scholarly journals Prediction of Deflection of Shear-Critical RC Beams Using Compatibility-Aided Truss Model

2021 ◽  
Vol 11 (23) ◽  
pp. 11478
Author(s):  
Sang-Woo Kim
Keyword(s):  
Shear Stress ◽  
Reinforced Concrete ◽  
Shear Deformation ◽  
Analytical Method ◽  
Rc Beams ◽  
Elastic Bending ◽  
Truss Model ◽  
Analytical Results

This study proposes a method for predicting the deflection of shear-critical reinforced concrete (RC) beams. Shear deterioration of shear-critical RC beams occurs before flexural yielding. After shear deterioration occurs in the shear-critical RC beams, the deflection caused by shear is greater than the flexural deflection obtained from the elastic bending theory. To reasonably predict the deflection of shear-critical RC beams, it is necessary to evaluate deflections due to shear as well as flexure. In this study, the deflections produced by flexure and shear were calculated and superposed to evaluate the deflection of shear-critical RC beams. The method recommended by ACI 318-19 was employed to calculate the flexural deflection, and a compatibility-aided truss model able to calculate the shear stress and shear deformation at each load stage was used to consider the shear deflection. A comparison of the experimental and analytical results showed that the proposed analytical method can effectively predict the deflection of shear-critical RC beams.

scholarly journals A Monotonic Smeared Truss Model to Predict the Envelope Shear Stress—Shear Strain Curve for Reinforced Concrete Panel Elements under Cyclic Shear

2021 ◽  
Vol 2 (1) ◽  
pp. 174-194
Author(s):  
Luís Bernardo ◽  
Saffana Sadieh
Keyword(s):  
Shear Stress ◽  
Reinforced Concrete ◽  
Shear Strain ◽  
Peak Load ◽  
Strain Curve ◽  
Fiber Reinforced Polymers ◽  
Shear Stresses ◽  
Cyclic Shear ◽  
Concrete Panels ◽  
Truss Model

In previous studies, a smeared truss model based on a refinement of the rotating-angle softened truss model (RA-STM) was proposed to predict the full response of structural concrete panel elements under in-plane monotonic loading. This model, called the “efficient RA-STM procedure”, was validated against the experimental results of reinforced and prestressed concrete panels, steel fiber concrete panels, and reinforced concrete panels externally strengthened with fiber-reinforced polymers. The model incorporates equilibrium and compatibility equations, as well as appropriate smeared constitutive laws of the materials. Besides, it incorporates an efficient algorithm for the calculation procedure to compute the solution points without using the classical trial-and-error technique, providing high numerical efficiency and stability. In this study, the efficient RA-STM procedure is adapted and checked against some experimental data related to reinforced concrete (RC) panels tested under in-plane cyclic shear until failure and found in the literature. Being a monotonic model, the predictions from the model are compared with the experimental envelopes of the hysteretic shear stress–shear strain loops. It is shown that the predictions for the shape (at least until the peak load is reached) and for key shear stresses (namely, cracking, yielding, and maximum shear stresses) of the envelope shear stress–shear strain curves are in reasonably good agreement with the experimental ones. From the obtained results, the efficient RA-STM procedure can be considered as a reliable model to predict some important features of the response of RC panels under cyclic shear, at least for a precheck analysis or predesign.

Analytical Method of Temperature Prediction in Reinforced Concrete Beams

2014 ◽  
Vol 5 (4) ◽  
pp. 367-380 ◽  
Author(s):  
Muhammad Rafi ◽  
Ali Nadjai
Keyword(s):  
Reinforced Concrete ◽  
Analytical Method ◽  
Elevated Temperatures ◽  
Reinforced Concrete Beams ◽  
Temperature History ◽  
Rc Beams ◽  
Temperature Prediction ◽  
Computational Support ◽  
In Fire

The determination of temperature profile within a reinforced concrete (RC) beam is essential for carrying out structural analysis at elevated temperatures. The temperatures are usually estimated using sophisticated numerical techniques which require computational support. Since the determination of rebar temperature in RC beams is more important than the concrete temperature a reliable analytical method of temperature prediction can become a helpful tool in simple beam analysis problems which are employed for determining residual strength in fire. This paper presents the details of development of an empirical equation for the prediction of temperature of rebar in RC beams. The equation is also capable of predicting concrete temperatures at different locations within the beam. The predictions made by the equation were compared with the temperatures determined from experimental beam testing and finite element (FE) analysis. A good correlation of the predicted temperatures was found for the entire time-temperature history with both the observed data and the estimated temperatures by FE models.

Shear Retrofitting Effect of RC Beams Damaged by Corrosion of Stirrup Strengthened with CFS

2007 ◽  
Vol 348-349 ◽  
pp. 441-444
Author(s):  
Sung Ho Tae ◽  
Han Seung Lee ◽  
Tae Soo Kim
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Shear Loading ◽  
Rc Beams ◽  
Loading Test ◽  
Shear Strengthening ◽  
Anchorage Length

In this study, an Ohno's anti-symmetric shear loading test was conducted after strengthening reinforced concrete (RC) beams damaged by corrosion of stirrup, with carbon fiber sheets (CFS) with a view to reviewing the effect of CFS on shear strengthening. As a result, it was found that CFS like stirrups could take shear stress, and that shear strength could be increased by using more CFS for reinforcement. It was also revealed that shear strength could be calculated by an existing evaluation equation by properly evaluating the effect of CFS on shear strengthening, based on the quantity of reinforcing CFS, ways of fixing the sheets and anchorage length as the effect on shear strengthening varied depending on the fixing method while sheet anchorage increased deformability.

scholarly journals Nonlinear Finite Element Analysis Formulation for Shear in Reinforced Concrete Beams

2019 ◽  
Vol 9 (17) ◽  
pp. 3503 ◽  
Author(s):  
Sang-Ho Kim ◽  
Sun-Jin Han ◽  
Kang Kim
Keyword(s):  
Shear Stress ◽  
Reinforced Concrete ◽  
Stress Function ◽  
Shear Stresses ◽  
Rc Beams ◽  
Test Results ◽  
Proposed Model ◽  
Load Displacement ◽  
Shear Stress Function ◽  
Column Element

This study suggests a novel beam-column element formulation that utilizes an equilibrium-driven shear stress function. The beam shear is obtained from the bi-axial states of micro-planes, through matrix condensation and zero vertical traction assumptions. This properly remedies the shear stiffening of a one-dimensional beam-column element, keeping its degrees of freedom to a minimum. For verification of the proposed method, a total of seven shear test results of reinforced concrete (RC) beams were collected from the literature, in which the key variables were the reinforcement ratio, the presence of shear reinforcement, and section shape. The advantages are clearly shown in the shear stresses distributions being accurately described and the global load-displacement relations being successfully obtained and matching well with various test results. The proposed model shows satisfactory descriptions of the monotonic load-displacement response of the RC beams failing in multiple modes that vary from diagonal-tension to flexural-compression. In addition, more accurate and reliable information of sectional responses including sectional shear deformation and stresses is collected, leading to better prediction of a potential shear failure mode. Finally, the advantages of the proposed model are demonstrated by comparing the analysis results of an RCT-beam by using the different shear assumptions that include the constant and parabolic shear strains, constant shear flow, and the proposed shear stress function.

scholarly journals Softened Truss Model for Reinforced Concrete Beams under Torsion Combined with Axial Force

2020 ◽  
Vol 1 (1) ◽  
pp. 79-96 ◽  
Author(s):  
Luís Bernardo ◽  
Cátia Taborda
Keyword(s):  
Reinforced Concrete ◽  
Prestressed Concrete ◽  
Concrete Beams ◽  
Solution Procedure ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Axial Forces ◽  
Truss Model ◽  
Theoretical Predictions ◽  
Good Agreement

The Generalized Softened Variable Angle Truss Model (GSVATM) allows one to compute the global behavior of reinforced concrete (RC) beams under torsion, including the pre- and post-cracking stage. In a previous study, such a model was successfully extended to cover prestressed concrete beams under torsion with longitudinal and uniform prestress. In order to continue to extend the theoretical model for other loading cases, in this article, the GSVATM is extended to cover RC beams under torsion combined with external and centered axial forces. The changes in GSVATM are presented, as well as the modified calculation solution procedure. Some theoretical predictions from the extended GSVATM are compared with numerical results from the non-linear finite element method (FEM), where good agreement is observed for the studied trends.

scholarly journals Evaluation of Smeared Constitutive Laws for Tensile Concrete to Predict the Cracking of RC Beams under Torsion with Smeared Truss Model

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1260
Author(s):  
Mafalda Teixeira ◽  
Luís Bernardo
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Constitutive Laws ◽  
Experimental Results ◽  
Rc Beams ◽  
3 Dimensional ◽  
Torsional Response ◽  
Truss Model ◽  
Early Loading ◽  
Section Type

In this study, the generalized softened variable angle truss-model (GSVATM) is used to predict the response of reinforced concrete (RC) beams under torsion at the early loading stages, namely the transition from the uncracked to the cracked stage. Being a 3-dimensional smeared truss model, the GSVATM must incorporate smeared constitutive laws for the materials, namely for the tensile concrete. Different smeared constitutive laws for tensile concrete can be found in the literature, which could lead to different predictions for the torsional response of RC beams at the earlier stages. Hence, the GSVATM is used to check several smeared constitutive laws for tensile concrete proposed in previous studies. The studied parameters are the cracking torque and the corresponding twist. The predictions of these parameters from the GSVATM are compared with the experimental results from several reported tests on RC beams under torsion. From the obtained results and the performed comparative analyses, one of the checked smeared constitutive laws for tensile concrete was found to lead to good predictions for the cracking torque of the RC beams regardless of the cross-section type (plain or hollow). Such a result could be useful to help with choosing the best constitutive laws to be incorporated into the smeared truss models to predict the response of RC beams under torsion.

Information content of the determinations of the amount of an analyte

1988 ◽  
Vol 53 (12) ◽  
pp. 3021-3028 ◽  
Author(s):  
Karel Eckschlager ◽  
Jiří Fusek
Keyword(s):  
Reference Material ◽  
Information Content ◽  
Analytical Method ◽  
Analytical Signal ◽  
Divergence Measure ◽  
Analytical Results

It is shown how the information content expressed in terms of the extended divergence measure I(r; p, p0) depends on the amount of the component to be determined when homoscedastic and heteroscedastic dependences of the analytical signal on the amount of the analyte are distinguished. The importance of the accuracy is pointed out, with which the amount of the analyte is known in a reference material employed for testing a particular analytical method. Rules are set, the maintaining of which is aimed at avoiding the origin of null information content of analytical results.

scholarly journals Time-Dependent Reliability Analysis of Reinforced Concrete Beams Subjected to Uniform and Pitting Corrosion and Brittle Fracture

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1820
Author(s):  
Mohamed El Amine Ben Seghier ◽  
Behrooz Keshtegar ◽  
Hussam Mahmoud
Keyword(s):  
Reinforced Concrete ◽  
Brittle Fracture ◽  
Reliability Analysis ◽  
Pitting Corrosion ◽  
Structural Reliability ◽  
Time Dependent ◽  
State Function ◽  
Rc Beams ◽  
Highly Nonlinear ◽  
Reliability Method

Reinforced concrete (RC) beams are basic elements used in the construction of various structures and infrastructural systems. When exposed to harsh environmental conditions, the integrity of RC beams could be compromised as a result of various deterioration mechanisms. One of the most common deterioration mechanisms is the formation of different types of corrosion in the steel reinforcements of the beams, which could impact the overall reliability of the beam. Existing classical reliability analysis methods have shown unstable results when used for the assessment of highly nonlinear problems, such as corroded RC beams. To that end, the main purpose of this paper is to explore the use of a structural reliability method for the multi-state assessment of corroded RC beams. To do so, an improved reliability method, namely the three-term conjugate map (TCM) based on the first order reliability method (FORM), is used. The application of the TCM method to identify the multi-state failure of RC beams is validated against various well-known structural reliability-based FORM formulations. The limit state function (LSF) for corroded RC beams is formulated in accordance with two corrosion types, namely uniform and pitting corrosion, and with consideration of brittle fracture due to the pit-to-crack transition probability. The time-dependent reliability analyses conducted in this study are also used to assess the influence of various parameters on the resulting failure probability of the corroded beams. The results show that the nominal bar diameter, corrosion initiation rate, and the external loads have an important influence on the safety of these structures. In addition, the proposed method is shown to outperform other reliability-based FORM formulations in predicting the level of reliability in RC beams.

scholarly journals A Practical Finite Element Modeling Strategy to Capture Cracking and Crushing Behavior of Reinforced Concrete Structures

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 506 ◽  
Author(s):  
Alexandre Mathern ◽  
Jincheng Yang
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Constitutive Relations ◽  
Fe Analysis ◽  
Rc Beams ◽  
Cracking Behavior ◽  
Concrete Cracking ◽  
Rc Structures ◽  
Nonlinear Fe Analysis ◽  
Modeling Strategy

Nonlinear finite element (FE) analysis of reinforced concrete (RC) structures is characterized by numerous modeling options and input parameters. To accurately model the nonlinear RC behavior involving concrete cracking in tension and crushing in compression, practitioners make different choices regarding the critical modeling issues, e.g., defining the concrete constitutive relations, assigning the bond between the concrete and the steel reinforcement, and solving problems related to convergence difficulties and mesh sensitivities. Thus, it is imperative to review the common modeling choices critically and develop a robust modeling strategy with consistency, reliability, and comparability. This paper proposes a modeling strategy and practical recommendations for the nonlinear FE analysis of RC structures based on parametric studies of critical modeling choices. The proposed modeling strategy aims at providing reliable predictions of flexural responses of RC members with a focus on concrete cracking behavior and crushing failure, which serve as the foundation for more complex modeling cases, e.g., RC beams bonded with fiber reinforced polymer (FRP) laminates. Additionally, herein, the implementation procedure for the proposed modeling strategy is comprehensively described with a focus on the critical modeling issues for RC structures. The proposed strategy is demonstrated through FE analyses of RC beams tested in four-point bending—one RC beam as reference and one beam externally bonded with a carbon-FRP (CFRP) laminate in its soffit. The simulated results agree well with experimental measurements regarding load-deformation relationship, cracking, flexural failure due to concrete crushing, and CFRP debonding initiated by intermediate cracks. The modeling strategy and recommendations presented herein are applicable to the nonlinear FE analysis of RC structures in general.

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