scholarly journals Effect of Shear Span to Effective Depth Ratio on the Behavior of Self-Compacting Reinforced Concrete Deep Beams Containing Openings Strengthened with CFRP

2019 ◽  
Vol 26 (1) ◽  
pp. 1-9
Author(s):  
Nabeel A. Al-Bayati ◽  
Bassman R. Muhammed ◽  
Muroj F. Oda
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Load ◽  
General Trend ◽  
Load Path ◽  
Deep Beams ◽  
Web Openings ◽  
Shear Span ◽  
Depth Ratio ◽  
Effective Depth ◽  
Strengthened Beam

Results of test on seven simply supported self-compacting reinforced concrete deep beams, including six of these beams containing circular openings in center of load path are reported in this paper. The objective of the tests was determined the influence of, changing shear span to effective depth ratio a/d, the existence of circular openings in shear span and using inclined strips of carbon fiber polymer (CFRP) on behavior of deep beams. The general trend in crack pattern, the load-deflection response, and the mode of failure of reinforced SCC deep beams were also investigated. All specimens had the same geometry, details of the flexure and shear reinforcement in both vertical and horizontal directions and they were tested under symmetrical two-point loads up to failure. The experimental results revealed that the web openings within shear spans caused an important reduction in the deep beam capacity by 50% when compared with the corresponding solid beam. The increase a/d ratio from 0.8 to 1.2 decreases the ultimate load by 21.7% and 22.5 % for the reference unstrengthened beam and strengthened beam, respectively, also it was found that the externally inclined CFRP strips in deep beams increased the ultimate strength up to 39.5%, and enhanced the stiffness of deep beams with openings.

Shear Behavior of Reinforced Concrete Deep Beams with Various Horizontal to Vertical Reinforcements and Shear Span-to-Effective Depth Ratios

2014 ◽  
Vol 931-932 ◽  
pp. 473-477
Author(s):  
Prach Amornpinnyo ◽  
Jaruek Teerawong
Keyword(s):  
Reinforced Concrete ◽  
Shear Behavior ◽  
Beam Specimen ◽  
Test Results ◽  
Deep Beams ◽  
Shear Span ◽  
Strut And Tie ◽  
Vertical Reinforcement ◽  
Effective Depth ◽  
Strut And Tie Model

This paper presents the test results on the shear behavior of reinforced concrete deep beams with six steel reinforcement configurations. They were designed in accordance with the method given in the ACI 318-11. The specimens were subjected to the single concentrated loading at mid-span. The horizontal to vertical reinforcement ratios and shear span-to-effective depth ratios were the variables studied. The shear span-to-effective depth ratios of the beam specimen were between 1.5 to 2.0. The strut-and-tie model was used for the analysis. The test results indicated that the first diagonal cracking load and the failure mode were controlled by the horizontal to vertical reinforcement ratios and the shear span-to-depth ratios. The tests consistently gave the strength values slightly less than those calculated by using the ACI model. A modified ACI model for strut-and-tie was thus proposed and was found to accurately fit the experimental results.

scholarly journals Shear strength enhancement of lightweight aggregate reinforced concrete deep beams by using CFRP strips

2018 ◽  
Vol 162 ◽  
pp. 04011 ◽  
Author(s):  
Ahlam Mohammad ◽  
Kaiss Sarsam ◽  
Nabeel Al-Bayati
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Ultimate Load ◽  
Lightweight Aggregate ◽  
Lightweight Aggregate Concrete ◽  
Shear Cracks ◽  
Deep Beams ◽  
Control Beam ◽  
Shear Span ◽  
Number Of Layers

In this research, results of an experimental investigation on the shear strengthening of lightweight aggregate reinforced concrete deep beams are presented. A total of eight lightweight aggregate deep beams were cast and tested in the experimental work to study the effect of externally bonded CFRP strips in improving their structural behavior, one of them was unstrengthened to serve as a control beam while the remaining seven beams were strengthened in different orientation, spacing and number of layers of CFRP. The locally available natural porcelanite rocks are used to seek the possibility of producing structural lightweight aggregate concrete. The beams were designed to satisfy the requirements of ACI 318M- 14 building code. Results show that the CFRP strips have increased the load carrying capacity for the strengthened deep beams up to 50 % when comparedto the unstrenghtened control one. The diagonal compression strut crack of unstrenghtened control beam is changed to several diagonal cracks in the mid-depth within the shear span of the strengthened beams and exhibited more ductile failure modes. The results also indicate that bonded CFRP system in the shear span was seen to delay the formation of diagonal shear cracks and provided positive restraint to the subsequent growth of cracks. Increasing the amount of CFRP (by increasing the number of layers from one to two layers) results in increase in the ultimate load by about 15%. However, the increase in the spacing between the strips (from 100 to 150mm) led to a decrease in the ultimate load by about 13%.

scholarly journals The improved design method of shear strength of reinforced concrete beams without transverse reinforcement

2017 ◽  
Vol 12 (2) ◽  
pp. 39-45 ◽  
Author(s):  
Pavlo Vegera ◽  
Rostyslav Vashkevych ◽  
Roman Khmil ◽  
Zinoviy Blikharskyy
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Design Method ◽  
Variable Parameter ◽  
Reinforced Concrete Beams ◽  
Shear Span ◽  
Depth Ratio ◽  
Effective Depth ◽  
Improved Design

Abstract In this article, results of experimental testing of reinforced concrete beams without transverse shear reinforcement are given. Three prototypes for improved testing methods were tested. The testing variable parameter was the shear span to the effective depth ratio. In the result of the tests we noticed that bearing capacity of RC beams is increased with the decreasing shear span to the effective depth ratio. The design method according to current codes was applied to test samples and it showed a significant discrepancy results. Than we proposed the improved design method using the adjusted value of shear strength of concrete CRd,c. The results obtained by the improved design method showed satisfactory reproducibility.

scholarly journals Retrofitting of shear strength self-compacting reinforced concrete deep beams with FRP

2018 ◽  
Vol 162 ◽  
pp. 04016
Author(s):  
Nabeel Al-Bayati ◽  
Bassman Muhammad ◽  
Sarah Sadkhan
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Ultimate Load ◽  
Load Capacity ◽  
Experimental Program ◽  
Deep Beams ◽  
Ultimate Load Capacity ◽  
Failure Loads ◽  
Effective Depth ◽  
Midspan Deflection

Experimental program were carried out to investigate the behavior of self-compacting reinforced concrete deep beams retrofitting with carbon fiber reinforced polymer (CFRP). Six simply supported deep beams were tested under symmetrically two point loads, three beams were tested up to failure without strengthening as a control beams with different shear span to effective depth ratio (a/d) while the other two beams were loaded up to 60% from the ultimate load of control beams for each a/d ratio and then retrofitted by the same configuration of CFRP to study the effect of a/d ratio on the properties of deep beams retrofitted. a/d for tested beams were (0.8, 1, 1.2). Study was focused on determining failure loads, cracking loads, failure modes, load midspan deflection. All the beams had the same compressive strength, overall dimensions and flexural and shear reinforcement. It was concluded that using this retrofitted method is very efficient and a gain in the ultimate load capacity of the deep beams was obtained also the results showed that when a/d ratio increase from 0.8 to 1.2, the ultimate load was decrease by 25% and midspan deflection was increased approximately at all load stages for control and retrofitted beams.

scholarly journals Behavior of Concrete Deep Beam Reinforced with Inclined Web Reinforcement around Different Opening Shapes

2019 ◽  
pp. 1-12
Author(s):  
Ahmed H. Abdel-Kareem ◽  
Ibrahim A. El-Azab
Keyword(s):  
Ultimate Load ◽  
Deep Beam ◽  
Loading Test ◽  
Web Openings ◽  
Improvement Rate ◽  
Shear Span ◽  
Depth Ratio ◽  
Web Reinforcement ◽  
New Type ◽  
Sharp Edges

The objective of this paper is to experimentally and analytically estimate the influence of inclined reinforcement placed above and below web openings having different shapes in reinforced concrete (RC) deep beam. Twenty RC deep beams had the same overall geometric dimensions were tested under two-point top loading. Test variables included amount of inclined reinforcement, opening shape (circular, square, rectangular and relatively new type rectangular with fillet edges) and shear span-to-depth ratio. The relationship between the amount of inclined reinforcement and the opening size was expressed as the effective inclined reinforcement factor. As this factor was increased, the behavior of tested beams improved, where the crack width and its development decreased, and the ultimate load increased. The improvement rate of ultimate load with increasing effective inclined reinforcement for beams with rectangular openings having fillet edges was higher than that with sharp edges. Beams with opening having square, circular, or rectangular with fillet edges shapes and having effective inclined reinforcement ratio above 0.085 and 0.091 under shear span-to-depth ratio 1.0 and 0.6, respectively had higher ultimate load than that of corresponding solid beams. The effect of inclined reinforcement on enhancing the behavior of deep beam with opening increased as the shear span-to-depth ratio decreased. The ultimate load of tested beams was estimated using upper-bound analysis of the plasticity theory and compared with the test results. It is shown that the prediction has a consistent agreement with the experimental results.

scholarly journals Retrofitting of SCC Deep Beams With Circular Openings Using CFRP

2021 ◽  
Vol 39 (7) ◽  
pp. 1092-1104
Author(s):  
Nabeel A. Al-Bayati ◽  
Dhiyaa H. Muhammad ◽  
Nawfal A. Abdul Jabbar
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Load ◽  
Fiber Reinforced Polymer ◽  
Hardened Concrete ◽  
Use Of Self ◽  
Load Path ◽  
Deep Beams ◽  
Self Compacting Concrete ◽  
Reinforced Polymer ◽  
Ultimate Failure

The main objectives of this study are: encouraging the production and use of self-compacting concrete, use of materials which are lightweight, easy to use, and highly efficient in the retrofitting of reinforced concrete buildings. Six deep beams specimens (L= length of 1400mm, h= height of 400mm, and b= width of 150mm) were cast using self-compacting concrete. The location of the openings is in the middle of assumed load path. Five patterns were adopted to arrange carbon fiber reinforced polymer (CFRP) strips. The cylinder compressive strength of the concrete was approximately equal for all beams and was about (44 MPa) at 28 days age. All the beams have the same steel reinforcement for shear and flexure. There have been many tests for fresh and hardened concrete. The reinforced concrete deep beams were tested up to (60%) of the ultimate load of control beams to simulate degree of damage, and then released the load. After that, the beams were retrofitted using (CFRP) strips, and then the beams were tested to failure. The study was focused on determining the vertical mid-span deflection, ultimate load, the load that causes first shear and flexural cracks, and mode of failure. The results showed that, the best increase in the ultimate failure load was (27.27%) and achieved using the inclined strips pattern and the pattern of vertical and horizontal strips together. Reduction in the deflection values for the retrofitted beams compared to the control beam by about (12-13%) due to restrictions imposed by CFRP strips and the...

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