid beams. DOI: 10.7176/CER/12-11-05 Publication date: November 30 th 2020