Aseismic Structural Systems for Buildings

2006 ◽  
Vol 1 (3) ◽  
pp. 358-377 ◽  
Author(s):  
Makoto Watabe ◽  
Keyword(s):  
Simple Structure ◽  
Dynamic Properties ◽  
Time History ◽  
Structural Systems ◽  
Initial Displacement ◽  
Single Degree Of Freedom ◽  
Principal Factors ◽  
History Of ◽  
Circular Frequency ◽  
General Dynamic

When structures are subjected to earthquake motions, the principal factors controlling their behavior are i) dynamic characteristics of the structure ii) characteristics of the input earthquake motions. In this sense, it is essential, first of all, to be acquainted with general dynamic properties. Let the simple structure – single degree of freedom system – as illustrated in Fig. 1 be considered. Spring, mass, and damper are the three elements which characterize the system. If to this system, an initial displacement is applied, then set it free, the time history of the displacement, velocity and acceleration will be as shown in Fig. 2. In Fig. 2 the basic concepts of period, frequency and circular frequency of the system are also explained.

Rain-Wind-Induced Analysis of Transmission Steel Tower

2012 ◽  
Vol 450-451 ◽  
pp. 64-67
Author(s):  
Li Qin ◽  
Wen Jing Ding
Keyword(s):  
Wind Speed ◽  
Power Spectrum ◽  
Dynamic Properties ◽  
Time History ◽  
Element Model ◽  
Transmission Tower ◽  
Vibration Period ◽  
Spectrum Simulation ◽  
History Of ◽  
Load Simulation

The paper established a finite element model of DZV674 linear tower (500 kV Shiyang - Wuyi transmission project) by ANSYS and studies its dynamic properties. Its first 10 order modes and natural vibration period are obtained. Based on the principle of Kaimal power spectrum and linear filtering method (AR) for simulation time-history of fluctuating wind speed, power spectrum simulation program of wind-speed is got by using Matlab. The rain load simulation is finished on the former simulation.The dynamic analysis of the transmission tower is calculated subject to wind load and rain-wind load.The results demonstrate that wind is the main design load in rain-wind-induced, but the effect of rain shouldn’t be neglected.

Qualitative dynamic characteristics of a non-viscously damped oscillator

2005 ◽  
Vol 461 (2059) ◽  
pp. 2269-2288 ◽  
Author(s):  
Sondipon Adhikari
Keyword(s):  
Dynamic Properties ◽  
Damping Factor ◽  
Viscous Damping ◽  
Damping Force ◽  
Single Degree Of Freedom ◽  
Fundamental Interest ◽  
Qualitative Dynamic ◽  
History Of ◽  
Damped Oscillators ◽  
Damped Oscillator

This paper considers the linear dynamics of a single-degree-of-freedom non-viscously damped oscillator. It is assumed that the non-viscous damping force depends on the history of velocity via a convolution integral over an exponentially decaying kernel function. Classical qualitative dynamic properties known for viscously damped oscillators have been generalized to such non-viscously damped oscillators. The following questions of fundamental interest have been addressed: (i) under what conditions can a non-viscously damped oscillator sustain oscillatory motions? (ii) how does the natural frequency of a non-viscously damped oscillator compare with that of an equivalent undamped oscillator? and (iii) how does the decay rate compare with that of an equivalent viscously damped oscillator? Introducing two non-dimensional factors, namely, the viscous damping factor and the non-viscous damping factor, we provide answers to these questions. Wherever possible, attempts are made to relate the new results with equivalent classical results for a viscously damped oscillator.

Reliability-Based Assessment of Vibrations on an Offshore Living-Quarters Platform in Mexico

2002 ◽  
Author(s):  
David de Leon
Keyword(s):  
Dynamic Properties ◽  
Time History ◽  
Response Spectra ◽  
Structural Safety ◽  
Plastic Behavior ◽  
Single Degree Of Freedom ◽  
Lateral Strength ◽  
Wave Heights ◽  
Lateral Displacements ◽  
The One

Structural safety, integrity and reliability of offshore marine platforms under extreme loading is generally a widely studied topic [2, 4, 9]. However, ordinary environmental forces on particularly flexible components may be important sources of dynamic excitation and significant vibrations. For those cases where the structural system of the superstructure is totally different of the one used for the substructure, the non-uniform vertical distribution of the stiffness may impact the dynamic response by adding significant amplifications on the resulting motions of the more flexible structure. Significant motions were reported on a Mexican living-quarters platform. The platform was monitored and its dynamic characteristics were identified in order to prevent excessive displacements and accelerations. The platform was modeled as a single degree of freedom system with elasto-plastic behavior and the dynamic properties were calibrated from records obtained throughout a monitoring campaign of response displacements and accelerations on the platform. Fourier amplitude response spectra were generated and the fundamental period and damping percent were estimated. On the basis of Monte Carlo simulation of time history accelerations, the probability to exceed prescribed thresholds for lateral displacements, accelerations and lateral strength under several given wave heights were estimated. As these probabilities are conditional to the occurrence of the wave height exciting the platform, the unconditional probabilities were obtained by convolving the conditional probabilities over the probability of occurrence of the wave heights prescribed for the site of the platform.

scholarly journals P-delta actions in seismic resistant structures

1992 ◽  
Vol 25 (1) ◽  
pp. 56-69 ◽  
Author(s):  
R. C. Fenwick ◽  
B. J. Davidson ◽  
B. T. Chung
Keyword(s):  
Ground Motion ◽  
Time History ◽  
Degree Of Freedom ◽  
Delta Method ◽  
Background Information ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Factors Influencing ◽  
Seismic Resistant ◽  
Principal Factors

The results of several thousands of inelastic time history analyses, which have been made on single degree of freedom structures to assess P-delta effects induced in earthquakes, are reviewed. The principal factors influencing P-delta actions are shown to be the ductility, the duration of the severe ground motion, the level of damping and the period of the structure. A method of designing for P-delta effects for single degree of freedom structures is presented. A limited number of analyses of multi-storey frames and walls indicate that the approach may be used for multi-storey structures. This paper gives background information on the P-delta method of analysis given in an appendix to the commentary of the proposed loading code.

scholarly journals Using a moving load to simultaneously detect location and severity of damage in a simply supported beam

2019 ◽  
Vol 25 (15) ◽  
pp. 2108-2123
Author(s):  
Mohsen Mousavi ◽  
Damien Holloway ◽  
J C Olivier
Keyword(s):  
Structural Damage ◽  
Moving Load ◽  
Time History ◽  
Static Deflection ◽  
Cracked Beam ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Damage Location ◽  
Wide Range ◽  
History Of

This paper demonstrates the feasibility of simultaneously identifying both the location and severity of structural damage in a beam by using two independent moving load experiments. First, a simple but sufficiently accurate single degree of freedom model is presented to simulate the structure efficiently over a wide range of relevant inputs. We then introduce a damage sensitive feature (DSF) based on the integral of the velocity time history of the beam at its midspan when the load moves over the beam. A critical velocity, a function only of the beam’s first natural frequency and length, is obtained for the proposed DSF, upon which the damage can be located more accurately. The only required data for the damage detection is the midspan velocity-time history of the cracked beam subjected to a moving load, and the midspan static deflection of the intact beam subjected to a load of the same magnitude. In the last section of this paper, the capability of the proposed DSF is examined in the presence of noise. The results demonstrate the capability of the proposed method to find both the damage location and severity successfully, and methods for further reducing the effects of noise are suggested.

PROGRAM OF PREDICTION AND MANAGEMENT OF COINTEGED DYNAMIC ECONOMIC PROCESSES BASED ON THE CYBERNETIC APPROACH

2019 ◽  
Author(s):  
Olena Bundak ◽  
Nataliia Zubovetska
Keyword(s):  
Computer Program ◽  
Pair Correlation ◽  
Time History ◽  
Critical Area ◽  
Concrete Object ◽  
Graphic Arts ◽  
Ex Post ◽  
History Of ◽  
Successive Change ◽  
Rms Errors

A method and computer program ConRow, which prognostication of development of the dynamically CPLD economic transients is executed by, is described in the article. Such prognostication of economic processes is very important in the cases when their development can result in undesirable consequences, that to go out in the so-called critical area. Extrapolation in a critical area with the use of information about the conduct of the system at an area, near to it, allows to estimate to the lead through of experiment in the critical area of his consequence. For the imitation of conduct of object the function of review is set on entrance influence. For a concrete object this function can express, for example, dependence of change of level sale from time-history of charges on advertising and set as a numeral row. Statistics as a result of analysis of row are represented in a table, where the level of meaningfulness is set statistician, and also parameters of the handed over criteria. The graphic reflection of information is intended for visualization of analysis. Here represented on the points of graphic arts, the crooked smoothing which are calculated as полиномиальные regressions is added. The best approaching is controlled by sight on the proper graph, and also by minimization of their rms errors. Models of prognostication by sight and as formulas represented on graphic arts, the middle is here determined tailings and their chance is checked up on statistics of signs. After the got models determined also and prognosis values of influences and reviews. Establishing an order models of Сr(p) of co integrate regression is carried out separate custom controls. The coefficient of clay correlation of ruФ shows by itself pair correlation between lines with a successive change in relation to each other on a size to лагу of l = 1, 2, 3 . The program was tested on the example of ex-post prognosis at establishing an integration connection and possibility of prognostication of growth of nominal average monthly settlings on the basis of these statistical indexes of consumer inflation in Ukraine.

scholarly journals Comparison of Novel Seismic Protection Devices to Attenuate the Earthquake Induced Energy

Actuators ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 73
Author(s):  
Osman Hansu ◽  
Esra Mete Güneyisi
Keyword(s):  
Lateral Displacement ◽  
Time History ◽  
Seismic Protection ◽  
Base Shear ◽  
Seismic Demands ◽  
Nonlinear Time History Analyses ◽  
History Of ◽  
Protection Devices ◽  
Nonlinear Time History ◽  
Better Than

This study addresses an alternative use of viscous dampers (VDs) associated with buckling restrained braces (BRBs) as innovative seismic protection devices. For this purpose, 4-, 8- and 12-story steel bare frames were designed with 6.5 m equal span length and 4 m story height. Thereafter, they were seismically improved by mounting the VDs and BRBs in three patterns, namely outer bays, inner bays, and all bays over the frame heights. The structures were modeled using SAP 2000 software and evaluated by the nonlinear time history analyses subjected to the six natural ground motions. The seismic responses of the structures were investigated for the lateral displacement, interstory drift, absolute acceleration, maximum base shear, and time history of roof displacement. The results clearly indicated that the VDs and BRBs reduced seismic demands significantly compared to the bare frame. Moreover, the all-bay pattern performed better than the others.

scholarly journals Development of a Field Deployable Firebrand Flux and Condition Measurement System

2020 ◽  
Author(s):  
Simone Zen ◽  
Jan C. Thomas ◽  
Eric V. Mueller ◽  
Bhisham Dhurandher ◽  
Michael Gallagher ◽  
...  
Keyword(s):  
Imaging Techniques ◽  
Time History ◽  
Infrared Camera ◽  
Thermal Conditions ◽  
Particle Characterization ◽  
Fire Dynamics ◽  
Rate Of Spread ◽  
New Instrument ◽  
History Of

AbstractA new instrument to quantify firebrand dynamics during fires with particular focus on those associated with the Wildland-Urban Interface (WUI) has been developed. During WUI fires, firebrands can ignite spot fires, which can rapidly increase the rate of spread (ROS) of the fire, provide a mechanism by which the fire can pass over firebreaks and are the leading cause of structure ignitions. Despite this key role in driving wildfire dynamics and hazards, difficulties in collecting firebrands in the field and preserving their physical condition (e.g. dimensions and temperature) have limited the development of knowledge of firebrand dynamics. In this work we present a new, field-deployable diagnostic tool, an emberometer, designed to provide measurement of firebrand fluxes and information on both the geometry and the thermal conditions of firebrands immediately before deposition by combining a visual and infrared camera. A series of laboratory experiments were conducted to calibrate and validate the developed imaging techniques. The emberometer was then deployed in the field to explore firebrand fluxes and particle conditions for a range of fire intensities in natural pine forest environments. In addition to firebrand particle characterization, field observations with the emberometer enabled detailed time history of deposition (i.e. firebrand flux) relative to concurrent in situ fire behaviour observations. We highlight that deposition was characterised by intense, short duration “showers” that can be reasonably associated to spikes in the average fire line intensity. The results presented illustrate the potential use of an emberometer in studying firebrand and spot fire dynamics.

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