Stochastic Floor Response Spectra for an Actively-Controlled Secondary System

2011 ◽  
Author(s):  
Takashi Mochio
Keyword(s):  
Structural Response ◽  
Response Spectra ◽  
Value Theory ◽  
Secondary System ◽  
Linear Quadratic ◽  
Gaussian Random Process ◽  
Floor Response Spectra ◽  
Active Mass Damper ◽  
State Space System ◽  
Response Amplification

The purpose of this paper is to propose a newly floor response spectra (FRS) in order to evaluate simply the structural response of the actively-controlled secondary system subjected to earthquake. This paper adopts a linear single-degree-of-freedom system as a main structure and an active mass damper (AMD) system as the active control technology. Also, the earthquake wave is modeled as product of a non-stationary envelope function and a stationary Gaussian random process of which power spectral density is equal to the Kanai-Tajimi spectrum. The control design is executed by using linear quadratic Gaussian control strategy against an enlarged state space system. Finally, the response amplification factor is given by the combination of the obtained statistical response values and the extreme value theory. Analytical results are compared with numerical simulations, and both show a good agreement. As a result, it seems that the validity of the proposed technique is confirmed.

Seismic actions on acceleration sensitive non-structural components in ductile frames

2010 ◽  
Vol 43 (2) ◽  
pp. 110-125 ◽  
Author(s):  
S. R. Uma ◽  
John X. Zhao ◽  
Andrew B. King
Keyword(s):  
Spectral Response ◽  
Limit State ◽  
Structural Response ◽  
Response Spectra ◽  
Ultimate Limit State ◽  
Structural Components ◽  
Floor Response Spectra ◽  
Potential Failure ◽  
Response Amplification ◽  
Floor Acceleration

Earthquake loadings standard NZS 1170.5:2004 has introduced new provisions for the design of building parts and non-structural components. The provisions include factors to define peak floor acceleration up the height of a building, and acceleration response amplifications for components that are quite different from overseas counterparts. In this study, acceleration demands on non-structural components located in ductile frame buildings are analysed under earthquake records from crustal and slab events, for design levels representing ultimate limit state and serviceability limit state. A floor response spectra approach is used to study the demands on non-structural components. It is noted that the peak floor acceleration demands with respect to that of the ground are not amplified up the height of the building to the extent suggested in NZS provisions. The floor response spectra show peaks near the modal periods of the building indicating higher demands on the components with periods closer to the building period. However, NZS provisions fail to include this effect, since the spectral response amplification is defined independent of building period. Spectral demands exceed the NZS provisions at the fundamental periods of the buildings, more significantly at serviceability conditions, indicating potential failure of non-structural components with periods close to the building periods. Following the analytical observations from the buildings considered in this study it is clear that the design provisions for non-structural components should be linked to the structural response for specific performance levels rather than the ‘life-safety’ performance level only that is currently adopted in the New Zealand design standard.

Direct generation of floor design spectra (FDS) from uniform hazard spectra (UHS) — Part I: formulation of the method

2020 ◽  
Vol 47 (12) ◽  
pp. 1372-1386 ◽  
Author(s):  
Amin Asgarian ◽  
Ghyslaine McClure
Keyword(s):  
Seismic Analysis ◽  
Three Dimensional ◽  
Response Spectra ◽  
Ambient Vibration ◽  
Uniform Hazard Spectra ◽  
Design Spectra ◽  
Floor Response Spectra ◽  
Response Amplification ◽  
Direct Generation ◽  
Ambient Vibration Measurements

In most current building codes, seismic design of non-structural components (NSCs) is addressed through empirical equations that do not capture NSC response amplification due to tuning effects with higher and torsional modes of buildings and that neglect NSC damping. This work addresses these shortcomings and proposes a practical approach to generate acceleration NSC floor design spectra (FDS) in buildings directly from their corresponding uniform hazard spectra (UHS). The study is based on the linear seismic analysis of 27 reinforced concrete buildings located in Montréal, Canada, for which ambient vibration measurements (AVM) are used to determine their in situ three-dimensional dynamic characteristics. Pseudo acceleration floor response spectra (PA-FRS) are derived at every building floor for four different NSCs damping ratios. The calculated roof FRS are compared with the 5% damped UHS and a formulation is proposed to generate roof FDS for NSCs with 5% damping directly from the UHS.

Use of RVT for Computation of In-Structure Response Spectra and Peak Responses and Comparison to Time History and Response Spectrum Analysis

2018 ◽  
Vol 34 (4) ◽  
pp. 1913-1930 ◽  
Author(s):  
Irmela Zentner
Keyword(s):  
Response Spectrum ◽  
Structural Response ◽  
Time History ◽  
Strong Motion ◽  
Response Spectra ◽  
Combination Rules ◽  
Floor Response Spectra ◽  
Power Spectral ◽  
Time Histories ◽  
Definition Of

The random vibration theory offers a framework for the conversion of response spectra into power spectral densities (PSDs) and vice versa. The PSD is a mathematically more suitable quantity for structural dynamics analysis and can be straightforwardly used to compute structural response in the frequency domain. This allows for the computation of in-structure floor response spectra and peak responses by conducting only one structural analysis. In particular, there is no need to select or generate spectrum-compatible time histories to conduct the analysis. Peak response quantities and confidence intervals can be computed without any further simplifications such as currently used in the response spectrum method, where modal combination rules have to be derived. In contrast to many former studies, the Arias intensity-based definition of strong-motion duration is adopted here. This paper shows that, if the same definitions of strong-motion duration and modeling assumptions are used for time history and RVT computations, then the same result can be expected. This is illustrated by application to a simplified model of a reactor building.

Blind Prediction of SMART 2008 Seismic Structural Response Test Results

2008 ◽  
Author(s):  
Pentti Varpasuo ◽  
Jukka Ka¨hko¨nen
Keyword(s):  
Numerical Simulation ◽  
Reinforced Concrete ◽  
Structural Response ◽  
Response Spectra ◽  
Test Results ◽  
Base Excitation ◽  
Structural Dynamic ◽  
Blind Prediction ◽  
Floor Response Spectra ◽  
Best Estimate

This paper describes the numerical simulation contribution of Fortum Nuclear Services Ltd. to the round-robin blind prediction of SMART 2008 seismic structural response tests to be conducted by Commissariat Energie Atomique in France in spring 2008. In order to assess the seismic tri-dimensional effects (such as torsion) and non-linear response of reinforced concrete buildings, a reduced scaled model (scale of 1/4th) of a nuclear reinforced concrete building is going to be tested in 2008 on AZALEE shaking table at Commissariat a` l’Energie Atomique (CEA Saclay, France). This test, supported by Commissariat a` l’Energie Atomique (CEA) and Electricite´ de France (EDF), will be part of the “SMART-2008” project (Seismic design and best-estimate Methods Assessment for Reinforced concrete buildings subjected to Torsion and non-linear effects). The first part of the project is a blind prediction of the structure behavior under different seismic loadings. It is presented as a contest, opened to teams from the practicing structural engineering as well as the academic and research community, worldwide. This phase will result in the creation of a predictive benchmark, which should allow us to compare and validate approaches used for the dynamic responses evaluation of reinforced concrete structures subjected to earthquake and exhibiting both 3-D and nonlinear behaviors. The objectives of the predictive benchmark are to: 1) Assess different conventional design methods of structural dynamic analyses, including floor response spectra evaluation; 2) Compare best-estimate methods for structural dynamic response and floor response spectra evaluation. In the next analytical phase to be carried out during the year 2009, the prediction contest will be compared to test results at various levels of seismic excitation (including ‘under-design’ and high ‘over-design’ levels), in order to: 1) Quantify variability in the seismic response of the structure and identify contribution coming from uncertainties in input parameters and random variables; 2) Investigate and compare different methods for fragility curves elaboration. The numerical simulation gives the best estimate values for acceleration response spectra values in five specified response points of the model in two perpendicular horizontal directions for base excitation values from 0.05g up to 0.8 g. Also the maximum and minimum values of the stresses and strains in the concrete and in the reinforcement of four vertical walls of the model are to be simulated as well as the acceleration and displacement response time histories at the top of the model for base excitation values from 0.05g up to 0.8 g.

scholarly journals On a feedback-feedforward identification control algorithm for feedback active controlled structures

2007 ◽  
Vol 29 (4) ◽  
pp. 507-516
Author(s):  
La Duc Viet ◽  
Nguyen Dong Anh
Keyword(s):  
Control Algorithm ◽  
Feedforward Control ◽  
Structural Response ◽  
Linear Quadratic Regulator ◽  
Identification Algorithm ◽  
Linear Quadratic ◽  
Lqr Control ◽  
Controlled Systems ◽  
Active Mass Damper ◽  
Feedback Algorithm

Linear quadratic regulator (LQR) is an effective method of feedback active control theory. However, the LQR control is not truly optimal because it is only a feedback algorithm, i.e. the external excitation term is ignored in the optimal equation. In a previous paper [1], the identification algorithm is presented for feedback active controlled systems to identify the excitation from the structural response measured. The aim of this paper is to propose a feedback-feedforward control algorithm using the identified excitation to improve the classical LQR control. A numerical simulation is applied to an eight story building subjected to base acceleration and controlled by active mass damper system.

scholarly journals Accuracy of Analytical Models to Predict Primary and Secondary System Response in Seismically Isolated Buildings

2021 ◽  
Author(s):  
Cengiz Ipek ◽  
Eric D. Wolff ◽  
Michael C. Constantinou
Keyword(s):  
Seismic Isolation ◽  
Response Spectra ◽  
Analytical Models ◽  
System Response ◽  
Primary System ◽  
Secondary System ◽  
Viscous Dampers ◽  
Floor Response Spectra ◽  
Analytical Results ◽  
Seismically Isolated

Abstract Seismic isolation is generally considered an effective earthquake protection strategy. As application of seismic isolation increases, decisions on the use of one particular isolator versus another isolator increasingly depend on computed responses with complex analytical models. Accordingly, validation of analytical models to predict primary (structural) and secondary system (non-structural component) response in seismically isolated buildings becomes very important. This paper presents comparisons of experimental and analytical results on the primary and secondary system response of a building model in order to provide information on the accuracy of the predicted response. The tested model was configured as a 6-story building at quarter length scale in a moment-frame configuration, and with the following seismic isolation systems: a) Low damping elastomeric bearings with and without linear or nonlinear viscous dampers, b) Single Friction Pendulum (FP) bearings with and without linear or nonlinear viscous dampers, and c) Lead-rubber bearings. Response quantities compared include story drifts and isolator shear forces and displacements for the primary system, and peak floor total velocities and floor response spectra that relate to secondary system response. This paper presents samples results out of a total of 288 comparisons of experimental and analytical results presented in an MCEER report. It is shown that the primary and secondary system response is computed with sufficient accuracy by the analytical models but some response quantities may be underestimated or overestimated by significant amounts.

Inclusion of Aircraft Crash into NPP Design Bases and Probabilistic Justification of Loads on Civil Structures and Equipment

2020 ◽  
pp. 35-47
Author(s):  
Nikita Chernukha
Keyword(s):  
Nuclear Power ◽  
Response Spectra ◽  
Mechanical Action ◽  
Exceedance Probability ◽  
Civil Structures ◽  
Method Of Calculation ◽  
Floor Response Spectra ◽  
Aircraft Trajectory ◽  
Probabilistic Justification ◽  
Aircraft Crash

The article is about nuclear power plant (NPP) safety analysis in case of aircraft crash. Specifically, the article considers the following problems: inclusion of aircraft crash into NPP design bases regarding calculation of frequency of an aircraft crash into NPP; aspects of justification of loads on NPP structures, systems and components (SSCs) caused by mechanical action of a primary missile – aircraft fuselage impact. Probabilistic characteristics of such random parameters as frequency of aircraft crash and direction of aircraft trajectory are determined by the results of analysis of world statistics of aviation accidents. Method of calculation of aircraft crash frequency on structures, buildings and NPP as a whole is presented. It takes into account options of accidental and intentional aircraft crashes and various aircraft approach scenarios. Procedure of probabilistic justification of loads on civil structures under aircraft impact is described. The loads are specified so as not to exceed allowable value of failure probability of NPP as a whole. Calculation of failure frequency of civil structures of existing NPP is given as an example to show analysis in case of a crash of an aircraft heavier than considered in NPP design. Procedure of probabilistic justification of dynamic loads on NPP equipment in case of aircraft impact is described. Method of floor response spectra (FRS) calculation with the required non-exceedance probability is given. Probabilistically justified loads in case of intentional aircraft impact (act of terrorism) are also considered. Additionally it is presented how internal forces calculated with the use of FRS with the required non-exceedance probability can be summed to provide analysis of subsystems.

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