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Buildings with reinforced concrete (RC) integrate steel reinforcement with concrete to increase the structure’s durability and load-bearing capability. A significant issue is the corrosion of the steel reinforcement, especially in high-humidity environments or when exposed to deicing salts. This paper proposes a novel technique for predicting the fundamental period (FP) of RC buildings considering infill walls and soil–structure interaction (SSI) effects. The proposed technique is the multi-component attention graph convolutional neural network (MCAGCNN). The primary objective of the proposed method is to achieve high prediction accuracy and minimal error in approximating the FP of RC frame-building models, thereby improving the reliability of structural analysis and design. Initially, data are collected from Housing Database Project Level Files. This study primarily investigated three types of buildings: Bare frames, buildings with fully unfilled walls, and buildings with an open first floor. The research considered the effects of various factors like infill stiffness, number of bays, SSI, bay width, and the FP of the buildings. The concrete grade, the number of stories, the building’s width and length, and the number of bays are the input parameters used to predict the FP. The FP of RC buildings with and without SSI effects is predicted using the proposed MCAGCNN technique. The proposed MCAGCNN approach improves accuracy by 19.36%, 26.42%, and 23.27%, increases precision by 22.36%, 15.42%, and 18.27%, and reduces RMSE by 18.36%, 16.42%, and 28.27%, compared to the existing techniques, including Genetic Algorithms (GA), Gradient Boosting Decision Trees (GBDT), and Artificial Neural Networks (ANN). The proposed study also demonstrates a lower $L\infty$ norm error of 0.045, indicating a high degree of accuracy and minimal deviation between predicted and actual values.

Two catastrophic earthquakes occurred in the Eastern Anatolian Fault Zone on February 6, 2023, in the city Kahramanmaraş in Türkiye and directly affected the Eastern and South-Eastern Anatolia regions, where 15 million people live. These earthquakes are among the most destructive earthquakes in the history of Türkiye and destroyed both old and new structures. While many studies have been conducted to report the caused damage in the existing building stock, common damage is worth in-depth discussion since it was observed in the seismic code-compliant new buildings. This damage is the buckling of compression reinforcement (BCR) in reinforced concrete beams. In this study, the observed damage mechanism has been evaluated with the design requirement of the recent seismic codes of Türkiye. The principles of anti-buckling design requirements in literature were searched and a certain deficiency in the codes was revealed. The outcomes of the study have been applied to an existing newly constructed reinforced concrete building that experienced BCR damage in its beam. It has been demonstrated that beams designed according to Türkiye’s recent seismic codes may fail to reach the ductility level specified in the literature due to buckling of their compression bars under extreme loading.

In this research, the differences in occurrences of settlement cracks on the RC slab with the concrete using type IV fly ash and the normal concrete are studied in order to comprehend the basic characteristics of the concrete with type IV fly ash. Results obtained from this study can be summarized as follows: (1) The number of settlement crack and average crack width can be reduced by having the type IV fly as substitute for sea sand in concrete. (2) Settlement cracks occur in the neighborhood of the outside frame of slab form and the steel bar for hanger of slab specimen easily.

Extensive use of reinforced concrete to build shock-protective structures calls for adequate analytical expertise to facilitate rational and safe structural designs. Although several researchers have studied these problems, there are still some uncertainties, particularly with regard to strain-rate effects. This paper presents a simplified, but accurate, numerical procedure for modeling the nonlinear behavior of reinforced concrete, using solid finite elements, which include strain-rate effects. The details of the material modeling for anisotropic concrete and isotropic steel are presented. A clamped circular plate subjected to uniformly distributed load and a clamped rectangular slab subjected to jet force are analyzed using 8-noded solid finite elements. Strain-rate effects are considered in the analyses.

The structural responses of infilled frames subjected to combined in-plane and out-of-plane loadings are usually analyzed by separately applying in-plane and out-of-plane loads. The interaction effect of in-plane and out-of-plane loads on the structural behavior of the frames is ignored; thus errors in predicting the actual force-transfer mechanisms and modes of failure of the structures can be incurred. To solve the problem, this paper presents a discrete finite element modeling technique, which employs a damage-based cohesive crack representation of fracture behavior of masonry infills, followed by a study on the force-transfer mechanisms and failure modes of the anchored and unanchored infilled reinforced concrete (RC) frames subjected to interactive in-plane and out-of-plane loads. The analysis indicates that under out-of-plane loading the diagonal compressive thrust of masonry-infill walls, which is induced by in-plane lateral loading and acts on the walls, may reduce the in-plane load capacity of the RC frame by up to 50% and cause buckling of infill walls. On the other hand, the anchorage can effectively prevent the separation of infill walls from the bounding frame and provide stabilizing forces to the walls against buckling.

This paper presents a simplified modeling strategy for simulating the nonlinear behavior of reinforced concrete (RC) structures under seismic loadings. A new type of Euler–Bernoulli multifiber beam element with axial force and bending moment interaction is introduced. To analyze the behavior of RC structures in the axial direction, the interpolation of the axial strain is enriched using the incompatible modes method. The model uses the constitutive laws based on plasticity for steel and damage mechanics for concrete. The proposed multifiber element is implemented in the finite element Code_Aster to simulate the nonlinear behavior of two different RC structures. One structure is a building tested on a shaking table; the other is a column subjected to cyclic loadings. The comparison between the simulation and experimental results shows that the performance of this approach is quite good. The proposed model can be used to investigate the behavior of a wider variety of configurations which are impossible to study experimentally.

Buckling is an important nonlinear behavior of steel reinforcing bars subjected to repeated compression and tension strain reversals, which significantly affects the overall cyclic behavior of reinforced concrete (RC) elements and impairs their load-carrying and energy-dissipation capacities during strong earthquakes. The accuracy of numerical assessment of the seismic performance of RC elements can be much improved if the buckling effect is effectively included in the stress–strain model of reinforcing bars. In this paper, modified Gomes–Appleton cyclic steel stress–strain relationship intended for improved accuracy is presented, which is suitable for inclusion in programs based on Opensees platform for the nonlinear analysis of RC elements. The modification is developed to improve the simulation accuracy of the inelastic buckling stress–strain path by a simplified model based on the equilibrium of a plastic mechanism of buckled bar consisting of four plastic hinges. Then an adjustment coefficient is introduced to further modify the developed buckled bar stress–strain model. A comparison of the numerical simulated results with experimental results of 36 steel bars subjected to reversed tension-compression loading is performed to verify the accuracy and effectiveness of the proposed model.

A new type of partially steel tubed concrete (PSTC) column is proposed that is suitable to be used in new high rise reinforced concrete (RC) buildings. Three exterior joint specimens consisting of RC beams and PSTC columns and two exterior RC joint specimens were designed and tested under high axial load and cyclic loading to investigate the joint behavior in terms of failure pattern, hysteresis response, deformation, energy dissipation capacity and degradation of strength and stiffness. Test results indicate that the PSTC column can benefit the performance of the joint in terms of strength, ductility and energy dissipation capacity and can partly compensate for the unfavorable effect induced by slab. The strong column–weak beam mechanism can also be ensured in RC beam to PSTC column joint.

In this paper, the effects of vertical irregularity of masonry-infill wall arrangements on the seismic performance and lateral stability of reinforced concrete (RC) frames have been investigated using nonlinear response history analysis. Discrete finite element models, which are endowed with a damage-based cohesive crack modeling, were developed for six prototype structures with different arrangements of infill panels. The analysis of failure modes and lateral force transfer mechanisms of infilled frames shows that the arrangement of infill panels can critically affect the dynamic properties and structural stability under seismic excitations. Diagonal continuity, infill ratios, and eccentricity of infill walls play essential roles in the lateral-load and displacement capacities of the structures. The hysteresis behavior, failure modes, and force transfer mechanisms of RC frames with concentric and eccentric arrangements of infill panels are compared and their implications on the seismic resistant design are discussed.

The performance-based plastic design (PBPD) method employs the global yield mechanism and target drift to design reinforced concrete moment resisting frames (RC-MRFs), which satisfies both the drift and strength limits without iterations. However, different structural systems have different hysteretic behaviors and the influence on the energy balance equation has not been dealt with in a quantitative manner. Moreover, the gravity loads are not considered in the plastic design procedure, which makes the beam design not within the safe margin for low and moderate seismic regions. In this paper, an improved PBPD method for RC-MRF is developed. Furthermore, a case study of seven-story RC-MRF is designed using both the improved PBPD and conventional equivalent static force design (ESFD) approaches. Comprehensive comparative analyses are performed in terms of nonlinear static pushover analysis, nonlinear dynamic analysis and seismic loss estimation. The results illustrate that the PBPD procedure can reduce the seismic losses. Hence, it is proved that PBPD is a viable and more robust design procedure as compared to the conventional ESFD procedure.

For the seismic design of a mid-rise reinforced concrete (RC) building considering the damage control, the main purpose of this work is to propose a simplified method that can be used to estimate the damage index or damage state induced by the near-fault and far-fault earthquakes. In addition to the maximum deformation response, the hysteretic energy dissipation induced the earthquakes is also considered in the damage index quantification based on the modified equivalent linearization method (MELM). Based on the damage index model in terms of the maximum deformation response and hysteretic energy dissipation under an earthquake, this work provides a convenient method by which an engineer can determine the damage-controlling minimal ductility requirement to ensure that the damage index remains under a specified value. For a mid-rise RC building structure, an engineer can also apply the simplified formula proposed in this work to obtain the damage-controlling yielding strength for a specified ductility capacity.

An effective rapid performance evaluation technique for structures is essential for disaster reduction, while it is difficult to realize particularly for complex hysteretic structures. The Bouc–Wen–Baber–Noori model is a versatile smooth hysteretic model that describes the features of stiffness degradation, strength degradation and pinching. However, the identification of these parameters is difficult owing to the lack of an effective identification algorithm for structures with complex hysteretic characteristic. To obtain the hysteretic parameters of the characteristic of self-centering shear walls efficiently, an optimization algorithm called the self-adaptive parallel genetic algorithm (SPGA) was developed based on the cyclical experiment results of seven self-centering shear walls, which are characterized by a very small residual deformation. This study focused on the problems of identification accuracy and efficiency, improving the genetic operators, optimizing the genetic strategies, and concerning about the searching stability, local convergence, and time consumption in high-dimensional and large-scale optimization spaces. The feasibility and superiority of the SPGA were verified by comparing the simulated hysteretic characteristic, lateral forces and stiffness degradation curve with the identification results of the standard genetic algorithm (SGA) and experimental data. A comparison of the convergence, fluctuation, and time consumption between the SPGA and SGA also demonstrates the advantage of the optimized algorithm.

This research explores the ability of 60mm thick reinforced concrete (RC) plates to resist impacts from ogive-nosed hard steel projectiles. The projectiles used in the present study have a diameter of 19mm, a length of 200mm, and a mass of 0.4kg impacted on the RC plates with incident velocities ranging from 92m/s to 161m/s. Numerical simulations were conducted using ABAQUS/Explicit finite element software to validate the experimental results. The Holmquist–Johnson–Cook (HJC) material model was employed to simulate the constitutive behavior of concrete, while the Johnson–Cook (JC) material model was used to simulate the material response of reinforcing steel bars. The residual velocities obtained from the simulations closely matched the actual experimental results, showing a polynomial correlation with the incidence velocities of the projectiles. Moreover, the experimentally and numerically determined ballistic limit for the 60mm thick RC plate was found to be 108m/s and 109.5m/s, respectively. In contrast, the ballistic limit calculated using empirical mathematical expressions was 107.4m/s. This alignment between predicted, calculated, and actual ballistic limits underscores the reliability and accuracy of both numerical and empirical approaches.

A computationally efficient and robust simulation method is presented in this work, for the cyclic modeling of reinforced concrete (RC) structures. The proposed hybrid modeling (HYMOD) approach alleviates numerical limitations regarding the excessive computational cost during the cyclic analysis and provides a tool for the detailed simulation of the 3D cyclic nonlinear behavior of full-scale RC structures. The simplified HYMOD approach is integrated in this work with a computationally efficient cyclic concrete material model so as to investigate its numerical performance under extreme cyclic loading conditions. The proposed approach adopts a hybrid modeling concept that combines hexahedral and beam-column finite elements (FEs), in which the coupling between them is achieved through the implementation of kinematic constraints. A parametric investigation is performed through the use of the Del Toro Rivera frame joint and two RC frames with a shear wall. The proposed modeling method managed to decrease the computational cost in all numerical tests performed in this work, while it induced additional numerical stability during the cyclic analysis, in which the required number of internal iterations per displacement increment was found to be always smaller compared with the unreduced (hexahedral) model. The HYMOD provides for the first time with the required 3D detailed FE solution tools in order to simulate the nonlinear cyclic response of full-scale RC structures without hindering the numerical accuracy of the derived model nor the need of developing computationally expensive models that practically cannot be solved through the use of standard computer systems.

The authors propose a mathematical model of shell structures taking into account the linear theory of hereditary material creep. This model is based on the total potential strain energy functional. Shells are reinforced with stiffeners, and the contact between the stiffener and the shell skin along a strip is taken into account. The Ritz method is applied to the functional, and a system of algebraic or integro-algebraic equations is found. The resulting system is first solved as a linear system (without account for the terms reflecting material creep), and the state of the structure under the specified load is determined. Then the iterative method is used to solve the creep problem for a given value of time. The paper presents the results of studying stiffened shallow shells of double curvature made of reinforced concrete under uniformly distributed load. The buckling of shells occurs over time as a result of the development of creep strains. Values of the buckling load as a result of material creep are found. It is shown that stresses are redistributed over the shell field over time and the maximum stress is observed near the contour of the structure.

A constitutive model for predicting the cyclic response of reinforced concrete structures is proposed. The model adopts the concept of a smeared crack approach with orthogonal fixed cracks and assumes a plane stress condition. Predictions of the model are compared firstly with existing experimental data on shear walls which were tested under monotonic and cyclic loading. The same model is then used in the finite element analysis of a complete shear wall structure which was tested under a large number of cyclic load reversals due to earthquake loading at NUPEC's Tadotsu Engineering Laboratory. Two different finite element approaches were used, namely a two-dimensional and a three-dimensional representation of the test specimen. The ability of the concrete model to reproduce the most important characteristics of the dynamic behaviour of this type of structural element was evaluated by comparison with available experimental data. The numerical results showed good correlation between the predicted and the actual response, global as well as local response being reasonable close to the experimental one.

An innovative and practical technique for the seismic rehabilitation of beam-column joints using fiber reinforced polymers (FRP) is presented. The procedure is to upgrade the shear capacity of the joint and thus allow the ductile flexural hinge to form in the beam. An experimental study is conducted in order to evaluate the performance of a full-scale reinforced concrete external beam-column joint from a moment resisting frame designed to earlier code then repaired using the proposed technique. The beam-column joint is tested under cyclic loading applied at the free end of the beam and axial column load. The suggested repair procedure was applied to the tested specimen. The composite laminate system proved to be effective in upgrading the shear capacity of the nonductile beam-column joint. Comparison between the behaviour of the specimen before and after the repair is presented. A design methodology for fibre jacketing to upgrade the shear capacity of existing beam-column joints in reinforced concrete moment resisting frames is proposed.

The deformation of beam-column joints may contribute significantly to drift of reinforced concrete (RC) frames. In addition, failure may occur in the joints due to cumulative concrete crushing from applied beam and column moments, bond slip of embedded bars or shear failure as in the case of existing frames with nonductile detailing. When subjected to earthquake loading, failure in RC structural wall is similar to failure of frame joints as it may occur due to cumulative crushing from high flexural stresses, bond slip failure of lap splice, shear failure or a combination of various mechanisms of failure. It is important to include these behavioural characteristics in a simple model that can be used in the analysis of RC frames and RC walls to predict their response under earthquake loading and determine their failure modes.

Global macro models for the beam-column joint and for RC structural walls are developed. The proposed models represent shear and bond slip deformations as well as flexural deformations in the plastic hinge regions. The models are capable of idealising the potential failure mechanism due to crushing of concrete, bond slip or shear with allowance for the simultaneous progress in each mode. The model predictions are compared with available experimental data and good correlation is observed between analytical results and the test measurements.

A model is proposed for the incremental force-deformation behaviour of reinforced concrete sections and members, under generalised load or deformation histories in 3D, including cyclic loading, up to ultimate deformation. At the section level the model is of the Bounding Surface type and accounts for the coupling between the two directions of bending and between them and the axial direction. For the construction of the member tangent flexibility matrix on the basis of the section tangent flexibility matrix, a piecewise-linear variation along the member is assumed for the nine terms of the tangent section flexibility matrix. Model parameters are derived on the basis of available test results for: (a) the force-deformation response under cyclic biaxial bending with normal force; (b) the hysteretic energy dissipation; (c) the secant-to-yield member stiffness, and (d) the ultimate deformation of the member under cyclic biaxial load paths.

The results of some simulated seismic load tests on reinforced concrete one-way interior and exterior beam-column joints with substandard reinforcing details typical of buildings constructed in New Zealand before the 1970s are described. The tests were conducted using both deformed and plain round longitudinal reinforcement. The interior beam-column joint cores lacked transverse reinforcement and the longitudinal bars passing through the joint core were poorly anchored. The exterior beam-column joint units contained very little transverse reinforcement in the members and in the joint core. In one exterior beam-column joint unit the beam bar hooks were not bent into the joint core. That is, the hooks at the ends of the top bars were bent up and the hooks at the ends of the bottom bars were bent down. This anchorage detail was common in many older buildings constructed before the 1970s. In the other exterior beam-column joint unit the hooks at the ends of the bars were bent into the joint core as in current practice. The improvement in performance of the joint with beam bars anchored according to current practice is demonstrated. In addition, tests were conducted on interior joints with lap splices in the beam longitudinal reinforcement bars near the column face. The tests were conducted using both deformed and plain round longitudinal reinforcement. Tests were also conducted on columns with plain round bar longitudinal reinforcement and inadequate transverse reinforcement.

The reinforcing details were close to identical to those in an existing seven storey reinforced concrete building that was designed and built in New Zealand in the late 1950s.

The test results give an indication of the performance of beam-column joints and members with the above now out-of-date reinforcing details.

The test results reported are a summary of results reported in a number of publications written since 1994.