Shear Wall-frame Building Research Articles

Effects of Soil–Structure Interaction on the Seismic Response of RC Frame–Shear Wall Building Structures Under Far-Field Long-Period Ground Motions

This paper focuses on the effect of soil–structure interaction (SSI) on the seismic response of high-rise RC frame–shear wall structures under far-field long-period ground motions. Elastic–plastic time–history analyses were performed using ABAQUS. The effects of the ground motion type, soil type, and structural frequency on the seismic response are analyzed and quantitatively evaluated. On this basis, the influence mechanism of SSI on the seismic response under far-field long-period ground motions is discussed and revealed through a ground motion spectrum analysis. The results show that the consideration of the SSI effect leads to an increase in the displacement response and a decrease in the shear response. The SSI coefficient of the base shear is all less than 1, ranging from 0.5 to 1. The SSI effect under far-field long-period ground motions is more pronounced than that under ordinary ground motions. The shear force reduction in the current code may not be applicable to the structural design considering the SSI effect under far-field long-period ground motions. The displacement response amplification of the SSI effect on loess soil (Site 2) is more remarkable than that on sand soil (Site 1). The SSI effect can reduce the structural frequency, especially for the structures with fewer floors on the softer soil site. The “bimodal characteristic” of the acceleration response spectrum for far-field long-period ground motions may lead to shear force amplification when SSI is considered.

Comparison of 5 and 10 Storey Frame Buildings and 5 and 10 Storey Shear Wall-Frame Buildings Under the Effect of Maras Earthquake According to the Turkish Building Earthquake Code 2018

In this study, the differences in the displacements, base shear forces, relative storey drifts and foundation stresses under different earthquake data on different storeys of shear wall frame systems and framed systems are investigated by using SAP2000 program. Within the scope of the study, four buildings with 5-storey frame, 5-storey shear wall frame, 10-storey frame and 10 storey shear wall frame are modelled. All four buildings were designed to be identical with 4 spans in X and Y directions and each span was designed as 5 meters. The height of each floor is designed as 3 meters for all four buildings. In sheared structures, shear walls are designed to be 4 meters from the corner columns to the columns closest to them. The earthquake data to be influenced on all four structures are the earthquake data from the Earthquake Hazard Map of Turkey published by AFAD at the coordinates of 41° latitude, 27° longitude of Kırklareli province, Luleburgaz district. Another earthquake parameter was taken from station 4615 during the earthquake in Kahramanmaras. The data recorded by station 4615 for the 7.6 Mw earthquake in Kahramanmaras was applied to all four structures. These two earthquake data were imposed on these four structures in order to compare the resulting displacements, relative storey drifts, base shear forces and foundation stresses. Since the structures are all symmetrical in both X and Y directions, only one direction of the displacements was calculated. As a result, when both the earthquake data from the Earthquake Hazard Map and the Kahramanmaras earthquake data were applied to these four structures, it was observed that the maximum values of the displacements occurred at the top floors of all structures and the effect of the Kahramanmaras earthquake data was higher in the displacements, relative storey drifts, base shear forces and foundation stresses than the effect of the other earthquake data.

Comparison on seismic resilience of hybrid, isolation, and damping control reinforced concrete frame-shear wall buildings

To investigate the effectiveness of different vibration control methods in realizing seismic resilience of reinforced concrete (RC) frame-shear wall structures, four cases with different control methods were designed, including the damping control building using energy dissipation cladding panels (EDCPs) (RCFSW7-D), isolated building (RCFSW7-I), isolated building with enhanced stiffness of superstructure (RCFSW7.5-I), and hybrid control building using both EDCPs and isolation (RCFSW7-H). The critical seismic responses and resilient performance of four cases were analyzed based on the Chinese code. Maximum inter-story drift ratios (MIDRs) of RCFSW7-I, RCFSW7.5-I, and RCFSW7-H under maximum considered earthquake were 36%, 51%, and 72% lower than that of RCFSW7-D, respectively. Although the stiffness of superstructure of RCFSW7.5-I and RCFSW7-H were approximately identical, the MIDR of RCFSW7-H was 44% smaller than that of RCFSW7.5-I. Meanwhile, the maximum absolute floor accelerations (MAFAs) of three isolated structure under MCE were approximately 70% lower than that of RCFSW7-D. The seismic resilience level of RCFSW7-D was Level 1, which is dominated by the damage of structural components (SCs) controlled by MIDR and acceleration-sensitive non-structural components (ASNSCs) controlled by MAFA. The seismic resilience levels of RCFSW7-I and RCFSW7.5-I successfully increased to Level 2, leading by the effectively control of MAFA and damage of ASNSCs. However, the MIDR was not sufficiently controlled even the stiffness of superstructure was increased. In contrast, hybrid control building significantly reduced both the MIDR and MAFA through the currently utilization of seismic isolation and EDCPs, especially the MIDR and damage of SCs, leading to a seismic resilience level of Level 3.

Seismic Response of High-Rise Frame–Shear Wall Buildings under the Influence of Dynamic Soil–Structure Interaction

Seismic Response of High-Rise Frame–Shear Wall Buildings under the Influence of Dynamic Soil–Structure Interaction

TMD Design by an Entropy Index for Seismic Control of Tall Shear-Bending Buildings.

This study proposes a new arrangement-tuning method to maximize the potential of tuned mass dampers (TMDs) in decreasing the seismic responses of tall buildings. The method relies on a Grammian-based entropy index with the physical meaning of covariance responses to white noise without the involvement of external inputs. A twelve-story RC frame-shear wall building was used as an example to illustrate the method. Indices were computed for the building with TMDs placed on different stories and tuning to different modes and were compared with responses to white noise (colored) time histories. Results showed that greater index reduction cases agree well with greater story-drift reductions cases, despite the differences in the time step of the white noises and structural model types (pure shear vs. shear-bending), and the optimal TMD is not necessarily the traditional "roof-1st mode tuning" case. Comparisons were also made for the shear-bending building under seven earthquake excitations. It is found that, though TMDs are not full-band effective controllers, the index-selected TMDs still perform the best in three out of seven earthquakes. So, the proposed internal-property-based entropy index provides a good controller design for large-scale structures under unpredictable none-stationary excitations.

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.

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.

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.

Reliability-based optimization of shear walls in RC shear wall-frame buildings subjected to earthquake loading

In most reinforced concrete (RC) multistory buildings, shear walls are provided to resist lateral loads arising from wind and earthquakes of moderate to high magnitude. The quantity and location of these walls play a significant role in controlling the building response, reliability, and overall construction cost, and therefore need to be optimized. In the literature, shear wall quantity and location are optimized without due consideration of the desired reliability level, which leads to structural designs with unknown safety levels. This paper addresses this issue by introducing the desired reliability level as an additional constraint. The methodology is demonstrated with the help of a set of representative unsymmetrical and symmetrical RC shear wall-frame buildings subjected to the El-Centro earthquake. The results of the study illustrate that the reliability constraint is, in general, a governing constraint in the optimization process of RC shear wall-frame buildings subjected to earthquake forces. The study is expected to be useful for practicing engineers and researchers to achieve the desired level of safety in structural design.

Seismic pounding damage to adjacent reinforced concrete frame–shear wall buildings and freestanding contents

AbstractClosely spaced tall buildings are common in modern urban areas due to limited supply of land to accommodate rapid growth of population. These buildings are vulnerable in seismically active regions particularly when earthquake‐induced pounding occurs between adjacent buildings, resulting in high floor acceleration spikes that may lead to excessive demands on building contents (BCs). This paper examines the effect of seismic pounding on damage to adjacent reinforced concrete (RC) frame–shear wall buildings and their freestanding contents using nonlinear response‐history analyses (RHA). A cascading analysis approach is adopted to obtain absolute floor accelerations of pounding tall buildings, which are then applied to determine response of freestanding contents dominated by either sliding or rocking motions. In order to provide a useful tool for practicing engineers and facilitate analyses, the buildings are simplified as story‐based multiple‐degree‐of‐freedom (MDOF) flexural‐shear models, and unanchored contents are idealized as single‐degree‐of‐freedom (SDOF) oscillators, all of which are approximated using OpenSees and verified against solutions to their exact equations of motion solved using Matlab. It is shown that seismic pounding leads to higher building damage and alters story damage distribution patterns. It is concluded that pounding significantly increases sliding potential and maximum sliding displacement demands on stocky contents, especially those on higher floors. The transitions of stick–slip response of the contents coincide well with pounding occurrences. It is also concluded that pounding has detrimental effects on slender rocking contents, but rocking rotation histories of these contents do not show abrupt changes upon impact.

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

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.

Seismic retrofitting of reinforced concrete frame-shear wall buildings using seismic isolation for resilient performance

Seismic retrofitting of a reinforced concrete frame-shear wall building (RCFSWB), which is widely adopted for public buildings, is critical for the seismic risk reduction of a city. Seismic isolation is considered as an effective retrofitting method for resilient performance. The resilience-oriented retrofitting of RCFSWBs through isolation was herein investigated with emphasis on the critical design parameter, the yield ratio of the isolation system. Engineering demand parameters (EDPs) affecting resilient performance of RCFSWBs before retrofitting were identified with the consideration of different stories through two cases. The effect of the yield ratio on resilient performance after retrofitting with seismic isolation was revealed through six cases, emphasizing the control effect of critical EDPs. A yield ratio of 2% was suggested for the resilience-oriented retrofitting of RCFSWB toward the highest resilience level in the Chinese code, and was used to conduct resilience-oriented retrofitting of a nine-story RCFSWB. This research provides a valuable reference for RCFSWB retrofitting through seismic isolation.

Quantitative evaluation and improvement of seismic resilience of a tall frame shear wall structure

SummaryTall buildings are an important part of a city, and their earthquake‐induced damage or collapse will lead to heavy losses, extended repair time, and casualties. Therefore, it is essential to quantify and improve the resilience of tall buildings. To this end, this paper develops a component damage‐based metric to characterize tall buildings' functionality loss and then proposes a general quantitative evaluation process to evaluate tall buildings' resilience. Next, the evaluation process is applied to a 42‐story reinforced concrete frame shear wall building to demonstrate its applicability. Finally, retrofit strategies on nonstructural components are discussed to enhance the building's resilience. It can be concluded that the proposed metric can be effectively used to evaluate tall buildings' functionality loss. The building being studied has great seismic resilience, with resilience values of 99.95%, 98.68%, and 88.69% at service level earthquake (SLE), design level earthquake (DBE), and maximum considered earthquake (MCE), respectively. The influence of nonstructural components on seismic resilience is greater than that of structural components at SLE and DBE levels. It is an effective alternative to enhance the seismic resilience of tall buildings under SLE and DBE by improving the performance of partition walls, ceilings, and equipment.

Modified Damage Index Calculation Method for Frame-Shear Wall Building Considering Multiple Demand Parameters

In this study, multiple objectives on earthquake damage assessment procedures have been investigated. The Unified performance-based design (UPBD) method was primarily used to design the Reinforced Concrete (RC) frame shear wall building. The nonlinear dynamic analysis is performed considering spectrum compatible ground motions (SCGM) as per EC-8 demand spectrum at 0.45g level and type B soil condition. It estimated the Damage index (DI) of the building by using Park and Ang method. This method is highly time-consuming as the storey height increases. Hence, it is not suitable for large scale investigation. Therefore, a new approach has been suggested to reduce the computational time and efforts in the case of complex structures to evaluate the global damage index (GDI). In this present study, the most three influencing parameters of the building has been considered to find the global damage index (GDI). And it has also been observed that the most damage occurs on the ground storey of the building compared to the remaining floors. The suggested method efficiently calculates a reliable GDI that can assess building damage from small to large scale.

Effect of damage limit states on the seismic fragility of reinforced concrete frame-shear wall buildings

Assessment of the seismic vulnerability of frame-shear wall buildings can be performed by non-linear dynamic analysis and it needs detailed analytical modeling, structural performance measures and various earthquake intensities. The codal based design method can hardly be used for designing buildings of pre-defined target objectives whereas the Unified performance-based design (UPBD) method can be designed for buildings of pre-defined target objectives. In the current study, the UPBD method for frame-shear wall buildings has been applied for different performance levels (PL) i.e. Immediate occupancy (IO), Life safety (LS) and Collapse prevention (CP) with 1%, 2% and 3% drift in both the directions of the buildings. The nonlinear dynamic analysis of the reinforced concrete (RC) frame-shear wall buildings is performed considering spectrum compatible ground motions (SCGM) as per EC-8 demand spectrum at 0.45g level and type B soil condition. Vulnerability assessment of the frame-shear wall buildings is conducted by generating fragility curves and the probability failure of structure is checked based on different configurations and damage limit states of the structure. Finally, the outcome of the work gives a proper idea of the nonlinear behavior of the dual system so that optimum design could be acquired for achieving higher safety aspects.

Collapse Mechanism of Ordinary RC Shear Wall-Frame Buildings Considering Shear Failure Mode

Most commercial buildings among existing RC buildings in Korea have a multi-story wall-frame structure where RC shear wall is commonly used as its core at stairways or elevators. The members of the existing middle and low-rise wall-frame buildings are likely arranged in ordinary details considering building occupancy, and the importance and difficulty of member design. This is because there are few limitations, considerations, and financial burdens on the code for designing members with ordinary details. Compared with the intermediate or unique details, the ductility and overstrength are insufficient. Furthermore, the behavior of the member can be shear-dominated. Since shear failure in vertical members can cause a collapse of the entire structure, nonlinear characteristics such as shear strength and stiffness deterioration should be adequately reflected in the analysis model. With this background, an 8-story RC wall-frame building was designed as a building frame system with ordinary shear walls, and the effect of reflecting the shear failure mode of columns and walls on the collapse mechanism was investigated. As a result, the shear failure mode effect on the collapse mechanism was evident in walls, not columns. Consequently, it is recommended that the shear behavior characteristics of walls are explicitly considered in the analysis of wall-frame buildings with ordinary details.

Distribution of Story Shear and Reinforcement in Dual System

Shear wall frame buildings are commonly used in buildings ranging from about 8 to about 30 stories. Shear walls may be simple planar walls, several wall segments commonly are connected to act as a three-dimensional unit, then may enclose spaces in buildings, such as stairs, wells or elevator shaft. In this case, 18 story building with shear wall as planar has been analyzed. The portion of frame is less than 25 % as required in Indonesian standard there are 11.64% in X direction and 12.12 % in Y direction, so the results are compared with the condition if shear wall is released, hence, only boundary elements are placed and taken the maximum value by giving 25 % earthquake load. In the 100 % base shear acting on structure the value of column shear force has greater value at the bottom story of column than if shear wall is released and only 25 % base shear is given. The value of shear force at shear wall in the bottom story is greater in the bottom because there is void in that area. The portion of frame is less than 25 % as greater in the bottom because there is void in that area, so the greater shear force in the story is obtained. As the result, at the lower story the correction of scale factor less than one factor for all story can give the economical design.

Considerations on computational modeling of concrete structures in fire

This paper presents an overview of selected issues in computational modeling for reinforced concrete structures in fire. The focus is on current modeling challenges, as well as aspects that are sometimes overlooked yet important for capturing the concrete material and structural behavior at elevated temperatures. Issues addressed include the consequences of realistic thermal exposures with cooling phases on the material properties and deformations, the uncertainties in material and structural response at elevated temperature, and the effect of the tensile fracture energy on the model response. The ability to capture membrane and shear failure modes is analyzed. The modeling of the residual response and potential failure during cooling is discussed. As an example, a five-story RC shear wall-frame building is modeled under natural fire. Finally, the paper ends with a discussion on the limits, research needs and opportunities with respect to computational modeling of concrete structures in fire.

Effect of Connection Deficiency on Seismic Performance of Precast Concrete Shear Wall-Frame Structures

The quality of precast concrete (PC) component connections is one of the main factors that affect the seismic reliability of PC structures. China is developing PC structures in high seismic regions, and it is important to assess the effect of connection deficiency on seismic performance of PC structures. This paper presents a comprehensive method to assess the seismic reliability of PC shear wall-frame structure whose wall panels are assembled through grouted sleeve connections which are susceptible to insufficient grouting. Considering the uncertainties associated with the number, locations and loading behavior of defected sleeve connections, the probabilistic behavior of PC shear wall with defected connections is estimated through point estimate method using simulation results of the experiment-validated finite element model. Then, a simple shear wall-frame building, designed for the seismic intensity of 8 according to China’s seismic design code, is modeled on platform of OpenSees. Static pushover analyses and seismic fragility analyses are performed on the structure with different degrees of connection deficiency, to investigate the effect of deficiency occurrence rate on seismic performance. The seismic performance is significantly affected by connection deficiencies; it no longer meets the requirement of seismic design as the deficiency occurrence rate exceeds 25%, so the occurrence rate of defected connections should be controlled carefully in construction site.

Damage assessment of shear wall components for RC frame–shear wall buildings using story curvature as engineering demand parameter

Reinforced concrete (RC) frame–shear wall structures are extensively used in urban areas. As a major part of the lateral load resisting system, the shear wall is a key component for the seismic performance assessment of such structures. In this study, a method for the seismic damage assessment of shear wall components is proposed by using the story curvature as the engineering demand parameter (EDP). The method involves (1) a shear wall story curvature calculation method and (2) a shear wall damage limit determination method that uses the story curvatures as the EDP. The story curvature adopted in this study denotes the maximum shear wall curvature within each story level. Based on the piecewise linear assumption of the curvature distribution, the story curvature calculation method requires story drifts and shear wall key design parameters as inputs. Meanwhile, based on the plane cross-sectional assumption and sectional analysis, the damage limits can be determined by considering the influences of the shear wall key design parameters, such as the axial load ratio, shear wall component length, and material information, thereby yielding more accurate estimation. Finally, the proposed method is validated by comparing it with the numerical results of several wall panels and an RC frame–shear wall structure. It is further validated by comparing it with the experiment results obtained from six shear wall tests and a full-scale shaking table test of a seven-story shear wall structure.