scholarly journals Accuracy of analytical models to predict primary and secondary system response in seismically isolated buildings

2021 ◽  
Vol 150 ◽  
pp. 106944
Author(s):  
C. Ipek ◽  
E.D. Wolff ◽  
M.C. Constantinou
Keyword(s):  
Analytical Models ◽  
System Response ◽  
Secondary System ◽  
Seismically Isolated

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.

scholarly journals Fragility Assessments of Multi-Story Piping Systems within a Seismically Isolated Low-Rise Building

2018 ◽  
Vol 10 (10) ◽  
pp. 3775 ◽  
Author(s):  
Yonghee Ryu ◽  
Shinyoung Kwag ◽  
Bu‐Seog Ju
Keyword(s):  
Seismic Isolation ◽  
Ground Motions ◽  
Seismic Energy ◽  
Analytical Models ◽  
Piping System ◽  
Building Structure ◽  
Strong Ground Motions ◽  
Piping Systems ◽  
Seismically Isolated ◽  
Strong Ground

A successful, advanced safety design method for building and piping structures is related to its functionality and sustainability in beyond-design-basis events such as extremely strong ground motions. This study develops analytical models of seismically isolated building-piping systems in which multi-story piping systems are installed in non-isolated and base-isolated, low-rise buildings. To achieve the sustainable design of a multi-story piping system subjected to strong ground motions, Triple Friction Pendulum (TFP) elements, specifically TFP bearings, were incorporated into the latter building structure. Then, a seismic fragility analysis was performed in consideration of the uncertainty of the seismic ground motions, and the piping fragilities for the seismically non-isolated and the base-isolated building models were quantified. Here, the failure probability of the piping system in the non-isolated building was greater than that in the seismically isolated building. The seismic isolation design of the building improved the sustainability and functionality of the piping system by significantly reducing the seismic energy of extreme ground motions which was input to the building structure itself.

Simplified analysis of a low-rise building seismically isolated with stable unbonded fiber reinforced elastomeric isolators

2009 ◽  
Vol 36 (7) ◽  
pp. 1182-1194 ◽  
Author(s):  
Hamid Toopchi-Nezhad ◽  
Michael J. Tait ◽  
Robert G. Drysdale
Keyword(s):  
Seismic Response ◽  
Lateral Displacement ◽  
Hysteresis Loops ◽  
Time History ◽  
Response Prediction ◽  
Analytical Models ◽  
Fiber Reinforced ◽  
Cyclic Shear ◽  
Compression Load ◽  
Seismically Isolated

The seismic response of an ordinary low-rise base isolated (BI) structure, employing stable unbonded-fiber reinforced elastomeric isolator (SU-FREI) bearings, is predicted by using two different simplified analytical models. Subsequently, the accuracy of the two models is evaluated by using measured test results from a shake table study. Two models simulate the nonlinear experimental lateral load–displacement hysteresis loops of these bearings. The experimental hysteresis loops were obtained from cyclic shear tests on prototype bearings under a constant compression load. Because of the nonlinear lateral response behavior of the SU-FREIs, these models are employed in an iterative time-history analysis approach, enabling the model variables and the calculated peak lateral displacement of the bearings to converge to their unique values. Analysis results show that the presented simplified models may be used effectively in seismic response prediction of ordinary low-rise buildings that are seismically isolated by SU-FREI bearings.

scholarly journals Design of Chatter-Resistant Damped Boring Bars Using a Receptance Coupling Approach

2020 ◽  
Vol 4 (2) ◽  
pp. 53 ◽  
Author(s):  
Ajay Yadav ◽  
Devangkumar Talaviya ◽  
Ankit Bansal ◽  
Mohit Law
Keyword(s):  
Stability Limit ◽  
Analytical Models ◽  
Classical Solutions ◽  
System Response ◽  
Chatter Vibration ◽  
Boring Bar ◽  
Damped System ◽  
Receptance Coupling ◽  
Coupling Approach ◽  
Stiffness And Damping

Deep hole boring using slender bars that have tuned mass dampers integrated within them make the boring process chatter vibration resistant. Dampers are usually designed using classical analytical solutions that presume the (un)damped boring bar which can be approximated by a single degree of freedom system, and the damper is placed at the free end. Since the free end is also the cutting end, analytical models may result in infeasible design solutions. To place optimally tuned dampers within boring bars, but away from the free end, this paper presents a receptance coupling approach in which the substructural receptances of the boring bar modelled as a cantilevered Euler–Bernoulli beam are combined with the substructural receptances of a damper modelled as a rigid mass integrated anywhere within the bar. The assembled and damped system response thus obtained is used to predict the chatter-free machining stability limit. Maximization of this limit is treated as the objective function to find the optimal mass, stiffness and damping of the absorber. Proposed solutions are first verified against other classical solutions for assumed placement of the absorber at the free end. Verified models then guide prototyping of a boring bar integrated with a damper placed away from its free end. Experiments demonstrate a ~100-fold improvement in chatter vibration free machining capability. The generalized methods presented herein can be easily extended to design and develop other damped and chatter-resistant tooling systems.

Predicting Macroscopic Dynamics in Large Distributed Systems: Part I

2011 ◽  
Author(s):  
K. L. Mills ◽  
J. J. Filliben ◽  
D.-Y. Cho ◽  
E. J. Schwartz
Keyword(s):  
Distributed Systems ◽  
Congestion Control ◽  
Analytical Models ◽  
Multidimensional Data ◽  
System Response ◽  
Small Scale ◽  
The Internet ◽  
Essential Information ◽  
Data Flows ◽  
Test Beds

Society increasingly depends on large distributed systems, such as the Internet and Web-based service-oriented architectures deployed over the Internet. Such systems constantly evolve as new software components are injected to provide increased functionality, better performance and enhanced security. Unfortunately, designers lack effective methods to predict how new components might influence macroscopic behavior. Lacking effective methods, designers rely on engineering techniques, such as: analysis of critical algorithms at small scale and under limiting assumptions; factor-at-a-time simulations conducted at modest scale; and empirical measurements in small test beds. Such engineering techniques enable designers to characterize selected properties of new components but reveal little about likely dynamics at global scale. In this paper, we outline an approach that can be used to predict macroscopic dynamics when new components are deployed in a large distributed system. Our approach combines two main methods: scale reduction and multidimensional data analysis techniques. Combining these methods, we can search a wide parameter space to identify factors likely to drive global system response and we can predict the resulting macroscopic dynamics of key system behaviors. We demonstrate our approach in the context of the Internet, where researchers, motivated by a desire to increase user performance, have proposed new algorithms to replace the standard congestion control mechanism. Previously, the proposed algorithms were studied in three ways: using analytical models of single data flows, using empirical measurements in test beds where a few data flows compete for bandwidth, and using simulations at modest scale with a few sequentially varied parameters. In contrast, by applying our approach, we simulated configurations covering four-tier network topologies, spanning continental and global distances, comprising routers operating at state-of-the-art speeds and transporting more than 105 simultaneous data flows with varying traffic patterns and temporary spatiotemporal congestion. Our findings identify the main factors influencing macroscopic dynamics of Internet congestion control, and define the specific combination of factors that must hold for users to realize improved performance. We also uncover potential for one proposed algorithm to cause widespread performance degradation. Previous engineering studies of the proposed congestion control algorithms were unable to reveal such essential information.

scholarly journals Evaluation of Clearance to Stop Requirements in A Seismically Isolated Nuclear Power Plant

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 6156
Author(s):  
Gyeonghee An ◽  
Minkyu Kim ◽  
Jae-Wook Jung ◽  
Gilberto Mosqueda ◽  
Joaquin Fabian Marquez
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Power Plants ◽  
Structural Model ◽  
Large Strain ◽  
Performance Criteria ◽  
Analytical Models ◽  
Design Standards ◽  
Strain Behavior ◽  
Seismically Isolated

Seismically isolated nuclear power plants (NPPs) can provide substantial benefits towards reducing the failure probability of NPPs, especially for beyond design basis earthquake shaking. One risk posed by seismic isolation is the potential for pounding to a stop or moat wall, with currently little guidance provided by design standards on how to address this concern. In this paper, a structural model of an isolated NPP based on the Advanced Power Reactor 1400 MW is enveloped with moat walls and advanced bearing models. The bearing models account for large strain behavior through failure based on full-scale experiments with lead rubber bearings (LRBs). Using these analytical models and a measured ultimate property diagram from LRB failure tests, the range of clearance to the stop considering the performance criteria for the NPP is investigated. Although the analysis results are dependent on the particular models, ground motions, and criteria employed, this research provides an overview of the seismic response and performance criteria of an isolated NPP considering the clearance to the stop.

Comparison of Linear and Nonlinear Electromagnetic Coupling Models for a Linear Oscillator

2011 ◽  
Author(s):  
Benjamin A. M. Owens ◽  
Brian P. Mann
Keyword(s):  
Peak Power ◽  
Nonlinear Models ◽  
Electromagnetic Coupling ◽  
Analytical Models ◽  
Linear Oscillator ◽  
System Response ◽  
Excitation Threshold ◽  
Current Response ◽  
And Behavior ◽  
Low Amplitude

This paper examines the modeling and behavior of two forms of electromagnetic coupling with a linear oscillator. With coupling as either a linear or a nonlinear term dependent on position, analytical results were derived and numerical simulations performed for the mechanical and electrical system response. Analytical models were found to correlate well with their respective simulations. Linear coupling showed wider power bandwidth at certain excitation levels and higher theoretical power output than nonlinear beyond an excitation threshold. Nonlinear models showed increasingly complex harmonic current response at high excitation amplitudes and increased peak power at low amplitude excitation levels for certain offset coil positions.

Analytical Models for Seabed Interaction Effects on Steel Catenary Riser in Touchdown Zone

2013 ◽  
Author(s):  
Kosar Rezazadeh ◽  
Yong Bai ◽  
Jiwei Tang ◽  
Liang Zhang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
System Performance ◽  
Analytical Models ◽  
System Response ◽  
Complex Nature ◽  
Element Analysis ◽  
Steel Catenary Riser ◽  
Steel Catenary Risers ◽  
Seabed Interaction

The complex nature of seabed interaction with steel catenary risers (SCR) in touch down zone (TDZ) of SCRs makes serious difficulties for engineering design industry. Design must ensure that the curvature remains well within elastic limits, and that fatigue damage remains acceptable during the life. Analytical methods, despite it is limited in the accuracy because of idealizations of the system response, it offers a first step in assessing the system performance. The paper compares the results of different seabed interaction models with those from finite element analysis to evaluate the accuracy and consistency of solutions for initial design assumptions and fatigue assessment.

Predicting Macroscopic Dynamics in Large Distributed Systems: Part II

2011 ◽  
Author(s):  
K. L. Mills ◽  
J. J. Filliben ◽  
D.-Y. Cho ◽  
E. J. Schwartz
Keyword(s):  
Distributed Systems ◽  
Congestion Control ◽  
Analytical Models ◽  
Multidimensional Data ◽  
System Response ◽  
Small Scale ◽  
The Internet ◽  
Essential Information ◽  
Data Flows ◽  
Test Beds

Society increasingly depends on large distributed systems, such as the Internet and Web-based service-oriented architectures deployed over the Internet. Such systems constantly evolve as new software components are injected to provide increased functionality, better performance and enhanced security. Unfortunately, designers lack effective methods to predict how new components might influence macroscopic behavior. Lacking effective methods, designers rely on engineering techniques, such as: analysis of critical algorithms at small scale and under limiting assumptions; factor-at-a-time simulations conducted at modest scale; and empirical measurements in small test beds. Such engineering techniques enable designers to characterize selected properties of new components but reveal little about likely dynamics at global scale. In this paper, we outline an approach that can be used to predict macroscopic dynamics when new components are deployed in a large distributed system. Our approach combines two main methods: scale reduction and multidimensional data analysis techniques. Combining these methods, we can search a wide parameter space to identify factors likely to drive global system response and we can predict the resulting macroscopic dynamics of key system behaviors. We demonstrate our approach in the context of the Internet, where researchers, motivated by a desire to increase user performance, have proposed new algorithms to replace the standard congestion control mechanism. Previously, the proposed algorithms were studied in three ways: using analytical models of single data flows, using empirical measurements in test beds where a few data flows compete for bandwidth, and using simulations at modest scale with a few sequentially varied parameters. In contrast, by applying our approach, we simulated configurations covering four-tier network topologies, spanning continental and global distances, comprising routers operating at state-of-the-art speeds and transporting more than 105 simultaneous data flows with varying traffic patterns and temporary spatiotemporal congestion. Our findings identify the main factors influencing macroscopic dynamics of Internet congestion control, and define the specific combination of factors that must hold for users to realize improved performance. We also uncover potential for one proposed algorithm to cause widespread performance degradation. Previous engineering studies of the proposed congestion control algorithms were unable to reveal such essential information.

scholarly journals Dynamical Behavior of a Pseudoelastic Vibration Absorber Using Shape Memory Alloys

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Hugo De S. Oliveira ◽  
Aline S. De Paula ◽  
Marcelo A. Savi
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Dynamical Behavior ◽  
Vibration Reduction ◽  
Hysteretic Behavior ◽  
System Response ◽  
Vibration Absorber ◽  
Primary System ◽  
Secondary System ◽  
Tuned Vibration Absorber

The tuned vibration absorber (TVA) provides vibration reduction of a primary system subjected to external excitation. The idea is to increase the number of system degrees of freedom connecting a secondary system to the primary system. This procedure promotes vibration reduction at its design forcing frequency but two new resonance peaks appear introducing critical behaviors that must be avoided. The use of shape memory alloys (SMAs) can improve the performance of the classical TVA establishing an adaptive TVA (ATVA). This paper deals with the nonlinear dynamics of a passive pseudoelastic tuned vibration absorber with an SMA element. In this regard, a single degree of freedom elastic oscillator is used to represent the primary system, while an extra oscillator with an SMA element represents the secondary system. Temperature dependent behavior of the system allows one to change the system response avoiding undesirable responses. Nevertheless, hysteretic behavior introduces complex characteristics to the system dynamics. The influence of the hysteretic behavior due to stress-induced phase transformation is investigated. The ATVA performance is evaluated by analyzing primary system maximum vibration amplitudes for different forcing amplitudes and frequencies. Numerical simulations establish comparisons of the ATVA results with those obtained from the classical TVA. A parametric study is developed showing the best performance conditions and this information can be useful for design purposes.

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