Behavior of Pocket-Type High-Strength RC Beams without or with Dapped Ends

Abstract

In precast grid systems, it is necessary to support the cross beams by the main girders using suitable methods. One of these proposals is by making voids or notches within the webs of the girder to include the supports of the cross beams. In this paper, an experimental study has been done on 10 reinforced concrete self-consolidating beams with loaded openings. The tested specimens have been categorized into two groups based on one inclusion of dapped ends. Each group consists of five specimens; one served as a control in which the opening is reinforced conventionally with two vertical stirrups at both sides. For the other specimens, the openings are reinforced with different schemes, namely using steel-fiber concrete, diagonal bars, jacketing by steel plates, and a composite section for the bottom chord. The behavior has been discussed in terms of history of crack propagation, loading history, ductility, and toughness. It was concluded that inclusion of the dapped ends reduced the capacity in range of 9%–12%. Moreover, results revealed that the composite section proposal yielded the highest enhancements of 21% and 23% for the two groups, respectively. Regarding ductility, maximum enhancements of 44% and 9% were noticed. For the toughness, the proposal of a composite section yielded the highest improvements by 91% and 19%, respectively.