scholarly journals Shear strength evaluation of reinforced recycled aggregate concrete beams

2021 ◽  
Author(s):  
Roya Shoghi Haghdoost
Keyword(s):  
Shear Strength ◽  
Shear Capacity ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Shear Behaviour ◽  
Strength Prediction ◽  
Shear Reinforcement ◽  
Aggregate Concrete ◽  
Ann Models ◽  
Shear Reinforcements

A theoretical study is conducted to investigate the shear behaviour of recycled aggregate concrete (RAC) beams with and without shear reinforcements along with the performance evaluation various Code based/other existing equations in predicting shear strength. In addition, three artificial neural network (ANN) models for shear strength prediction of RAC beams with and without shear reinforcements are developed and their performance validated by using 108 beams from available research studies. Most of the Codes and existing methods underestimate the shear capacity of RAC beams with/without shear reinforcement. However, over estimation of shear strength by Codes/existing methods for about 10% RAC beams needs to be addressed when using such Codes/existing methods for shear strength prediction. All three ANN models are found to predict shear strength of RAC beams. Developed ANN models are able to simulate the effect of shear reinforcement on the shear strength of RAC beams.

scholarly journals Shear strength evaluation of reinforced recycled aggregate concrete beams

2021 ◽  
Author(s):  
Roya Shoghi Haghdoost
Keyword(s):  
Shear Strength ◽  
Shear Capacity ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Shear Behaviour ◽  
Strength Prediction ◽  
Shear Reinforcement ◽  
Aggregate Concrete ◽  
Ann Models ◽  
Shear Reinforcements

A theoretical study is conducted to investigate the shear behaviour of recycled aggregate concrete (RAC) beams with and without shear reinforcements along with the performance evaluation various Code based/other existing equations in predicting shear strength. In addition, three artificial neural network (ANN) models for shear strength prediction of RAC beams with and without shear reinforcements are developed and their performance validated by using 108 beams from available research studies. Most of the Codes and existing methods underestimate the shear capacity of RAC beams with/without shear reinforcement. However, over estimation of shear strength by Codes/existing methods for about 10% RAC beams needs to be addressed when using such Codes/existing methods for shear strength prediction. All three ANN models are found to predict shear strength of RAC beams. Developed ANN models are able to simulate the effect of shear reinforcement on the shear strength of RAC beams.

scholarly journals SHEAR STRENGTH OF REINFORCED RECYCLED AGGREGATE CONCRETE BEAMS WITHOUT SHEAR REINFORCEMENTS

2016 ◽  
Vol 23 (1) ◽  
pp. 76-84 ◽  
Author(s):  
Hyun-Do YUN ◽  
Won-Chang CHOI
Keyword(s):  
Shear Strength ◽  
Concrete Beams ◽  
Construction Materials ◽  
American Concrete Institute ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Sustainable Construction ◽  
Shear Behaviour ◽  
Aggregate Concrete ◽  
Current Code

As the demand for sustainable construction materials has risen over recent years, researchers have conducted several studies to expand the practical application of recycled construction materials, such as recycled aggregate. The author’s previous research shows the potential application of recycled aggregate over a broad range of structural mem­ber types. This paper continues the earlier work and investigates the shear behaviour of reinforced recycled aggregate concrete beams without shear reinforcement using findings from the author’s previous research. The variables in the test program are replacement rate (0%, 30%, 60%, and 100%) of recycled aggregate and shear span-to-depth ratio (2.0, 2.5, 3.0, 4.0, and 5.0). This work compares the experimental results with results obtained using current code equations found in American Concrete Institute (ACI) 318 (2014) and equations proposed in the literature. This research has found that the current code equations can adequately predict the shear strength of recycled coarse aggregate concrete beams and possibly can be applied for the use of recycled aggregate in structural elements.

scholarly journals Recycled Aggregates Concrete Compressive Strength Prediction Using Artificial Neural Networks (ANNs)

2021 ◽  
Vol 6 (2) ◽  
pp. 17
Author(s):  
Mohamad Ali Ridho B K A ◽  
Chayut Ngamkhanong ◽  
Yubin Wu ◽  
Sakdirat Kaewunruen
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Strength Prediction ◽  
Concrete Compressive Strength ◽  
Conventional Concrete ◽  
Aggregate Concrete ◽  
Ann Models

The recycled aggregate is an alternative with great potential to replace the conventional concrete alongside with other benefits such as minimising the usage of natural resources in exploitation to produce new conventional concrete. Eventually, this will lead to reducing the construction waste, carbon footprints and energy consumption. This paper aims to study the recycled aggregate concrete compressive strength using Artificial Neural Network (ANN) which has been proven to be a powerful tool for use in predicting the mechanical properties of concrete. Three different ANN models where 1 hidden layer with 50 number of neurons, 2 hidden layers with (50 10) number of neurons and 2 hidden layers (modified activation function) with (60 3) number of neurons are constructed with the aid of Levenberg-Marquardt (LM) algorithm, trained and tested using 1030 datasets collected from related literature. The 8 input parameters such as cement, blast furnace slag, fly ash, water, superplasticizer, coarse aggregate, fine aggregate, and age are used in training the ANN models. The number of hidden layers, number of neurons and type of algorithm affect the prediction accuracy. The predicted recycled aggregates compressive strength shows the compositions of the admixtures such as binders, water–cement ratio and blast furnace–fly ash ratio greatly affect the recycled aggregates mechanical properties. The results show that the compressive strength prediction of the recycled aggregate concrete is predictable with a very high accuracy using the proposed ANN-based model. The proposed ANN-based model can be used further for optimising the proportion of waste material and other ingredients for different targets of concrete compressive strength.

scholarly journals Machine Learning-Based Evaluation of Shear Capacity of Recycled Aggregate Concrete Beams

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4552
Author(s):  
Yong Yu ◽  
Xinyu Zhao ◽  
Jinjun Xu ◽  
Cheng Chen ◽  
Simret Deresa ◽  
...  
Keyword(s):  
Machine Learning ◽  
Shear Strength ◽  
Concrete Beams ◽  
Structural Parameters ◽  
Shear Capacity ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Conventional Concrete ◽  
Aggregate Concrete ◽  
Concrete Production

Recycled aggregate concrete (RAC) is a promising solution to address the challenges raised by concrete production. However, the current lack of pertinent design rules has led to a hesitance to accept structural members made with RAC. It would entail even more difficulties when facing application scenarios where brittle failure is possible (e.g., beam in shear). In this paper, existing major shear design formulae established primarily for conventional concrete beams were assessed for RAC beams. Results showed that when applied to the shear test database compiled for RAC beams, those formulae provided only inaccurate estimations with surprisingly large scatter. To cope with this bias, machine learning (ML) techniques deemed as potential alternative predictors were resorted to. First, a Grey Relational Analysis (GRA) was carried out to rank the importance of the parameters that would affect the shear capacity of RAC beams. Then, two contemporary ML approaches, namely, the artificial neural network (ANN) and the random forest (RF), were leveraged to simulate the beams’ shear strength. It was found that both models produced even better predictions than the evaluated formulae. With this superiority, a parametric study was undertaken to observe the trends of how the parameters played roles in influencing the shear resistance of RAC beams. The findings indicated that, though less influential than the structural parameters such as shear span ratio, the effect of the replacement ratio of recycled aggregate (RA) was still significant. Nevertheless, the value of vc/(fc)1/2 (i.e., the shear contribution from RAC normalized with respect to the square root of its strength) predicted by the ML-based approaches appeared to be insignificantly affected by the replacement level. Given the existing inevitable large experimental scatter, more shear tests are certainly needed and, for safe application of RAC, using partial factors calibrated to consider the uncertainty is feasible when designing the shear strength of RAC beams. Some suggestions for future works are also given at the end of this paper.

scholarly journals Study on the Strength Performance of Recycled Aggregate Concrete with Different Ages under Direct Shearing

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2312
Author(s):  
Xin Liang ◽  
Fang Yan ◽  
Yuliang Chen ◽  
Huiqin Wu ◽  
Peihuan Ye ◽  
...  
Keyword(s):  
Shear Strength ◽  
Shear Force ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Displacement Curve ◽  
Direct Shear ◽  
Replacement Ratio ◽  
Aggregate Concrete ◽  
Concrete Failure ◽  
Load Displacement

In order to study the mechanical properties of recycled aggregate concrete (RAC) at different ages, 264 standard cubes were designed to test its direct shear strength and cube compressive strength while considering the parameters of age and recycled aggregate replacement ratio. The failure pattern and load–displacement curve of specimens at direct shearing were obtained; the direct shear strength and residual shear strength were extracted from the load–displacement curves. Experimental results indicate that the influence of the replacement ratio for the front and side cracks of RAC is insignificant, with the former being straight and the latter relatively convoluted. At the age of three days, the damaged interface between aggregate and mortar is almost completely responsible for concrete failure; in addition to the damage of coarse aggregates, aggregate failure is also an important factor in concrete failure at other ages. The load–displacement curve of RAC at direct shearing can be divided into elasticity, elastoplasticity, plasticity, and stabilization stages. The brittleness of concrete decreases with its age, which is reflected in the gradual shortening of the elastoplastic stage. At 28 days of age, the peak direct shear force increases with the replacement ratio, while the trend is opposite at ages of 3 days, 7 days, and 14 days, respectively. The residual strength of RAC decreases inversely to the replacement ratio, with the rate of decline growing over time. A two-parameter RAC direct shear strength calculation formula was established based on the analysis of age and replacement rate to peak shear force of RAC. The relationship between cube compressive strength and direct shear strength of recycled concrete at various ages was investigated.

Study on the Basic Mechanical Properties of Recycled Concrete Hollow Block Masonry

2013 ◽  
Vol 438-439 ◽  
pp. 749-755 ◽  
Author(s):  
Tong Hao ◽  
Dong Li
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Shear Behavior ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Test Results ◽  
Aggregate Concrete ◽  
Mortar Strength ◽  
Hollow Block

By the experimental studying on the basic mechanical properties of recycled concrete hollow block masonry, the compressive and shear behavior of recycled aggregate concrete hollow block masonry under different mortar strength were analyzed. Research indicated that the compressive and shear behavior of recycled aggregate concrete hollow block masonry was similar to that of ordinary concrete hollow block masonry. The normal formula was recommended to calculate the compressive strength of the masonry. The shear strength of the masonry was affected by the mortar strength. The shear strength calculation formula of recycled concrete hollow block masonry was proposed according to the formula of masonry design code. The calculating results were in good agreement with the test 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.

Shear strength of interfaces in natural and in recycled aggregate concrete

2017 ◽  
Vol 44 (3) ◽  
pp. 212-222
Author(s):  
Shakeel Ahmad Waseem ◽  
Bhupinder Singh
Keyword(s):  
Shear Strength ◽  
Shear Plane ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Failure Envelope ◽  
Interface Shear ◽  
Aggregate Concrete ◽  
Normal Strength ◽  
Strength Models

Shear strength of interfaces in natural aggregate concrete and in recycled aggregate concrete has been investigated using initially uncracked push-off specimens by varying the following parameters: replacement level of the recycled aggregates (0%, 50%, and 100%), concrete grade (normal-strength and medium-strength), and clamping force on the shear plane. Development of truss action for resisting interface shear was indicated by the observed crack patterns in the tested specimens and a truss-based analysis recommended in the literature in combination with a simplified failure envelope for concrete subjected to biaxial stresses has been used for shear strength predictions of the tested specimens. The proposed methodology, which is considered to be more rational than the empirical shear strength models available in the literature was calibrated for both the concrete types and gave conservative and reasonably accurate shear strength predictions for selected experiments taken from the literature.

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