Behavior of Self-Compacting Reinforced Concrete Dapped End Beams

Abstract

Dapped end is an essential part of the precast concrete industry, but its unusual shape made it complex in design and sensitive to stresses. It may be needed to upgrade such elements due to errors in design; over loading or the deterioration of members due to severe environments. The concept of dapped-end beams is extensively used in precast concrete construction as buildings, parking structures, bridge girder and recently in footings. It provides better lateral stability and reduces overall height of the structure and to match with geometry of corbel or bracket. In the present work, an experimental study has been conducted to investigate of reinforced SCC dapped beams. The program consists of testing 5-specimens with dimension (200x400x1600 mm), and two values of (a/d) (1.5, 1.0) under effect of a single point load. Two of samples that have been tested have been significantly tested as controller specimens as a full reinforced., also three beams have been reduced the Hanger and Nib reinforcement. It is found that the (a/d) ratio has a noticeable effect on the behavior of dapped end beam. So, the tested control beams (full reinf.), the reduction of (a/d) from (1.5) to (1.0), due to improve the failure load by (48%) with shifted the type of failure from the diagonal at extended end to the diagonal in the re-entry corner. Also, it is found that the reduction of hanger reinf. (40%), resulted reduction of the failure (6%) for (a/d) equal 1 value, higher deflection at failure about (18%). Also, reduction of the nib reinforcement by about (50%), results reduction in capacity of the failure load by about (12%) for a/d=1.5 and (12.4%)%) for a/d=1.0.