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This paper presents an analysis and prediction of the shear strength of wide-shallow reinforced concrete beams, utilizing Finite Element Analysis (FEA) and machine learning techniques. The methodology involves validating a detailed Finite Element Model (FEM) against experimental results, conducting a parametric study, and developing three Machine Learning prediction equations. The FEM captures concrete and steel behaviors, including cracking and crushing for concrete and linear isotropic properties for steel reinforcement. Loading and boundary conditions are defined for accuracy and validated against 13 experimental specimens, exhibiting a maximum 8% and 12% difference in loads and deflections, respectively. A parametric study generates a dataset of 77 wide beam configurations, exploring variations in beam widths, concrete strengths, compression rebars, and shear reinforcement. This dataset is used to develop machine learning models, including "Genetic Programming (GP)", "Evolutionary Polynomial Regression (EPR)", and "Artificial Neural Network (ANN)". Comparative analysis reveals GP and EPR models with over 95% correlation, while the ANN model outperforms with 99% accuracy. Sensitivity analysis underscores the significant influence of concrete strength and beam aspect ratio on shear strength. In conclusion, the study demonstrates the potential of FEA and machine learning models to predict shear strength in wide-shallow reinforced concrete beams, providing valuable insights for architectural design and engineering practices and emphasizing the role of concrete strength and beam geometry in shear behavior. [ABSTRACT FROM AUTHOR]

This study investigates the impact of shear reinforcement amount and arrangement on the shear capacity of shallow/wide RC beams. Seven specimens of shallow/wide beams with different ultimate shear reinforcement stress (µ.Fys), longitudinal spacing to depth ratio (S/d), and transversal spacing to depth ratio (S'/d) were tested under a monotonic three-point bending test. All the specimens were designed to fail at shearing. The results showed that the shear reinforcement was fully functioning until it yielded; also, the amount of shear reinforcement had the major impact on the shear capacity; in addition, the transverse spacing had more influence on the shear capacity than the longitudinal spacing. The measured shear capacities were compared to six design codes, in which the results ranged from 95% to 110%, with the Japanese code (JSCE) being the closest to the experimental results. Two AI-based predicting equations, "Genetic Programming" (GP) and "Evolutionary Polynomial Regression" (EPR), were also compared to the experimental, with accuracies of 78% and 86% of the measured capacities, respectively. Initial stiffness, final stiffness, dissipated energy, and ductility were all discussed for the seven specimens, with ultimate shear reinforcement stress being the most impactful on the total shear capacity of the wide beams. [ABSTRACT FROM AUTHOR]

This paper investigates the impact of the aspect ratio, the characteristics strength of the concrete, and the compression steel ratio on the shear capacity of wide-shallow beams. An experimental program consists of seven specimens, including a control specimen, all tested under a three-point load test. Three specimens were considered for each parameter (the control specimen was included in all three variables). The experimental results were compared to the theoretical values of six different codes of practice; they were also analyzed to determine the ductility, stiffness, and dissipated energy of each specimen. The results indicated that the shear reinforcement was fully functioning until it yielded, with a minimum contribution of 55% of the total shear capacity of the specimens. The aspect ratio and the characteristic strength had a notable impact on the shear capacity of the specimens, while the compression steel ratio had a minor effect on the shear capacity, but it improved the stiffness and the ductility of the beams. Theoretical concrete shear strengths from design codes ranged between 77 and 163% of the experimental values; EN-1992 was the closest code to the experimental results. A comparison between the experimental results and predicted values using GP and EPR methods from previous research showed accuracies of 72% and 81%, respectively. [ABSTRACT FROM AUTHOR]

Wide beams are commonly used in reinforced concrete (RC) structures for architectural considerations such as facilitating the placement of services and providing adequate clear height. However, behaviour of these beams is not as efficient as normal width beams due to the small structural depth. Motivated by the lack of guidelines for wide RC beams with spiral reinforcement, this paper investigates their shear behaviour using innovative lateral reinforcement configurations. A comprehensive experimental program was conducted by testing nine beams under four-point loading. The effect of different parameters on the behaviour of such beams was investigated. These parameters included number, dimensions, and configurations of spirals. The experimental program also included testing of 18 standard cylinders spirally reinforced under compression to study the performance of confined concrete in the compression zone of wide beams. The results showed that the spiral lateral reinforcement is an efficient alternative for traditional closed stirrups for shear resistance in wide beams. Compared to regular closed stirrups, using spiral reinforcement or inclined links with regular closed stirrups can greatly improve the shear capacity and deformation. Also, reduction in the amount of lateral reinforcement can be achieved if the proposed lateral reinforcement is adopted instead of traditional stirrups. Based on the test results and the ACI 318–19 code, an equation is proposed and validated to estimate the shear strength of wide beams with regular/spiral lateral reinforcement. [ABSTRACT FROM AUTHOR]

Moderate magnitude seismic events have occurred during the last decade in non-seismic areas and have highlighted that many existing buildings do not sufficiently resist these types of events. The objective of this work is to illustrate that most buildings dating from 2002-2010 constructed from wide beams, which were designed to previous earthquake resistance codes, do not offer a satisfactory seismic behaviour, and to identify which structural attributes can best help alleviate this problem. In this work the effect of a real earthquake of medium magnitude (Lorca, 2011) on buildings of three, five and eight stories with unidirectional frames of wide-beam concrete was assessed. The methodology included non-linear static (pushover) analyses and dynamic response simulations with the aim to understand the effect on the seismic performance of changing some of the geometrical and material parameters. Maximum displacements and capacity curves for the top floor of a set of representative buildings were evaluated and compared. In particular, capacity curves obtained from non-linear static (pushover) analysis are compared for different building configurations, as well as the maximum displacements obtained through non-linear dynamic analysis. This paper highlights the seismic vulnerability of buildings constructed between 2002 and 2010 and the results indicate that a higher density of infill walls (walls whose bricks are not part of the main structure) is the feature that most significantly improves the seismic behaviour of the structures analysed. Moreover, counterintuitively, incorporating stronger concrete and reinforcing steel and using alternative column arrangements only have a small positive effect on the seismic behaviour of these types of buildings. [ABSTRACT FROM AUTHOR]

Some Mediterranean seismic codes consider wide-beam reinforced concrete moment resisting frames (WBF) as horizontal load carrying systems that cannot guarantee high ductility performances. Conversely, Eurocode 8 allows High Ductility Class (DCH) design for such structural systems. Code prescriptions related to WBF are systematically investigated. In particular, lesson learnt for previous earthquakes, historical reasons, and experimental and numerical studies underpinning specific prescriptions on wide beams in worldwide seismic codes are discussed. Local and global ductility of WBF are then analytically investigated through (1) a parametric study on chord rotations of wide beams with respect to that of deep beams, and (2) a spectral-based comparison of WBF with conventional reinforced concrete moment resisting frames (i.e. with deep beams). Results show that the set of prescriptions given by modern seismic codes provides sufficient ductility to WBF designed in DCH. In fact, global capacity of WBF relies more on the lateral stiffness of the frames and on the overstrength of columns rather than on the local ductility of wide beams, which is systematically lower with respect to that of deep beams. [ABSTRACT FROM AUTHOR]

The shear behavior of six wide beams was was studied to investigate the effectiveness of various types of shear reinforcement in improving the shear capacity of wide beams. One specimen each was provided: without vertical stirrups, with vertical stirrups, independent bent-up bars, independent middepth horizontal bars, and the combination of vertical stirrups and bent-up bars. To study the effectiveness of longitudinal flexural reinforcement on the shear capacity of wide beams, an additional specimen without stirrups, but including approximately two-thirds of longitudinal flexural reinforcement that were arranged in column band, was investigated. The performances were measured in terms of deflection, crack patterns, concrete and steel strains, ultimate load, and modes of failure. The results showed that independent bent-up bars increased the shear capacity and ductility of wide beams. It was revealed that, although independent horizontal bars increased the shear capacity to some extent, the beam was less ductile through failure. The results also indicated that the beam with banded main reinforcement achieved larger failure load. [ABSTRACT FROM AUTHOR]

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method for assessing the vulnerability of existing frames in terms of an energy-based seismic index is proposed. The ground motion is characterized by the so-called Seismic Hazard Energy Factor AE, and the susceptibility of the frame to damage is a function of two counterpart energy factors, AE and AE. AE represents the level of the 'maximum earthquake' that the frame can sustain within the elastic range. AE characterizes the level of the 'ultimate earthquake' associated with the collapse of the structure. The procedure takes into account the relation between the dynamic properties of the existing frame and the spectral shape of the ground motion expected at the site. The seismic index used by the method has a transparent and direct physical meaning; thus, it is useful not only for screening existing buildings but also to design a seismic retrofit solution, if needed. The method is applied to reinforced concrete frames with wide beam-column connections built in the southern part of Spain during the 1970's, 1980's and 1990's. [ABSTRACT FROM AUTHOR]

Observations after the 2011 Van-Erciş earthquake show that some of the recently constructed reinforced-concrete buildings were either heavily damaged or had collapsed. As a building subtype, wide-beam, infill-joist block reinforced-concrete frames got attention because of their mode of failure. There were several such buildings that failed in strong-column, weak-beam mode. Considering the demand created by the earthquake, structures were not expected to reach their full capacity. The purpose of this study is to review the history and current practice of infill-joist frames in Turkey and to conduct a performance evaluation of infill-joist frames designed per the current earthquake code (2007). Regulations for this building subtype are critically reviewed, and the designer's response to code regulations is discussed. Results indicate that the force-based design approach used in the current code is not always adequate to satisfy the displacement demands. In addition, it is observed that layout, proportioning, and detailing requirements of beam-end regions and beam-column connections do not always warrant ductile behavior as targeted. [ABSTRACT FROM AUTHOR]