Slender Reinforced Research Articles

Experimental and numerical modelling studies of slender reinforced concrete walls with single-layer reinforcement in Peru

The deficit in affordable residential construction in Lima has generated the construction of several mid to high-rise buildings using the structural system of Slender Reinforced Concrete (RC) Walls. In Peru, this system is known as ‘walls of limited ductility’ and their main characteristics are a fast construction time and an affordable price. Due to the expected non-ductile behaviour, Peruvian RC slender wall buildings follow the same seismic design criteria as traditional RC wall buildings but with a smaller reduction factor of elastic seismic forces and minor permissible story displacement drift. However, there is limited experience of the seismic response of such buildings in severe earthquakes and seismic design criteria have been obtained from just a few experimental tests. This work presents an experimental program of cyclic in-plane testing, developed at the Pontificia Universidad Católica del Perú (PUCP) to obtain more knowledge about the lateral behaviour of typical Peruvian slender walls. According to quasi-static tests, the slender walls reached a maximum story drift of 1.27% after damage occurred, including diagonal tension, diagonal compression, sliding shear, concrete crushing, and buckling of the vertical reinforcement. Experimental results for the slender RC walls were computed to obtain the Damage States, Equivalent Lateral Stiffness (Keff), Ductility (μ), Equivalent Damping Ratio (ξeq) and Bending/Shear/Sliding deformations. In this work, a calibration process on numerical models was developed using OpenSees software. This work shows that slender RC walls in Peru show the typical hysteretic response of structural walls until a maximum drift of 1.27%, despite their deficiencies in slenderness, squat geometry, and the absence of confinement zones.

Machine Learning-Based Model for Predicting the Shear Strength of Slender Reinforced Concrete Beams without Stirrups

The influence of concrete mix properties on the shear strength of slender structured concrete beams without stirrups (SRCB-WS) is a widespread point of contention. Over the past six decades, the shear strength of SRCB-WS has been studied extensively in both experimental and theoretical contexts. The most recent version of the ACI 318-19 building code requirements updated the shear strength equation for SRCB-WS by factoring in the macroeconomic factors and the contribution of the longitudinal steel structural ratio. However, the updated equation still does not consider the effect of the shear span ratio (a/d) and the yield stress of longitudinal steel rebars (Fy). Therefore, this study investigates the importance of the most significant potential variables on the shear strength of SRCB-WS to help develop a gene expression-based model to estimate the shear strength of SRCB-WS. A database of 784 specimens was used from the literature for training and testing the proposed gene expression algorithm for forecasting the shear strength of SRCB-WS. The collected datasets are comprehensive, wherein all considered concrete properties were considered over the previous 68 years. The performance of the suggested algorithm versus the ACI 318-19 equation was statistically evaluated using various measures, such as root mean square error, mean absolute error, mean absolute percentage error, and the coefficient of determination. The evaluation results revealed the superior performance of the proposed model over the current ACI 318-19 equation. In addition, the proposed model is more comprehensive and considers additional variables, including the effect of the shear span ratio and the yield stress of longitudinal steel rebars. The developed model reflects the power of employing gene expression algorithms to design reinforced concrete elements with high accuracy.

Finite Element Analysis of Slender Reinforced Concrete Columns Subjected to Eccentric Axial Loads and Elevated Temperature

Finite Element Analysis of Slender Reinforced Concrete Columns Subjected to Eccentric Axial Loads and Elevated Temperature

Nonlinear Analysis of Hollow Slender Reinforced Concrete Columns Subjected to Concentric and Eccentric Loads

Abstract This paper investigates the load capacity and failure modes of slender hollow RC column under axial and eccentric loads. For the slender hollow columns, different load eccentricities and hole shapes are used. The finite element software ABAQUS is used to model and analyze the columns. The experimental test result is used to conduct a verification investigation of the nonlinear finite element modeling. All specifications of the experimentally tested columns are taken into consideration in the modeling to establish the verification of the model. When the modeling and test results are compared, it is noticeable that they are in good agreement. As a result, the modeling’s accuracy is proved. Then, a parametric study included different slenderness ratio, section shape, concrete strength and SFR strengthened has been done with the same modeling method. The effects of these variables on the column load capacity are investigated. It is found that increasing slenderness ratio led to smaller peak load. Increasing of moment of inertia of square and circular section decreased the peak load capacity. The maximum bearing capacity increased with higher concrete strength. Also, SFR distribution through the length of columns effected on load bearing capacity.

Analytical Study on Behaviour of Slender Reinforced Concrete Columns with Gfrp Bars and Discrete Fibres

Analytical Study on Behaviour of Slender Reinforced Concrete Columns with Gfrp Bars and Discrete Fibres

Construction of Uniaxial Interaction Diagram for Slender Reinforced Concrete Column Based on Nonlinear Finite Element Analysis

Slender reinforced concrete column may fail in material failure or instability failure. Instability failure is a common problem which cannot be analyzed with first-order analysis. So, second-order analysis is required to analyze instability failure of slender RC column. The main objective of this study was to construct uniaxial interaction diagram for slender reinforced concrete column based on nonlinear finite element analysis (FEA) software. The key parameters which were studied in this study were eccentricity, slenderness ratio, steel ratio, and shape of the column. Concrete damage plasticity (CDP) was utilized in modeling the concrete. Material nonlinearity, geometric nonlinearity, effect of cracking, and tension stiffening effect were included in the modeling. The results reveal that, as slenderness ratio increases, the balanced moment also increases, but the corresponding axial load was decreased. However, increasing the amount of steel reinforcement to the column increases the stability of the column and reduces the effect of slenderness ratio. Also, the capacity of square slender RC column is larger than rectangular slender RC column with equivalent cross section. However, the result is close to each other as slenderness ratio increased. Finally, validation was conducted by taking a benchmark experiment, and it shows that FEA result agrees with the experimental by 85.581%.

Experimental Verification of Slender Reinforced Concrete Columns Design

The columns have been part of the constructions since the beginning of the buildings and have retained their design and construction importance to the present. The advantage of using more slender elements are less material consumption and more usable space in the interiors. The continuous improvement of the building materials and the use of hybrid structural elements leads to the downsizing of the structural elements. The aim of this article is the nonlinear analysis of the slender rein-forced concrete columns and the loss of stability verified by the experimental tests. Nonlinear calculations can be considered as the most accurate calculation option for the load bearing structural elements. On the other hand, the effect of the “black box” has been, and will be the cause of a large number of building defects. In the Eurocode 2 in chapter 5.8.6 of the European Concrete Design Standard, there is a possibility of using the general nonlinear method in practice, even for the com-pressed elements. In the design of the slender structures, the influence of second-order theory is a very important part of the design. In this publication are described theoretical and experimental analyses of the slender columns, that failed due to loss of stability inside of their design interaction diagram - much sooner than the critical cross-sections reached its resistance. As a part of the experimental preparations, reinforced concrete columns were designed, based on numerous numerical analyses. Later, the chosen columns were tested in the laboratories of TU Wien in Vienna. Experimental verification is one of the main parts of my dissertation thesis.

Experimental Study of Hollow Slender Reinforced Concrete Columns Subjected to Eccentric Loads

Abstract This paper was focused on the investigating on the behavior of hollow slender reinforced concrete columns subjected to the axial loads. A total of seven specimens were designed as slender reinforced columns and these were divided into two groups. Each column is symmetrical and had a rectangular cross section of 140 × 80 mm and 2000 mm in length. The column was reinforced by 6Ø6mm for longitudinal reinforcement and Ø6@6 mm bars were used for transverse reinforcement ties. The effect of strengthening by CFRP sheet on the buckling of column, eccentricity 20, 40 and 120 mm and opening shape were studied. The results showed that the strengthened columns by CFRP caused an in the ultimate load CFRP were 26.3 % and 76.3 % for strengthened lengths of L/4 and L respectively compared with the un-strengthened column. The ultimate load of columns is reduced with existing the load eccentricity and amount of losses in strength increased with increasing the eccentricity. Also, it was found the hollow columns having circular holes had better performance compared to hollow columns having rectangular hole

The Proposition of an EI Equation of Square and L–Shaped Slender Reinforced Concrete Columns under Combined Loading

The stability and strength of slender Reinforced Concrete (RC) columns depend directly on the flexural stiffness EI, which is a major parameter in strain calculations including those with bending and axial load. Due to the non-linearity of the stress-strain curve of concrete, the effective bending stiffness EI always remains variable. Numerical simulations were performed for square and L-shaped reinforced concrete sections of slender columns subjected to an eccentric axial force to estimate the variation of El resulting from the actual behavior of the column, based on the moment-curvature relationship. Seventy thousand (70000) hypothetical slender columns, each with a different combination of variables, were used to investigate the main variables that affect the EI of RC slender columns. Using linear regression analysis, a new simple and linear expression of EI was developed. Slenderness, axial load level, and concrete strength have been identified as the most important factors affecting effective stiffness. Finally, the comparison between the results of the new equation and the methods proposed by ACI-318 and Euro Code-2 was carried out in connection with the experimental results of the literature. A good agreement of the results was found.

Reliability of Slender Reinforced Concrete Columns in Second Generation of Eurocodes

Design of slender reinforced concrete columns based on currently valid series of codes has its blank spaces. Authors of this articles are systematically working on filling these blank spaces with theoretical and experimental verifications, with focus on upcoming series of Eurocodes. They are attending the meetings of work group TC250-SC2-WG1, which is preparing changes in the new series. In this article we are presenting our suggested changes based on calculations and series of slender reinforced concrete columns experiments.

A Comparative Study of the Performance of Slender Reinforced Concrete Columns with Different Cross-Sectional Shapes

Most reinforced concrete (RC) structures are constructed with square/rectangular columns. The cross-section size of these types of columns is much larger than the thickness of their partitions. Therefore, parts of these columns are protruded out of the partitions. The emergence of columns edges out of the walls has some disadvantages. This limitation is difficult to be overcome with square or rectangular columns. To solve this problem, new types of RC columns called specially shaped reinforced concrete (SSRC) columns have been used as hidden columns. Besides, the use of SSRC columns provides many structural and architectural advantages as compared with rectangular columns. Therefore, this study was conducted to explain the structural performance of slender SSRC columns experimentally and numerically via nonlinear finite element analysis. The study is based on nine RC specimens tested up to failure, as well as eighteen finite element (FE) models analyzed by Abaqus soft wear program. The use of SSRC columns led to increase strength by about 12% and reduce deformations, especially with slenderness ratio more than 40 as compared with equivalent square-shaped columns. Two design formulas were proposed to determine the compressive strength of SSRC columns under concentric loading. The results obtained indicate a good structural performance of SSRC columns when compared with equivalent square-shaped columns.

Prediction of Shear Capacity of Slender Reinforced Concrete Beams with Steel Fiber

Prediction of Shear Capacity of Slender Reinforced Concrete Beams with Steel Fiber

Numerical Modeling Strategy for the Simulation of Nonlinear Response of Slender Reinforced Concrete Structural Walls

Numerical Modeling Strategy for the Simulation of Nonlinear Response of Slender Reinforced Concrete Structural Walls

Seismic Performance Limitations and Detailing of Slender Reinforced Concrete Walls

Seismic Performance Limitations and Detailing of Slender Reinforced Concrete Walls

Out-of-Plane Behavior of Slender Reinforced Masonry Shear Walls under In-Plane Loading: Experimental Investigation

AbstractThis paper presents the results of a multiphase research program aimed at investigating the out-of-plane stability of slender reinforced masonry shear walls (RMSWs) under in-plane reversed-...

Experimental and Analytical Study of Slender Reinforced Concrete Shear Wall under Cyclic In‐Plane Lateral Load

This study describes a slender reinforced concrete shear wall experimental test under in‐plane cyclic lateral load, and the development of an analytical model which uses the fiber method approach to consider hysteretic nonlinear constitutive material models behavior. The shear wall tested had bending behavior, since the amount of longitudinal reinforcing bars produced weak bending capacity compared to the shear strength. The analytical model tries to represent global and local behavior of the wall, and its calibration is based on reaching experimental parameters like area enclosed and secant stiffness on every loop. After the analytical model was calibrated, the relation between some performance points and damage states observed during the test is studied.

Closure to “Simplified Shear Design of Slender Reinforced Concrete Beams with Stirrups” by Zhi-Qi He, Zhao Liu, and Zhongguo John Ma

Closure to “Simplified Shear Design of Slender Reinforced Concrete Beams with Stirrups” by Zhi-Qi He, Zhao Liu, and Zhongguo John Ma

Discussion of “Simplified Shear Design of Slender Reinforced Concrete Beams with Stirrups” by Zhi-Qi He, Zhao Liu, and Zhongguo John Ma

Discussion of “Simplified Shear Design of Slender Reinforced Concrete Beams with Stirrups” by Zhi-Qi He, Zhao Liu, and Zhongguo John Ma

Design of Slender Reinforced Concrete Bridge Columns Considering the Interaction between Columns

Forces on columns caused by second-order effects are routinely over-estimated, which results in a waste of valuable resources and in construction difficulties because of high reinforcement ratios. This paper introduces a simplified method for the design of slender reinforced concrete (RC) bridge columns that reproduces the interaction between columns of the structure and its effects on their second-order behavior. The method considers that the instability of the more slender columns is affected by the horizontal displacement stiffness of the less slender columns, thereby increasing the horizontal forces acting on the less slender elements. Two application examples are presented and the results obtained with the new method are compared with the results obtained by applying the simplified formulations of two major concrete design codes, as well as a nonlinear finite element design of the whole structure. The results show that the codes tend to produce over-conservative designs for slender elements while the new method produces designs that better match the results obtained using the more sophisticated finite element approach, still maintaining a margin of additional safety.

묶음 대각철근을 갖는 세장한 철근콘크리트 연결보의 이력거동

묶음 대각철근을 갖는 세장한 철근콘크리트 연결보의 이력거동