scholarly journals Experimental and Numerical Evaluation of Shear Strength of Directly and Indirectly Loaded Flanged Recycled Self-Compacted Reinforced Concrete Deep Beams

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Thamer Hussein Amer Alhussein ◽  
Jamal Abdul Samad Khudhair
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Ultimate Load ◽  
American Concrete Institute ◽  
Shear Capacity ◽  
Recycled Concrete ◽  
Experimental Results ◽  
Experimental Result ◽  
Deep Beams ◽  
Aashto Lrfd

Experimental and numerical investigations of the behavior of directly and indirectly loaded flanged reinforced concrete (RC) deep beams cast with self-compacted concrete (SCC) containing recycled concrete as coarse aggregate (RCA) were conducted in this research. Seventeen RC deep flanged beams were designed to fail in shear. These beams were divided into three groups: twelve indirectly loaded beams without shear reinforcement; three directly loaded beams without stirrups; and two indirectly loaded beams with vertical stirrups. These beams were also classified according to the RCA ratio and shear span-to-effective depth (a/d) ratio, which will be detailed later. The RCA ranged from 0% to 75%, while the a/d ratio was taken as 1.0, 1.35, and 1.7. Experimental results show that the use of RCA reduces the cracking and ultimate capacities, and this finding complies with the conclusions of several research studies in the literature as will be detailed later. It was observed that beams with higher RCA exhibited higher deflection, strain, and crack width. Furthermore, by increasing the a/d ratio, the ultimate load was decreased due to the lower contribution of arch action shear transfer in the beam. A web reinforcement spaced at 100 mm and 50 mm increases the ultimate load by 35% and 48%, respectively. Strut and tie model (STM) presented by the American Concrete Institute (ACI) 318-14 and the American Association of State Highway and Transportation Officials (AASHTO LRFD 2012) was used to predict the ultimate shear capacity of the beams. STM predicted lower beam capacity than the experimental result. The ultimate strength calculated using ACI318-14 and AASHTO LRFD 2012 was on average 38% and 52% lower than the experimental data, respectively, which reflects the conservative nature of this approach. Finally, 3D finite element models were created to investigate the responses of the beams. The FE results showed very good agreement with the experimental data, where FE-predicted shear capacities were on average 9% higher than the experimental results.

scholarly journals Shear Behavior of Steel-Fiber-Reinforced Recycled Aggregate Concrete Deep Beams

Buildings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 423
Author(s):  
Nancy Kachouh ◽  
Tamer El-Maaddawy ◽  
Hilal El-Hassan ◽  
Bilal El-Ariss
Keyword(s):  
Shear Behavior ◽  
Shear Capacity ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Steel Fibers ◽  
Recycled Aggregate ◽  
Shear Reinforcement ◽  
Deep Beams ◽  
Control Beam ◽  
Shear Response

Results of an experimental investigation aimed at studying the effect of steel fibers on the shear behavior of concrete deep beams made with a 100% recycled concrete aggregate (RCA) are presented in this paper. The study comprised testing of seven concrete deep beam specimens with a shear span-to-depth ratio (a/h) of 1.6. Two beams were made of natural aggregates (NAs) without steel fibers, two beams were made of a 100% RCA without steel fibers, and three beams were made of RCA-based concrete with steel fibers at volume fractions (vf) of 1, 2, and 3%. Two of the beams without steel fibers included a minimum shear reinforcement. Test results showed that the beam with a 100% RCA without steel fibers exhibited a lower post-cracking stiffness, reduced shear cracking load, and lower shear capacity than those of the NA-based control beam. The detrimental effect of the RCA on the shear response was less pronounced in the presence of the minimum shear reinforcement. The addition of steel fibers significantly improved the shear response of the RCA-based beams. The post-cracking stiffness of the RCA-based concrete beams with steel fibers coincided with that of a similar beam without fibers containing the minimum shear reinforcement. The use of steel fibers in RCA beams at vf of 1 and 2% restored 80 and 90% of the shear capacity, respectively, of a similar beam with the minimum shear reinforcement. The response of the RCA specimen with vf of 3% outperformed that of the NA-based control beam with the minimum shear reinforcement, indicating that steel fibers can be used in RCA deep beams as a substitution to the minimum shear reinforcement. The shear capacities obtained from the tests were compared with predictions of published analytical models.

scholarly journals Assessing the Instantaneous Stiffness of Cracked Reinforced Concrete Beams Based on a Gradual Change in Strain Distributions

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Chunyu Fu ◽  
Dawei Tong ◽  
Yuyang Wang
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Cross Section ◽  
Concrete Beams ◽  
Internal Force ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Gradual Change ◽  
Concrete Cracking ◽  
Good Agreement

Concrete cracking causes a gradual change in strain distributions along the cross section height of reinforced concrete beams, which will finally affect their instantaneous stiffness. A method for assessing the stiffness is proposed based on the gradual change, which is considered through modeling different strain distributions for key sections in cracked regions. Internal force equilibria are adopted to find a solution to top strains and neutral axes in the models, and then the inertias of the key sections are calculated to assess the beam stiffness. The proposed method has been validated using experimental results obtained from tests on five reinforced concrete beams. The predicted stiffness and displacements are shown to provide a good agreement with experimental data. The instantaneous stiffness is proven to greatly depend on the crack number and depth. This dependence can be exactly reflected by the proposed method through simulating the gradual change in concrete strain distributions.

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 Shear behavior of reinforced concrete wide beams strengthened with CFRP sheet without stirrups

2019 ◽  
Vol 12 (1) ◽  
pp. 80-98
Author(s):  
Ali Laftah Abass
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Load ◽  
Concrete Strength ◽  
Shear Behavior ◽  
Shear Capacity ◽  
Rc Beams ◽  
Shear Reinforcement ◽  
Control Beam ◽  
Cfrp Sheet ◽  
Wide Beams

Reinforced concrete wide beams (WBS) have been used in construction buildings because its provide many advantages; reducing the reinforcement congestion, reducing the quantity of the required formwork, providing simplicity for replication, and decreasing the storey height. The current study presents the results of four full-scale wide RC beams in order to study their shear behavior and investigate the effectiveness of carbon fiber reinforced polymer (CFRP) when using as shear reinforcement to improve the shear capacity of wide RC beams, one these beams was fabricated by (ANSYS) program this beam was unstrengthened with CFRP and without stirrups (control beam), the other two beams was strengthened with vertical and inclined CFRP sheet without stirrups and the last beam reinforced with shear stirrups (WBS). All beams casted with normal concrete strength (30 MPa), simply supported and under two point loads. The performances of these beams were measured in terms of; ultimate load, crack patterns, concrete and steel strains, deflection, and mode of failure. The results showed an increasing in ultimate load of strengthened beams with inclined, vertical CFRP and beam with shear reinforcement by (19.9%), (7.14%) and (39.8%) respectively as compared with the control beam, and this results means possibility of replacing the internal shear reinforcement with externally bonded CFRP.

scholarly journals Effect of Steel Fiber Ratios on Behavior of High Strength Hybrid Reinforced Concrete Deep Beams under Repeated Loading

2018 ◽  
Vol 12 (1) ◽  
pp. 108-121
Author(s):  
Sawsan Akram Hassan ◽  
Ansam Hassan Mhebs
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Load ◽  
Steel Fiber ◽  
High Strength ◽  
Point Load ◽  
Monotonic Loading ◽  
Repeated Loading ◽  
Percentage Increase ◽  
Deep Beams ◽  
Hybrid Beam

Introduction: The present work presents experimental and analytical investigation of the effect of steel fiber ratio of behavior of high strength hybrid reinforced concrete deep beams under monotonic and repeated two point load. Methods: The experimental work included casting and testing of six deep beams, three of which were tested under monotonic loading (control beams) and other beams were tested under repeated loading at level of 75% of ultimate load of control beams. The effect of different SF ratios (0%,1% and 2%) with constant amount of web reinforcement (pw) were studied in terms of crack patterns, ultimate load and load versus mid span deflection. Results and Conclusion: From the experimental test results, it was observed the percentage increase ultimate load for hybrid beam cast with SF ratio 1% is 9.62% as compared with hybrid beam with SF ratio 0%. Also, the ultimate load for hybrid beam cast with SF ratio 2% is 28.85% as compared with hybrid beam with SF ratio 0% and 17.54% as compared with hybrid beam with SF ratio 1% under monotonic loading. Strut and Tie Model (STM) procedures were used to analyze the experimentally tested hybrid deep beams under monotonic loading of the present investigation.

scholarly journals Punching shear resistance of reinforced concrete footings: evaluation of design codes

2018 ◽  
Vol 11 (2) ◽  
pp. 432-454
Author(s):  
D. F. A. SANTOS ◽  
A. F. LIMA NETO ◽  
M. P. FERREIRA
Keyword(s):  
Reinforced Concrete ◽  
Progressive Collapse ◽  
Shear Resistance ◽  
Test System ◽  
Shear Capacity ◽  
Experimental Results ◽  
Punching Shear ◽  
Complex Method ◽  
Shear Design ◽  
Eurocode 2

Abstract Punching is a possible failure mode for slender footings and it may lead a structure to ruin through progressive collapse. Although footing present different geometric characteristics, their punching shear design is based on the empirical methods used for flat slabs. This paper uses experimental results from 216 tests to evaluate the performance of design code recommendations presented by ACI 318 (2014), ABNT NBR 6118 (2014) and Eurocode 2 (2010) to estimate the punching shear resistance of reinforced concrete footings. Great dispersion between theoretical and experimental results was observed, being evident that the test system affects the punching shear capacity of footings. The more complex method proposed by Eurocode 2 resulted in a better correlation with experimental results.

scholarly journals Shear capacity of reinforced concrete deep beams using genetic algorithm

2020 ◽  
Vol 910 ◽  
pp. 012002
Author(s):  
Tadesse Wakjira ◽  
Mohamed Ibrahim ◽  
Bilal Sajjad ◽  
Usama Ebead
Keyword(s):  
Genetic Algorithm ◽  
Reinforced Concrete ◽  
Shear Capacity ◽  
Deep Beams
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