scholarly journals Effect of Cyclic Loadings on the Shear Strength and Reinforcement Slip of RC Beams

2017 ◽  
Vol 3 (2) ◽  
pp. 111-123 ◽  
Author(s):  
Mohammed A Sakr
Keyword(s):  
Finite Element ◽  
Shear Strength ◽  
Reinforced Concrete ◽  
Finite Element Model ◽  
Failure Mode ◽  
Failure Modes ◽  
Concrete Beams ◽  
Kinematic Hardening ◽  
Element Model ◽  
Reinforced Concrete Beams

Numerous studies of the response of reinforced concrete members under cyclic loadings, many of which have been summarized and have indicated that, in general, the flexural strength of under-reinforced beams remains unimpaired under cyclic loadings consisting of a reasonable number of cycles. However, there is a body of evidence indicating that their shear strength may suffer under such loadings. The first objective of the current study is to construct an accurate 2D shell finite element model of reinforced concrete beams under cyclic loadings. The second objective is carrying out a parametric study on reinforced concrete beams, using the suggested 2D shell model.  The objective of this study was to observe the effect of the stirrup spacing, steel-to-concrete bond properties on the performance of reinforced concrete beams under cyclic loadings. For this purpose, an efficient and accurate finite element model was established taking into account the compression and tensile softening introducing damage in the concrete material, the Baushinger effect using nonlinear isotropic/kinematic hardening in the steel and an adequate bond-slip law for the concrete–steel interface. The simulated results of numerical models were verified by experimental results available in literature in order to validate the proposed model, including hysteretic curves, failure modes, crack pattern and debonding failure mode. The model provided a strong tool for investigating the performances of reinforced concrete beam. The results showed that: Cyclic loadings may change the failure mode of the beam to bond failure even though it has sufficient bond length to resist static loadings. So that under cyclic loadings additional anchorage length must be taken, cyclic loadings also influence the ductility and peak load for beams fail in shear. All these topics are of the utmost importance to RC behaviour to be considered by construction codes.

Uniform loading on the reinforced concrete beam produced by the specific cylinder-shaped rubber bags fully filled with air or water

2020 ◽  
Vol 23 (9) ◽  
pp. 1934-1947
Author(s):  
Dapeng Chen ◽  
Li Chen ◽  
Qin Fang ◽  
Yuzhou Zheng ◽  
Teng Pan
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Finite Element Model ◽  
Concrete Beam ◽  
Concrete Beams ◽  
Element Model ◽  
Reinforced Concrete Beam ◽  
Reinforced Concrete Beams ◽  
Uniform Loading ◽  
Air Bag

The bending behavior of reinforced concrete beams under uniform pressure is critical for the research of the blast-resistance performance of structural components under explosive loads. In this study, a bending test of five reinforced concrete beams with the dimensions of 200 mm (width) × 200 mm (depth) × 2500 mm (length) under uniform load produced by a specific cylinder-shaped rubber bag filled with air or water was conducted to investigate their flexural performances. An air bag load was applied to three of the reinforced concrete beams, a water bag load was applied to one reinforced concrete beam, and the remainder beam was subjected to the 4-point bending load. The experimental results highlighted that the air bag and water bag loading methods can be used to effectively apply uniform loads to reinforced concrete beams. Moreover, the stiffness of the air bag was improved by 123% in accordance with the initial pressure increases from 0.15 to 0.45 MPa. In addition, a finite element model of the test loading system was established using ABAQUS/Standard software. Moreover, the critical factors of the air bag loading method were analyzed using the numerical model. The calculated results were found to be in good agreement with the test data. The established finite element model can therefore be used to accurately simulate the action performances of the uniform loading technique using rubber bags filled with air or water.

scholarly journals COMPARACIÓN TEÓRICO – EXPERIMENTAL DEL COMPORTAMIENTO A FLEXIÓN DE VIGAS DE HORMIGÓN ARMADO MEDIANTE GRÁFICAS MOMENTO-CURVATURA

2021 ◽  
Vol 6 (1) ◽  
pp. 1
Author(s):  
W. Stalin Alcívar ◽  
Néxar Josué Párraga Zambrano ◽  
Juan Carlos Vélez Chunga
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Finite Element Model ◽  
Concrete Beams ◽  
Element Model ◽  
Reinforced Concrete Beams ◽  
Simultaneous Action ◽  
Experimental Comparison ◽  
Finite Element Software ◽  
The Moment

  Para vigas de hormigón armado el confinamiento mediante el refuerzo transversal mejora su desempeño a flexión (acción simultánea de tracción y compresión), permitiendo mayor resistencia y como consecuencia mayores deformaciones, a la vez que incrementa la ductilidad del elemento, misma propiedad que relaciona la capacidad estructural en el rango elástico y plástico en función de los desplazamientos, todo esto resumido en la gráfica momento-curvatura (M-Φ). El presente trabajo muestra la comparación teórico-experimental del comportamiento a flexión de vigas de hormigón armado mediante la gráfica momento-curvatura, partiendo de una viga base con geometría estándar preestablecida, que se ensaya con una configuración de simple apoyo sometida a una fuerza puntual creciente en el centro de la luz que delimita su deformación. A partir de resultados de ensayos experimentales realizados en la Universidad Técnica de Manabí se genera la gráfica momento curvatura (M-Φ), misma que es confrontada con la obtenida a partir de softwares de elementos finitos y puesta en consideración en base a las teorías clásicas de la flexión del hormigón. En virtud de los resultados obtenidos a partir de la calibración de un modelo de elementos finitos con un porcentaje de error del 2,89% en función de los puntos de cedencia de la gráfica momento-curvatura entre el modelo experimental y el modelo de elementos finitos, se llega a la conclusión de que el elemento puesto en estudio sufre los mismos efectos de fallas (falla primaria: dúctil, falla secundaria: frágil) las cuales están determinadas por el comportamiento que adquiere la gráfica momento curvatura (M-Φ) en dependencia de las deformaciones de los materiales.   Palabras claves: Deformaciones, desplazamientos, gráfica momento curvatura, ensayos experimentales, elementos finitos, teorías clásicas.   Abstract— For reinforced concrete beams, confinement through transverse reinforcement improves their flexural performance (simultaneous action of tension and compression), allowing greater resistance and consequently greater deformations, while increasing the ductility of the element, the same property that relates to capacity. Structural in the elastic and plastic range as a function of the displacements, all this summarized in the moment-curvature graph (M-Φ). The present work shows the theoretical-experimental comparison of the bending behavior of reinforced concrete beams through the moment-curvature graph, starting from a base beam with pre-established standard geometry, which is tested with a simple support configuration subjected to an increasing point force in the center of the light that defines its deformation. From the results of experimental tests carried out at the Universidad Técnica de Manabí, the curvature moment graph (M-Φ) is generated, which is compared with that obtained from finite element software and taken into consideration based on classical theories. of concrete flexure. By virtue of the results obtained from the calibration of a finite element model with an error percentage of 2.89% as a function of the yield points of the moment-curvature graph between the experimental model and the finite element model , it is concluded that the element under study suffers the same failure effects (primary failure: ductile, secondary failure: brittle) which are determined by the behavior acquired by the curve moment graph (M-Φ) in dependence of the deformations of the materials. Index Terms: Strains, displacement, moment curvature graph, experimental essays, finite elements, classical theories.

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 Modeling the flexural behavior of corroded reinforced concrete beams with considering stirrups corrosion

2020 ◽  
Vol 14 (3) ◽  
pp. 26-39
Author(s):  
Nguyen Ngoc Tan ◽  
Nguyen Trung Kien
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Finite Element Model ◽  
Limit State ◽  
Nonlinear Behavior ◽  
Element Model ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Bending Test ◽  
Fe Model

The reinforcement corrosion is one of the most dominant deterioration mechanisms of existing reinforced concrete structures. In this paper, the effects of the stirrup corrosion on the structural performance of five corroded beams have been simulated using the finite element model with DIANA software. These tested beams are divided into two groups for considering different inputs: (i) without corroded stirrups in flexural span, (ii) with locally corroded stirrups at different locations (e.g. full span, shear span, middle span). FE model has been calibrated with experimental results that were obtained from the four-point bending test carried out on the tested beams. This study shows that the stirrups corrosion should be received more attention in the serviceability limit state since its considerable effect on flexural behavior. Based on a parametric study, it shows that the effect of the cross-section loss of tension reinforcements on the load-carrying capacity of the corroded beam is more significant than the bond strength reduction. Keywords: reinforced concrete; beam; stirrup corrosion; finite element model; flexural nonlinear behavior.

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