Effect of the arching action on the behavior of the RC precast concrete deep beams: comparison between several hybrid models.

The application of precast industry in production various structural elements increased dramatically. deep beams is an important kind of such elements that is used to support heavy loads. In the present work, two proposals of concrete-hybrid deep beams have been studied and compared with the non-hybrid and conventionally hybrid deep beams. Five specimens of deep beams have been tested under gradually increased mid-span static load up to failure. The response has been discussed in terms of cracking pattern, mode of failure, load-deflection curves and history of crack width. The proposed models aimed study the effect of configuration of distribution of concrete types within the cross-section of the deep beam. In such proposals, the costly concrete used within the regions that may contribute effectively on resisting the external loading and may be considered as the path of stress transfer from points of load application to supports. The proposed models (curved) and (arched) aimed to control the most possible causes of failure in deep beams. This may give ability to improve the capacity of the deep beams with keeping cost as low as possible by making the volume of SFC as small as possible. Results revealed that using the curved models improved capacity by 21% relative to the non-hybrid model. While using the arched model improved capacity by 15% and 23% with using vertical and inclined stirrups respectively. Moreover, maximum enhancement in the flexural toughness of 62% was obtained.