Story Shear Research Articles

Seismic Response of Stiffness Irregularity at Ground Floor with and without Shear Walls

In today's scenario, one of the greatest challenges for structural engineers is designing and constructing seismic-resistant structures. Seismic activity, or earthquakes, poses a significant threat to civil engineering structures, and ensuring that buildings can withstand the forces generated during an earthquake is crucial for public safety and infrastructure resilience. Irregular configurations, whether in the building's floor plan or its elevation, are widely acknowledged as significant contributors to failure during seismic events. These irregularities can lead to uneven distribution of forces and stresses, compromising the building's ability to withstand the seismic forces and potentially resulting in structural failure. Soft storeys, typically located at ground levels for various functional purposes, pose challenges in seismic regions due to their lack of sufficient lateral load-resisting elements resulting in excessive lateral deformation and collapse during intensive earthquakes. Hence, the present study investigated the seismic response of irregular reinforced concrete structures possessing stiffness irregularity at ground floor with and without shear walls. A ten-storey regular frame is modified by incorporating vertical irregularity in elevation by increasing the height of the ground floor. The complete structural analysis and modeling are carried out by using the software ETABS 2020. The Time History method is applied, and the study is focused on seismic zones V in India. The performance of structures are compared based on criteria such as storey displacement, storey drift, storey shear and overturning moment. The results lead to the conclusion that a building structure exhibiting stiffness irregularity is prone to instability which is indicated by higher displacement and drift values. Structures incorporating shear walls have demonstrated greater stability compared to structures without shear wall as they exhibited higher base shear values and experienced a reduction in lateral displacement by more than 40%. The presence of shear walls also has enhanced the stability and strength of the structure, showing a linear response during critical earthquakes.

Seismic Parametric Analysis of RC Multi-Storied Buildings with and Without Fluid Viscous Dampers

Earthquakes are enormous natural disasters that increase the energy within the structural system, causing catastrophic destruction. Various control systems, such as passive, active, hybrid, and semi active control systems, can be used to dissipate this unwanted energy. The fluid viscous damper is one such dissipation device used in this study. The goal of this project is to use a fluid viscous damper to lessen the seismic response of the Symmetrical and unsymmetrical G+9 structure in ETABS2017. To obtain the seismic response with and without a fluid viscous damper, ETABS2017 was used to analyse symmetrical and unsymmetrical structures with and without a fluid viscous damper. The analysis takes into account nonlinear temporal history, which is derived using fast nonlinear analysis of Electro data. The position and function of dampers are discussed in this study. For seismic evaluation of buildings with and without fluid viscous dampers, the equivalent static approach and response spectrum method are utilised. The structure was examined utilizing ETABs 2017 programming, with seismic zone IV and medium soil (Type II) according to IS 1893-2016. The structure’s exhibition is assessed utilizing story removal, story shear, story float, and modular periods and frequencies. The objective of this study is to about the consequences of static and reaction range examination in both longitudinal and cross over bearings for damper development with and without damper structure.

A Comparative Study of Analyzing the Impact of Various RCC Building Shapes on Wind Performance

The analysis, design, and creation of high-rise buildings necessitate a comprehensive information of wind-induced vibration, a critical factor that considerably impacts structural integrity. In this context, the existing study undertakes an exploration of the results of wind load on diverse building shapes, aiming to envision the most structurally stable configuration for multi-storey structures. Focusing usually on L-form and H-form buildings, the studies conduct a comparative evaluation to assess how wind load influences those distinct shapes. Each case study represents a structure located in Wind zone IV with Terrain category II, adhering to the specs mentioned in IS 875(part-3): 2015 standards. Emphasizing reinforced concrete (RCC) framed structures, the research delves into the repercussions of wind loads on critical parameters including maximum shear force, bending moment, and storey displacement. The resulting data is meticulously presented through tables and charts, elucidating the overall performance metrics for every case (H-shape and L-form) in terms of storey displacement, shear force, bending moment, and axial force. Eventually, an intensive evaluation is conducted to determine any disparities in structural behaviour and reaction to wind loads a number of the various constructing shapes, providing precious insights into most efficient design concerns for enhancing structural stability and resilience in excessive-rise constructions.

Seismic Vulnerability Assessment of Reinforced Concrete Educational Buildings Using Machine Learning Algorithm

The main objective of this paper is to assess the vulnerability of reinforced concrete (RC) educational buildings in Dhaka city to seismic activity by utilizing machine learning (ML) algorithms. There are three main stages in traditional seismic vulnerability assessment: rapid visual assessment (RVA), preliminary engineering assessment (PEA), and detailed engineering assessment (DEA). The conventional three‐step evaluation process for determining the seismic vulnerability of existing buildings is time‐consuming and expensive, especially when dealing with a large building stock or a city. This study focuses on using an ML‐based approach to evaluate seismic vulnerability, specifically in terms of the story shear ratio (SSR), which serves as the risk index. The main concept is the utilization of RVA data to obtain analytical results (SSR). The dataset utilized in this study comprises RVA data for 268 buildings and corresponding PEA data for the same 268 buildings. The RVA data include the construction year, condition, typical floor area, number of stories, total floor area, additions, alterations, redundancy, pounding, and irregularities. The PEA data comprise SSR, which was generated from linear dynamic analysis. These data were collected from the Urban Resilience Project of Rajdhani Unnayan Kartripakkha (RAJUK), which is the development authority of Dhaka. Random forest regression (RFR), support vector regression (SVR), and artificial neural networks (ANNs) are employed to determine the SSR of existing educational RC buildings. A comparative analysis for each model is also made. From the analysis results, it shows that RFR, ANN, and SVR achieved coefficient of determination (R2) of 20%, 25%, and 35%, respectively. Based on the findings from the three separate model analyses, it can be concluded that SVR produced the highest performance among the considered models.

Non-Linear Pushover Analysis Of RCC Framed Structure By Providing Fluid Viscous Dampers At Different Locations

The increasing need of shelter in urban cities due to overpopulated spaces and land inadequacy people are forced to keep space and their needs strictly limited. High-rise buildings are the best solution for providing people spaces for living and to work on. In this age of urban development and rapid modernization the need of high-rise structures is rapidly increasing. As structures have become higher, structural engineering has become more difficult to achieve appropriate stability criteria. In tall buildings, stiffness is the key to sustainability. Fluid Viscous Dampers (FVD) are one of the efficient solutions for tall structures. These are hydraulic devices that, when stroked, dissipate the energy placed on a structure by seismic events. The viscous dampers convert the kinetic energy of the structural movement into heat and then dissipate that energy into the air, thereby obeying the laws of physics through the conservation of energy. To determine effectiveness of FVDs as well as determine best location for FVDs in high-rise buildings subjected to seismic loads, the current research is being carried out.In this study twelve (12) RCC framed structures of 15 storeys of which four (4) are square shaped in plan, four (4) are rectangle shaped in plan with sides of ratio 1.5:1 and the other four (4) are rectangle shaped in plan with sides of ratio 2:1. These three (3) different shaped buildings considered are having approximately same plan area and damper positions. A floor-to-floor height 3m is taken. The buildings are located in Zone III. By using ETABS 2017 software, which helps to analyse and design the models, the analysis method used for this study is the Push Over analysis. This research work presents the results of an investigation on different parameters like Base shear, Modal mass participation, Time period, Storey Drift, Storey Shear and Storey Stiffness.

Near-fault ground motion effect on self-centering modular bracing panels considering soil-structure interaction

This study investigates the nonlinear seismic response behavior of self-centering modular steel bracing panel (SCMBP) systems subjected to near-fault ground motion records, considering the soil-structure interaction (SSI) effect. Analytical formulas for the load-displacement relationship of an SCMBP were validated through nonlinear 3D continuum finite element analysis while a simplified 2D wireframe model utilizing a constitutive spring model was verified by the 2D refined finite element model and subsequently adopted for time history analysis of the SCMBP structures with SSI effect. Based on the nonlinear time history analysis of a 6-story prototype building subjected to a suite of near-fault ground motions, the prototype structure is found to be able to re-center itself even under near-fault ground motion scaled to the design basis earthquake (DBE) level while frame members remain undamaged, except for fuse devices. Additionally, SSI reduces inter-story drift ratios under both far-field and near-fault ground motions. The findings provide insights into the promising performance of using SCMBP systems as a seismic strengthening system for sites with potential SSI effects and near-fault earthquake impact. The findings of this study can be insightful to other self-centering systems with flag-shaped story shear hysteresis.

Effect of unreinforced masonry infills on seismic performance of reinforced concrete frame‐shear wall buildings

SummaryReinforced concrete (RC) shear wall buildings with unreinforced masonry (URM) infilled moment frames are common in India and neighboring countries. This study assesses the influence of the URM infills on their seismic performance. Fully infilled, open first‐storied, and bare frame versions of a 25‐story shear wall building are considered. Multiple stripe analysis is conducted at five return periods to estimate their performance. Fragility functions for the collapse prevention limit state, which is based on seven engineering demand parameter exceedance thresholds, are generated and compared. The presence of infills (full or partial) is observed to have an overall positive effect on the performance of the RC frame‐shear wall buildings. The performance of the open first‐story building was comparable to that of the fully infilled building. The ratio of story shear carried by the moment frames and shear walls is studied at all return periods to understand the variation in frame shear wall interaction with increased damage for each building. In the case of buildings with infills, the frames carry a higher proportion of story shear at lower return periods. For all three buildings, the fraction of story shear carried by moment frames increases along the height of the building.

Structural Behavior Comparison on Earthquake Resistance of High-Rise Mall Building (Framed Structure,Flat Slab and PT Flat slab)

The rate of urban population growth and the amount of available space had a significant impact on the construction of high-rise mall buildings in developing countries like the USA, UK, Australia, and Hong Kong. These high-rise mall constructions may be constructed using a variety of structural techniques. Today, RC Frame structures are often employed in constructing. Usually, these structures are employed to counteract the sizeable moments brought on by applied stresses. On the other hand, flat slab structural systems, in which the slab is directly supported by columns, have lately been adopted in many buildings because they have the advantage of greater clear floor-to-floor heights to satisfy the economical, easier form-work, quicker construction duration, and architectural needs. On the other hand, with a post-tensioned slab, the PT flat slab Structural System uses high-strength tensioned steel strands to compress the slab, maintaining the bulk of the concrete in compression. When compared to RC framed structural system, this results in a very efficient construction that minimizes partial consumption and reduces the economic span range. Three cellar+Ground+9 higher floors structural models of a high rise mall building with RC framed structure, flat slab, and PT flat slab structural system arrangement are taken into consideration in the current study. The study is completed by taking into account seismic zone II and type I soil condition, and it takes into consideration the susceptibility of purely RC framed structures, solely flat slab, and completely PT flat slab systems. The structural behavior of an RC-framed structure, a flat slab, and a PT flat slab are being compared for earthquake loads. The response spectrum approach is used to do the analysis.With the use of analytical tools, parameters such as storey displacement, storey drift, base shear, and storey shear are calculated. The findings are then compared between three structural system.

The use of steel X-bracing combined with shear link to seismically upgrading reinforced concrete frames

This study examines the feasibility of utilizing steel concentrically X-bracing rigidly connected to shear link to retrofit seismically defected reinforced concrete (RC) frames. It involves examining the lateral behavior of two hypothetical frames strengthened using this proposed system, a single story-single bay RC frame, and a five-story RC office building. For the former, both elastic and inelastic push-over analyses were performed to examine the lateral behavior of strengthened and original RC frames, while the original and strengthened five-story frames were analyzed under the action of monotonically increasing lateral loads and nonlinear time histories. In detailing the strengthening scheme, procedure complying with the capacity design concept was adopted whereby the shear links were detailed to yield prior to RC frames structural elements to reduce the demand on them. The stiffnesses, strengths, and plastic hinging formation patterns for original and strengthened frames under the action of different loading conditions were determined and evaluated. Story shears and maximum story displacements were recorded and examined. It was concluded that this system is feasible for seismically strengthening the defected RC frames. Guidelines for detailing this scheme were provided within the context of this research study.

Seismic Performance Assessment of RCC Building with Podium

With the advancements in structural engineering, seismic performance of buildings can be adjudged on the basis of performance-based techniques. This paper presents the performance based seismic evaluation of buildings with podiums for varying ratios of tower area to podium area. The structural system of the building consists of shear walls and moment resisting frames. Buildings with podiums have been designed and analysed with and without connection between the tower portion and the podium portion for Seismic Zone IV, by carrying out response spectrum analysis as per IS 1893-2016. The structural responses have been compared in terms of diaphragm forces, base shear, time period, storey stiffness, storey shear, storey displacement etc. for the variations in number of podiums i.e., single, double & three podium levels. Performance-based seismic evaluation of the buildings has been carried out with podium and tower as a connected unit with varying ratios of 0.35, 0.45, and 0.55 of tower area to podium area i.e., by keeping the tower area constant and increasing the podium extents. Pushover analysis is carried out and comparison is done for the influence of podium on the non-linear behaviour of the structures.

Seismic studies on energy dissipation device performance for irregular steel structure in different soil conditions using ETABS

Earthquakes are sudden loads that occur and cause low to severe damage to the structure. Based on the intensity of an earthquake, the zones are divided into II, III, IV and V as per IS code 1893:2016(Part-1). Regular, Stiffness Irregular and Mass Irregular G+7 steel building is designed for four zones in ETABS software. Linear Static and Linear Dynamic analyses are performed on all zones for different conditions of soils. In this work, a steel G+7 storeyed structure is developed in ETABS and subjected to seismic loading. For Energy dissipation, the dampers are installed in the building and the analysis process is done. In this research, seismic study is carried out on various models using energy dissipation devices such as fluid viscous damper. The different irregularities in a building in four zones are analyzed with and without using dampers. The study is concluded by comparing displacement and storey shear values for different models.

Comparative Study of the Seismic Behaviour of G+20 Storey Building for Unsymmetrical Plan Area Using Light Weight Concrete and Normal Weight Concrete

Abstract: This research examines and compares the performance of structural lightweight concrete (SLWC) made with scoria and normal weight concrete (NWC), and normal and light weight concrete (NAL) in multi-storey buildings. A G+20 multi-storey unsymmetrical plan building is analysed using the response spectrum method with SLWC and NWC. Bending moment, shear force, storey shear, axial force, storey drift, and storey displacement are considered. The results show that SLWC can be used to reduce the weight of buildings without sacrificing strength or performance. This can lead to significant cost savings on construction and materials

Analysis of Multi-Storied Buildings with the Use of Coupled Shear Walls

The present study focuses on the use of coupled shear walls with and without dampers for resisting seismic loads. Multistory structures with and without shear walls are analysed. Different parameters, such as the structure's base shear, storey drift, storey displacement, storey stiffness, and storey shear, are evaluated, and a comparative study is performed. It is observed that coupled shear walls with fluid viscous dampers reduce storey drift by 24% and storey displacement by 45% when compared to buildings without shear walls. A coupled shear wall with a damper has a 29% higher stiffness than a coupled shear wall without a damper, thus performing effectively in resisting lateral forces induced by an earthquake.

Lateral Load and Design Disparity between BNBC1993 and BNBC2020

Building codes are the minimal requirements for design and construction to assure a safe and resilient structure. A building code recognized as the Bangladesh National Building Code (BNBC) is existent in Bangladesh (BD), just like in other developing nations. It's now a difficult task to comply with the code because of the extensive update after two decades. The main goal of this work is to compare the analytical and design requirements for lateral loads between BNBC2020 and BNBC1993. To do so, a large number of structural models are assessed using ETABS following the considered code procedure at different locations in the country. It also compares the lateral load parameters such as zone coefficient, wind velocity, building period, story shear, base shear, drift, deflection, reinforcement ratio etc. The parametric comparison of the outcomes has demonstrated that BNBC2020 is more conservative and boosts the safety factor against lateral loads. Engineers will be able to comprehend the differences in lateral load between these codes after perusing this study.

Seismic Assessment of High-Rise Buildings Having Transfer Elements

This paper investigates the seismic behavior of high-rise buildings having transfer elements. Three constructed reinforced concrete (RC) buildings having either transfer slabs or transfer girders were analyzed using the response spectrum (RS) and time-history (TH) methods. For each building, the story shear, bending moment, displacement, drift, and time period were obtained. Furthermore, pushover analysis (POA) method was conducted to evaluate the capability of these buildings to resist the expected seismic loads. Results of the studied buildings showed that, the base shears obtained using pushover analysis are ranging between 50% to 83% of those calculated using the static approach. In addition, the response modification factors (R) for these buildings were calculated to show their sensitivity due to the irregularity of buildings. For the studied cases in this research, the R values given in the building codes were overestimated for the cases with transfer slabs and underestimated for cases with transfer girders.

A Comparative Study of the Seismic Behaviour of G+20 Storey Symmetrical Buildings Constructed with Light Weight Concrete and Normal Weight Concrete

Abstract: Concrete with a density of less than 2000 kg/m^3 is considered lightweight concrete. Structural lightweight concrete (SLWC) is used to reduce the dead load of concrete structures. The purpose of this research is to examine and compare the results of SLWC made with scoria and normal weight concrete (NWC) and normal and light weight concrete(NAL) multistorey buildings. Multistorey buildings are often constructed of ordinary concrete, steel, and other materials. They are subjected to heavy loads, requiring heavy construction that may not be cost-effective. In this paper, a G+20multistorey plan symmetrical building is analysed using the response spectrum method with SLWC and NWC. Bending moment, shear force, storey shear, storey drift, and storey displacement are considered. The results of the NWC and SLWC and NAL buildings are compared . Concluding the research work that when comparing symmetrical plan area cases of normal concrete, light weight concrete and combination of normal and light weight concrete for all the result parameters, light weight concrete seems to be very efficient and most favorable case. Hence should be recommended when this type of construction procedure will be adopted, i.e. always use building with lightweight concrete

Linear and Nonlinear Dynamic Analysis of Reinforced Concrete Building with V Shape Steel Bracing

In this study, the RC-MRCBFs were used with V braced frame. The core objective of this examination is to understand the earthquake behavior of the RC-MRCBFs in steel V braced frames. Response spectrum analysis (RSA) is used to understand the seismic performance of the steel braced and un-braced RC frames. Total 12 steel braced RC frames and 12 un-braced frames for all 4 story, 8story, 12 stories and 16 stories are studied and observed the seismic parameter such as fundamental time period (FTP), top story displacements, inter-story drift, base shear and story stiffness of the structures. After studying the parametric study of the 4 to 16 story buildings with a linear and nonlinear analysis tool it was observed that to get the effective braced frame with expected failure mechanism, ductility, the columns should be designed such that, they resist at least 50% base shear contributions. It is observed that using the steel V bracing in the low rise to mid-rise buildings, improves the seismic behaviors of the structures. The steel bracing reduces the maximum top story displacements, drift and time period of the building and increases the seismic base shear demand, stiffness of the structures. The result shows that as increasing the base shear contribution in the columns, the drift and displacement of the story increases and base shear decreases. Key Words: Response Spectrum Analysis, displacement, Maximum storey drift, Storey shear, Storey stiffness, braced frame, RC buildings.

Seismic Analysis of RC Buildings with and without Shear Wall using NBC

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.

Comparative Analysis of Multistory Building of Conventional Slab and Grid Slab with Shear Wall and Bracings on Seismic Zone V

Abstract: In the present study, response spectrum analysis is performed on various structural configurations using ETABS software. The primary objective is to investigate the seismic behaviour and response of different models subjected to earthquake forces as per the IS 1893:2002 standard. The structural configurations considered are as follows: Regular Structure: A basic building model with a regular grid of columns and beams. Grid Slab: The regular structure with the addition of a grid-type concrete slab system. Grid Slab with Shear Wall: The grid slab model augmented with shear walls. Grid Slab with Bracings: The grid slab model equipped with diagonal bracings. In the present project G+10 building having 3m storey height is considered. By considering the medium soil. Here the seismic analysis is conducted for the seismic zone Ⅴ as per IS 1893:2002. The analysis focuses on evaluating displacement, story shear, and auto lateral loads under seismic conditions

Equivalent Lateral Forces for Design of Multistory Sliding Base Structures

The sliding base (SB) technique is an efficient and economical approach to mitigating seismic damage of low-rise buildings in rural areas. Based on the previous work on single-story SB structures, this study investigates the earthquake forces acting on multistory SB structures. Response history analyses of SB structures subjected to three-component earthquake excitations were performed. The computed results indicate that the increase in the number of stories tends to reduce the mean value of the peak base shear but has little influence on the coefficient of variation of the peak base shear. The peak story shears of a multistory SB structure subjected to an earthquake ground motion are reached at different time instants for different stories. The distributions of the equivalent lateral forces for SB structures with different story numbers follow the same trend, and the equivalent lateral forces tend to concentrate at the upper floors as the normalized peak ground acceleration and mass ratio increase. Simplified equations for computing the distribution of equivalent lateral forces were developed for design purposes.