Measured natural periods of concrete shear wall buildings: insights for the design of Canadian buildings

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):  
Anurag Kumar Pandey

Abstract: In This I have studied the seismic response of various types of slab in commercial buildings and their seismic behavior is studied. As we know every year uncountable number of earthquakes occur at different places, that means, small movements of tectonic plates occur all the time causing earthquakes. A seismic resistant designed building can provide safety for more people. slabs and roofs needed more columns if we design seismic resistant design but at some places like airport, shopping mall, commercial building more column can create some problem. To overcome this problem seismic design of grid slab or waffle slabs was comes out. Grid /Waffle slab consists of Concrete beams spaced at uniform intervals in perpendicular directions which are monolithically casted with slab and they are more safe in earthquake situation as comparison of to normal conventional slab. Keywords: Grid Slab, Earthquake Load , Response Spectrum , Storey Drift, Storey Displacement , E-Tab 2018 , Base Shear, Time Period , Mode Shapes.


Author(s):  
Ankur Verma

Abstract: Today, larger part of designs around us are built up concrete cement (RCC) outlined constructions. To forestall harm because of quake there is a need to foster powerful procedure to expand the strength and flexibility of elevated structures. Shear wall are steadier and more pliable and thus can bear more even loads. In this paper, we have proposed a relative report between block facade, shear divider and uncovered casing by using ETABS programming. This review is essentially centered around seismic conduct of G+12 building. The outcomes are talked about as far as base shear, sidelong relocation, story float, story solidness and normal period for every one of the three models. We find that shear wall has least parallel uprooting and least time span when contrasted and block facade and uncovered edge. Likewise, we track down that the shear divider model is more adaptable because of lesser float when contrasted and different models. The upsides of removal and float for shear wall is likewise not as much as block facade since the tallness of the structure increments. Keywords: shear wall, bare frame, Response spectrum, Earthquake, ETABS


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 8 (4) ◽  
pp. 3633-3637

Precast concrete structures are widely used in construction. It consists of prefabricated elements casted in industry and connected to each other to form a homogeneous structure. Connections function is to transfer moments and axial forces. Many engineers assume precast connection as pinned, but in reality, they are semi-rigid connections that transfer forces to other members. Lack of design and detailing of connection leads to improper behaviour of the structure, which then leads to the collapse of the building. Past earthquake studies show that many precast buildings performed poorly, and the main reasons were connections. This paper mainly focuses on understanding the seismic behaviour of mid-rise i.e seven-storey precast reinforced concrete buildings with various beam-column joints i.e rigid, semi-rigid, pinned and column-base supports i.e, fixed and hinged supports. Building is modelled and analyzed using ETABS v17 software. Rotational stiffness of precast billet connection is adopted for modelling of semi-rigid beam-column connections. Response spectrum and modal analysis are carried out. Results of displacements, storey drift, storey shear, storey stiffness, base shear, time periods and first mode shapes of models are discussed. It is observed, precast reinforced concrete building models with semi rigid connection performs better than building models with pinned connections and building models with fixed supports reduces the structural response to a great extent.


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.


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


Author(s):  
Gajagantarao Sai Kumar ◽  
Purushotham Rao ◽  
Partheepan Ganesan

Multi-storey buildings tend to get damaged mainly during earthquake. Seismic analysis is a tool for the estimation of structural response in the process of designing earthquake resistant structures and/or retrofitting vulnerable existing structures. The principle purpose of this work is to analyze and design a building with a shear wall and also to find the appropriate position of shear wall that result in maximum resistance towards lateral forces and minimum displacement of the structure. In this study, a G+7 multi-storey building of 15 m ×20 m in plan area has been chosen and modelled using ETABS. The developed model was validated by solving manually and the results were validated in ETABS. Thereafter, 4 different new plans were modelled in ETABS located in the same earthquake zone area. These plans have shear wall concepts are implemented on the building at four different locations. Seismic, vibration and response spectrum analysis were performed on these structures. Salient parameters such as storey stiffness, storey displacement and storey drift were computed using the ETABS model. These were compared with that of the frame having no shear walls. By comparing the results obtained at different shear wall locations, the best plan with the shear wall having minimum lateral storey displacement and maximum stiffness is suggested for this location.


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.


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