Design Approach Based on UAFR Spectra for Structures with Displacement-Dependent Dissipating Elements

2007 ◽  
Vol 23 (2) ◽  
pp. 417-439 ◽  
Author(s):  
J. Luz Rivera ◽  
Sonia E. Ruiz
Keyword(s):  
Seismic Response ◽  
Response Spectra ◽  
Design Criterion ◽  
Limit States ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Mdof Systems ◽  
Concrete Building ◽  
Hazard Curves ◽  
Ultimate Limit

In the first part of this paper an algorithm is proposed to obtain demand hazard curves and, from them, seismic-response spectra with uniform annual failure rates for single-degree-of-freedom (SDOF) systems with energy-dissipating devices (EDDs). In the second part, a performance-based dual-level approach is proposed for the design of buildings with EDDs. The criterion establishes acceptance conditions (related to serviceability—and to ultimate limit-states) that correspond to the main system and to the dissipating elements. The uncertainties implicit in the transformation between the response of SDOF and MDOF systems with EDDs are taken into account by means of their demand hazard curves. The reliability-based dual-level design criterion proposed is illustrated by means of a ten-story reinforced concrete building rehabilitated with steel energy-dissipating devices.

Seismic Response Reduction Caused by Coupling Between Beam-Type and Oval-Type Vibrations of a Cylindrical Water Storage Tank Under Large Excitation

2007 ◽  
Author(s):  
Akira Maekawa ◽  
Katsuhisa Fujita ◽  
Michiaki Suzuki
Keyword(s):  
Seismic Response ◽  
Water Storage ◽  
Degree Of Freedom ◽  
Seismic Excitation ◽  
System Model ◽  
Single Degree Of Freedom ◽  
Water Storage Tank ◽  
Single Degree ◽  
Input Acceleration ◽  
Beam Type

This study describes the response reduction caused by coupling between the beam-type and the oval-type vibrations of a cylindrical water storage tank under seismic excitation. In this study, the seismic response experiment is performed by using a 1/10 reduced scale model of an actual tank and then numerical simulation is performed by the simplified model. The authors conducted the sinusoidal response experiment for the tank and reported that the coupling between the beam-type and the oval-type vibrations causes the resonance frequency of the beam-type vibration to shift to the lower frequency and the response in the beam-type vibration (the response of the tank) to reduce. The seismic response experiment of the tank model filled with water up to 95% is performed by a shaking table. The El Centro 1940 NS and the improved standard seismic wave for Japanese LWR are used as the input seismic wave. The experimental results show that the maximum response acceleration does not enlarge linearly as the maximum input acceleration increases. The dominant resonance frequency slightly shifts to the lower frequency as the maximum input acceleration increases. It is concluded that the coupling between the beam-type and the oval-type vibrations make an influence on the beam-type vibration in seismic excitation. In the meantime, the authors propose the nonlinear single-degree-of-freedom system model to explain that the vibration response of the tank reduces. This model is based on geometric nonlinearity due to the out-of-plane deformation of the side-wall of the tank caused by the oval-type vibration. The numerical simulation of the seismic response is conducted using the nonlinear single-degree-of-freedom system model proposed by the authors. The analytical results agree with the experimental results as a general trend. Therefore, it is concluded that the response reduction of the tank is generated by coupling between the beam-type and the oval-type vibrations in the seismic excitation as well as the sinusoidal excitation. In addition, the response reduction rate of the tank under much larger seismic excitation can be estimated by using the nonlinear single-degree-of-freedom system model.

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.

A Design Criterion for Avoiding Resonance in Lumped Mass Normal Mode Systems

1989 ◽  
Vol 111 (1) ◽  
pp. 48-52
Author(s):  
A. D. S. Ross ◽  
D. J. Inman
Keyword(s):  
Normal Mode ◽  
Design Criterion ◽  
Degree Of Freedom ◽  
Simple Design ◽  
Parameter System ◽  
Lumped Mass ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Lumped Parameter

A simple design criterion that determines whether a normal mode multiple degree of freedom damped linear lumped parameter system can or cannot resonate is presented. The relations are derived based on criteria for resonance in the single degree of freedom case, and on the definiteness of certain combinations of coefficient matrices. An example follows that both numerically verifies the derivation and illustrates the simplicity of implementing the result as a design criterion.

Vibrations

2017 ◽  
pp. 44-93
Keyword(s):  
Degrees Of Freedom ◽  
Normal Modes ◽  
Mode Shapes ◽  
Continuous Systems ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Mdof Systems ◽  
Parametric Coupling ◽  
Bending Modes ◽  
Stability Concepts

Vibration concepts are reviewed. Single degree-of-freedom vibration (SDOF) are analyzed. Subsequently, the analysis is extended to two degrees-of-freedom (2DOF) systems and coupling in a 2DOF system. The analysis of parametric coupling is introduced. Two sections on energy flow and the modeling of damping follow. Normal modes and mode shapes for systems with multiple degrees-of-freedom (MDOF) will then be considered. By generalizing MDOF systems to continuous systems, we can analyze bending modes in plates. Experimental modal analysis is introduced to prepare the reader for later application of this technique to full-scale operational gates. The second section of this chapter reviews fundamental concepts of fluid-structure systems with resonance. The chapter concludes with a short discussion of stability concepts.

Dynamics of High-Speed Cam-Driven Mechanisms—Part 1: Linear System Models

1975 ◽  
Vol 97 (3) ◽  
pp. 769-775 ◽  
Author(s):  
Fan Y. Chen ◽  
N. Polvanich
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Response Spectra ◽  
System Model ◽  
Single Degree Of Freedom ◽  
System Parameters ◽  
Response Characteristics ◽  
Single Degree ◽  
Design Charts ◽  
Driven System

The dynamic response of the cam-driven mechanism is investigated for a variety of cam motion profiles. Based on a linear, lumped system model of single degree of freedom, the results of the response characteristics of the follower are presented in the form of nondimensional primary and residual shock response spectra. These spectra are also recasted in four-coordinate log-log grid forms. The extension of this approach to treat the system model of two degrees of freedom is delineated. Furthermore, the analysis of a two-freedom model of the cam-driven system was also undertaken to clarify the effects of many system parameters and for obtaining an optimal design. Fundamental design charts are presented.

Dynamics of High-Speed Cam-Driven Mechanisms—Part 2: Nonlinear System Models

1975 ◽  
Vol 97 (3) ◽  
pp. 777-781 ◽  
Author(s):  
F. Y. Chen ◽  
N. Polvanich
Keyword(s):  
Nonlinear System ◽  
High Speed ◽  
Phase Plane ◽  
Response Spectra ◽  
Equation Of Motion ◽  
Dynamic Responses ◽  
System Model ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Shock Response

The dynamic responses of the cam-driven mechanism are investigated, based on a non-linear lumped system model. The nonlinearity is an energy-dissipating element which consists of viscous, quadratic, Coulomb and static frictions combined. The nonlinear equation of motion of a single degree of freedom is first analyzed using a numerical method and the results of time responses are presented and characterized in the phase-plane. The primary and residual shock response spectra in nondimensional form for a number of typical cam input excitations are presented and compared with those of the associated linear cases.

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