Shear Wall Buildings Research Articles

Impact of the position and quantity of shear walls in buildings on the seismic performance

Impact of the position and quantity of shear walls in buildings on the seismic performance

Simplified shear wall building model for design optimization

Structural design can be inefficient due to its manual and iterative nature, requiring costly and time-consuming revisions by experienced engineers; thus, there is a growing demand for automated and intelligent design approaches. In light of these factors, we propose a simplified model of shear wall buildings based on connected 3D beam columns to quickly derive the fundamental period, base shear, and moment. Our approach formulation considers an initial topologic configuration of the shear wall rectangular members, featuring intricate element connectivity and variable layout for the basement, first, and typical floors, offering a flexible approach to handle inputs from various sources, like grid-based layouts or vectorized image floor plans. Concerning the model, the column-based design yields an adequate estimation of the structure's fundamental translational period, with an R2 of around 0.7 and a roof displacement with an R2 of 0.85. Our findings, coupled with an average computing time of 1.6 s, enable the model integration into machine learning pipelines or the swift optimization of solutions by assembling fitness functions that consider parameters like building weight, roof displacement, or base shear and moment, ultimately reducing search space and saving costs in the design process.

Comparative Assessment of Performance-Based Design Methodologies Applied to a R.C. Shear-Wall Building

Performance-based design has been increasingly used in practice due to computational improvements, the sophistication and dissemination of nonlinear analysis methods, and the development of commercial programs that facilitate its use. We can evaluate the nonlinear effects of seismic events of great magnitude on the structural behavior of a building, verify preliminary designs based on force-based methods, validate standard design regulations, determine deformations, and calculate accelerations that can be translated into parameters of structural damage and economic losses, among other functions. Guiding documents have presented methodologies to establish requirements, evaluation criteria, analysis methods, etc., each with different objectives, revealing the lack of a consensus method. In this paper, the state of the art of performance-based design is studied, and some of the most relevant methods, such as ASCE 41-17, ASCE 7-16, and the alternative procedure of ACHISINA, are applied to a structure with shear walls designed according to current Chilean regulations. Additionally, modal-response spectrum analysis is used. The modeling of the earthquake-resistant structure of the building, the preparation of seismic records, and the consideration of aspects that limit the rigorous application of the method are addressed in a nonelastic analysis framework. Results obtained in the respective analyses that are used to evaluate the structural performance are compared with the corresponding performance criteria for each standard, considering the characteristics of each methodology. Moreover, the main complications that can occur during the application of the methods are discussed.

A Force-based Method for the Numerical Simulation of a Reinforced Concrete Shear Wall Building

Reinforced Concrete (RC) shear walls are structural elements that resist lateral loads. This research aims to present the numerical modeling of RC shear walls in order to evaluate the seismic performance of structures. Various types of numerical models of RC frame elements are implemented in nonlinear analysis packages. These numerical models are based on different theories and assumptions, something that poses a significant difficulty to practicing engineering and limits confidence in the analysis of the numerical results. In this study, inelastic force-based elements and distributed plasticity methods are used for the modeling of the inelastic behavior of these elements (infrmFB). The efficiency of the inelastic force-based element and distributed plasticity method is evaluated through the comparison with the experimental results of a shear wall structure subjected to seismic loadings. The accuracy of the numerical model is assessed in terms of top displacement, inter-story drift, base shear force, and the absolute maximum values of the overturning moment.

Application of power algorithm optimization for optimal placement of BRB in 3D shear wall frame building structure

This paper examines the optimal placement, optimal numbers, and the optimal shape of Buckling Restrained Braces (BRB) for a 3D shear-wall frame building structure based on linear static analysis utilizing ETABS software. The total amount of BRBs referred to as the number of BRBs are considered as design variables and the objective function to be minimized is the maximum story displacement and inter-story drift. The diagonal shape (D), X-shape (X), V-shape (V), and Inverted V-shape (Inv-V) of BRBs are installed between shear walls simultaneously with initial stiffnesses of 1K0, 2K0, 4K0, and 8K0, respectively. Then, the performance efficiency analysis is carried out to identify the effectiveness of initial stiffness, BRB shapes, and optimal stories. Based on the results of the optimization procedure and efficiency analysis, it is found that the performance of the structure can be improved by optimizing BRB placement within the optimal stories rather than using the maximum amount of BRBs in all stories. The most optimal location to install BRBs is the middle stories and the BRB placement at the upper and lower stories is shown to have minor or no effects on reducing story responses of the structure. Furthermore, the model with Inv-V, V, and X shapes of BRB have almost the same maximum efficiency performance, while the model with diagonal shapes has the lowest performance efficiency. Additionally, the maximum performance of the structure can be achieved by using larger initial stiffness. The proposed method is further validated by comparing the results of ETABS with MATLAB programming. It concludes that the method proposed in this study saves 40% of the total amount of BRBs used in the structure by optimal placement of BRBs within the height of the structure. This method of optimization allows the structural designer to decide the optimal placement, optimal shape, and optimal stiffness of BRBs either by the predetermined performance level of the structure or based on experiences in RC shear wall-frame building structures.

Effects of Using High-Strength Reinforcement in the Seismic Performance of a Tall RC Shear Wall Building

Chile’s reinforced concrete (RC) design is based on ACI 318-08, where high-strength reinforcement is not allowed in seismic force-resistant members. In 2019, new requirements adopted by ACI 318 permitted the incorporation of high-strength reinforcement in walls. This study compared the seismic performance of two Chilean 20-story residential buildings on soft soil, one designed with traditional Grade 60 and the other with high-strength Grade 80 reinforcement. The performance was assessed in terms of the probability of exceeding the ASCE 41 limit states during a 50-year lifecycle. Analyses showed that both buildings had similar seismic performance. However, the reduction in reinforcement in the Grade 80 building was close to 18%. It is concluded that using high-strength reinforcement in a typical wall building implies a significant reduction in the reinforcement used without affecting the seismic performance.

Seismic design and engineering practice of 10‐story shear wall structure with replaceable viscoelastic coupling beams

SummaryStructures with replaceable energy‐dissipating elements are attractive systems for improving building resilience. Damage in these structures is mainly limited to dissipating elements, which can be replaced after earthquakes. Among the energy‐dissipating elements, viscoelastic dampers (VEDs) can dissipate energy even under small deformations while providing stable fatigue performances, which benefits high‐rise buildings in resisting both wind and earthquake loadings. This paper presents the seismic design of an engineering practice of a 10‐story shear wall building with replaceable viscoelastic coupling beams. A new type of viscoelastic material that has negligible frequency dependency is adopted to provide stable constraint for the wall piers. The design details, including VEDs, nonreplaceable segment, and the detachable connection, are exemplified. The numerical model of the replaceable structure is established and analyzed under dynamic loadings. Results confirm that the implementation of replaceable viscoelastic coupling beams improves structural seismic performance. The plastic rotation at the end of the coupling beam is significantly reduced up to 41.4% compared with the traditional coupled shear wall structure.

Drift‐ and energy‐based seismic performance assessment of retrofitted wood frame shear wall buildings: Shake table tests

AbstractIn 2004, the Province of British Columbia (BC) announced a multi‐year $1.5 billion seismic retrofit program for the province's 750 at‐risk public schools. The purpose of this program was to quantify the seismic risk of the province's public‐school buildings and to expedite the seismic upgrading of the most at‐risk schools. In order to provide a safe and cost‐effective implementation of this program, the Engineers and Geoscientists BC, in collaboration with the University of British Columbia, has developed a performance‐based probabilistic method and guidelines for the seismic risk assessment and retrofit of low‐rise buildings. As part of this initiative, a number of laboratory experiments have been conducted to provide data that would support the recommendations provided in the guidelines. The laboratory experiments included several full‐scale shake table tests of wood frame systems. The specimens were subjected to sequences of earthquake motions to simulate their performance under main shock‐aftershocks. This paper presents details of seven of the experiment and wood‐frame buildings considered. A detailed discussion of the results of the analyses of the shake table tests data, and performance assessment using drift‐ and energy‐based damage indices is presented. This study highlights the importance of considering the effects of subduction earthquake and mainshock‐aftershock sequences for design and retrofit of wood frame structures.

Damage Detection and Localization in a Full-Scale Slice of a Seven-Story Shear Wall Building Tested on the UCSD-NEES Shake Table

Damage Detection and Localization in a Full-Scale Slice of a Seven-Story Shear Wall Building Tested on the UCSD-NEES Shake Table

Analytical Study on Seismic Behavior of Rectangular Shear Wall Connected to Floor Slabs

For construction of reinforced concrete buildings over four stories, structural walls are the predominant form for lateral load resistance under earthquakes. Current Indian seismic code for design of frame shear wall buildings (FSWB) do not explicitly consider the forces transferred from the floor slabs to the shear wall for seismic design. To assess stress concentration at the wall-slab junction region of the building and to observe the extent of possible damages in wall, slab and their junction region, nonlinear static analyses is carried out using ABAQUS program. Further, a wall-slab sub-assemblage is also analyzed to stimulate the observed behavior of the walls in the multistoried buildings and the behavior is compared with the isolated cantilever shear wall. The main intention of the study carried out is to study the behavior of the junction region between the shear wall and the floor slab and to develop a simplified but efficient analytical model to analyse a shear wall - floor slab junction. It is observed that the presence of floor slab at different levels along the height of slender shear wall tends to partition the wall into squat wall panels between two consecutive floors. Thus, an overall seismic design methodology for damage avoidance behavior of floor slabs in multistoried RC frame-wall building needs to be evolved.

A rapid machine learning-based damage detection algorithm for identifying the extent of damage in concrete shear-wall buildings

This paper presents a rapid machine learning-based damage detection framework for identifying the damage extent of concrete shear wall buildings. For this purpose, a parametric study was carried out to determine the most efficient machine learning algorithm in classifying the damage states of the building. According to this parametric study, the K-Nearest Neighbor (KNN) learner was selected as the reference prediction model because of the higher accuracy achieved by this algorithm. Bayesian Optimization (BO) algorithm was used to tune the hyperparameters affecting the accuracy of the model. The most efficient attributes were selected from the set of damage indicators through the BO algorithm to train the model. Three different benchmark buildings, including 7-,9-, and 13-story concrete shear wall buildings, were used to evaluate the robustness of the proposed framework. A suite of 111 pair motions, originally developed for the SAC project, were employed to create a generalized dataset. These motions were uniformly scaled from 0.05 g to 1.5 g to expand the intensity range of the events. All the acceleration signals were polluted to 10% noise using white Gaussian signals to simulate the field condition. Results reveal the efficiency of the proposed framework in identifying the extent of damage in concrete shear wall elements of the building. In addition, a parametric study was conducted to illustrate the reliability of two commonly used features, called Cumulative Absolute Velocity (CAV) and the energy ratio between the acceleration response and the input excitation, in determining the damage states of the shear walls under seismic motions.

Nonlinear behaviour of FRP-retrofitted RC coupled shear walls

This paper presents a numerical study of the effectiveness of fibre-reinforced polymer (FRP) composites in upgrading the seismic performance of conventional reinforced concrete (RC) coupled shear walls. The study investigates the performance of two RC coupled shear wall buildings with different heights when their coupling beams are retrofitted using FRP U-wraps for increased ductility of the beams. The 10- and 15-storey existing buildings are located in Montreal, Canada, and were designed according to the 1970 National Building Code of Canada (NBCC). The FRP retrofit aims to increase the shear capacity of nominally ductile coupling beams, and hence increase their rotational ductility to the limited ductility, moderate ductility, and ductile levels. Nonlinear incremental dynamic analyses were conducted for existing and FRP-retrofitted buildings when subjected to twelve ground motion records with different frequency contents. The seismic behaviour of the analyzed cases was compared based on the maximum earthquake intensity that can be resisted by the building, maximum interstorey drift ratio, maximum storey shear, maximum coupling moment, maximum energy dissipated, and maximum wall forces. Moreover, the twelve earthquake records were scaled to match the NBCC 2015 design response spectrum of Montreal to determine the optimum retrofit level for the coupling beams of the two buildings in consideration.

New adaptive robust [formula omitted] control of smart structures using synchrosqueezed wavelet transform and recursive least-squares algorithm

Two kinds of uncertainties, one due to the dynamic earthquake loads with a wide frequency band and the other due to structural parameters exist in large and complex real-life structures. Most existing control algorithms consider only one of them, resulting in difficulty to guarantee necessary control performance for large complex structures, such as better vibration suppression on structural peak response and robustness performance. Considering the two uncertainties simultaneously, in this paper, a new adaptive robust H∞ control methodology is presented for vibration control of structures through adroit integration of synchrosqueezed wavelet transform (SWT) and recursive least-squares (RLS) algorithm. The robust H∞ control is more effective than the traditional LQR/LQG control in terms of the stability and robustness of the control system. The external excitation signal from ground sensors is filtered by a low-pass filter based on SWT and then inputted into the filtered-x RLS adaptive controller. The effectiveness, accuracy, and computational efficiency of the new adaptive control method is demonstrated using a 76-story wind-excited benchmark super high-rise building structure and a 24-story shear-wall building with an active tuned mass damper (ATMD) system on the top floor. Compared with the existing linear quadratic Gaussian control algorithm, the wavelet-hybrid feedback-least mean square algorithm and the robust H∞ control algorithm, the simulation results show that the control effect and robust performance indexes of the structure are increased by 5%–35% and 5%–25%, respectively, using the new control methodology.

Impact of Revised Seismic Hazard Values in NBCC 2015 on RC Shear Wall Buildings

Impact of Revised Seismic Hazard Values in NBCC 2015 on RC Shear Wall Buildings

Machine Learning for Enhanced Regional Seismic Risk Assessments

The ability to conduct accurate regional seismic risk assessments is key to informing a risk-reduction policy and fostering community resilience. This paper presents a machine learning-based framework to predict a building’s postearthquake damage state using structural properties and ground motion intensity measures as model inputs. The machine learning techniques assessed, namely, logistic regression, k-nearest neighbors, decision tree, random forest, AdaBoost, and gradient boosting, are trained using a dataset of nonlinear response history analysis results from 36 detailed structural models of modern reinforced concrete shear wall buildings ranging from four to 24 stories and subjected to approximately 500 ground motion records with a range of shaking intensities. The results indicate that the gradient boosting classifier is the most efficient algorithm by achieving a prediction success (F1-score) of 87%. The proposed framework also leverages synthetic data samples to support the prediction of severe damage state instances, that is, collapse. The percentage of observed collapse cases correctly classified by the gradient boosting algorithm is increased from 76% to 93% when synthetic data are also used for training. The framework is implemented in a portfolio of reinforced concrete shear wall buildings across the Metro Seattle region to quantify earthquake-induced damage and collapse risk. The framework shows great potential for enhancing regional seismic risk assessments by leveraging datasets of detailed nonlinear response history analysis results.

Predicting nominal shear capacity of reinforced concrete wall in building by metaheuristics-optimized machine learning

Reinforced concrete shear walls are used in many structural systems to resist earthquake loading. In recent earthquakes, shear wall buildings have tended to perform well. Modern building codes include provisions concerning shear capacity, which are recognized for their effectiveness. Studies have demonstrated that the American Concrete Institute (ACI) 318-19 provision uses a low safety factor and does not cover high-strength concrete shear walls whereas the Eurocode 8 provision is overly conservative. A rational method for predicting shear wall capacity could be used as an alternative to the simplified provision in the codes. Nevertheless, the use of rational methods may present some difficulties for structural engineers because they require an iterative calculation to determine the peak strengths of shear walls. Accordingly, an appropriate data-driven machine learning scheme that accurately determines shear capacity is needed. Three experimental cases that involve various input variables are adopted herein to train single models and ensemble models. Numerical analytics show that the best result is achieved by using extreme gradient boosting (XGBoost), which involves conventional parameters and synthetic parameters that are inspired by the ACI shear wall strength equation. Subsequently, two metaheuristic optimization algorithms are used to fine-tune the hyperparameters of the generally recognized XGBoost. Two proposed metaheuristically hybrid models, jellyfish search (JS)-XGBoost and symbiotic organisms search (SOS)-XGBoost, outperform the ACI provision equation and grid search optimization (GSO)-XGBoost in the literature in predicting the nominal capacity of reinforced concrete shear walls in buildings. Metaheuristics-optimized machine learning models can be used to improve building safety, simplify a cumbersome shear capacity calculation process, and reduce material costs. The systematic approach that is utilized herein also serves as a general framework for quantifying the performance of various mechanical models and empirical formulas that are used in design standards.

Intelligent generative structural design method for shear wall building based on “fused-text-image-to-image” generative adversarial networks

Like the way engineers designing buildings, competent generative design methods try to understand the prescriptive requirement in text and architectural sketches, apply engineering principles and develop the structural design. However, this requirement may be challenging to existing methods because they are not good at simultaneously taking text and image input and then generating designs. This study proposed an innovative design approach, TxtImg2Img, to overcome the difficulties. Based on generative adversarial networks architecture, the generator is proposed to encode, extract and fuse texts and images, and generate new design images; the discriminator is developed to judge real and fake images and texts. Consequently, TxtImg2Img is advantageous in extracting features from the multimodal text and image data, fusing the features using the Hadamard product, and generating designs to satisfy the text-image requirements after learning from a limited number of design samples. Specifically, TxtImg2Img can generate structural design images without distortion, and the corresponding structural design meets the mechanical requirements, after being trained by dozens of words and hundreds of image data. The case studies confirm performance improvement of up to 21% and that the proposed approach presents a promising breakthrough for intelligent construction.

Could building replacements significantly contribute to seismic vulnerability mitigation at urban scale? Case studies of two typical swiss cities

This paper contains an investigation on the potential decrease of seismic vulnerability related to building replacements for the cities of Sion and Martigny in Switzerland. Those two cities were identified for the present research based on the accuracy of the corresponding available information. Seismic assessment at urban scale was recently achieved for both cities and new buildings are systematically indexed according to the construction regulation of the canton of Wallis (Valais). Sion and Martigny belong to the largest cities of the canton of Wallis and this region is characterized by the highest seismicity within Switzerland. The investigation focuses on a 4-year period between 2016 and 2019. Cases for which an existing building is demolished and replaced by a new one were identified and checked. Those cases do not represent general practice. The majority of new buildings are built on free land. Consequently, the building replacement rate is too low to lead to a significant decrease of the seismic vulnerability at urban scale. In addition to the systematic appropriate seismic design of new buildings, retrofitting of existing buildings therefore remains the adequate strategy for seismic vulnerability mitigation. In case of replacement, low-rise buildings are generally replaced by mid-rise buildings. Moreover, unreinforced masonry buildings are usually replaced by reinforced concrete shear-wall buildings. This slightly impacts the building stock distributions but the seismic vulnerability is not significantly changed, since the demolished buildings are not the most vulnerable ones. Nevertheless, few obvious isolated vulnerability decreases occurred with respect to the demolition of soft-story buildings for instance. By contrast, seismic vulnerability may also be increased in the case where a new building is built against an existing one with a different story level and without an adequate seismic separation joint.

Seismic Damage Assessment for Isolated Buildings with a Substructure Method

A seismic damage detection method for isolated buildings is proposed based on substructure identification with incomplete contaminated measurements. A concept of a pseudo substructure with virtual conditions is constructed for the proof of the proposed substructure identification method. This identification method is implemented in a two-stage procedure. The interface forces of the target substructure are identified in the first stage and the parameter of the target substructure is updated in the second stage, which can enable the parameter identification of substructures with unknown input. Two computational methods are also proposed to improve the two-stage identification algorithm. A sub-time zone identification method is utilized to reduce the computation effort and the simultaneous identification of the unknown force and initial structural responses is presented in the first-stage identification for a general case in practical engineering. Numerical studies of a shear frame with nonlinear base isolation subject to earthquake ground motion are investigated to validate the proposed seismic damage detection method. A fourteen-storey concrete shear wall building with a two-storey steel frame on top connected by isolation is studied experimentally with shaking table tests to further validate the proposed method. The shear wall structure is taken as the target substructure for damage assessment. The interface force and parameter of the concrete shear wall building are estimated with the proposed method. Results from both the numerical simulations and laboratory tests indicate that the proposed method can estimate seismic isolated structures and detect damage effectively based on only a few accelerometers. It is also demonstrated that the parameter identification results based on the structure response measurement during the earthquake are more accurate than the identification with post-earthquake structural response measurement.

Analytical Structural Health Monitoring of Shear Wall Building

Abstract: Structural health monitoring techniques have been utilized to inspect the current conditions of structures, as well as their post-earthquake performances. The dynamic characteristics of a building, such as modal periods, shapes and damping ratios can be obtained by analysing the ambient vibration data. It is well-known that dynamic characteristics generated from the finite element model (FEM) and vibration data, even for the intact building, show remarkable differences. Assumptions made in the FEM are one of the main reasons for those differences. To examine feasible solutions to such problems mentioned above Here an attempt has been made to study the behaviour of different structures of reinforced concrete with different heights with and without shear walls. Coupled shear walls have also been studied to understand the comparative merit or demerit of framed structures with shear wall structures. Studies have been carried out on sample model structures and analysis has been carried out by ETABS software. It has been ensured to consider sample models that represent the current practices in structural design to include different structural configurations. Models having varied structural configurations like framed, shear wall, coupled shear wall, central core shear wall, core in core etc. have been taken into consideration. The inherent asymmetry present in the structures have also been dealt. Natural frequencies and mode shapes of the structure were determined by frequency domain decomposition method. In addition, identification of damping was performed due to the fact that damping ratio plays a significant role in the magnitude of inter-story drift during an earthquake. The FEM of the structure was constructed based on design drawings and updated to represent the real mode shapes and frequencies of the structure. By using the updated FEM with standard damping ratio in Indian Earthquake Code and the identified damping ratio, seismic performance assessment of the building for a possible earthquake.