Abstract
This study aimed to investigate the shear capacity performance for eight deep beams with HTRB600 reinforced high strength concrete under concentrated load to enable a better understanding of the effects of shear span–depth ratio, longitudinal reinforcement ratio, vertical stirrup ratio and in order to improve design procedures. The dimension of eight test specimens is 1600 mm × 200 mm × 600 mm. The effective span to height ratio l0/h is 2.0, the shear span–depth ratio λ is 0.3, 0.6 and 0.9, respectively. In addition, the longitudinal reinforcement ratio ρs is set to 0.67%, 1.05%, 1.27%, and the vertical stirrup ratio is taken to be 0%, 0.25%, 0.33%, 0.5%. Through measuring the strain of steel bar, the strain of concrete and the deflection of mid-span, the characteristics of the full process of shear capacity, the failure mode and the load deflection deformation curve were examined. The test results showed that the failure mode of deep beams with small shear span–depth ratio is diagonal compression failure, which is influenced by the layout and quantity of web reinforcement. The diagonal compression failure could be classified into two forms: crushing-strut and diagonal splitting. With decreasing of shear span–depth ratio and increasing longitudinal reinforcement ratio, the shear capacity of deep beams increases obviously, while the influence of vertical web reinforcement ratio on shear capacity is negligible. Finally, the shear capacity of eight deep beams based on GB 50010-2010 is calculated and compared with the calculation results of ACI 318-14, EN 1992-1-1:2004 and CSA A23.3-04, which are based on strut-and-tie model. The obtained results in this paper show a very good agreement with GB50010-2010 and ACI 318-14, while the results of EN 1992-1-1:2004 and CSA A23.3-04 are approved to be conservative.
Highlights
According to GB 50010-2010 [1], beams can be known as deep beams when the effective span to height ratio l0 /h ≤ 2 or continuous beams l0 /h ≤ 2.5
A practical and unified calculation formula of shear capacity which was suited to reinforced concrete deep beams, short beams and shallow beams was put forward [4,5]
To 1.27%, the influence on the normal sectionCompared cracking load and the diagonal section is decreased by 37.12% and 38.46%, and the ultimate load is increased by 20.46% and diagonal section cracking load of the test specimen is negligible, while the ultimate load increases
Summary
According to GB 50010-2010 [1], beams can be known as deep beams when the effective span to height ratio l0 /h ≤ 2 or continuous beams l0 /h ≤ 2.5. Since the 1980s, the special research group of deep beams in People’s Republic of China (P.R.C) has carried out numerous experimental researches on supported deep beams, continuous deep beams [2] and deep beams with web openings [3]. On this basis, a practical and unified calculation formula of shear capacity which was suited to reinforced concrete deep beams, short beams and shallow beams was put forward [4,5]. Based on STM, many scholars come up with theoretical methods for Materials 2020, 13, 1218; doi:10.3390/ma13051218 www.mdpi.com/journal/materials
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