Experimental investigation of RC deep beams with web reinforcement and improvement of ACI 318–19 strut coefficient

Structures ◽  
2021 ◽  
Vol 32 ◽  
pp. 914-928
Author(s):  
R. Kondalraj ◽  
G. Appa Rao
2013 ◽  
Vol 343 ◽  
pp. 21-26
Author(s):  
Raj J. Leon ◽  
G. Appa Rao

The behaviour of reinforced concrete deep beams is complex due to small shear span-to-depth ratios, which deviates its behaviour from the classical Bernoullis beam behaviour. Such behaviour is predominant in cases where members are supported over small spans carrying heavy concentrated or distributed loads. Such is the case in the structural members like pile cap, transfer girder, panel beam, strap beam in foundation, walls of rectangular water tank, shear wall etc. This paper reports on the influence of Poly propylene fibers combined with and without steel fibers on the stiffness, spall resistance and shear strength of RC deep beams. A total of 21 beams were tested to failure under two-point loading, which were compared with the ACI code provisions. The shear span-to-depth ratios adopted were 0.7 to 0.9 incorporating three steel fiber volume fractions of 0%, 1%, 1.25% along with two different fibers of Steel and Poly propylene with volume fractions of (1.0 + 0.0) %, and (1.0 + 1.0) %. The beams with shear span-to-depth ratios 0.7, 0.8 and 0.9 showed an increase of 21.9%, 23.43% and 23.9% in the ultimate load carrying capacity with combined steel and poly propylene fibers as replacement of web reinforcement with reference to that of the beam without web reinforcement. With the above combinations, the shear strength and stiffness of the beams have been found to be improved. When the horizontal shear reinforcement was increased, the shear strength was found to increase.


2018 ◽  
Vol 7 (4.20) ◽  
pp. 86 ◽  
Author(s):  
Jasim M. Mhalhal ◽  
Thaar S. Al-Gasham ◽  
Hussain A. Jabir

This study suggested a new technique to improve a behavior of RC deep beams using mild steel plates as a vertical web reinforcement rather than the conventional rebars. Nine simply supported RC deep beams were tested under the effect of four-point load with a ratio of shear span to an effective depth (a/d) ranged from 0.75 to 1.75 at intervals of 0.5. The test specimens were divided into three groups, each one included three beams. The first group included specimens with conventional vertical web reinforcement. The second and third groups included specimens with mild steel plates as the vertical web reinforcement. The mild steel plates in the second and third groups were configured as strips and sheets, respectively. All the specimens had a length of 1200 mm, a clear span of 900 mm, and a rectangular cross-section of 150 mm wide and of 300 mm depth. The test results confirmed that both of mild steel plate configurations contributed effectively in improving the ultimate load capacity of tested beams, compared with those of conventional shear re-bars, by about (15.4% to 28.26%) and the ductility factor by about (6.06% to 30.56%). Furthermore, specimens with mild steel plates had a low sectional height under tension by about (10.11% to 32.08%).  


2020 ◽  
Vol 10 (1) ◽  
pp. 5242-5246
Author(s):  
A. Y. Pranata ◽  
D. Tjitradi ◽  
I. Prasetia

A deep beam is a beam with a small ratio of its shear span to its effective depth. Deep beams at failure under shear mechanism behave as brittle in contrast to the normal beams which become ductile under the flexural mechanism. The shear failure of deeps beams can be prevented by providing a sufficient amount of web shear reinforcements. Providing horizontal web reinforcement to the RC deep beams is a way to increase their capacity to shear. Testing of the studied deep beams was performed by Finite Element Method (FEM) modeling with the aid of ANSYS software. To obtain valid parameters for modeling RC deep beams in FEM modeling, calibrating test have to be done through verification and validation processes. The study results of all studied RC deep beams show that by closing up the spacing between the horizontal web reinforcement results in increment in the ultimate load, while the ultimate deflection and the curvature ductility were found to be decreasing. For RC deep beams, the placing configuration of horizontal web reinforcement at 0.5h-0.7h was found to be efficient for gaining higher values of ultimate deflection and curvature ductility compared to the placing configuration at 0.3h-0.5h with similar values of ultimate load. It was also found that all the specimens’ crack patterns at the first crack state were caused by flexural-tension while at the ultimate state, they were caused by the shear mechanism.


Structures ◽  
2021 ◽  
Vol 31 ◽  
pp. 1106-1129
Author(s):  
Mona K. Ghali ◽  
Mohamed Said ◽  
T.S. Mustafa ◽  
Abdallah A. El-Sayed

2020 ◽  
Vol 21 (3) ◽  
pp. 917-933
Author(s):  
Xi Liu ◽  
Tao Wu ◽  
Yuanyuan An ◽  
Yang Liu

Fibers ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 52 ◽  
Author(s):  
Constantin Chalioris ◽  
Parthena-Maria Kosmidou ◽  
Nikos Papadopoulos

The effectiveness of a new retrofitting technique to upgrade the structural behaviour of reinforced concrete (RC) deep beams without steel stirrups using carbon fibre-reinforced polymer (CFRP) ropes as the only transverse shear reinforcement is experimentally investigated. Five shear-critical beams with rectangular and T-shaped cross-section are tested under monotonic loading. The strengthening schemes include (a) one vertical and one diagonal single-link CFRP rope that are internally applied through the web of the rectangular beam using an embedded through-section (ETS) system and (b) two vertical U-shaped double-link ropes that are applied around the perimeter of the web of the flanged beam using a near-surface-mounted (NSM) system. In both cases, the free lengths of the CFRP ropes have been properly anchored using epoxy bonded lap splices of the rope as NSM at (a) the top and the bottom of the web of the rectangular beam and (b) the top of the slab of the T-beam. Promising results have been derived, since the proposed strengthening technique enhanced the strength and altered the brittle shear failure to a ductile flexural one. The experimental results of this study were also used to check the validity of an analytical approach to predict the strength of shear strengthened deep beams using FRP ropes as transverse link reinforcement.


Sign in / Sign up

Export Citation Format

Share Document