Seismic Performance Of Shear Walls Research Articles

Seismic behavior of BFRP bar reinforced shear walls strengthened with ultra-high-performance concrete boundary elements

Reducing the amount of steel reinforcement in construction is imperative, driven by the objectives of reducing carbon emissions and mitigating steel corrosion. Among the various alternatives to steel reinforcement, basalt fiber reinforced polymer bar (BFRP) is considered a promising solution. The aim of this study is to examine the seismic performance of shear walls entirely reinforced with BFRP bars, utilizing BFRP for both longitudinal and transverse reinforcement. To address the inherent limitations of BFRP bars, a novel composite shear wall, incorporating BFRP bars, ultra-high-performance concrete (UHPC) and normal strength concrete, is proposed. Specifically, UHPC boundary elements are employed to strengthen the potential compression zone of BFRP reinforced shear walls. Four shear wall specimens, fully reinforced with BFRP bars, were fabricated and tested for their seismic performance, with two specimens incorporating UHPC boundary elements. Comprehensive test results, including failure modes, load-bearing capacity, ductility, energy dissipation, stiffness degradation and rebar strain, are presented and discussed. A detailed discussion of the effects of axial load ratio (ALR) and UHPC boundary elements is included. The test results indicate that the specimens featuring UHPC boundary elements showed significant improvements in deformability, lateral strength and energy dissipation capacity. This reveals that the integration of UHPC boundary elements considerably enhances the seismic performance of BFRP bar reinforced shear walls. Moreover, although all test specimens experienced failure due to concrete crushing in the compression zone, those with UHPC boundary elements manifested higher tensile strain on the BFRP bars on the tension side, facilitating more effective utilization of the high tensile strength of the BFRP bars. Ultimately, a method to ascertain the flexural capacity of BFRP bar reinforced shear walls, both with and without UHPC boundary elements, is proposed and validated by the test results.

Global sensitivity analysis for seismic performance of shear wall with high-strength steel bars and recycled aggregate concrete

In terms of bearing lateral loads, a reinforced concrete shear wall (SW) is one of the most crucial structural elements in structures. Despite their significance, recent experimental research and post-earthquake surveys have exposed the inadequate safety margins of the SWs. Significant SW components cannot be accurately identified due to the absence of empirical and mechanistic models. This study introduces a novel paradigm for assessing the SW's crucial elements by using two consecutive modeling strategies. Initially, a finite element model is calibrated to mimic one of the laboratory-experimented SW structures. Then, deep residual neural networks (DRNNs) for non-parametric techniques are used to enhance the Abaqus software prediction skills and comprehensively understand the input parameters' influence on the selected SW structure's displacement value. The suggested DRNNs' design uses residual shortcuts (i.e., connections) that skip several levels in the deep network structure in order to address the issue of training with high accuracy. A thorough global sensitivity analysis (GSA) is done using the Latin Hypercube Simulation. Three distinct GSA techniques are used to emphasize the influence of each input variable on the amount of displacement in real-world applications while limiting the risk of result misinterpretation owing to interactions between input variables. In each GSA approach, an effort would be made to rank, filter, or map the input variables. The performance metrics of the DRNNs prediction models lend confidence to the GSA's results. The diameter of steel stirrups is reported to be the most significant component in the SW structure, while SW's displacement is more sensitive to higher and lower values of the lateral load domain.

Seismic performance of innovative prefabricated reinforced recycled concrete shear walls

In this study, the seismic performance of innovative prefabricated recycled concrete shear walls has been investigated. Unlike the conventional grouting sleeve connections, the "button-head bars" grouting connections to connect the walls have been proposed. Four shear wall specimens with different construction types (two semi-prefabricated, one fully-prefabricated, and one cast-in-place) were tested under low-cyclic loading. The fully-prefabricated wall was connected to the foundation only using the proposed button-head bars; while for the semi-prefabricated walls, the two cast-in-place concealed columns were arranged at both edges of the wall. The failure modes, hysteretic behavior, skeleton curves, strength, ductility, stiffness and degradation process, energy dissipation, and strain characteristics were investigated. The influence of axial force ratio and construction type on the seismic performance of the shear walls was analyzed. The results showed that the seismic performance of semi-prefabricated shear walls and cast-in-place shear walls was similar. The shear slip for the cast-in-place, semi-prefabricated, and fully-prefabricated shear walls was 0.3 mm, 0.32 mm, and 0.78 mm, respectively. The cast-in-place concealed columns could effectively limit horizontal shear slip. An increase in the axial force ratio significantly enhanced the strength and energy dissipation capacity of semi-prefabricated specimens. The ultimate strength according to different design codes was calculated, with the Chinese GB-50010 design code providing the most accurate prediction of the strength of prefabricated shear walls.

Effect of boundary element detailing on the seismic performance of reinforced concrete masonry shear walls

Laboratory tests demonstrated that reinforced masonry shear walls (RMSWs) can provide sufficient strength and ductility to be considered an efficient seismic force resisting system (SFRS) for mid-rise buildings. The ductility and overall seismic performance of shear walls were increased by providing confinement to the end zones of the walls to form boundary elements (BEs)., which enhanced the ultimate masonry compressive strain and curvature ductility of the walls. Regular stretcher blocks are commonly used in the construction of masonry boundary elements; however, they impose some constraints due to their geometrical characteristics. This study investigated the construction and testing of three half scale specimens of reinforced masonry shear walls with boundary elements (RMSWs+BEs) that were characterized by flexural dominance under reversed cyclic moment and lateral loading. In the lower story panel of a 12-story RMSW building, these walls constitute the plastic hinge zone, which is represented by a plastic hinge wall. In this study, C-shaped masonry units were used instead of stretcher units to construct BEs with different sizes and vertical reinforcement ratios. The findings of this work revealed that employing C-shaped masonry units to construct the BEs was effective in overcoming the construction limits imposed by stretcher units. Additionally, the results of this study demonstrated that when RMSWs+BEs are subjected to quasi-static reversed cyclic loading, they are capable of providing a high level of ductility with minimal loss of strength.

Experimental study on the seismic performance of concrete shear walls partially replaced by MRPC

Shear wall structures are widely used in high-rise buildings, due to their satisfactory integrity and force transmission, thus superior seismic performance. However, due to insufficient material strength, non-standard construction, and the fact that some buildings have reached their design service life, many shear wall structures can no longer resist natural disasters such as earthquakes, nor can they meet the functional requirements. Therefore, it is of practical significance to reinforce shear wall structures and study their seismic performance. This paper uses the partial replacement method to reinforce and renovate concrete shear walls, using modified reactive powder concrete (MRPC) with excellent durability and toughness as the replacement material. The effects of different materials and different replacement positions on the seismic performance of shear walls were studied. A total of 5 shear wall specimens were designed and manufactured, including Specimen SW1 that did not reach the designed concrete strength, Specimen SW2 that met the original design strength, SW3 with the middle part of the wall was replaced by MRPC, and another two specimens that used ordinary concrete (SW4) or MRPC (SW5) to replace the two ends of the wall. Pseudo-static tests were carried out on the specimens and their seismic performance indicators such as bearing capacity, stiffness degradation, displacement ductility, and energy dissipation capacity were analyzed. Finally, finite element simulation analysis was also performed for the specimens. The results show that compared with the original design strength specimen SW2, the specimens SW4 and SW5, which used C45 concrete and MRPC to replace the two ends of the walls, effectively improved the bearing capacity, energy dissipation, and ductility of the shear wall. By comparing the mechanical properties of SW3 and SW5, it can be found that replacing the two ends of the shear wall can obtain better results.

Experimental study and mechanism analysis of out-of-plane seismic performance of reinforced concrete shear walls

Compared with the in-plane seismic performance, the out-of-plane seismic performance of reinforced concrete shear walls is weak and usually neglected, which leads to an inadequate study of the out-of-plane damage mechanism of shear walls and a lack of clear protective measures. In order to compare the similarities and differences in seismic performance of reinforced concrete shear walls when subjected to in-plane and out-of-plane loads in different directions and to clarify the key influencing factors, low cyclic loading tests were carried out on typical shear wall specimens in both in-plane and out-of-plane directions. The moment-curvature simulations of shear wall sections in both in-plane and out-of-plane directions are analyzed. The effects of parameters such as axial pressure ratio, wall thickness, height to width ratio and concrete grade on in-plane and out-of-plane seismic performance were analyzed at the member level in combination with finite element variable parameter analysis; at the structural system level, the time history analysis of 2 frame shear wall structures for single seismic action and main-aftershock sequence is established, and the structural damage is evaluated through the maximum story drift and rotation. The results reveal that the out-of-plane seismic performance of shear walls is significantly weaker than their in-plane seismic performance, with a difference of 1/20∼1/15 times in bearing capacity, where wall thickness and aspect ratio are the main parameters affecting in-plane and out-of-plane seismic performance; when the shear walls in the structure are subjected to seismic action in the out-of-plane direction, their out-of-plane direction will undergo large deformation and damage will occur easily, especially in the Single directional wall with less structure. The out-of-plane nonlinear analysis of the cross-section can be performed more accurately and quickly by using the new principal structure model proposed in this manuscript and some traditional principal structures. In the seismic design of shear walls, both in-plane and out-of-plane seismic performance should be ensured, and the wall thickness and height to width ratio of shear walls should be reasonably controlled.

On efficient seismic fragility assessment using sequential Bayesian inference and truncation scheme: A case study of shear wall structure

The seismic performance of shear walls in nuclear power plants is critical because a failure of such structures can cause severe accidents. Thus, research on the seismic fragility of shear walls in nuclear power plants has been attempted. However, conventional seismic fragility analysis requires high computational costs. In this context, several researchers proposed an efficient seismic fragility method by reducing required numerical analyses. But, this method still demands quite an amount of numerical cost. To overcome this issue, this paper presents an enhanced method for more efficiently assessing the seismic fragility of shear walls through sequential Bayesian inference and truncation strategy. The core idea of the proposed method introduces a binary analysis result chain and combines such a chain with sequential Bayesian inference. The sub-strategy of the method employs the truncation strategy for reducing the number of analyses. Also, an approach to evaluate a convergence index of a seismic fragility curve for each step is embedded into the sequential Bayesian inference for minimizing additional analysis cost. As a result, the proposed method of this paper reduces the computational cost even though it provides similar accuracy results compared to the existing seismic fragility methods.

Study on seismic performance of green fiber-reinforced concrete shear wall

Reinforced concrete shear walls are widely used in civil engineering and it is necessary to study new environmental protection methods to improve its seismic performance.The green fibers (namely recycled steel fibers, collectively referred to as green fibers in this article) formed by cutting high quality steel wires extracted from waste tires and have good tensile, flexural, and yield strength.So the improvement effect of green fibers on the seismic performance of concrete shear wall is studied in this paper. Cyclic loading experiments are used to explore the seismic performance of plain concrete shear wall specimen, green fiber-reinforced concrete shear wall specimen mixed with green fibers 1.0 L (L is the length of shear wall, the same as below) and 1.5 L height and fiber volume ratio of 1.5%. The results show that with the addition of green fibers and the increases in incorporation height of green fibers, the ultimate bearingcapacity, ductility, and energy dissipation capacity of concrete shear wall specimens gradually increase. As the specimen increases the fiber incorporation height, the ultimate bearing capacity of the shear wall increases, and the ductility and energy dissipation capacity increase, and stiffness degradation of specimens gradually slows down. That is, the seismic performance of shear wall specimens is gradually improved. The error between the experimental values and calculated values obtained by the deduced calculation formula is within the allowable range. The results of Abaqus finite element numerical simulation are in good agreement with the experimental results. And through the numerical simulation of the other two specimens, it can be concluded that the flexural performance of green fiber-reinforced concrete shear wall specimens increases with the increases in fiber volume ratio and the decreases in axial compression ratio. This study can provide a reference for the research on the seismic performance of fiber-reinforced concrete shear wall and the application of steel wires extracted from waste tires in practical engineering.

Experimental Study on the Seismic Performance of Shear Walls with Different Coal Gangue Replacement Rates

To replace conventional concrete with coal gangue concrete in the construction industry, lateral cyclic loading tests were applied to three shear walls with different coal gangue replacement rates in this study, in which the replacement rate of coal gangue was 0%, 50%, and 100%. The load-displacement hysteretic curves and backbone curves of the shear walls obtained from tests were analyzed to compare the failure process and seismic performance of each shear wall. The results indicate that the stress performance and failure morphology of coal gangue concrete shear walls and conventional concrete shear walls are extremely similar, and the characteristics of the hysteretic and backbone curves are approximately the same. With the increase in the coal gangue replacement rate, the bearing capacity and ductility of the three shear walls gradually decrease, the strength degradation gradually becomes significant, and the energy dissipation capacity becomes worse, but the difference is not obvious, and all of them can meet the requirements of seismic performance. In addition, with the increase in the coal gangue replacement rate, the stiffness degradation gradually slows, so it is feasible to construct a shear wall using coal gangue concrete instead of conventional concrete.

Influence of shear depth on seismic performance of shear wall reinforced with BFRP bars: mesoscale modelings

Influence of shear depth on seismic performance of shear wall reinforced with BFRP bars: mesoscale modelings

Seismic performance of precast shear wall of insufficient grouting material strength strengthened with steel plate

The sleeve-connected precast shear wall is used widely in engineering practice due to its high engineering quality and environmental protection. However, the insufficient grouting material strength due to negligent management affects greatly the mechanical properties of the precast shear walls. Three different strengthening methods of steel plate were proposed, and the seismic performance of the shear walls was studied under the horizontal low-cycle repeated loading. Results demonstrated that the extension of the cracks of the shear walls strengthened with steel plate was limited effectively and the damage degree was reduced significantly. The failure characteristic of the first crack in the shear walls was revealed. The peak load of the specimen with insufficient grouting material strength (CPSW) was 80.05% of the specimen with normal grouting material strength (NPSW). The cracking and peak loads of specimens strengthened with different methods (CPSW-R1, CPSW-R2, and CPSW-R3) were improved significantly, and the ductility of shear walls was 108.9%, 102.7%, and 100.7% of the specimen NPSW, respectively. The stiffness and energy dissipation capacity of the shear walls strengthened were restored to the level of the specimen NPSW. The results of this paper could provide some insight into the strengthening and maintenance of shear walls with insufficient grouting material strength.

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

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 Study on a Low-Rise Shear Wall with the Built-In Shear Steel Plate

In this paper, a new reinforcement scheme is proposed to improve the seismic performance of low-rise shear walls. The new system combines the advantages of slotted and composite shear walls to exhibit a high bearing capacity and good deformation performance. Two low-cycle repeated loading tests with different forms of shear walls were conducted to accurately understand its seismic performance. Seismic performance indexes, such as failure mode, bearing capacity, hysteresis curve, stiffness degradation, and energy dissipation capacity, of the new shear wall under the low-cycle reciprocating load were obtained to verify its reliability. The results show that the newly reinforced shear wall has two clear seismic defense lines. Its deformation and energy-dissipation capacities and lateral stiffness stability are greatly improved compared with traditional low-rise shear walls. Thus, the proposed method can provide a new means for enhancing the seismic performance of shear walls.

Mechanisms and Prediction Model of Load-carrying Capacity in Staggered Perforated RC Flanged Shear Walls

In order to understand the loading path and further anticipate the bearing capacity of the staggered perforated RC flanged shear walls, this paper proposed an improved strut-and-tie model and perforated reduction coefficient based on the theoretical and numerical analysis. The finite element model has been validated experimentally. The parametric study was conducted numerically to investigate the influence of shear-span ratio, axial compression load ratio, flange, dimension of perforation, and the additional rebar on the seismic performance of shear walls. When the ratio of perforation area to the wall is ranged from 10% to 26%, the proposed strut-and-tie model can effectively predict the loading path and the lateral ultimate bearing capacity with the different combinations of shear-span ratio and axial compression load ratio; however, if the ratio of the perforation area is either lower than 10% or higher than 26%, the proposed strut-and-tie model is not applicable. While the perforated reduction coefficient can be used to calculate the lateral ultimate bearing capacity of the perforated shear wall.

Experiment and numerical analysis on seismic performance of resilient shear walls using high strength recycled aggregate concrete

In this paper, ultra-high strength bars (UHSB) was innovatively applied to the high-strength recycled aggregate concrete (RAC) shear walls to achieve resilient performance. In order to explore the resilient and seismic performance of the shear wall, five specimens with shear span ratio of 2.2 were tested under cyclic loading. The variables also included the type of longitudinal reinforcement in boundary elements, the presence of anti-corrosion coating in UHSB and the replacement ratio of recycled coarse aggregate (RCA). The results showed that the use of UHSB in the boundary elements significantly improved secondary stiffness and reduced the residual displacement and residual crack width of the shear walls. The anti-corrosion coating decreased bond strength between UHSB and RAC, but it had negligible effect on the seismic and resilient performance of the specimens before 2% drift ratio. Increasing replacement ratio of RCA slightly decreased the lateral force of the specimens under the same drift ratio, but the walls represented satisfactory resilient performance. In addition, finite element models were established in ABAQUS, and the effect of UHSB bond performance, the strength of longitudinal reinforcement with anti-corrosion coating, and the substitution rate of UHSB were analyzed. The results showed that the numerical analysis results were in good agreement with experiment results.

Seismic Performance of Assembled Shear Wall with Defective Sleeve Connection

In this paper, three kinds of shear walls with full sleeve grouting, fully defective sleeve and partially defective are designed for finite element analysis to analyze the influence of defects on the seismic performance of shear walls. The research shows that at the beginning of loading (5 s), the three models begin to appear compressive damage at the bottom of the wall in all three models. The damage of the defect-free model develops rapidly, and the damage of the fully defective model is basically the same as that of the partially defective model. With the gradual increase of displacement control (15 s), the compressive damages at the foot of the wall in the defect-free and partially defective grouting model are obvious, with plastic hinge formed in the foot of the wall, and the phenomenon of development along the pier body showing up. When the structure is damaged, the overall compressive damages of the wall in the defect-free and partially defective models are obvious, and the damage on the defective side of the partially defective model is slightly deficient. While the maximum stress of pre-stressed reinforcement in the defect-free model is concentrated at the top of the sleeve, the maximum stress of the pre-stressed steel bar in the fully defective model appears at the end of the steel bar in the sleeve. The hysteresis curve shape of the non-defect model and partially defective model are basically the same, showing a “shuttle” shape with a sound energy dissipation effect. The hysteresis curve shape of the fully defective model appears an obvious “pinch” phenomenon. The yield displacement levels of the defect-free and partially defective models are smaller than that of the fully defective model structure. The stiffness degradation curves of the three models basically overlap with one another. Before the limit displacement, the stiffness results of the non-defect model and the partially defective model are greater than that of the fully defective model. When the displacement is loaded to 20 mm, the stiffness degradation of the three models is equivalent.

Shear Wall and Frame Dual Systems Featuring Discontinuous Load Paths in Frame Elements in Low-to-Moderate Seismic Regions

ABSTRACT Reinforced concrete buildings constitute a significant portion of construction in Australia. Many existing buildings in Australia and other low to moderate seismic regions have been designed with little to no consideration for ductile detailing. The majority of these buildings also possess vertical irregularities, which can exacerbate their vulnerability in an earthquake event. The seismic performance of shear wall and frame dual systems possessing discontinuities in frame elements in the form of ductility and failure mechanism has been assessed. And design recommendations in terms of response modification factors and designation of appropriate methods of analysis have been provided.

A mechanical bond model for reinforcing bar in concrete subjected to monotonic and reversed cyclic loading

The reinforcing bar with diameters of 10 mm and 12 mm are widely used in shear walls, whose bond-slip performance has great influence on the seismic performance of the shear walls. Besides, the bond stress-slip model plays an important role in the theoretical analysis of the seismic performance of shear walls. Therefore, an analytical solution for the maximum bond stress was carried out and modified based on the thick-walled cylinder model and the tensile stress-strain model of concrete. The bond-slip tests of reinforcing bars in concrete were conducted on 48 specimens under monotonic and reversed cyclic loading. The effects of concrete strength, diameter of bar and bonding length on the bond-slip performance were examined and analyzed. The test results showed both the maximum bond stress and residual bond stress increased with increasing concrete strength, but decreased with increasing diameter of bar or bonding length. The reversed cyclic loading can cause the degeneration of the maximum bond stress and the bond stiffness. According to the bond-slip performance, the bond stress-slip model was established based on the analytical solution for the maximum bond stress, which is suitable for calculating both monotonic and reversed cyclic loading. A good agreement was observed by comparing the proposed models with the test curves in the study.

Experimental study on seismic performance of recycled aggregate concrete shear wall with high-strength steel bars

In order to investigate the seismic behavior of recycled aggregate concrete (RAC) shear wall using high-strength steel bars (HSS), five concrete walls with an aspect ratio of 2.2 were tested under the horizontal cyclic load. The influence of various parameters which include replacement percentage of recycled coarse aggregate (RCA), concrete strength, and the grade of longitudinal bars at boundary elements on the seismic performance of shear walls were analyzed. The failure mode, hysteresis behavior, skeleton curve, stiffness and energy consumption of RAC shear walls were analyzed. The results showed that as the replacement rate of RCA increased, the seismic performance of the wall hardly changed. The use of higher concrete strength could significantly improve the bearing capacity, initial stiffness and energy dissipation of the shear walls, while the ductility was similar. Almost all seismic indexes of the shear wall reinforced with HRB400 bars decreased. Reasonable matching of HSS and RAC could help the shear wall to achieve better seismic performance. The flexural strength and secondary stiffness of the RAC wall with ultra-high-strength steel bars (UHSS) were significantly improved and the concrete damage was reduced. In addition, the restoring force model based on experimental data was established and the hysteretic behavior of RAC shear walls was well predicted.

Experimental study on seismic performance of shear wall with precast concrete hollow molds

AbstractA new type of connection between shear walls is proposed for the shear wall with precast concrete hollow molds (PCHM). The overlapping reinforcements are inserted into the PCHM before pouring concrete into the hollow in this method. Full‐scale test specimens are tested under low cyclic loading test to analyze their seismic performance, such as failure modes, hysteretic characters, stiffness degradation, energy dissipation, and ductility. For the precast specimen, although the penetrating crack appears at the horizontal connection, there is no large slippage leading to anchorage failure and disengagement of interfaces. Generally, compared with cast‐in‐situ shear walls, shear walls with PCHM have no large difference in bearing capacity, failure mode, stiffness degradation, energy dissipation and ductility. Therefore, the proposed shear wall with the new type of connection method is worth popularizing and utilizing in practical engineering projects with similar design procedure to cast‐in‐situ structures.