Showing papers on "Shear wall published in 2022"

Seismic performance and material-level damage evolution of retrofitted RC framed structures by high-performance AVED under different shear-span ratio

Abstract: To upgrade the seismic performance of reinforced concrete framed structures with insufficient seismic capability, the high-performance acrylate viscoelastic dampers (AVED) are developed. A series of dynamic mechanical performance tests are carried out on high-performance AVED. A new strategy for retrofitting RC framed structures using AVED is proposed. To systematically study this new retrofitting structural system, the seismic performance of seven RC frame specimens and seven AVED-added RC frame specimens with different shear-span ratios of 2.0–8.0 are compared. On this basis, the influence rule of shear-span ratio on structural damage evolution is qualitatively analyzed. The structural damage evolution at material-level under different shear-span ratios is qualitatively comparted and analyzed in the whole process. The research results show that the self-developed AVED has excellent energy-consumption capability, and dynamic mechanical properties and energy-consumption capability are strongly dependent on frequency and displacement amplitude. The added AVED greatly improves the seismic performance of the retrofitted RC frame structure. At the same time, AVED effectively improves the failure mode of the structure and avoids the brittle failure mode of the beam-column joints under low shear-span ratios.

A novel macroelement for seismic analysis of unreinforced masonry buildings based on MVLEM in OpenSees

Abstract: Unreinforced masonry (URM) buildings are susceptible to extraordinary actions such as earthquakes compared to steel or reinforced concrete buildings. Various methods have been developed for the computational analysis of URM buildings in the last few decades. The equivalent frame method (EFM) is one of the numerical modeling approaches widely used for the nonlinear analyses of URM buildings. Different macroelements in the context of the EFM have been proposed. However, there is still a need for an efficient modeling approach in the computational effort that can predict the real behavior of URM structural components with sufficient agreement and available in opensource structural analyses software packages. For this purpose, a new macroelement based on the multiple vertical line element method (MVLEM) element has been developed in this study. The MVLEM is available in the OpenSees software platform comprising vertical uniaxial macro-fibers and a shear spring as an efficient macroelement for nonlinear analysis of flexure-dominated reinforced concrete walls. The novel macroelement, double modified MVLEM (DM-MVELM) element has been proposed consisting of two modified MVLEM elements tied with a nonlinear shear spring at the middle with a trilinear backbone behavior. DM-MVLEM can capture the axial-flexural interaction with lower computational effort than finite element models and fiber beam-column elements. The DM-MVLEM has been validated against the test results at the structural components level and a full-scale perforated URM wall. Unified method (UM) and composite spring method (CSM) are two existing EFMs that are presented in this study. A study is performed by comparing the seismic behavior of the perforated URM walls modeled using the UM, CSM, and DM-MVLEM modeling strategies. Results show that the DM-MVLEM can predict the damage patterns, and nonlinear behavior of spandrels can be simulated that was usually modeled with linear behavior in EFMs.

Data-driven damage assessment of reinforced concrete shear walls using visual features of damage

Abstract: This paper proposes a damage assessment framework based on the visual features of a damaged reinforced concrete shear wall , such as crack pattern distribution, crushing areal density, aspect ratio, and the presence of the boundary condition. The study contains two parts including: identifying the performance level of the damaged walls (i.e., Immediate Occupancy, Life Safety, and Collapse Prevention) and estimating the residual strength and drift ratio of the walls. The research database contains 236 images of 72 reinforced concrete shear walls tested in the laboratory under the quasi-static cyclic loadings at various drift ratios between 0 and 4%. To identify the performance level of a damaged wall, six supervised learning techniques, including Decision Tree, Random Forest, K_Nearest Neighbor, Gradient Boost, AdaBoost, and Naïve Bayes, are used for classification, and the most efficient method is introduced. Afterward, predictive equations are presented to estimate the residual strength and drift ratio of the walls. The proposed regression equations for drift and reserved capacity are finally used for the estimation of the backbone curve of the hysteretic cyclic loops. In other words, simultaneous employment of both predictive equations for drift ratio and reserved capacity allows for reconstructing the backbone of the cyclic curve just by looking at the progressive damage. The results of the performance level classification show that the Random Forest model is the most efficient method in comparison with other methods with 81.4% accuracy for the test dataset . Predictive equations are also capable of estimating the peak drift ratio and residual strength with an R-factor of 0.9 and 0.83, respectively. • This study proposes an automated prompt method for post-earthquake assessment of RCSWs using visual features of damage. • Six machine learning methods are trained using the crack patterns data to identify the performance level of a damaged RCSW. • A set of nonlinear regression equations are provided to predict the peak-experienced drift ratio and residual strength of a damaged RCSW. • This paper investigates and interprets the correlation between parametrized damage features and the integrity of the RCSWs.

Lateral behavior of trapezoidally corrugated wall plates in steel plate shear walls, Part 2: Shear strength and post-peak behavior

Abstract: This research focuses on the shear strength and post-peak behavior of trapezoidally corrugated wall plates in vertically or horizontally Corrugated Steel Plate Shear Walls (CoSPSWs) through nonlinear pushover analyses. Results showed that different from flat wall plates, corrugated wall plates could develop a shear strength close to the shear yield strength at relatively low lateral drifts, and the lateral load-drift curves usually experienced a descending stage, which was closely related to the elastic shear buckling stress, the dominant shear buckling mode, and the shear yield strength. Corrugated wall plates with higher elastic shear buckling stress, dominant global shear bucking mode, or lower shear yield strength would generally have slightly higher peak nominal shear stress ratio and much higher ductility than wall plates with lower elastic shear buckling stress, dominant interactive or local shear bucking mode, or higher shear yield strength. A shear slenderness ratio λs was then introduced as the square root of the ratio between the shear yield strength and the elastic shear buckling stress, and simplified lateral load-drift curves were proposed for corrugated wall plates with different dominant shear buckling modes and range of λs values. The proposed curves could accurately predict the initial lateral stiffness, the shear strength as well as the post-peak descending behavior of corrugated wall plates.

A Comprehensive Study on the Effect of Regular and Staggered Openings on the Seismic Performance of Shear Walls

Abstract: Shear walls have high strength and stiffness, which could be used at the same time to resist large horizontal loads and weight loads, making them pretty beneficial in several structural engineering applications. The shear walls could be included with openings, such as doors and windows, for relevant functional requirements. In the current study, a building of G + 13 stories with RC shear walls with and without openings has been investigated using ETABS Software. The seismic analysis is carried out for the determination of parameters like shear forces, drift, base shear, and story displacement for numerous models. The regular and staggered openings of the shear wall have been considered variables in the models. The dynamic analysis is carried out with the help of ETABS software. It has been observed that shear walls without openings models perform better than other models, and this is in agreement with the previous studies published in this area. This investigation also shows that the seismic behaviour of the shear wall with regular openings provides a close result to the shear wall with staggered openings. At the roof, the displacement of the model with regular openings was 38.99 mm and approximately 39.163 mm for the model with staggered openings. However, the model without a shear wall experienced a displacement of about 56 mm at the roof. Generally, it can be concluded that the openings have a substantial effect on the seismic behaviour of the shear wall, and that should be taken into consideration during the construction design. However, the type of opening (regular or staggered) has a slight effect on the behaviour of shear walls.

Experimental and numerical study on the seismic performance of an L-shaped double-steel plate composite shear wall

Abstract: In recent years, steel plate-wrapped concrete shear wall has been widely used in high-rise buildings as a new form of the composite member. Five L-shaped double steel plate-concrete composite shear wall (LDSCW) specimens (two specimens with wide flange and three specimens with narrow flange) were tested under cyclic load at loading beam. According to test results, the hysteresis performance, stiffness degradation, bearing capacity degradation, energy dissipation, cyclic ductility, and shear lag behavior were discussed in detail. In addition, finite element models were generated by ABAQUS. Specimens with wide flange exhibited higher bearing capacity and initial stiffness, while specimens with narrow flange had better cyclic ductility and energy dissipation capacity.

Determination of optimal behavior of self-centering multiple-rocking walls subjected to far-field and near-field ground motions

Abstract: In recent years, innovative seismic resistant systems have been introduced based on the Damage Avoidance Design (DAD) philosophy rather than the conventional plastic design-based methods to reduce damages to buildings and to decrease post-earthquake repair costs. Self-centering multiple-rocking walls are amongst these innovative systems. This study aims to determine the optimum number of rocking sections in self-centering concrete multiple rocking walls. To this aim, the seismic behavior of self-centering (SC) concrete rocking walls of 8, 12, 16, and 20 stories with different numbers of rocking sections were examined. Several non-linear time-history analyses were carried out via OpenSEES software in a two-¬dimensional framework. Three sets of ground motions were considered including 22 Far-Field (FF), 14 Near-Field-Pulse (NFP), and 14 Near-Field-no Pulse (NFnP). Five types of quad-rocking walls and one type of dual-rocking walls were specified and compared with base-rocking walls and fixed-base walls. To perform this comparison, a set of utility coefficients was defined to integrate different response aspects including shear and moment demands as well as the residual drifts. The results showed that the effects of higher modes (shear and moment demand) increase with the increase in the height of the rocking structures. Furthermore, NFnP and FF records produced higher mode effects in rocking systems as compared to NFP records. The results suggested that the quad-rocking walls with the reduced tendon area in the first block (R4-S1) are highly effective in reducing the effects of higher modes in NFP and NFnP records. They showed maximum utility coefficients of 67% and 65%, respectively. Also, quad-rocking walls with the reduced tendon area in the third block (R4-S3) were more effective under FF records and their maximum utility coefficient was 65%. The residual roof drift of rocking walls was so negligible that its maximum value in the 8-story structure under NFP records was 0.0008.

Spatial analysis of damage evolution in cyclic-loaded reinforced concrete shear walls

Abstract: This paper introduces a probabilistic framework to quantify the spatial distribution of cracking and crushing in rectangular reinforced concrete shear walls at different drift ratios. In this research, a comprehensive probabilistic spatial analysis is conducted on an extensive collected database of reinforced concrete shear walls tested under the quasi-static cyclic loading. The database includes 235 images of 72 damaged walls with various geometry and material properties at different drift ratios between 0.0 and 4.0%. Various image processing filters are implemented to the images to highlight the wall areas that are more prone to cracking and crushing. Then, advanced statistical analysis is carried out at the post-processing phase in order to quantify the spatial distribution of the damage. The results of the probabilistic analysis are presented for three major classes based on the variation of the wall aspect ratio. The damage heat maps are produced for each class, which show the concentration and severity of the occurred damages. In the following, statistical mixture models have been used to formulate the spatial variation of the damage over the 2D space of the concrete shear walls. A set of nonlinear predictive equations are also proposed to predict the probability of cracking at any specific zones of the walls based on the wall drift ratio. A major contribution of this study is to propose a visual benchmark for the inspectors to predict the peak-experienced drift ratio of a damaged wall (especially after a terminated cyclic-load) based only on the ultimate spatial distribution of damages. Therefore, the presented framework plays a crucial role in determining the post-hazard status of reinforced concrete shear walls based on the prediction of the peak drift ratio. • A probabilistic framework is introduced to study the spatial distribution of cracking and crushing in reinforced concrete shear walls. • Application of image processing filtering introduces the damage heat maps, showing the evolution and concentration of damages along with increasing the drift ratio. • Statistical Gaussian Mixture Models (GMMs) are used to reconstruct the 3D probability density function of cracking and crushing. • A set of predictive nonlinear-regressions is introduced that estimates the cracking-density probability based on the drift ratio.

Lateral behavior of trapezoidally corrugated wall plates in steel plate shear walls, Part 1: Elastic buckling

Abstract: This paper deals with the elastic shear buckling behavior of trapezoidally corrugated wall plates in vertically or horizontally Corrugated Steel Plate Shear Walls (CoSPSWs) considering constraints from neighboring subpanels and boundary frame members through eigenvalue buckling analyses and static analyses. Results showed that constraints from boundary frame members along the corrugated edges of wall plates had obvious influences on the shear buckling behavior, while constraints along the straight edges had negligible influence. When the waveform configuration remained the same, the global shear buckling stress of corrugated wall plates increased slightly with the plate thickness, reduced obviously with the straight edge length but barely changed with the corrugated edge length. When the external dimension and thickness remained the same, the global shear buckling stress of corrugated wall plates increased most significantly with the inclined subpanel width, corrugation angle, or corrugation depth. Formulas were proposed for the local shear buckling coefficient, global shear buckling coefficient and interactive shear buckling correlation coefficient of vertically and horizontally corrugated wall plates in CoSPSWs considering constraints from neighboring subpanels and the boundary members. A mode factor was defined to predict the dominant shear buckling mode, and a comprehensive formula was proposed to calculate the shear buckling stress of corrugated wall plates, with good accuracy within the given ranges of geometric parameters from practical engineering.

Determination of optimal behavior of self-centering multiple-rocking walls subjected to far-field and near-field ground motions

Abstract: In recent years, innovative seismic resistant systems have been introduced based on the Damage Avoidance Design (DAD) philosophy rather than the conventional plastic design-based methods to reduce damages to buildings and to decrease post-earthquake repair costs. Self-centering multiple-rocking walls are amongst these innovative systems. This study aims to determine the optimum number of rocking sections in self-centering concrete multiple rocking walls. To this aim, the seismic behavior of self-centering (SC) concrete rocking walls of 8, 12, 16, and 20 stories with different numbers of rocking sections were examined. Several non-linear time-history analyses were carried out via OpenSEES software in a two-¬dimensional framework. Three sets of ground motions were considered including 22 Far-Field (FF), 14 Near-Field-Pulse (NFP), and 14 Near-Field-no Pulse (NFnP). Five types of quad-rocking walls and one type of dual-rocking walls were specified and compared with base-rocking walls and fixed-base walls. To perform this comparison, a set of utility coefficients was defined to integrate different response aspects including shear and moment demands as well as the residual drifts. The results showed that the effects of higher modes (shear and moment demand) increase with the increase in the height of the rocking structures. Furthermore, NFnP and FF records produced higher mode effects in rocking systems as compared to NFP records. The results suggested that the quad-rocking walls with the reduced tendon area in the first block (R4-S1) are highly effective in reducing the effects of higher modes in NFP and NFnP records. They showed maximum utility coefficients of 67% and 65%, respectively. Also, quad-rocking walls with the reduced tendon area in the third block (R4-S3) were more effective under FF records and their maximum utility coefficient was 65%. The residual roof drift of rocking walls was so negligible that its maximum value in the 8-story structure under NFP records was 0.0008.

Behaviour of buckling-restrained steel plate shear wall with concrete-filled L-shaped built-up section tube composite frame

Abstract: To improve the space utilisation rate and seismic performance of high-rise buildings, a new seismic structural system, this paper proposes a buckling-restrained steel plate shear wall (SPSW) with a concrete-filled L-shaped built-up section tube composite frame. In this composite shear wall system, the columns in the frame are composed of hot-rolled carbon steel H-section members and carbon steel square hollow section tubes, which are connected by steel plates and filled with concrete, and the SPSW is comprised of an embedded steel plate and several pairs of cold-formed steel hat-section buckling-restraining strips. To study the seismic performance of this new type of shear wall system, two specimens were prepared and tested under a horizontal cyclic load. The test results showed that the two specimens had a high bearing capacity, good ductility, and good energy dissipation capacity. This indicated that the new shear wall system was reliable and effective at resisting lateral forces. Finite element models were established and validated against experimental results. Based on the results of a parametric analysis, a value of 0.85 was proposed for coefficient η to modify the method based on the plate–frame interaction theory, which could be used to calculate the bearing capacity of the buckling-restrained SPSW with the concrete-filled L-shaped built-up section tube composite frame.

Study and Numerical Analysis on Seismic Performance of Concrete U-Shaped Shear Wall

Abstract: Rectangular, L-shaped, and T-shaped section concrete shear walls in high-rise buildings are more frequently used in engineering and are widely studied. However, there are few studies related to the load-bearing performance of concrete shear walls with U-shaped sections. In this article, the seismic performance and damage mechanisms are analyzed in a systematic manner. In addition, a finite element model was developed using ABAQUS software, and numerical simulation was carried out. The damage forms and load-carrying capacity of shear walls with U-shaped sections were validated. Finally, reasonable suggestions and construction measures are given for the design of shear walls with U-shaped sections, and a benchmark is provided for relevant engineering applications.

Shear‐controlling rocking‐isolation podium system for enhanced resilience of high‐rise buildings

Abstract: Rapid urban growth has been paired with a rapid increase in the demand for high‐rise buildings, and has accelerated the need for developing more resilient high‐rise buildings in earthquake‐prone regions. Current best practices for the seismic design of high‐rise buildings follow a performance‐based design approach that allows the designer to use innovative structural systems, select performance objectives, and verify seismic performances targeted at multiple levels of seismic intensity. As shortcomings in conventional code‐designed high‐rise buildings continue to be revealed by strong earthquakes, the importance of more resilient high‐rise systems is increasingly evident. Several high‐performance systems have been proposed to limit the excessive seismic demands attributed to higher‐mode effects in high‐rise buildings. However, these systems still face design challenges associated with distributed damage and residual deformations. This paper proposes a novel self‐centering base mechanism for high‐rise buildings that independently limits both shear forces and overturning moments at the base to mitigate higher‐mode effects, while eliminating residual deformations and controlling concentrated stresses within the structure that otherwise would need to be designed for. The schematic overview of the proposed system is first introduced, followed by the detailed design of a physical embodiment developed based on a reference 42‐story RC core wall building. Results of a numerical case‐study comparison confirm that an enhanced seismic performance is achieved through the proposed system with minimum damage and negligible residual deformations even following major seismic loading. The proposed system, with further investigations, also has the potential to be applied to a wider range of structural systems.

Modeling of seismic actions in squat reinforced concrete walls exposed to acid deposition

Abstract: Acid deposition has a noticeable influence on reinforced concrete (RC) buildings which could cause catastrophic injuries and safety risks accompanied by loss of life and property. This study aims to establish a modeling method for predicting the nonlinear response of corroded squat reinforced concrete (RC) walls caused by the acidic attack. Compression tests on corroded confined concrete are performed to provide the stress-strain relationship of concrete after erosion. Quasi-static experiments on corroded RC walls with different corrosion levels and design parameters were conducted, and the test results were used for calibration and verification. Then, a numerical simulation method of corroded squat RC walls is proposed based on the fiber-based element SFI-MVELM in the OpenSees platform, considering the influence of corrosion on three main aspects, i.e., material mechanical properties, shear mechanism, and bond-slip effect. The comparison results show that the proposed model captures the cyclic responses of the tested wall specimens with reasonable accuracy in terms of hysteresis curves, indicating that the modeling method is suitable for investigating the seismic behavior of corroded RC walls and can meet the needs of a lifecycle seismic performance evaluation of RC structure in an acidic environment.

Optimization of the structural coupling between RC frames, CLT shear walls and asymmetric friction connections

Abstract: Abstract This paper focuses on the optimum design of the e-CLT technology. The e-CLT technology consists in adding cross laminated timber (CLT) walls to an existing reinforced concrete (RC) infilled frame via asymmetric friction connection (AFC). The authors carried out quasi-static and nonlinear dynamic analyses. The RC frame is modeled in OpenSees by fiber-section-based elements with force-based formulation. The contribution of the infill is simulated using a degrading data-driven Bouc–Wen model with a slip-lock element while the AFC is modelled with a modified Coulomb model. Different types of infill, aspect ratio, scaling, and member size are considered. The benefits of using e-CLT technology are discussed and the ranges of optimum performance of the AFC are estimated. A comparison of the performance of traditional infills with the e-CLT system is presented. The authors provide optimum intervals of the ratio between slip force and in-plane stiffness of the CLT panel, following energy and displacement-based criteria. The seismic displacement demand under various seismic scenario is investigated. Correlations between the RC characteristics and the optimum design ratios bestow possible criteria for the design of the AFC.

Intelligent design method for beam and slab of shear wall structure based on deep learning

Abstract: Beam and slab design is a critical component of shear wall structure design. Currently, conventional manual design is time-consuming, and defining objective functions and design variables of an optimization design is challenging. In contrast, deep learning methods can learn high-dimensional image features and generate new designs, providing new solutions for efficient and intelligent structural design. Therefore, based on deep neural networks, this study proposes an intelligent layout design method for beams of reinforced concrete shear-wall structures using the input of fused building space and element attributes. This method learned the implicit laws of existing designs and realized the inferential generation of new layout schemes. Subsequently, based on mathematical statistics, methods to determine the type and size of coupling and frame beams are proposed. A typical case study shows that the structural performance of the beam and slab designed by this method was comparable to that of competent engineers. The maximum inter-story drift ratio of the result designed by the proposed method differs from that designed by engineers by no more than 5 × 10−5. The differences in the maximum vertical typical-floor-slab displacement, the concrete consumption, and the steel consumption between the design result of the proposed method and the engineer's design result are 0.8%, 2.88%, and 6.20%, respectively. Moreover, the design efficiency was significantly improved by more than 30 times.

Resilience-Based Retrofitting of Adjacent Reinforced Concrete Frame–Shear Wall Buildings Integrated into a Common Isolation System

Abstract: Adjacent buildings of three to five stories with small spaces between them are widely used as offices, schools, and hospital wards. The seismic resilience of such buildings is critical, and...

Resilience-Based Retrofitting of Adjacent Reinforced Concrete Frame–Shear Wall Buildings Integrated into a Common Isolation System

Abstract: Adjacent buildings of three to five stories with small spaces between them are widely used as offices, schools, and hospital wards. The seismic resilience of such buildings is critical, and retrofitting adjacent buildings by integrating them into a common isolation system is considered effective. The resilience-based retrofitting of adjacent RC frame–shear wall buildings was investigated through a case study. First, the critical engineering demand parameters (EDPs) dominating the resilience performance of such buildings were identified. An isolation scheme was designed to improve their seismic resilience, emphasizing control effect of seismic isolation on critical EDPs. The effect of the yield ratio of the isolation system on the seismic resilience of retrofitted buildings was investigated by comparing three cases. A yield ratio of 2.5% is preliminarily recommended as a valuable reference for the resilience-based retrofitting of adjacent RC frame–shear wall buildings.