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.

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.

Microstructural changes in soft quick clay at failure

1970 ◽  
Vol 7 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Roland Pusch
Keyword(s):  
Shear Deformation ◽  
Shear Zone ◽  
Residual Strength ◽  
Rigid Bodies ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Shear Forces ◽  
Microstructural Investigation ◽  
Shear Process ◽  
Quick Clay

A series of unconfined compression tests has been made on a marine, quick clay and small specimens were extracted for microstructural investigation. The natural microstructural pattern was characterized by a network of small aggregates connected by links of particles. The links broke down successively at increasing shear deformation and formed domain-like groups of particles. In the macroscopic shear zone the shear forces tended to orient and deform the aggregates.The aggregates behaved as rigid bodies to a certain stress level during the shear process. The concept of residual strength may correspond to the state where the majority of the links have been broken while the aggregates are still intact.

Conditioned Simulation of Ground-Motion Time Series at Uninstrumented Sites Using Gaussian Process Regression

2021 ◽  
Author(s):  
Aidin Tamhidi ◽  
Nicolas Kuehn ◽  
S. Farid Ghahari ◽  
Arthur J. Rodgers ◽  
Monica D. Kohler ◽  
...  
Keyword(s):  
Time Series ◽  
Gaussian Process ◽  
Ground Motion ◽  
San Francisco ◽  
Earthquake Engineering ◽  
Seismic Analysis ◽  
Ground Motions ◽  
Free Field ◽  
Gaussian Process Regression ◽  
Motion Time

ABSTRACT Ground-motion time series are essential input data in seismic analysis and performance assessment of the built environment. Because instruments to record free-field ground motions are generally sparse, methods are needed to estimate motions at locations with no available ground-motion recording instrumentation. In this study, given a set of observed motions, ground-motion time series at target sites are constructed using a Gaussian process regression (GPR) approach, which treats the real and imaginary parts of the Fourier spectrum as random Gaussian variables. Model training, verification, and applicability studies are carried out using the physics-based simulated ground motions of the 1906 Mw 7.9 San Francisco earthquake and Mw 7.0 Hayward fault scenario earthquake in northern California. The method’s performance is further evaluated using the 2019 Mw 7.1 Ridgecrest earthquake ground motions recorded by the Community Seismic Network stations located in southern California. These evaluations indicate that the trained GPR model is able to adequately estimate the ground-motion time series for frequency ranges that are pertinent for most earthquake engineering applications. The trained GPR model exhibits proper performance in predicting the long-period content of the ground motions as well as directivity pulses.

Effects of Seismic Incident Directionality on Ground Motion Characteristics and Responses of a Single-Mass Bi-Degree-of-Freedom System

2021 ◽  
pp. 2150119
Author(s):  
Jun Gong ◽  
Xudong Zhi ◽  
Feng Fan ◽  
Shizhao Shen ◽  
Da Qaio ◽  
...  
Keyword(s):  
Ground Motion ◽  
Large Scale ◽  
Seismic Analysis ◽  
Ground Motions ◽  
Propagation Distance ◽  
Degree Of Freedom ◽  
Different Types ◽  
Single Mass ◽  
Motion Characteristics ◽  
The Impact

To investigate the variability of ground motion characteristics (GMC) with the angle of seismic incidence (ASI) and the impact of seismic incident directionality on structural responses, first, a large-scale database of recorded ground motions was used to analyze the causes of GMC variability due to the seismic incident directionality effect (SIDE). Then a single-mass bi-degree-of-freedom system (SM-BDOF-S) with different types of symmetrical sections was selected to explore the influence mechanism of SIDE on the seismic responses. The results illustrated that the GMC has substantial variability with the ASI, which is independent of the earthquake source, propagation distance, and site condition, and exhibits complex random characteristics. Additionally, a classification method for ground motions is proposed based on this GMC variability to establish a criterion for selecting ground motions in seismic analysis considering the SIDE. Moreover, for an SM-BDOF-S, the response spectral plane is proposed to explain the transition behavior of spectral responses that are very similar among different stiffness ratios, but divergent for different types of ground motions. The influence of SIDE on structures is determined by their stiffness and stiffness ratio in the [Formula: see text]- and [Formula: see text]-directions, as well as the type of ground motion.

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.

Seismic analysis of offshore platforms subjected to pulse-type ground motions compatible with European Standards

2020 ◽  
Vol 129 ◽  
pp. 105713 ◽  
Author(s):  
F.D. Konstandakopoulou ◽  
K.I. Evangelinos ◽  
I.E. Nikolaou ◽  
G.A. Papagiannopoulos ◽  
N.G. Pnevmatikos
Keyword(s):  
Seismic Analysis ◽  
Ground Motions ◽  
Offshore Platforms ◽  
Pulse Type ◽  
European Standards

Seismic analysis of hydraulic structures affected by alkali-aggregate reaction: a case study

2001 ◽  
Vol 28 (2) ◽  
pp. 332-338 ◽  
Author(s):  
M Parvini ◽  
S Pietruszczak ◽  
V Gocevski
Keyword(s):  
Power Plant ◽  
Single Unit ◽  
Hydraulic Structure ◽  
Seismic Analysis ◽  
Numerical Procedure ◽  
Seismic Excitation ◽  
Hydraulic Structures ◽  
Seismic Load ◽  
Alkali Aggregate Reaction

This paper describes the results of numerical analysis of a hydraulic structure subjected to seismic load. The paper is divided into two main parts. First, a numerical procedure for the description of mechanical effects of alkali-aggregate reaction in concrete structures is briefly outlined. Subsequently, a single unit of the Beauharnois power plant, situated in Quebec (Canada), is analysed in the context of seismic excitation. The numerical simulations are aimed at assessing the dynamic stability of this unit and investigating the evolution of damage associated with inception of macrocracks.Key words: alkali-aggregate reaction, plasticity, seismic analysis, hydraulic structures.

A study on the improvement of seismic coefficients for pseudo static analysis of gravity type quay wall via dynamic centrifuge tests

2020 ◽  
Author(s):  
Moon-Gyo Lee ◽  
Hyung-Ik Cho ◽  
Chang-Guk Sun ◽  
Han-Saem Kim
Keyword(s):  
Dynamic Behavior ◽  
Seismic Analysis ◽  
Inertial Force ◽  
Gravitational Acceleration ◽  
Ground Acceleration ◽  
Natural Period ◽  
The Real ◽  
Analysis And Design ◽  
Centrifuge Tests ◽  
Quay Wall

<p>The pseudo-static approach has been conventionally applied for the design of gravity type quay walls. In this method, the seismic coefficient (<em>k<sub>h</sub></em>), expressed in terms of acceleration due to gravity, is used to convert the real dynamic behavior to an equivalent pseudo-static inertial force for seismic analysis and design. The existing <em>k<sub>h</sub></em> is simply defined as the expected peak ground acceleration (<em>PGA</em>) of the ground divided by the gravitational acceleration (<em>g</em>), which does not sufficiently reflect the real dynamic behavior. In order to improve the <em>k<sub>h</sub></em> definition, a number of studies have been performed for reducing the differences between pseudo-static and true dynamic behavior. In this regard, questions regarding the need for considering the effect of frequency characteristics of input earthquake, natural period of the backfill soil and the subsoil underneath the wall, and wall height on the deformation of quay wall crown (<em>D<sub>h</sub></em>) have been explored. In this study, dynamic centrifuge tests were conducted using the gravity type quay wall models designed with a <em>k<sub>h</sub></em> value of 0.13 to assess the behavior of the model wall during earthquakes. Three different variables: input earthquake motions, wall heights and the thickness of subsoil underneath the wall were considered, and the test results were compared and analyzed to assess the validity of the conventional <em>k<sub>h</sub></em> concept under these conditions. In addition, some improvements that should be considered for the future revision of the <em>k<sub>h</sub></em> definition are discussed.</p>

Static and dynamic behavior of FGM plate using a new first shear deformation plate theory

2016 ◽  
Vol 57 (1) ◽  
pp. 127-140 ◽  
Author(s):  
Lazreg Hadji ◽  
M. Ait Amar Meziane ◽  
Z. Abdelhak ◽  
T. Hassaine Daouadji ◽  
E.A Adda Bedia
Keyword(s):  
Shear Deformation ◽  
Dynamic Behavior ◽  
Plate Theory ◽  
Shear Deformation Plate Theory

Parametric study of stochastic seismic responses of base-isolated liquid storage tanks under near-fault and far-fault ground motions

2016 ◽  
Vol 24 (24) ◽  
pp. 5747-5764 ◽  
Author(s):  
Sina Safari ◽  
Reza Tarinejad
Keyword(s):  
Base Isolation ◽  
Seismic Analysis ◽  
Ground Motions ◽  
Characteristic Parameter ◽  
Statistical Linearization ◽  
Storage Tanks ◽  
Earthquake Excitation ◽  
Isolation System ◽  
Near Fault ◽  
Liquid Storage

Seismic response of base isolated steel liquid storage tanks is investigated in this study by a stochastic approach in frequency domain. For the purpose of evaluating different frequency contents of seismic events on the responses of fixed and isolated tanks, the earthquake excitation is characterized by power spectral density function. Since earthquake is a random process, stochastic seismic analysis is used and root mean square response predicts behavior of system properly. Two types of isolation system are assumed and nonlinear behavior of base isolation systems are developed by an iterative statistical linearization scheme. The study demonstrates the influence of each characteristic parameter of the storage tanks and isolation system and also excitation features. It is confirmed that near-fault earthquake excitations amplify the overall response of the system. Base isolation is known as an effective technique to reduce responses appropriately. It is demonstrated that the sloshing responses of the tanks is significantly reduced by sliding bearing. Further, excitation parameters, PGV/PGA ratio of records and pulse period in near-fault ground motions, that represent differences in two sets of earthquakes are defined to recognize variation of responses.

Sign in / Sign up

Export Citation Format

Share Document