scholarly journals A note about base shear

1969 ◽  
Vol 2 (2) ◽  
pp. 171-175
Author(s):  
A. L. Andrews
Keyword(s):  
New Zealand ◽  
Seismic Analysis ◽  
Rational Method ◽  
Base Shear ◽  
Vibration Period ◽  
Shear Coefficient ◽  
Mode Vibration

Californian and Japanese seismic analysis rules have in common with New Zealand seismic rules a relation between the base shear coefficient and the prime mode vibration period. The prime mode period may be assessed by a rational method or it may be approximated.

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
Keyword(s):  
Seismic Analysis ◽  
Dynamic Properties ◽  
Response Spectrum ◽  
Shear Wall ◽  
Mode Shapes ◽  
Design Stage ◽  
Base Shear ◽  
Period Equation ◽  
Input Load ◽  
Structural Engineers

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.

Determination of seismic design forces by equivalent static load method

2003 ◽  
Vol 30 (2) ◽  
pp. 287-307 ◽  
Author(s):  
JagMohan Humar ◽  
Mohamed A Mahgoub
Keyword(s):  
Seismic Design ◽  
Static Load ◽  
Base Shear ◽  
Uniform Hazard Spectra ◽  
Uniform Hazard Spectrum ◽  
Higher Mode Effects ◽  
Mode Effects ◽  
Equivalent Static Load ◽  
Adjustment Factors ◽  
Mode Vibration

In the proposed 2005 edition of the National Building Code of Canada (NBCC), the seismic hazard will be represented by uniform hazard spectra corresponding to a 2% probability of being exceeded in 50 years. The seismic design base shear for use in an equivalent static load method of design will be obtained from the uniform hazard spectrum for the site corresponding to the first mode period of the building. Because this procedure ignores the effect of higher modes, the base shear so derived must be suitably adjusted. A procedure for deriving the base shear adjustment factors for different types of structural systems is described and the adjustment factor values proposed for the 2005 NBCC are presented. The adjusted base shear will be distributed across the height of the building in accordance with the provisions in the current version of the code. Since the code-specified distribution is primarily based on the first mode vibration shape, it leads to an overestimation of the overturning moments, which should therefore be suitably adjusted. Adjustment factors that must be applied to the overturning moments at the base and across the height are derived for different structural shapes, and the empirical values for use in the 2005 NBCC are presented.Key words: uniform hazard spectrum, seismic design base shear, equivalent static load procedure, higher mode effects, base shear adjustment factors, distribution of base shear, overturning moment adjustment factors.

scholarly journals Review on Seismic Analysis of Multistoried Building in Hilly Region

2021 ◽  
Vol 9 (12) ◽  
pp. 73-79
Author(s):  
Harsh Joshi
Keyword(s):  
Seismic Analysis ◽  
Response Spectrum ◽  
Center Of Mass ◽  
Time History ◽  
Lateral Loads ◽  
Base Shear ◽  
Building Frames ◽  
Building Frame ◽  
History Analysis ◽  
Hilly Region

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.

scholarly journals A simplified method for seismic analysis of rooftop telecommunication towers

2007 ◽  
Vol 34 (10) ◽  
pp. 1352-1363
Author(s):  
Rola Assi ◽  
Ghyslaine McClure
Keyword(s):  
Seismic Analysis ◽  
Seismic Excitation ◽  
Base Shear ◽  
Shear Forces ◽  
Modal Superposition ◽  
Dynamic Analyses ◽  
Simplified Method ◽  
Excitation Dynamic ◽  
Telecommunication Towers ◽  
Definition Of

A simplified method is presented in this paper for the estimation of forces at the base of telecommunication towers mounted on building rooftops due to seismic excitation. Although some codes and standards propose simplified methods for the evaluation of base shear forces for towers founded on ground, no method yet exists for the evaluation of overturning moments. The proposed simplified method is based on numerical simulations using truncated modal superposition, which is widely used for seismic analysis of linear structures. The method requires the prediction of input seismic acceleration at the building–tower interface, the definition of an acceleration profile along the building-mounted tower, and the determination or evaluation of the mass distribution of the tower along its height. The method was developed on the basis of detailed dynamic analyses of three existing towers assumed to be mounted separately on three buildings. It was found that the method yields conservative results, especially for the overturning moments.Key words: self-supporting towers, earthquake, horizontal excitation, dynamic analysis, acceleration, modal superposition.

scholarly journals The Effect Analysis of Strain Rate on Power Transmission Tower-Line System under Seismic Excitation

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Li Tian ◽  
Wenming Wang ◽  
Hui Qian
Keyword(s):  
Strain Rate ◽  
Power Transmission ◽  
Seismic Analysis ◽  
Three Dimensional ◽  
Element Model ◽  
Seismic Excitation ◽  
Transmission Tower ◽  
Base Shear ◽  
Effect Analysis ◽  
Line System

The effect analysis of strain rate on power transmission tower-line system under seismic excitation is studied in this paper. A three-dimensional finite element model of a transmission tower-line system is created based on a real project. Using theoretical analysis and numerical simulation, incremental dynamic analysis of the power transmission tower-line system is conducted to investigate the effect of strain rate on the nonlinear responses of the transmission tower and line. The results show that the effect of strain rate on the transmission tower generally decreases the maximum top displacements, but it would increase the maximum base shear forces, and thus it is necessary to consider the effect of strain rate on the seismic analysis of the transmission tower. The effect of strain rate could be ignored for the seismic analysis of the conductors and ground lines, but the responses of the ground lines considering strain rate effect are larger than those of the conductors. The results could provide a reference for the seismic design of the transmission tower-line system.

Development of New Zealand seismic bridge standards

2013 ◽  
Vol 46 (4) ◽  
pp. 201-221 ◽  
Author(s):  
L. S. Hogan ◽  
L. M. Wotherspoon ◽  
J. M. Ingham
Keyword(s):  
New Zealand ◽  
Lateral Spreading ◽  
Base Shear ◽  
Design Standards ◽  
Foundation Design ◽  
Ground Shaking ◽  
Lower Base ◽  
Current Design ◽  
Shear Demand ◽  
Structural Detailing

During seismic assessments of bridges where there is a lack of construction documentation, one method of determining likely structural detailing is to use historic design standards. An overview of the New Zealand bridge seismic standards and the agencies that have historically controlled bridge design and construction is presented. Standards are grouped into design era based upon similar design and loading characteristics. Major changes in base shear demand, ductility, foundation design, and linkage systems are discussed for each design era, and loadings and detailing requirements from different eras were compared to current design practices. Bridges constructed using early seismic standards were designed to a significantly lower base shear than is currently used but the majority of these bridges are unlikely to collapse due to their geometry and a preference for monolithic construction. Bridges constructed after the late 1970s are expected to perform well if subjected to ground shaking, but unless bridges were constructed recently their performance when subjected to liquefaction and liquefaction-induced lateral spreading is expected to be poor.

scholarly journals Response Quantities of Framed Buildings under Dynamic Excitation

2019 ◽  
Vol 8 (11) ◽  
pp. 3798-3804
Keyword(s):  
Seismic Analysis ◽  
Structural Response ◽  
Base Shear ◽  
Response Factors ◽  
Analysis And Design ◽  
Dynamic Excitation ◽  
Combination Methods ◽  
Time Period ◽  
Moment Resisting ◽  
Seismic Forces

Seismic analysis of structure is employed to make the structure enable to resist the seismic forces and perform against the factors causing the failure of the structure under dynamic excitation. Among various response factors, the base shear and time period of buildings are predominant factors used in the analysis and design of the structure. The prime objective of the paper is to present an analytical study on non-linear seismic analysis of moment resisting framed buildings (as per Indian code IS1893 – 2016) to evaluate the base shear of different configurations of buildings according to different mode combination methods. The obtained results have been presented the comparative analysis of different combination methods. The paper also presents the evaluated results in the form of the time period values of the different buildings depending upon variation in its configuration. As a result, the responses of multistoried moment-resisting framed buildings have been evaluated for various models of considered buildings based on different mode combination methods, and the results of obtained responses have been analyzed in a comparative manner to understand the behaviour of buildings under various methods and configuration conditions. The work presented in the paper can support to develop better understanding of structural response and efficient designing of structures.

scholarly journals Controlling Seismic Excitation in the RCC Building with a Tuned Mass Damper

2021 ◽  
Vol 1197 (1) ◽  
pp. 012039
Author(s):  
Avinash Kalamkar ◽  
N.H. Pitale ◽  
P.B. Patil
Keyword(s):  
Seismic Analysis ◽  
Tall Buildings ◽  
Seismic Excitation ◽  
Earthquake Response ◽  
Contemporary History ◽  
Base Shear ◽  
Tuned Mass Dampers ◽  
Rc Structures ◽  
Mass Damper ◽  
The Time Domain

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.

scholarly journals Design and Seismic Analysis of Ground Supported Water Tank

10.29007/gqkl ◽  
2018 ◽  
Author(s):  
Rahul Patel ◽  
Rishi Dave ◽  
Prutha Vyas
Keyword(s):  
Program Analysis ◽  
Seismic Analysis ◽  
Hydrodynamic Pressure ◽  
Water Tank ◽  
Base Shear ◽  
Moment Capacity ◽  
Spreadsheet Program ◽  
Analysis And Design ◽  
Working Stress ◽  
Seismic Forces

The ground supported tanks are firmly attached with ground and tank walls are subjected to hydrostatic as well as hydrodynamic pressure due to seismic forces. Base of the tank is subjected to weight of water and pressure of soil. Top of the tanks may be covered and is designed by using IS 3370:2009 Part (I, II) [4] and IS 1893:2007 (part-2) draft code[3] is used for the seismic analysis of the tank. This paper gives idea behind the design of liquid retaining structure (rectangular ground supported water tank) using working stress method. This paper includes the seismic analysis and design of the tank. The values are obtained with the help of spreadsheet program. Analysis of ground supported water tank has been carried out and relationship between tank capacity with moment capacity and reinforcement area, base shear with impulsive height and overturning moment with convective height is derived.

scholarly journals Seismic Analysis of a Residential Building Considering Different Types of Opening Arrangement in the Infill Wall

2021 ◽  
Vol 9 (10) ◽  
pp. 649-656
Author(s):  
Kapil Shankar Soni
Keyword(s):  
Failure Modes ◽  
Seismic Analysis ◽  
Response Spectrum ◽  
Residential Building ◽  
Base Shear ◽  
Seismic Behaviour ◽  
Infill Wall ◽  
Infill Walls ◽  
Time Period ◽  
Natural Time

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.

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