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.

A simplified method for seismic analysis of lattice telecommunication towers

2000 ◽  
Vol 27 (3) ◽  
pp. 533-542 ◽  
Author(s):  
Mohamed A Khedr ◽  
Ghyslaine McClure
Keyword(s):  
Dynamic Analysis ◽  
Seismic Analysis ◽  
Response Spectrum ◽  
Axial Mode ◽  
Height Range ◽  
Vertical Excitation ◽  
Modes Of Vibration ◽  
Excitation Dynamic ◽  
Telecommunication Towers ◽  
Acceleration Profile

A simplified static method for estimating the member forces in self-supporting lattice telecommunication towers due to both horizontal and vertical earthquake excitations is presented in this paper. The method is based on the modal superposition technique and the response spectrum approach, which are widely used for seismic analysis of linear structures. It is assumed that the lowest three flexural modes of vibration are sufficient to correctly estimate the tower's response to horizontal excitation, while only the lowest axial mode is sufficient to capture the response to vertical excitation. An acceleration profile along the height of the tower is defined using estimates of the lowest three flexural modes or the lowest axial mode, as appropriate, together with the spectral acceleration values corresponding to the associated natural periods. After the mass of the tower is calculated and lumped at the leg joints, a set of equivalent static lateral or vertical loads can be determined by simply multiplying the mass profile by the acceleration profile. The tower is then analyzed statically under the effect of these loads to evaluate the member forces. This procedure was developed on the basis of detailed dynamic analysis of ten existing three-legged self-supporting telecommunication towers with height range of 30-120 m. The maximum differences in member forces obtained with the proposed method and the detailed seismic analysis are of the order of ±25% in the extreme cases, with an average difference of ±7%. The results obtained for two towers with heights of 66 and 83 m are presented in this paper to demonstrate the accuracy and practicality of the proposed method.Key words: self-supporting tower, earthquake, vertical excitation, dynamic analysis.

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.

Earthquake amplification factors for self-supporting telecommunication towers

1999 ◽  
Vol 26 (2) ◽  
pp. 208-215 ◽  
Author(s):  
Mohamed Khedr ◽  
Ghyslaine McClure
Keyword(s):  
Seismic Analysis ◽  
Strong Motion ◽  
Regression Analyses ◽  
Base Shear ◽  
Amplification Factors ◽  
Dynamic Forces ◽  
Reaction Amplification ◽  
Telecommunication Towers ◽  
Lattice Towers ◽  
Simple Regression

In the absence of specific guidelines for the seismic analysis of self-supporting telecommunication towers, designers may be tempted to apply building-code approaches to these structures. However, these towers respond to earthquakes in a different fashion than shear buildings. In this study, earthquake amplification factors for the base shear and the total vertical reaction of self-supporting latticed telecommunication towers are suggested based on modal superposition analysis performed on 10 existing towers, each being subjected to a set of strong-motion accelerograms acting in the horizontal and the vertical directions separately. Results are presented in detail for two of the towers studied, with heights of 66 and 121 m, respectively. Simple regression analyses are performed on the results from which the base shear and vertical reaction amplification factors are found. These factors are presented as functions of the tower's largest flexural period or largest axial period of vibration as appropriate, and can be used by designers to estimate the expected level of dynamic forces developed in self-supporting telecommunication towers due to an earthquake.Key words: dynamic analysis, lattice towers, base shear, vertical reaction.

scholarly journals Dynamic seismic analysis of bridge using response spectrum and time history method

2021 ◽  
Author(s):  
Marame Brinissat ◽  
Rajmund Kuti ◽  
Zouhir Louhibi
Keyword(s):  
Seismic Analysis ◽  
Response Spectrum ◽  
Time History ◽  
Bending Moment ◽  
Highway Bridge ◽  
Structural Elements ◽  
Base Shear ◽  
Shear Forces ◽  
Nonlinear Analyses ◽  
Ground Motion Records

Dynamic analysis is very important to better understand the performance of structural elements of a bridge. For this purpose, a seismic analysis of an Algerian highway bridge designed with the new Algerian seismic bridge regulation (RPOA -2008) was carried out using linear and nonlinear analyses. Therefore, response spectrum, time history analyses were performed to evaluate the seismic responses of the designed bridge. The performance of the designed bridge is assessed using 10 ground motion records. The proposed methodology allows an efficient comparison of the seismic response of the bridge in terms of base shear forces, bending moment and displacements. Finally, the paper concludes with a discussion of the specific outcomes.

scholarly journals The Effect of Soil Poissons Ratio on the Response of Buildings with Sufficient Embedment Depth

2020 ◽  
pp. 23-33
Author(s):  
Ahmed Hafiz Yasseen Essawy
Keyword(s):  
Shear Deformation ◽  
Dynamic Behavior ◽  
Interaction Effect ◽  
Seismic Analysis ◽  
Ground Motions ◽  
Seismic Excitation ◽  
Embedment Depth ◽  
Shear Forces ◽  
Structure Control ◽  
Poissons Ratio

The present study highlights the effect of soil poissons ratio on the response of buildings with sufficient embedment depth. The interaction effect between the structure and its foundation control the dynamic behavior of the structure during seismic analysis. Not only the foundation of structure control the results of seismic analysis but also the embedment depth of the structure increase this effect. The ground motions produced by the seismic excitation at the base of the building are the result of shear deformation in the soil. The effect of the inertial resistance of soil surrounding the basement floors is taken into consideration by adding virtual masses to the basement floors to obtain more accurate shear forces acting on the flexible basement columns. The study calculates the response values at any required time and the maximum response values in addition to its time of occurrence.

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.

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.

Nonlinear Dynamic Analysis of Prefabricated Concrete Shear Wall Structure under Seismic Excitation

2017 ◽  
Vol 873 ◽  
pp. 259-263
Author(s):  
Hao Zhang ◽  
Zi Hang Zhang ◽  
Yong Qiang Li
Keyword(s):  
Finite Element ◽  
Kinematic Hardening ◽  
Nonlinear Dynamic Analysis ◽  
Shear Wall ◽  
Seismic Excitation ◽  
Wall Structure ◽  
Base Shear ◽  
Wall Structures ◽  
Story Drift

The dynamic behavior of the prefabricated and cast in situ concrete shear wall structures subjected to seismic loading is investigated by finite element method. This paper adopted a prefabricated concrete shear wall in a practical engineering. The Precise finite element models of prefabricated and cast in situ concrete shear wall were established respectively by ABAQUS. The damaged plasticity model of concrete and kinematic hardening model of reinforcing steel were used. The top displacement, top acceleration, story drift ratio and base shear forceof prefabricated and cast in situ concrete shear wall under different seismic excitation were compared and analyzed. The earthquake resistant behaviorsof the two kinds of structuresare analyzed and compared. Results show that the performances of PC structure were equal to the cast-in-situ ones.

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