Shear Concentration in Shear Walls Immediately above the Transfer Floor in Tall Buildings under Seismic Loading

A transfer floor is the floor system which supports a vertical as well as lateral load resisting system and transfer its loading to different underneath system. Transfer floor distribute the load from closely spaced columns to the columns with long span. This study presented, a seismic analysis of high rise building with transfer floor. A number of proto type models of high rise building were analyzed using linear response spectrum analysis. The models were analyzed using structural software for building analysis ETABS 2016 software. The analyzed models has transfer slab system at different floor levels in high rise building. In this paper, five different models of 10 storey building had studied by providing a transfer slab at different floor levels such as first floor, second floor, third floor, fourth floor and fifth floor of the building. And the vertical position of transfer slab with respect to building height was investigated. The seismic response of high rise building such as storey shear, storey moment, storey displacement, inter-storey were numerically evaluated. Key Words: Transfer slab, Response spectrum analysis, Storey shear, Storey moment, ETABS 2016.

Currently, there is an increase in the demand for tall buildings in the city of Lima. This research proposes to reduce the dynamic amplification factor through the seismic design of tall buildings based on the requirements of Peruvian code considering that they are regular in plan and height. Minimum base shear values according to the comparison of static seismic shear and dynamic shear from the spectral modal analysis were reviewed for cases of buildings larger than 120 m. The study of 28 reinforced concrete buildings was proposed, with different heights - varying from 24 to 36 floors, with different floor configurations, as well as the arrangement of the walls considering as a rigid core structural system. Additionally, the characteristics of the materials, the loads and combinations were defined. The responses of these buildings were determined by the response spectrum analysis (RSA) and then compared with those obtained by the lineal response history analysis (LRHA), for the last analysis, five Peruvian seismic records were used and scaled to 0.45 g. The seismic responses of the LRHA procedure were taken as a benchmark. The result of this study is the analysis and proposal of the C/R factor for high-rise buildings, as well as obtaining the base shear and drift verification. Minimum base shear values can be reduced for high or long-term buildings, being regular in plan and height.

Performance-based seismic design (PBSD) has been recognized as a framework for designing new buildings in the United States in recent years. Various guidelines and standards have been developed to codify and document the implementation of PBSD, including “ Seismic Evaluation and Retrofit of Existing Buildings” (ASCE 41-17), the Tall Buildings Initiative’s Guidelines for Performance-Based Seismic Design of Tall Buildings (TBI Guidelines), and the Los Angeles Tall Buildings Structural Design Council’s An Alternative Procedure for Seismic Analysis and Design of Tall Buildings Located in the Los Angeles Region (LATBSDC Procedure). The main goal of these documents is to regularize the implementation of PBSD for practicing engineers. These documents were developed independently with experts from varying backgrounds and organizations and consequently have differences in several degrees from basic intent to the details of the implementation. As the main objective of PBSD is to ensure a specified building performance, these documents would be expected to provide similar recommendations for achieving a given performance objective for new buildings. This article provides a detailed comparison among each document’s implementation of PBSD for reinforced concrete buildings, with the goal of highlighting the differences among these documents and identifying provisions in which the designed building may achieve varied performance depending on the chosen standard/guideline. This comparison can help committees developing these documents to be aware of their differences, investigate the sources of their divergence, and bring these documents closer to common ground in future cycles.

<p>Earthquake actions for tall buildings are significant, thus numerous tall buildings are controlled by earthquake actions. Inadequate lateral stiffness may cause excessive damage to non-structural components, thus story drift limitations under earthquake actions are specified in Chinese Code. Response spectrum analysis is one of the most common methods for seismic analysis of structures. A sensitivity analysis method is carried out based on response spectrum methodunder story drift constraint.The sensitivities of story drift constraint of each mode related to design variables are first determined from the design spectrum, and the sensitivities of different modal responses are then combined using combination rules to produce the overall story drift sensitivities related to design variables. A 2-story planar frame is used to validate the sensitivity analysis method. And an artificial structural optimization method is developed in this paper for optimal seismic design of tall buildings. According to the sensitivity coefficients, cost effective structural design is achieved by means of reasonably distributing materials among the various components. A 468-meter tall building project is employed to illustrate the applicability and effectiveness of the proposed optimal seismic design method.</p>

A comparative analytical study for the seismic response of high-rise buildings with transfer floors is presented. A number of prototype models were analyzed using elastic linear response spectrum and inelastic nonlinear time history techniques using three-dimensional finite element models. The analyzed models had different transfer floor system: transfer slabs and transfer girders. The vertical position of the transfer system with respect to the building height was investigated. Global seismic response of the buildings such as storey shear and bending moment distribution, and inter-storey drift were numerically evaluated. The results showed the localization of damage in the vicinity of the transfer floor in addition to the first floor; the location of the transfer floor influenced the global seismic response of the structure. The numerical analysis revealed that the transfer girders system is a competitive alternative to the slab system in terms of reducing the seismic weights as well as the material cost with a slight change in the global seismic behaviour of the building. Transfer girders system is more flexible compared to slab system and generate lower straining actions on the structural vertical elements.

- The objective of this study is to evaluate the seismic performance of various structural systems and identify the most efficient configuration for tall buildings. Ensuring adequate lateral stability and ductility is critical for reducing damage during strong earthquakes, particularly in high-rise structures located in severe seismic zones. In this work, seven structural models of a G+20 storey building with a plan dimension of 27.5 m × 27.5 m and a storey height of 3.6 m are analyzed. The models include a conventional moment-resisting frame, shear wall system, core wall system, frame with diagonal bracing, diagrid with periphery columns, diagrid without periphery columns, and a combined diagrid–shear wall system. Using ETABS 2015, seismic analysis is performed for Zone V conditions through equivalent static analysis, response spectrum analysis, and time-history analysis. The seismic performance is assessed using key parameters such as bending moments, shear forces, axial forces, storey displacement, drift, stiffness, and overall economy. The comparative results provide insights into the lateral load-resisting efficiency of each structural system and help determine the most suitable configuration for high-rise buildings in high seismic regions. Keywords: Seismic performance, Tall buildings, Diagrid system, Shear wall, Core wall, Braced frame, ETABS, Response spectrum, Time-history analysis, Storey drift, Lateral stability

This paper aims at comparing seismic (EQ) and blast (TNT) loadings using different TNT weights on 12-storey reinforced concrete residential building with and without shear walls. These types of loading should be taken into considerations now in Iraq. The explosions besides earthquakes must be studied in Iraq to avoid significant losses in the lives of people and their public and private property. The same reinforced concrete multistory building was designed with three different TNT weights; 100, 350 and 750 kg in order to discuss drift, displacement and story shear. A commercial package ETABS2018 was used to analyze this 36-meter-high building. The building was designed according to ACI 318-14 and US Department of Defense TM5-1300 for blast load. As for the blast load, in case of shear wall existence, the maximum increase in drift was seen on the 11th and 12th stories about 1306-187% and 1232-175 %, respectively for each TNT weight compared with EQ. The maximum increase in drift was found on the 11th and 12th stories about 4236-618% and 2646-386% for each TNT weight. The maximum increase in story shear was seen on the 2nd and 3rd stories 5150-698% and 4625-618% for each TNT weight compared with EQ.

Performance-based seismic engineering has brought new dimensions to tall building design, leading to a major transformation from the prescriptive/linear strength-based approach to the explicit non-prescriptive/nonlinear deformation-based design approach. In this context, current tall building seismic design practice is based on a well-established design methodology, which starts with a preliminary design followed by two performance evaluation stages. In this methodology, preliminary design represents the critical phase of the tall building design where all structural elements have to be preliminarily proportioned and reinforced for the subsequent performance evaluation stages. However, there are several problems inherent in the existing preliminary design practice. Preliminary design based on linear analysis could lead to unacceptable sizing and reinforcing of the main structural elements of tall buildings. In particular, linear preliminary design procedures applied to coupled core wall systems would most likely lead to an overdesign of coupling beams with inappropriate and heavily congested reinforcement requirements. In addition, linear analysis with reduced seismic loads may result in under-designed wall elements especially in terms of their shear strength. Simple procedures based on first principles have been developed to estimate base overturning moment capacity, total coupling shear capacity and overall ductility demand of the coupled core wall systems, which can be efficiently used in the preliminary seismic design of tall buildings.

<p>As a result of rapid economic growth and urbanization, a huge amount of tall buildings have been constructed in Mainland China in the recent two decades. Tall buildings are the symbols of our industrialized societies and provide us more living and working spaces in the limited land. They have become one of the most important infrastructures in the renewal of our urban environment as well as the creation of new urban area throughout the world. However, tall buildings suffered serious damages during the past earthquakes. Some research and practice work of seismic performance and response control of tall buildings in Mainland China in recent years are introduced here, including the general methodologies for performance-based seismic design of tall buildings, shaking table model tests on complex tall buildings to evaluate the seismic performance of structures and accordingly revise the structural design, and a new type of earthquake resilient shear wall structure with replaceable coupling beams and replaceable foot parts.</p>

The abstract of the study that is titled "Effective Position of Shear Wall for Higher Rise for Time History Analysis" focuses on the investigation of the best placement of shear walls in tall buildings in order to improve the seismic performance of these buildings via the use of time history analysis. By doing this research, the researchers hope to find a solution to the essential problem of establishing the most effective location of shear walls in high-rise structures in order to reduce the effects of seismic forces. Evaluating the dynamic response of tall buildings under earthquake loading circumstances is the purpose of this work. This evaluation is accomplished through the utilisation of sophisticated numerical simulations and time history analytic methodologies. In order to conduct a full analysis of the structural behaviour, the investigation takes into account a number of parameters, including the height of the building, the configuration of the shear wall, and the seismic intensity. Additionally, the study analyses the influence of varied shear wall placements on key performance measures including base shear, story drift, and acceleration responses. The purpose of this research is to determine the ideal position and configuration of shear walls for higher buildings by means of systematic analysis and comparison of the results. This will help to reduce the structural vulnerability of the building and increase its seismic resilience. Those structural engineers and designers who are involved in the seismic design of high-rise structures will find the findings of this study to have significant implications. These findings provide valuable insights into effective strategies for improving the earthquake resistance of tall buildings through optimized shear wall placement. Keywords: Shear walls, High-rise buildings, Seismic analysis, Time history analysis, Structural optimization, Finite element analysis, Seismic performance, Building dynamics, Structural stability, Optimal placement.

Shear wall, steel bracing and combined system are the most commonly used lateral-load resisting technique for high-rise buildings. Shear walls have very high in-plane strength and stiffness, which can be used simultaneously for resisting large horizontal and gravity loads. The aim of this study is to examine how well reinforced concrete buildings withstand seismic activity using various systems for resisting lateral loads. In this study, a reinforced concrete building with 12 floors (G+12) and 5 X 5 bays is selected, and various lateral load resisting frame systems are applied in different positions. These are shear wall, bracings, shear wall-bracings combinations (Combined) at five different locations/patterns i.e., at outer corners (Type- I), center of outer sides (Type- II), middle corners (Type- III), center of middle sides (Type- IV), and inner core and middle sides (Type- V) respectively. A total of sixteen models are created for this study, with one being a bare frame and the other fifteen consisting of three types of lateral load resisting systems arranged in five different configurations each. With the assistance of ETABS all models are analyzed by Equivalent Static Analysis and Response Spectrum Analysis. The performance of building is evaluated on the basis of following parameters- maximum storey displacement, maximum storey drift and storey shear. At last the results are compared for different models. Among the three systems, the shear wall system exhibits the least displacement and the highest stiffness. Response of combined system is better than that of bracing system. Overall, the Type II shear wall model is more earthquake-resistant and structurally efficient than the other fifteen models. Key Words: Equivalent Static Analysis, Response Spectrum Analysis, Maximum storey displacement, Maximum storey drift, Storey shear

The principle objective of this project is to analysis and design a multi-storeyed building [G + 10 (3-dimensional frame)] using SAP2000. The design involves load calculations manually and analyzing the whole structure by SAP2000. The design methods used in SAP2000 analysis are conforming to Indian Standard Code of Practice and features a state-of-the-art user inter face, visualization tools, powerful analysis and design engines with advanced finite element and dynamic analysis capabilities. From model generation, analysis and design to visualization and result verification. The project is designed in accordance with Indian codes, considering various loads such as Reinforced concrete (IS 456-2000), dead load (IS875-1987 part1), live load (IS875-1987 part2), wind load (IS875-1987 part3), seismic load (IS1893-2016 part1) and load combinations are considered as per the (IS875-1987 part-5) code books. The analysis considers seismic zone III and ensures safety by considering dead load, live load, seismic and wind forces, and balancing economy and safety. Structural design is crucial for Civil Engineers, and proper analysis can prevent structure failure and loss of life. Engineers analyze structures considering constraints like serviceability and deformability, following IS codes. Our project focuses on analyzing and designing superstructures like slabs, beams, and columns, considering dead load, live load, seismic and wind forces Response Spectrum Analysis and Shear Wall. The analysis parameters such as shear force, bending moment, and displacement. KEYWORDS: Response Spectrum Analysis, Shear Wall, SAP2000, Seismic and Wind loads.

Earthquake effects on the buildings must be evaluated within the current standard provision. The shape of building gives a unique seismic performance on the structure. In typical hotel building, the lobby area in the first floor usually has some slender columns due to the needs of higher clearance to give a widely space area. The slender columns in the big hall tends to create asymmetric building and torsional behaviour on seismic performance. This behaviour is one of the most frequent source of structural damage and failure. One of the solution is to add shear wall in elevator area. The purpose of this paper is to seek the effect of shear wall configuration in elevator area on the seismic performance through numerical analysis. There are some requirements for structural analysis under seismic load, such as: time period, modal analysis, story drift, and other details. In building with dual system, story shear in frame at each level must carry over 25 % of total story shear at that level. In this study, an eleven-storey hotel building located in Tanjung Pinang City, Indonesia was evaluated due to gravity and seismic load. For the building, the requirements of the time period from the standard are 1.21 sec (minimum) and 1.70 sec (maximum). As results, two-sided shear wall in X direction and two-sided shear wall in Y direction is recommended because it has the best seismic performance, time period below the minimum, story drift below allowable, the dynamic lateral load has meet minimum requirement (85% Static Load), and frame structure has carry more than 25% lateral load in dual system building.

Shear wall are not avoidable in construction of buildings. However, the behavior of structures with these Shear wall during earthquake needs to be studied. By taking adequate precautions, the main objective of Earthquake Engineering is to design and build a structure in such a way that the damage to the structure and its structural components during an earthquake is minimized. Constructions can suffer diverse damages when they are put under seismic excitations. Although for a same structural configuration, region& earthquake, damages in the system are neither equal nor homogenous. So, there are several factors for these like – Structural system, Earthquake characteristics, the quality of construction, soil of location and its maintenance that define the seismic behavior of the structure. Present study represents the behavior with shear wall and not with shear wall of building. In this present study ten storey building is considered. The building is modeled in ETABS-2018 with shear wall and not with shear wall considered for analysis. For analysis purpose various loads are considered like dead load, live load and earthquake load in X and Y-direction. Various loads combinations are considered according to NBC 105:2020. The main objective of this project is to find out which will have better seismic performance either building with shear wall or without shear wall. The analysis of model is done using dynamic method in ETABS software. Finally the results of seismic behavior of buildings are compared with respect to time period, base shear, storey shear, member forces, overturning moment, displacement, stiffness and drifts. Keyword: Shear wall, RC buildings, NBC, Displacements, Drift.

Linear dynamic analysis of high-rise irregular structures with or without LFRS & frictional damper