scholarly journals Seismic Analysis of Twin Tower Structures

Author(s):  
Shruti Nagar

Abstract: In today's world, new concepts for skyscraper construction are required to mitigate the negative effects of seismic and wind forces. Since the world's most populous cities are experiencing land shortage, in this area tall buildings act as very important roles in modern cities. Due to the speedy increase in population and reduction in accessibility of land, vertical accommodation is obtaining a lot of preference which is resulting in vertical town development. Nowadays tall buildings rise higher and higher, with more and more complex and individual plan and elevation, such as multi-tower buildings. The multi-tower buildings refer to two or more towers connected with one large podium or conjunction parts at different levels. It is well known that the podium and conjunction parts shall be designed very carefully to meet the internal force and thedeformation between towers. Nowadays, when building multistory building, height is not the only pursuit. More unique forms are in trend to show the rich connotation and vitality of buildings. Connected twin tower structures conform to these requirements, and many connected structures in different forms have been or are being built in recent years. In present research work considering effects of influencing parameters like the height of the tower, connection with podium and depth of podium with two parallel towers (Twin-Tower). The main objective of this study is to analyze twin tower structure G+4 podium+25 floor building using linear dynamic earthquake analysis. We have considered four models with different combinations of twin tower with podium to achieve desirable results in terms of story drift, displacement and base shear under seismic forces for seismic zone IV and medium type of soil using Response Spectrum Analysis with the help of ETABS v19 software. Keyword: Twin Tower Structure, Podium, Etabs Software Packages.

In the present study, the behavior of plan irregular (C, T, I shaped irregular building and regular building) tall building subjected to the seismic load alongwith the importance of infill wall is considered. The modeling and analysis of (G+14) storey structure for seismic zone (III), soil type (II) with importance factor (1) and M20 grade concrete are carried out, by equivalent static and response spectrum method, as per IS 1893-2016(Part-1), using E-tabs 2015 commercially available software.. The results obtained are discussed in terms of base shear, storey displacement and storey drift. Many critical observations are drawn from the analysis. From these critical observations, it is concluded that, in almost all shape of plan irregular tall buildings, storey displacement and storey drift are found to be more in bare frame when compared with infill frame, whereas the base shear will be less in bare frame compared with infill frame. However, the results obtained amongst the different shapes, indicates that C, I and regular shaped tall building are yielding lesser storey displacement and storey drift compared to T shaped building. Presence of infill walls will increase the stiffness of the frame.


2012 ◽  
Vol 39 (8) ◽  
pp. 867-877 ◽  
Author(s):  
Damien Gilles ◽  
Ghyslaine McClure

Structural engineers routinely use rational dynamic analysis methods for the seismic analysis of buildings. In linear analysis based on modal superposition or response spectrum approaches, the overall response of a structure (for instance, base shear or inter-storey drift) is obtained by combining the responses in several vibration modes. These modal responses depend on the input load, but also on the dynamic characteristics of the building, such as its natural periods, mode shapes, and damping. At the design stage, engineers can only predict the natural periods using eigenvalue analysis of structural models or empirical equations provided in building codes. However, once a building is constructed, it is possible to measure more precisely its dynamic properties using a variety of in situ dynamic tests. In this paper, we use ambient motions recorded in 27 reinforced concrete shear wall (RCSW) buildings in Montréal to examine how various empirical models to predict the natural periods of RCSW buildings compare to the periods measured in actual buildings under ambient loading conditions. We show that a model in which the fundamental period of RCSW buildings varies linearly with building height would be a significant improvement over the period equation proposed in the 2010 National Building Code of Canada. Models to predict the natural periods of the first two torsion modes and second sway modes are also presented, along with their uncertainty.


Author(s):  
Ashutosh Shrivastava ◽  
Rajesh Chaturvedi

Nowadays, as in the urban areas the space available for the construction of buildings is limited. So in limited space we have to construct such type of buildings which can be used for multiple purposes such as lobbies, car parking etc. To fulfill this demand, high rise buildings is the only option available. The performance of a high rise building during strong earthquake motion depends on the distribution of stiffness, strength and mass along both the vertical and horizontal directions. If there is discontinuity in stiffness, strength and mass between adjoining storeys of a building then such a building is known as irregular building. The present study focuses on the seismic performance of regular and vertical irregular building with and without masonary infills. In the present study G+11 building is considered for the analysis with modelling and analysis done on ETABS software v17.0.1. The earthquake forces are calculated as per IS 1893 (part 1): 2016 for seismic zone III. The width of strut is calculated by using equivalent diagonal strut method. Total five models are considered for the analysis i.e. regular building with bare frame, regular building with masonary infill, soft storey building with open ground storey, mass irregular building with masonary infill and vertical geometric irregular building with masonary infill. The non-linear static analysis (pushover analysis) and linear dynamic analysis (response spectrum analysis) are performed for all the models and thereby compare their results. From analysis, the parameters like performance point, time period, maximum storey displacement, maximum storey drifts, storey shears and overturning moments are determined and also comparative study is done for all the models. From the comparison, it is observed that the vertical geometric irregular building shows better performance under seismic loading and bare frame building shows inferior performance. Moreover, the performance of masonary infilled frame building is f


Author(s):  
Harsh Joshi

Abstract: Due to sloping land and high seismically active zones, designing and construction of multistory buildings in hilly regions is always a challenge for structural engineers. This review paper focuses to establish a review study on the Possible Types of building frame configuration in the hilly region and he behavior of Such building frames under seismic loading conditions, and (3) The recent research and developments to make such frames less vulnerable to earthquakes. This paper concludes that the dynamics characteristics of such buildings are significantly different in both horizontal and vertical directions, resulting in the center of mass and center of stiffness having eccentricity at point of action and not vertically aligned for different floors. When such frames are subjected to lateral loads, due to eccentricity it generates torsion in the frame. Most of the studies agree that the buildings resting on slanting ground have higher displacement and base shear compared to buildings resting on plain ground and the shorter column attracts more forces and undergoes damage when subjected to earthquake. Keywords: Building frame configuration, Seismic behavior, Dynamic characteristics, Response spectrum analysis, time history analysis.


2021 ◽  
Vol 1197 (1) ◽  
pp. 012039
Author(s):  
Avinash Kalamkar ◽  
N.H. Pitale ◽  
P.B. Patil

Abstract The use of multiple tuned mass dampers (MTMDs) to monitor earthquake response of tall buildings is investigated. The MTMDs are located in three locations in the reinforced concrete (RC) structures. The time domain seismic analysis is performed on Etabs Software using imperial Earth movement used to analyze contemporary history. The performance of the MTMDs is compared to that of a TMD on the top floor, a TMD on the third and fifth floors, a TMD on each floor, and no TMD. The base shear vs time and displacement parameters were examined, and it was determined that the MTMDs on each floor are better for the building’s seismic response. Furthermore, it has been discovered that MTMDs are more powerful than STMDs.


Earthquake is an unexpected and expensive disaster for both livelihood and economy. In the modern day construction, there has been a lot of importance to make the structure resistant against lateral loads for multi storied building. Shear walls are an option of lateral load resisting system. The Concept of designing shear wall is to provide building structure with sufficient strength and deformation capacity to sustain the demands imposed by lateral loads with adequate margin of safety. The study focuses on effect of shear wall on R.C. building at different heights. For this purpose five models of different heights 15m, 30m, 45m, 60m and 75m and with different aspect ratios of 1.33, 0.66, 0.44, 0.33 and 0.26 respectively have been considered. All the models were designed for seismic zone V. For analysis purpose response spectrum method of analysis is considered as per IS: 1893-2002. The comparative study has been done for base shear, storey displacement, storey drift and storey stiffness. Utilization of shear walls when placed at corners of the building of low aspect ratio in high rise buildings is more effective compared to the low rise buildings of higher aspect ratio, as it gives the larger base shear and lesser displacement. The storey stiffness and storey drift is greatly improved when shear wall is placed at corners of the building


2021 ◽  
Vol 1 (1) ◽  
pp. 1-7
Author(s):  
Anjeet Singh Chauhan ◽  
◽  
Rajiv Banerjee

The RC buildings' construction has increased in the preferred location of north & eastern hilly areas during the last few decades due to population increase, urbanization, and tourists. The buildings located in the hilly areas are more susceptible to seismic loading as compared to the location of the flat surface building. The shape of the building on the sloping ground differs from the flat surface situated buildings. So, the construction of the building on hilly areas are irregular both vertically & horizontally, thus this type of building is susceptible to severe damage when applied to the seismic condition. The column of the base storey having unequal height due to sloping ground. In this study, the behaviour of a 10 storey stepback building with mass and diaphragm irregularity on the sloping ground is analysed in seismic zone V by Response Spectrum. The analysis of the building is carried out by Etabs software as per IS 1893:2016 to compare the building based on their dynamic response and also identify the vulnerability frame in the sloping ground.


Author(s):  
Kapil Shankar Soni

Abstract: Infill walls are inevitable components of any structure to create dispassion between interior space and external condition. In general, there are some prevalent openings inside the infill walls because of practical needs, architectural observations or aesthetic inspections. In current design practice, strength and inflexibility contribution of infill walls aren't thought of. However, the presence of infill walls may impact the seismic reaction of structures exposed to earthquake loads and cause a conduct which is not the same as that estimated for a bare frame. Additionally, partial openings inside infill walls are significant parameter prompting the seismic behaviour of infilled frames in this manner retreating lateral stiffness and strength. In this study is proposed to compare various models of buildings considering the openings (10% of surface area) at different locations in the infill walls for the seismic behaviour. A G+13 residential building is considered in Zone III with soil type II and analysis is carried out by Response Spectrum Method. Various parameters are considered such as Natural Time period, Base shear, Storey displacement, Storey drift and Storey stiffness were studied. The comparative study could simplify designers and code developers in selecting and recommending appropriate analytical models for estimating strength, stiffness, failure modes and other properties of infill frames with openings. Keywords: Residential Building, Openings Infill Wall, ETAB Software, Natural Time Period, Base Shear, Storey Shear, Storey Displacement, Storey Drift, Storey Stiffness.


Seismic analysis of structural systems with floor diaphragms has been a requisite in the recent past. The duty of a structural engineer is to be prudent about the behavior of every structural system adopted. Amongst the structural systems that are adopted world over, diaphragm with rigid and semi-rigid floor plate are adopted widely in the analysis. This research focuses on the backstay effect i.e. podium structural interaction with the tower area and consideration of retaining wall as increment of lateral stiffness as specified in latest tall building code IS6700:2016 for low and high rise structures. In the current study models were prepared with low to high rise storeys with rigid and flexible diaphragms considering backstay diaphragm placing tower at center and corner. The models were subjected to seismic forces; response spectrum along with the combination of the gravity loads. The structural responses like natural periods, base shear, displacement and inter storey drift were also studied.


The offshore jacket platforms are primarily installed in the large oceans mainly for drilling the crude oil, carbohydrates and production of electricity. The current studies emphasize on the structural performance of offshore deck jacket platform with different bracing systems. Earthquake analysis has been performed to calculate the seismic responses, with the help of bracings to control the seismic induced vibrations of the jacket platforms. For this study, a jacket platform made up of steel members has been modeled and then analyzed under earthquake and wave loadings. This paper mainly deals to compute and compare the seismic behavior of offshore steel deck platform using SAP 2000 v20 software with bracing in the horizontal plane and bracing in both horizontal and vertical planes. The total number of 8 models has been analyzed in the SAP2000 software with bracing i.e. X, V, Inverted V and K in the vertical plane and bracing i.e. X, V, Inverted V and K in both horizontal and vertical plane. A relative study has been carried out in Time period, deck displacement and base shear. Seismic analysis using linear static, i.e. Equivalent static method (ESA) and linear dynamic, i.e. Response spectrum method (RSA) has been performed. Further deck displacement, time period and base shear are determined by Equivalent static method and Response spectrum method for various types of bracing models in both horizontal and vertical planes. Among the all various types of bracing models, Inverted V bracing in the vertical plane is found to be the optimum model among all other models.


Sign in / Sign up

Export Citation Format

Share Document