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.

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.

scholarly journals A comparative study on a complex URM building: part II—issues on modelling and seismic analysis through continuum and discrete-macroelement models

2021 ◽  
Author(s):  
G. Castellazzi ◽  
B. Pantò ◽  
G. Occhipinti ◽  
D. A. Talledo ◽  
L. Berto ◽  
...  
Keyword(s):  
Seismic Analysis ◽  
Dynamic Properties ◽  
Limit State ◽  
Central Italy ◽  
Nonlinear Static Analysis ◽  
Structural Safety ◽  
Masonry Building ◽  
Maximum Acceleration ◽  
Capacity Curves ◽  
Comparison Of The Results

AbstractThe paper presents the comparison of the results obtained on a masonry building by nonlinear static analysis using different software operating in the field of continuum and discrete-macroelement modeling. The structure is inspired by an actual building, the "P. Capuzi" school in Visso (Macerata, Italy), seriously damaged following the seismic events that affected Central Italy from August 2016 to January 2017. The activity described is part of a wider research program carried out by various units involved in the ReLUIS 2017/2108—Masonry Structures project and having as its object the analysis of benchmark structures for the evaluation of the reliability of software packages. The comparison of analysis was carried out in relation to: global parameters (concerning the dynamic properties, capacity curves and, equivalent bilinear curves), synthetic parameters of structural safety (such as, for example, the maximum acceleration compatible with the life safety limit state) and the response in terms of simulated damage. The results allow for some insights on the use of continuum and discrete-macroelement modeling, with respect to the dispersion of the results and on the potential repercussions in the professional field. This response was also analyzed considering different approaches for the application of loads.

scholarly journals Numerical Analysis of the Effect of Binary Typhoons on Ocean Surface Waves in Waters Surrounding Taiwan

2021 ◽  
Vol 8 ◽  
Author(s):  
Tzu-Yin Chang ◽  
Hongey Chen ◽  
Shih-Chun Hsiao ◽  
Han-Lun Wu ◽  
Wei-Bo Chen
Keyword(s):  
Surface Waves ◽  
Ocean Surface ◽  
Separation Distance ◽  
Ocean Surface Waves ◽  
Significant Wave ◽  
Storm Wave ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
The One ◽  
Along Track

The ocean surface waves during Super Typhoons Maria (2018), Lekima (2019), and Meranti (2016) were reproduced using hybrid typhoon winds and a fully coupled wave-tide-circulation modeling system (SCHISM-WWM-III). The hindcasted significant wave heights are in good agreement with the along-track significant wave heights measured by the altimeters aboard the SARAL (Satellite with ARgos and ALtiKa) and Jason-2 satellites. Two numerical experiments pairing Super Typhoons Maria (2018) and Meranti (2016) and Super Typhoons Lekima (2019) and Meranti (2016) were conducted to analyze the storm wave characteristics of binary and individual typhoons. Four points located near the tracks of the three super typhoons were selected to elucidate the effects of binary typhoons on ocean surface waves. The comparisons indicate that binary typhoons not only cause an increase in the significant wave height simulations at four selected pints but also result in increases in the one-dimensional wave energy and two-dimensional directional wave spectra. Our results also reveal that the effects of binary typhoons on ocean surface waves are more significant at the periphery of the typhoon than near the center of the typhoon. The interactions between waves generated by Super Typhoons Maria (2018) and Meranti (2016) or Super Typhoons Lekima (2019) and Meranti (2016) might be diminished by Taiwan Island even if the separation distance between two typhoons is <700 km.

Kinematic Drift of Single-Axis Gyroscopes

1958 ◽  
Vol 25 (3) ◽  
pp. 357-360
Author(s):  
R. H. Cannon
Keyword(s):  
Experimental Verification ◽  
Spatial Orientation ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Momentum Vector ◽  
Single Degree ◽  
The One ◽  
Platform Motions

Abstract A gyroscope can incur steady drift by kinematically rectifying angular vibrations of the platform on which it is mounted. The phenomenon, for an unrestrained single-degree-of-freedom gyro, results from oscillatory precession of the gyro momentum vector from its nominal spatial orientation, so that it senses platform motions about axes other than the one it is controlling. The magnitude of the drift can be accurately predicted and the vibration climate of the platform restricted accordingly. Quantitative experimental verification is presented.

Response of higherise buildings to ground motion from underground nuclear detonations

1969 ◽  
Vol 59 (6) ◽  
pp. 2343-2370
Author(s):  
John A. Blume
Keyword(s):  
Ground Motion ◽  
Las Vegas ◽  
Spectral Response ◽  
Vertical Plane ◽  
Time History ◽  
Tall Buildings ◽  
Response Spectra ◽  
Statistical Parameters ◽  
Typical Data ◽  
Earthquake Design

abstract Typical data obtained thus far in the AEC nuclear test program on the response of highrise Las Vegas buildings to ground motion from distant nuclear events including Boxcar and Benham are presented, together with measured building response to distant earthquakes and to wind gusts. Major variations in response spectra are shown over the city for a specific event, from period band to period band at the same location for different events, and statistical parameters are shown for the randomness of spectral response. The peak response of tall buildings is shown for the top levels in translation and in orbital motion, and in the vertical plane with simultaneous multi-level measurements. The variation of peak modal response is shown with elapsed time, modal combinations are noted, and an example of time-history computed response is compared to measured response. It is shown that highrise Las Vegas buildings respond to ground motion with considerable amplification, that the fundamental modes tend to dominate the peak responses although there are exceptions, that there can be significant modification of loading conditions because of simultaneous motion in the two horizontal axes even though a building is symmetric, and that some building periods vary with amplitude and history of non-damaging prior response while others do not. In general there are indications that code earthquake design criteria are by no means conservative.

Response spectral matching of horizontal ground motion components to an orientation-independent spectrum (RotDnn)

2020 ◽  
pp. 875529302097098
Author(s):  
Luis A Montejo
Keyword(s):  
Ground Motion ◽  
Response Spectrum ◽  
Time History ◽  
Response Spectra ◽  
Major Axis ◽  
Component Level ◽  
Nonlinear Characteristics ◽  
Target Spectrum ◽  
Horizontal Ground Motion ◽  
Median Spectrum

This article presents a methodology to spectrally match two horizontal ground motion components to an orientation-independent target spectrum (RotDnn). The algorithm is based on the continuous wavelet transform decomposition and iterative manipulation of the two horizontal components of a seed record. The numerical examples presented follow current ASCE/SEI 7 specifications and therefore maximum-direction spectra (RotD100) are used as target for the match. However, the proposed methodology can be used to match other RotDnn spectra, like the median spectrum (RotD50). It is shown that with the proposed methodology the resulting RotDnn from the modified horizontal components closely match the smooth target RotDnn spectrum, while the response spectrum for each horizontal component continue to exhibit a realistic jagged behavior. The response spectra variability at the component level within suites of spectrally matched motions was found to be of the same order than the variability measured in suites composed of amplitude scaled records. Moreover, the spectrally matched records generated preserved most of the characteristics of the seed records, including the nonlinear characteristics of the time history traces and the period-dependent major axis orientations.

Seismic Analysis of High Pier Three-Span Continuous Bridge

2015 ◽  
Vol 744-746 ◽  
pp. 890-893
Author(s):  
Xun Wu ◽  
Yong Lan Zhang
Keyword(s):  
Seismic Analysis ◽  
Linear Time ◽  
Time History ◽  
Response Spectra ◽  
Elastic Response ◽  
Modeling And Analysis ◽  
Continuous Beam Bridge ◽  
Comparison Results ◽  
Elastic Response Spectra ◽  
Nonlinear Time History

In this paper, SAP2000 and ANSYS software are used to modeling and analysis athree-span continuous beam bridge with high piers case study.By using differentbearing types and combinations to form different options, create two finiteelement models.Analysis dynamic characteristics ,elastic response spectra,linear time history and nonlinear time history .And focus on comparing dynamiccharacteristics of the earthquake response of the two programs .Running outputdata processing and comparison results show that the application of thedifferent parameters of the rational combination of rubber bearing basin bridgearrangement has better seismic performance.

Neural Networks for the Simulation and Identification Analysis of Buildings Subjected to Paraseismic Excitations

2007 ◽  
pp. 393-432 ◽  
Author(s):  
Krystyna Kuzniar ◽  
Zenon Waszczyszyn
Keyword(s):  
Neural Networks ◽  
Structural Dynamics ◽  
Dynamic Properties ◽  
Response Spectra ◽  
Engineering Practice ◽  
Identification Analysis ◽  
Dynamics Problems ◽  
Mining Tremors ◽  
Testing Patterns ◽  
Mining Regions

The chapter deals with an application of neural networks to the analysis of vibrations of medium-height prefabricated buildings with load-bearing walls subjected to paraseismic excitations. Neural network technique was used for identification of dynamic properties of actual buildings, simulation of building responses to paraseismic excitations as well as for the analysis of response spectra. Mining tremors in strip mines and in the most seismically active mining regions in Poland with underground exploitation were the sources of these vibrations. On the basis of the experimental data obtained from the measurements of kinematic excitations and dynamic building responses of actual structures the training and testing patterns were formulated. It was stated that the application of neural networks enables us to predict the results with accuracy quite satisfactory for engineering practice. The results presented in this chapter lead to a conclusion that the neural technique gives new prospects of efficient analysis of structural dynamics problems related to paraseismic excitations.

Effects of human-induced load models on tuned mass damper in reducing floor vibration

2019 ◽  
Vol 22 (11) ◽  
pp. 2449-2463
Author(s):  
Jun Chen ◽  
Ziping Han ◽  
Ruotian Xu
Keyword(s):  
Response Spectra ◽  
Tuned Mass Damper ◽  
Design Guidelines ◽  
Degree Of Freedom ◽  
Dynamic Responses ◽  
Single Degree Of Freedom ◽  
Load Model ◽  
Load Models ◽  
Single Degree ◽  
Mass Damper

Dozens of human-induced load models for individual walking and jumping have been proposed in the past decades by researchers and are recommended in various design guidelines. These models differ from each other in terms of function orders, coefficients, and phase angles. When designing structures subjected to human-induced loads, in many cases, a load model is subjectively selected by the design engineer. The effects of different models on prediction of structural responses and efficiency of vibration control devices such as a tuned mass damper, however, are not clear. This article investigates the influence of human-induced load models on performance of tuned mass damper in reducing floor vibrations. Extensive numerical simulations were conducted on a single-degree-of-freedom system with one tuned mass damper, whose dynamic responses to six walking and four jumping load models were calculated and compared. The results show a maximum three times difference in the acceleration responses among all load models. Acceleration response spectra of the single-degree-of-freedom system with and without a tuned mass damper were also computed and the response reduction coefficients were determined accordingly. Comparison shows that the reduction coefficient curves have nearly the same tendency for different load models and a tuned mass damper with 5% mass ratio is able to achieve 50%–75% response reduction when the structure’s natural frequency is in multiples of the walking or jumping frequency. All the results indicate that a proper load model is crucial for structural response calculation and consequently the design of tuned mass damper device.

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