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Abstract 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.

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]

Current formulations proposed by Eurocode 8 part 3 for the inelastic deformations of existing reinforced concrete members are assessed separately for wide beams (WB) and conventional deep beams (DB). The current approach, based on a large experimental database of members, predicts larger ultimate chord rotation but lower chord rotation ductility for WB rather than for DB despite the similar curvature ductility, due to lower plastic hinge lengths in WB. However, if the data are disaggregated into DB and WB, predicted chord rotations are consistently conservative for DB and not conservative for WB if compared with experimental values, especially at ultimate deformation. Thus, plastic hinge length may be even greater for DB in comparison to WB. Therefore, some feasible corrections of the formulations for chord rotations are proposed, in order to reduce the bias and thus increase the robustness of the model for cross-section shape variability.

This paper presented an experimental study of the behaviour of wide reinforced concrete beams with different shear spacing and beam width. Eight specimens in two groups, the group one contains four specimens with the dimensions of (200x500x1600mm) and shear reinforcement spacing (d/2, 0.65d, 3/4d and 1.0d), the group two contains four specimens with the dimensions of (200x600x1600mm) and shear reinforcement spacing (d/2, 0.55d, 3/4d and 1.0d), Variables studied in this study shear reinforcement spacing and width of wide beam, the increasing of shear reinforcement spacing gives close results in RC wide beam, increased shear reinforcement spacing decreased the ultimate loud by 6.6% and when increasing width of beam the ultimate loud decreased by 9.5%, The ultimate deflection decreased by 16.5% and when increasing width of beam decreased by 7.2 %,The number of flexural cracks was equal in all beams, when increasing width of beam the number of flexural crack increased by 2 cracks, The average spacing between shear cracks decreased by 7%, when increasing width of beam average spacing between shear cracks decreased by 19%. Conclusions Increasing the spacing of shear reinforcement from (d/2 in WB1-G1) control beam to (0.65d ,3/4d and 1.0d) in WB2-G1, WB3-G1and WB4-G1 gives close results in RC wide beam when use width to depth ratio 2.5 (width of beam 500mm) (group one) in all the following tests: • The ultimate shear load gives very close value with control beam (spacing d/2), all beams decreased by 4.25%, 6% and 9.5% respectively • the first flexural crack increased by 10.5%, 5.6% and 15% respectively, the first diagonal crack too increased in all beams by 8.5%, 10.7% and 12.7% for respectively. • The ultimate deflection decreased in all beams by average 16.5%. • The width of first flexural crack increased in WB2-G1 by 25% and decreased in WB3-G1 by 33%, and the WB4-G1 give same width with WB1-G1. • The number of flexural cracks was equal in all beams, the number of shear cracks increased in WB2-G1 by one crack and decreased by one crack in WB3-G1 and WB4-G1. • The average spacing between shear cracks increased in WB3-G1 by 13.6% and decreased by 5.7% and 8.5% for WB2-G1 and WB4-G1 respectively compared with WB1-G1 control beam. When increase the width to depth ratio from 2.5 to 3 (the width from 500mm to 600mm) (group two) notice the following: • The increase width in group two give increase ultimate loud by average 14.25% for all beams compared with group one, when increasing the spacing between stirrups in this group WB2-G2 give same ultimate load with WB1-G2 and the WB3-G2, WB4-G2 decreased by 13.5% and 16.6% respectively compared with WB1-G2 control beam. • The increase width in group two It led to the emergence of the first flexural cracks early by average 14.25% for all beams compared with group one, increasing the shear spacing in this group give increased in WB2-G2 and WB4-G2 by 5.9% and 13% respectively and decreased in WB3-G2 by 12.5% compared with WB1-G2,The first diagonal crack in beams of width 600 mm (group two) decreased in all beams by average 41.7% compared with beams of width 500 mm (group one), but whin increasing the shear spacing in this group give decreased in all beams by 1.5%, 23% and 22% for WB2-G2, WB3-G2 and WB4-G2 respectively compared with WB1-G2 control beam. • The increase width in group two give increase ultimate deflection in all beam by average 22.6% except WB4-G2 (spacing 1.0d) decreased by 16.7% compared with beams in group one (width 500mm), increasing the shear spacing in this group give decreasing in ultimate deflection by 27% compared with WB1-G2 control beam. • The increase width in group two give increase in width of first flexural crack by average 32% compared with beams in group one (width 500mm), increasing the shear spacing in this group gives increased for all beams by average 27.3 % compared with WB1-G2 control beam. • The increase width in group two give increase in number of flexural cracks by average 2 cracks, the diagonal cracks increased too by average 2 cracks, increasing the shear spacing in this group gives decreased by 1 crack in WB3-G2 and increased by 1 crack in WB4-G2 and WB2-G2 give same number of crack compared with WB1-G2 control beam and the number of diagonal cracks decreased in WB2-G2 and WB3-G2 by 2 cracks and the WB4-G2 gives same number of diagonal cracks compared with WB1-G2 control beam. • The increase width in group two give increase in average spacing between shear cracks by 14% in WB1-G2 and WB4-G2 and decreased by 13.5% in WB2-G2 and WB3-G2 compared with beams in group one (width 500mm), increasing the shear spacing in this group gives increased by 5% in WB2-G2 and decreased by 25%and13% for WB3-G2 and W4-G2 respectively compared with WB1-G2 control beam.

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]

The shear behavior of reinforced concrete wide beams was investigated. The experimental program consisted of nine beams of 29 MPa concrete strength tested with a shear span-depth ratio equal to 3.0. One of the tested beams had no web reinforcement as a control specimen. The flexure mode of failure was secured for all of the specimens to allow for shear mode of failure. The key parameters covered in this investigation are the effect of the existence, spacing, amount and yield stress of the vertical stirrups on the shear capacity and ductility of the tested wide beams. The study shows that the contribution of web reinforcement to the shear capacity is significant and directly proportional to the amount and spacing of the shear reinforcement. The increase in the shear capacity ranged from 32% to 132% for the range of the tested beams compared with the control beam. High grade steel was more effective in the contribution of the shear strength of wide beams. Also, test results demonstrate that the shear reinforcement significantly enhances the ductility of the wide beams. In addition, shear resistances at failure recorded in this study are compared to the analytical strengths calculated according to the current Egyptian Code and the available international codes. The current study highlights the need to include the contribution of shear reinforcement in the Egyptian Code requirements for shear capacity of wide beams.

Reinforced Concrete Wide-Beam Frames (WBF) are a common architectural solution in Mediterranean countries. On this structural typology there is not yet a uniform approach among European codes: while Eurocode 8, as other relevant seismic codes in USA and New Zealand, considers WBF capable of high ductility performances, still in recent versions of Spanish and Italian seismic codes there is cap to the maximum behaviour factor ( q ) for this structural system. In order to verify the appropriateness of such provisions, seismic performances of WBF and conventional deep beam frames (DBF) are comparatively assessed through nonlinear static analyses. The same architectural layout of a typical European 5-storey RC housing unit is designed as WBF and DBF according to Eurocode 8, adopting different stiffness assumptions, and according to the Spanish seismic code NCSE-02. Based on detailed assessment results, a simplified parametric assessment of 72 frames designed according to Eurocode 8, Italian seismic code NTC and NCSE-02 is then considered assuming similar q for WBF and DBF. Results suggest that any reduction of behaviour factor prescribed for wide-beam frames is at least obsolete. In fact, even if wide beams show lower local ductility than deep beams, generally WBF provide at least similar global seismic capacities than DBF, especially in frames whose design is ruled by serviceability limit state (i.e., damage limitation). [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]

Lorca earthquake (11-05-2011) is most destructive event recorded in Spain, causing nine fatalities and other severe consequences. Its important intensity was rather unexpected, and serious concern arose regarding risk of building stock in Spain. This paper analyzes performance, under Lorca earthquake, of RC buildings with one-way slabs with wide beams. This construction type is chosen for its high vulnerability and for being vastly widespread in Spain. This study is conducted on 3 and 6-story prototype representative buildings. These buildings are designed for three major seismic zones in Spain: low seismicity, moderate seismicity (as Lorca) and medium seismicity (as Granada). Seismic performance under Lorca earthquake is numerically investigated through nonlinear time-history analyses. Results show that buildings designed without any seismic provision (i.e. those in low seismicity zones) do not survive Lorca record, even with cooperation of masonry infill walls. Buildings with seismic design (i.e. those in Lorca and Granada zones) can survive Lorca earthquake only with collaboration of infill walls. To raise reliability of these conclusions, a sensitivity analysis to most influencing parameters is conducted. [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.

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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Abstract: The shear behavior of reinforced concrete wide beams was investigated. The experimental program consisted of nine beams of 29MPa concrete strength tested with a shear span-depth ratio equal to 3.0. One of the tested beams had no web reinforcement as a control specimen. The flexure mode of failure was secured for all of the specimens to allow for shear mode of failure. The key parameters covered in this investigation are the effect of the existence, spacing, amount and yield stress of the vertical stirrups on the shear capacity and ductility of the tested wide beams. The study shows that the contribution of web reinforcement to the shear capacity is significant and directly proportional to the amount and spacing of the shear reinforcement. The increase in the shear capacity ranged from 32% to 132% for the range of the tested beams compared with the control beam. High grade steel was more effective in the contribution of the shear strength of wide beams. Also, test results demonstrate that the shear reinforcement significantly enhances the ductility of the wide beams. In addition, shear resistances at failure recorded in this study are compared to the analytical strengths calculated according to the current Egyptian Code and the available international codes. The current study highlights the need to include the contribution of shear reinforcement in the Egyptian Code requirements for shear capacity of wide beams. [Copyright &y& Elsevier]

Abstract: A significant number of short-to-mid height RC buildings with wide beams have been constructed in areas of moderate seismicity of Spain, mainly for housing and administrative use. The buildings have a framed structure with one-way slabs; the wide beams constitute the distinctive characteristic, their depth being equal to that of the rest of the slab, thus providing a flat lower surface, convenient for construction and the layout of facilities. Seismic behavior in the direction of the wide beams appears to be deficient because of: (i) low lateral strength, mainly because of the small effective depth of the beams, (ii) inherent low ductility of the wide beams, generated by high amount of reinforcement, (iii) the big strut compressive forces developed inside the column-beam connections due to the low height of the beams, and (iv) the fact that the wide beams are wider than the columns, meaning that the contribution of the outer zones to the resistance of the beam-column joints is unreliable because there is no torsion reinforcement. In the orthogonal direction, the behavior is worse since the only members of the slabs that contribute to the lateral resistance are the joists and the façade beams. Moreover, these buildings were designed with codes that did not include ductility requirements and required only a low lateral resistance; indeed, in many cases, seismic action was not considered at all. Consequently, the seismic capacity of these structures is not reliable. The objective of this research is to assess numerically this capability, whereas further research will aim to propose retrofit strategies. The research approach consists of: (i) selecting a number of 3-story and 6-story buildings that represent the vast majority of the existing ones and (ii) evaluating their vulnerability through three types of analyses, namely: code-type, push-over and nonlinear dynamic analysis. Given the low lateral resistance of the main frames, the cooperation of the masonry infill walls is accounted for; for each representative building, three wall densities are considered. The results of the analyses show that the buildings in question exhibit inadequate seismic behavior in most of the examined situations. In general, the relative performance is less deficient for Target Drift CP (Collapse Prevention) than for IO (Immediate Occupancy). Since these buildings are selected to be representative of the vast majority of buildings with wide beams that were constructed in Spain without accounting for any seismic consideration, our conclusions can be extrapolated to a broader scenario. [Copyright &y& Elsevier]

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]

Abstract: A methodology for assessing the seismic capacity of existing frames in terms of energy is proposed. It estimates the global amount of input energy—in form of a factor AEIU —and hysteretic energy that the overall structure can dissipate until collapse under earthquake-type loadings. The method requires static pushover analyses to determine the ductility factor and energy shape of an equivalent single-degree-of-freedom system for the first—two or more—modes. The procedure accounts for the relation between the frequency content of the earthquake expected at the site and the dynamic properties of the existing structure. It can be useful for evaluating the possible deficit on energy dissipation capacity of existing structures, and for designing seismic retrofit solutions. Finally, the methodology is applied to reinforced concrete frames with wide beam-column connections representative of existing post-1970 buildings located in the earthquake-prone southern part of Spain. [Copyright &y& Elsevier]

The use of wide beam–column systems has become increasingly popular in low to moderate seismic regions, despite very little information being available on their performance under seismic action. Therefore, this investigation was conducted to determine the behavior and likely failure mode of wide beam connections when subjected to earthquake loading. In this investigation, two interior reinforced concrete wide beam subassemblages and one post-tensioned concrete wide beam subassemblage were tested under quasi-static cyclic loading up to a drift ratio of 3.5%. It was found that the wide beam connection is likely to experience severe torsion cracking in the beam portions located at the sides of the column when subjected to severe earthquake loading. A special detailing strategy was developed to inhibit the torsion cracking and was found to be effective in the subsequent tests. The experimental behavior of the subassemblages is reported in this paper. [Copyright &y& Elsevier]

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]