scholarly journals Effect of Corrosion in the Transverse Reinforcements in Concrete Beams: Sustainable Method to Generate and Measure Deterioration

2020 ◽  
Vol 12 (19) ◽  
pp. 8105
Author(s):  
P. Castro-Borges ◽  
C. A. Juárez-Alvarado ◽  
R. I. Soto-Ibarra ◽  
J. A. Briceño-Mena ◽  
G. Fajardo-San Miguel ◽  
...  
Keyword(s):  
Shear Strength ◽  
Failure Modes ◽  
Shear Failure ◽  
Corrosion Potential ◽  
Concrete Beams ◽  
Ultimate Shear Strength ◽  
Cross Sectional ◽  
Mass Losses ◽  
Consistent Method ◽  
Theoretical Results

A consistent method to generate and measure deterioration by corrosion in transverse reinforcements for concrete beams is presented and discussed in this work. This approach could be applied in other circumstances, such as bending, compression or combinations of stresses, with comparable results and therefore can be used to ensure sustainability. In marine environments, macro-cells are produced primarily from a transverse reinforcement, which works as an anode and therefore becomes a critical part of the structural analysis. To evaluate the adaptation efficiency of our proposed method, the corrosion potential, mass losses and cross-section reductions of the steel were measured. The shear stress behavior of the beams was investigated, including beam responses to load deformations, failure modes and cracking. The method ensured that all the beams exhibited a shear failure from diagonal stress with almost 50% less deflection when mechanically tested. The critical cross-sectional area, calculated according to the experimental diameter with the greatest cross-sectional loss due to the corrosion of the deteriorated stirrup, proved to be a reliable value for predicting the ultimate shear strength of concrete beams deteriorated by severe corrosion. A reduction of up to 30% in the shear strength of deteriorated versus non-deteriorated beams was found. Additional results showed that there is a correlation between the experimental and theoretical results and that the method is reproducible.

scholarly journals Influence of coarse aggregate on shear resistance of self-consolidating concrete beams

2017 ◽  
Vol 10 (1) ◽  
pp. 30-40
Author(s):  
G. SAVARIS ◽  
R. C. A. PINTO
Keyword(s):  
Shear Strength ◽  
Failure Modes ◽  
Coarse Aggregate ◽  
Concrete Beams ◽  
Shear Resistance ◽  
Self Consolidating Concrete ◽  
Coarse Aggregates ◽  
Lower Shear ◽  
Nominal Size ◽  
High Flowability

Abstract Self-consolidating concrete is characterized by its high flowability, which can be achieved with the addition of superplasticizer and the reduction of the amount and size of coarse aggregates in the concrete mix. This high flowability allows the concrete to properly fill the formwork without any mechanical vibration. The reduction in volume and particle size of the coarse aggregates may result in lower shear strength of beams due to a reduced aggregate interlock. Therefore, an experimental investigation was conducted to evaluate the influence of the reduction in the volume fraction and the nominal size of coarse aggregate on concrete shear strength of self-consolidating beams. Six concrete mixes were produced, four self-consolidating and two conventionally vibrated. A total of 18 beams, with flexural reinforcement but without shear reinforcement were cast. These beams were tested under a four-point loading condition. Their failure modes, cracking patterns and shear resistances were evaluated. The obtained shear resistances were compared to the theoretical values given by the ACI-318 and EC-2 codes. The results demonstrated a lower shear resistance of self-consolidating concrete beams, caused mainly due to the reduced aggregate size.

Shear Failure Analysis of Concrete Beams Reinforced with Newly Developed GFRP Stirrups

2006 ◽  
Vol 324-325 ◽  
pp. 995-998
Author(s):  
Cheol Woo Park ◽  
Jong Sung Sim
Keyword(s):  
Failure Modes ◽  
Shear Failure ◽  
Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Experimental Program ◽  
Shear Stresses ◽  
Fiber Reinforced ◽  
Shear Span ◽  
Reinforced Polymer ◽  
A New Technique

Even though the application of fiber reinforced polymer (FRP) as a concrete reinforcement becomes more common with various advantages, one of the inherent shortcomings may include its brittleness and on-site fabrication and handling. Therefore, the shape of FRP products has been limited only to a straight bar or sheet type. This study suggests a new technique to use glass fiber reinforced polymer (GFRP) bars for the shear reinforcement in concrete beams, and investigates its applicability. The developed GFRP stirrup was used in the concrete instead of ordinary steel stirrups. The experimental program herein evaluates the effectiveness of the GFRP stirrups with respect to different shear reinforcing ratios under three different shear span-to-depth testing schemes. At the same shear reinforcing ratio, the ultimate loads of the beams were similar regardless the shear reinforcing materials. Once a major crack occurs in concrete, however, the failure modes seemed to be relatively brittle with GFRP stirrups. From the measured strains on the surface of concrete, the shear stresses sustained by the stirrups were calculated and the efficiency of the GFRP stirrups was shown to be 91% to 106% depending on the shear span-to-depth ratio.

Investigation into Impact of Column Rectangularity on Shear Strength of No-Stirrup Rc Members in General Shear

2010 ◽  
Vol 163-167 ◽  
pp. 1456-1459
Author(s):  
Da Ren ◽  
Chao Yang Zhou
Keyword(s):  
Shear Strength ◽  
Regression Analysis ◽  
Lower Bound ◽  
Failure Modes ◽  
Shear Failure ◽  
Unified Model ◽  
Design Equation ◽  
Physical Explanation ◽  
New Approach ◽  
Practical Concern

Based on the links among various shear failure modes and the unified model for beam-like shear and symmetrical punching previously proposed, a new approach is presented to allow for the effect of column rectangularity on the shear capacities of members in general shear, which includes punching and beam-like shear as two particular extremes. In succeeded regression analysis, linear metric form is selected out of practical concern, and a lower-bound design equation is finally developed that can not only measure the influence of this variable on members in general shear, but can give a clear physical explanation to the measurement, as is absent in certain codes.

Implication of Unbondedness in Reinforced Concrete Beams

2012 ◽  
Vol 587 ◽  
pp. 36-41 ◽  
Author(s):  
S.F.A. Rafeeqi ◽  
S.U. Khan ◽  
N.S. Zafar ◽  
T. Ayub
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Failure Mode ◽  
Shear Failure ◽  
Concrete Beams ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Flexural Capacity ◽  
Flexural Reinforcement

In this paper, behaviour of nine (09) RC beams (including two control beams) after unbonding and exposing flexural reinforcement has been studied which were intentionally designed and detailed to observe flexural and shear failure. Beams have been divided into three groups based on failure mode and unbounded and exposed reinforcement. Beams have been tested under two-point loading up to failure. Experimental results are compared in terms of beam behaviour with respect to flexural capacity and failure mode which revealed that the exposed reinforcement does not altered flexural capacity significantly and unbondedness positively influences shear strength; however, serviceability performance of beams with unbonded and exposed reinforcement is less.

scholarly journals Shear tests on GFRP reinforced concrete beams

2020 ◽  
Vol 323 ◽  
pp. 01009
Author(s):  
Damian Szczech ◽  
Renata Kotynia
Keyword(s):  
Failure Modes ◽  
Shear Failure ◽  
Concrete Beams ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Shear Behaviour ◽  
Experimental Program ◽  
Glass Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Glass Fibre Reinforced

This paper aims to investigate the shear failure mechanisms in beams reinforced with longitudinal and transverse glass fibre reinforced polymer bars. It is a part of comprehensive research on shear in concrete beams reinforced with steel and GFRP bars. The experimental program is composed of six real-scale single-span, simply-supported T-cross section concrete beams. The beams varied mainly with respect to the longitudinal reinforcement ratio (2.91% and 3.69%), bar diameter (25mm and 28mm, respectively) and transverse reinforcement ratio (0.16% and 0,33%). The paper presents test results, cracking patterns, failure modes and an analysis of the influence of variable parameters on the shear behaviour of elements.

Direct Strut-and-Tie Model for Ultimate Shear Strength of Reinforced Concrete Structural Walls

2011 ◽  
Vol 255-260 ◽  
pp. 89-93
Author(s):  
Ji Yang Wang ◽  
Yi Lin Sun ◽  
Masanobu Sakashita
Keyword(s):  
Shear Strength ◽  
Failure Modes ◽  
Ultimate Shear Strength ◽  
Structural Walls ◽  
Strut And Tie ◽  
Transverse Tensile ◽  
Compressive Stresses ◽  
Proposed Model ◽  
Strut And Tie Model

A direct strut-and-tie model to calculate the ultimate shear strength of structural walls based on an interactive mechanical model (C.Y.Tang et al.) is presented. Two common failure modes, namely, diagonal splitting and concrete crushing, are examined in this paper. Ultimate shear strengths of structural walls are governed by both the transverse tensile stresses perpendicular to the diagonal strut, and the compressive stresses in the diagonal strut. Such proposed model is verified aganist three experimental case studies of structural walls. Generally, predictions by the proposed model are not only accurate and consistent in each case study, but also conservative.

scholarly journals Failure mechanism of hollow tree trunks due to cross-sectional flattening

2017 ◽  
Vol 4 (4) ◽  
pp. 160972 ◽  
Author(s):  
Yan-San Huang ◽  
Fu-Lan Hsu ◽  
Chin-Mei Lee ◽  
Jia-Yang Juang
Keyword(s):  
Urban Areas ◽  
Failure Modes ◽  
Shear Failure ◽  
Maximum Shear Stress ◽  
Mode Iii ◽  
Buckling Mode ◽  
Cross Sectional ◽  
Longitudinal Splitting ◽  
Bending Failure ◽  
Hollow Tree

Failure of hollow trees in urban areas is a worldwide concern, and it can be caused by different mechanisms, i.e. bending stresses or flattening-related failures. Here we derive a new analytical expression for predicting the bending moment for tangential cracking, and compare the breaking moment of various failure modes, including Brazier buckling, tangential cracking, shear failure and conventional bending failure, as a function of t / R ratio, where t and R are the trunk wall thickness and trunk radius, respectively, of a hollow tree. We use Taiwan red cypress as an example and show that its failure modes and the corresponding t / R ratios are: Brazier buckling (Mode I), tangential cracking followed by longitudinal splitting (Mode II) and conventional bending failure (Mode III) for 0 <  t / R  < 0.06, 0.06 <  t / R  < 0.27 and 0.27 <  t / R  < 1, respectively. The exact values of those ratios may vary within and among species, but the variation is much smaller than individual mechanical properties. Also, shear failure, another type of cracking due to maximum shear stress near the neutral axis of the tree trunk, is unlikely to occur since it requires much larger bending moments. Hence, we conclude that tangential cracking due to cross-sectional flattening, followed by longitudinal splitting, is dominant for hollow trunks. Our equations are applicable to analyse straight hollow tree trunks and plant stems, but are not applicable to those with side openings or those with only heart decay. Our findings provide insights for those managing trees in urban situations and those managing for conservation of hollow-dependent fauna in both urban and rural settings.

Shear Strength of Concrete and Gypsum Composite Walls

2013 ◽  
Vol 368-370 ◽  
pp. 976-983 ◽  
Author(s):  
Kang Liu
Keyword(s):  
Shear Strength ◽  
Glass Fiber ◽  
Shear Failure ◽  
Design Procedure ◽  
Green Product ◽  
Ultimate Shear Strength ◽  
Glass Fiber Reinforced ◽  
Shear Performance ◽  
Save Energy ◽  
Composite Walls

Gypsum walls are a green product that helps to save energy and protect the environment. This paper investigates the shear strength of glass fiber reinforced gypsum (GFRG) walls fully or partially filled with concrete in the hollow cores. Eight full scale GFRG walls were tested. The shear performance of the tested walls, including the shear failure mode, hysteresis responses, the ultimate shear strength were studied in the paper. A design procedure for the shear strength of the concrete filled GFRG walls is developed.

Influence of synthetic fibers on the shear behavior of lightweight concrete beams

2017 ◽  
Vol 20 (11) ◽  
pp. 1671-1683 ◽  
Author(s):  
Ayman Ababneh ◽  
Rajai Al-Rousan ◽  
Mohammad Alhassan ◽  
Mohammed Alqadami
Keyword(s):  
Shear Strength ◽  
Lightweight Concrete ◽  
Concrete Beams ◽  
Shear Behavior ◽  
Fiber Content ◽  
Reinforced Concrete Beams ◽  
Experimental Program ◽  
Shear Reinforcement ◽  
Ultimate Shear Strength ◽  
Synthetic Fibers

Incorporating discontinuous structural synthetic fibers in general enhances the performance of concrete and increases its durability by minimizing its potential to cracking and providing crack arresting mechanism. Synthetic fibers are non-corrosive, alkali resistant, simple to apply, and added in small quantities due to their low density; thus, a substantial number of uniformly distributed fibers are added. In this research, an experimental program was undertaken to investigate the shear behavior of lightweight concrete beams containing discontinuous structural synthetic fibers. The studied parameters include fiber content and shear reinforcement. The tests were conducted under four-point loading in a simply supported span of 0.85 m. The beams were divided into three groups based on shear reinforcement. Group 1 was designed without shear reinforcement, Group 2 with closed vertical stirrups placed at d/4 spacing (where d is the effective depth), and Group 3 with closed vertical stirrups placed at d/2 spacing. Each group contains four identical specimens except in terms of the fiber content: 0, 3, 5, and 7 kg/m3 equivalent to fiber volume fractions of 0%, 0.33%, 0.55%, and 0.77%, respectively. The experimental results showed that the discontinuous structural synthetic fibers improve the ultimate shear strength, ductility, stiffness, and toughness of lightweight concrete beams significantly. Therefore, design codes are encouraged to consider their contribution to shear strength and revise the maximum stirrups spacing when discontinuous structural synthetic fibers are used. The results also showed that addition of discontinuous structural synthetic fibers reduces the crack width of lightweight reinforced concrete beams. The effectiveness of the discontinuous structural synthetic fibers decreases as the stirrups spacing decreases.

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