Comparison between fixed base and isolated base in seismic response of high-rise buildings: a case study

2020 ◽  
Vol 6 (4) ◽  
pp. 204
Author(s):  
Anas M. Fares

In this study, the influence of soil condition under the isolated and fixed bases is studied by using ETABS 16 software for the high-rise regular building. A regular building with 10 floors is modeled and the results are obtained for story displacements, story shear forces and spectral acceleration according to Uniform Building Code 97 (UBC-97) code. The time history analysis has been performed by using 1999 Izmit earthquake record. 3 types of soil which had different stiffnesses are considered in this study. The results show that the value of base shear increases when the soil stiffness decreases. It also noticed that the spectral acceleration is larger in soft soil condition than that of other soil conditions; and this confirms that the structural response spectrum is associated with the soil condition. In addition, when using base isolated building the drift of lower floors will be larger than that of using base isolated, but in the upper floors the drifts of fixed base building will be larger than that of the isolated base building. Finally, time history method in the seismic design will produce base shear less than that from equivalent static method, so calibration factor for design purpose shall be used.

2020 ◽  
Vol 156 ◽  
pp. 05026
Author(s):  
Fauzan ◽  
Afdhalul Ihsan ◽  
Mutia Putri Monika ◽  
Zev Al Jauhari

The amount of potential investment in Padang City, Indonesia since 2017 attracted many investors to contribute to the city. One of the investments is a 12-story hotel that will be constructed in By Pass Street of the city. The hotel is located in a high seismic zone area, so the seismic base isolation has been proposed to be used in the hotel building. The main aim of using a seismic base isolation device is to reduce the inertia forces introduced in the structure due to earthquakes by shifting the fundamental period of the structure out of dangerous resonance range and concentration of the deformation demand at the isolation system. An analytical study on the Reinforced Concrete (RC) hotel building with and without rubber bearing (RB) base isolation is carried out using the response spectrum and time history analysis methods. The results show that internal forces and inter-story drift of the building with high damping rubber bearing (HDRB) are lower than that of the fixed base with a remarkable margin. From this study, it is recommended to use the HDRB base isolation for medium and high rise buildings with soft soil in Padang City, Indonesia.


2020 ◽  
Vol 9 (1) ◽  
pp. 1986-1990

The structural response of any structure is the result of various dynamic phenomenon which lead to vibrations or shaking of the structure , depending on the duration of the ground motion, its frequency and time period. In the present work, dynamic analysis of a typical steel silo is done by using linear Time History Analysis and Response Spectrum method for earthquake Zone V as per Indian code. Two analyses are carried out namely, Time History Analysis (THA) and Response Spectrum Analysis (RSA) using STAAD.ProV8i software. The Load combinations are worked out as per IS-1893-2002. The results in terms of Fundamental natural period, Design Base shear, Lateral Displacements, are compared for the two different silo models considered in the present study.


2019 ◽  
Vol 2 (1) ◽  
pp. 153-164
Author(s):  
Umesh Jung Thapa ◽  
Ramesh Karki

In this paper, study of the response (base shear, time period, storey drift, storey displacement) of a structure is done for the tall building including basement with fixed base and with pile foundation considering Soil Structure Interaction (SSI). Finite element based program ETABS2016 v16.1.0 is used for the analysis of the superstructure. Seismic analysis is done to get the dynamic response of superstructure for two types of model,one model is with fixed baseand second is Model with Winkler spring for Chhaya Center, Thamel, a high rise building with 14 story including double basements. Itisobserved with the consideration of Soil Structure Interaction (SSI). The soil is replaced by spring and assigned at joints. El Centro earthquake (1940) is used for time history analysis. The response obtained due to SSI effect is compared with fixed based model. Results of analysis presented include the comparison of natural periods, base shears, displacements and overturning moment. It is observed that the natural periods increase and the base shears decrease as the base become more flexible.


2019 ◽  
Vol 5 (2) ◽  
pp. 123
Author(s):  
Jonie Tanijaya

Earthquakes are natural events caused by tectonic plate movements and it is unpredictable. Thus, the building design regulation has an important role in ensuring the Earthquake resistant structure. A commonly used method is the response spectrum method. For different soil types, the value of the design spectra may increase or decrease. Therefore this study aims to determine the effect of soil type on the strength of reinforced concrete structures, especially the building behavior and structural internal forces. Analysis results show that the increase of base-shear value of Makassar is about 34% and 103% for medium soil and soft soil condition compared to hard soil. The increase of beam negative moment is about 27% to 39% in soft soil compared to hard soil, while the value is about 8% to 14% in medium soil compared to hard soil. The increase of beam positive moment varies considerably between 8% to 50%. The increasing moment is directly proportional to the required reinforcement area of the beam. Demand capacity ratio of column has also increased about 10% to 35% for medium soil and soft soil compared to hard soil.


CONSTRUCTION ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 93-101
Author(s):  
Saffuan Wan Ahmad ◽  
Muhammad Aimran Amzar Kamarudin ◽  
Wan Aniq Ridhwan Wan Ariffin

On the 5th June 2015, an earthquake hit Ranau, Sabah with a magnitude of 6.0 that caused 18 casualties and several injuries are one of the examples that show Malaysia is not safe from any seismic event. Most of the structure in Malaysia was designed not to include seismic action.  Furthermore, an area that has a high density of population such as in the central region (Klang valley) and several main cities in Malaysia has less available land to build landed housing and uses high-rise apartments as an alternative. High-rise buildings that are normally having problems with soft story mechanisms and plan irregularity which could lead to severe damage when earthquakes happen. This study aims to observe the response of high-rise buildings when under different earthquakes in the presence of shear walls. To achieve this objective two models were modelled and analyzed by using ETABS software, the one with a shear wall and the one with no shear wall. The methods used in this study were the response spectrum method and time-history analysis. In the end, the parameters observed were base shear, story stiffness, story drift, and story displacement. The observations highlighted that the effect of earthquake intensities shows a significant effect. The acquired results indicated that the building with the shear wall is more resistant and strong structures as compared to buildings without shear wall when undergoing seismic analysis.


2019 ◽  
Vol 1 (2) ◽  
pp. 87-102
Author(s):  
Zulfazly Putra ◽  
Johannes Tarigan

Abstract. The earthquake resistant steel frame structure is designed to be able to withstand large inelastic deformations in the case of an earthquake. The applicable regulations still allow the use of elastic design methods in the form of pushover analysis and time history analysis evaluation as the basis for the design. The building under consideration consists of six floors with the function as an office building. The location of the building is in Banda Aceh with soft soil conditions. The structural analysis used the help of the Extended Three Dimensional Analysis of Building System Program (ETABS). The method of analysis of steel portal structures used was pushover analysis. Analysis of the given load was static loading based on 1987 PPPURG, and earthquake dynamic loading used a variety of response spectrum procedure analysis based on SNI 03-1726-2012. Structural analysis was assumed to be the strong column weak beam concept. From the results of calculations, it is found that the steel portal structures (with and without braces) designed based on allowable interstory drift limits have met the requirements. The performance level of the steel portal structure without bracing was LS, while the performance level of the steel portal structure using bracing was IO. The largest amount of steel used in terms of weight was found in the case of a portal without braces.


2013 ◽  
Vol 756-759 ◽  
pp. 4482-4486
Author(s):  
Chun Gan ◽  
Xue Song Luo

In recent years, frequent earthquakes have caused great casualties and economic losses in China. And in the earthquake, damage of buildings and the collapse is the main reason causing casualties. Therefore, in the design of constructional engineering, a seismicity of architectural structure is the pressing task at issue. Through time history analysis method, this paper analyzes the time history of building structural response and then it predicts the peak response of mode by response spectrum analysis. Based on this, this paper constructs a numerical simulation model for the architecture by using finite element analysis software SATWE. At the same time, this paper also calculates the structure seismic so as to determine the design of each function structure in architectural engineering design and then provides reference for the realization of earthquake-resistant building.


2013 ◽  
Vol 788 ◽  
pp. 558-561
Author(s):  
Jian Qiang Wang ◽  
Wen Tao Ma ◽  
Min Jing Ma

Steel reinforced concrete composite structure which apply in the high-rise buildings, not only save steel, but also have excellent properties in fire prevention, anti-corrosion, and seismic performance, and improve the speed of construction, economic efficiency.This thesis based on the analyse of a steel reinforced concrete composite structure tower and the domestic and foreign experts study use Finite Element Analysis software SAP2000 analyze the dynamic Performance of the structure to draw the inherent vibration period and frequency of the structure. The structure is analyzed to obtain its deformation with different height of the structural elements under a small earthquake. Structure and component in elastic stage when suffur a small earthquake. Using the mode decomposition response spectrum method and method of linear time history analysis, the maximum horizontal displacements of the structural layer, the maximum inter-story displacement and the maximum inter-story displacement angle is obtained to see if the results within a predetermined range.


Author(s):  
Dion Marriott

This paper discusses the application of the Structural Performance factor (SP) within a Direct Displacement-Based Design framework (Direct-DBD). As stated within the New Zealand loadings standard, NZS1170.5:2004 [1], the SP factor is a base shear multiplier (reduction factor) for ductile structures, i.e. as the design ductility increases, the SP factor reduces. The SP factor is intended to acknowledge the better-than-expected structural behaviour of ductile systems (both strength, and ductility capacity) by accounting for attributes of response that designers are unable to reliably estimate. The SP factor also recognizes the less dependable seismic performance of non-ductile structures, by permitting less of a reduction (a larger SP factor) for non-ductile structures. Within a traditional force-based design framework the SP factor can be applied to either the design response spectrum (a seismic hazard/demand multiplier), or as a base shear multiplier at the end of design (structural capacity multiplier) – either of these two approaches will yield an identical design in terms of the required design base shear and computed ULS displacement/drift demands. However, these two approaches yield very different outcomes within a Direct-DBD framework – in particular, if SP is applied to the seismic demand, the design base shear is effectively multiplied by (SP)2 (i.e. a two-fold reduction). This paper presents a “DBD-corrected” SP factor to be applied to the design response spectrum in Direct-DBD in order to achieve the intent of the SP factor as it applies to force-based design. The proposed DBD-corrected SP factor is attractive in that it is identical to the SP relationship applied to the elastic site hazard spectrum C(T) for numerical integration time history method of analysis within NZS 1170.5:2004 [1], SP,DDBD = (1+SP)/2.


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.


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