scholarly journals Identification of first and second order models for the superstructure of base-isolated buildings using free vibration tests: A case study

2020 ◽  
Vol 135 ◽  
pp. 106178 ◽  
Author(s):  
Anastasia Athanasiou ◽  
Nicholas D. Oliveto ◽  
Felice C. Ponzo
Keyword(s):  
Free Vibration ◽  
Second Order ◽  
Vibration Tests

scholarly journals Effects of Precast Cladding Systems on Dynamic Characteristics of Steel Frame Buildings by Ambient and Free Vibration Tests

2017 ◽  
Vol 2017 ◽  
pp. 1-20 ◽  
Author(s):  
Jun Ma ◽  
Shinji Nakata ◽  
Akihito Yoshida ◽  
Yukio Tamura
Keyword(s):  
Free Vibration ◽  
Dynamic Characteristics ◽  
Steel Frame ◽  
Ambient Vibration ◽  
Test Cases ◽  
Vibration Method ◽  
External Wall ◽  
Wide Range ◽  
Cladding Panels ◽  
Vibration Tests

Full-scale tests on a one-story steel frame structure with a typical precast cladding system using ambient and free vibration methods are described in detail. The cladding system is primarily composed of ALC (Autoclaved Lightweight Concrete) external wall cladding panels, gypsum plasterboard interior linings, and window glazing systems. Ten test cases including the bare steel frame and the steel frame with addition of different parts of the precast cladding system are prepared for detailed investigations. The amplitude-dependent dynamic characteristics of the test cases including natural frequencies and damping ratios determined from the tests are presented. The effects of the ALC external wall cladding panels, the gypsum plasterboard interior linings, and the window glazing systems on the stiffness and structural damping of the steel frame are discussed in detail. The effect of the precast cladding systems on the amplitude dependency of the dynamic characteristics and the tendencies of the dynamic parameters with respect to the structural response amplitude are investigated over a wide range. Furthermore, results estimated from the ambient vibration method are compared with those from the free vibration tests to evaluate the feasibility of the ambient vibration method.

Characterization of hydrodynamic properties from free vibration tests of a large-scale bridge model

2021 ◽  
Vol 106 ◽  
pp. 103368
Author(s):  
Thomas Schumacher ◽  
Alaa W. Hameed ◽  
Christopher Higgins ◽  
Brittany Erickson
Keyword(s):  
Free Vibration ◽  
Large Scale ◽  
Hydrodynamic Properties ◽  
Bridge Model ◽  
Vibration Tests

scholarly journals Macroscopic and Multi-Scale Models for Multi-Class Vehicular Dynamics with Uneven Space Occupancy: A Case Study

Axioms ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 102
Author(s):  
Maya Briani ◽  
Emiliano Cristiani ◽  
Paolo Ranut
Keyword(s):  
Road Network ◽  
Real Data ◽  
Second Order ◽  
Heavy Vehicles ◽  
First Order ◽  
Multi Scale ◽  
Stop And Go ◽  
Scale Models ◽  
Road Space

In this paper, we propose two models describing the dynamics of heavy and light vehicles on a road network, taking into account the interactions between the two classes. The models are tailored for two-lane highways where heavy vehicles cannot overtake. This means that heavy vehicles cannot saturate the whole road space, while light vehicles can. In these conditions, the creeping phenomenon can appear, i.e., one class of vehicles can proceed even if the other class has reached the maximal density. The first model we propose couples two first-order macroscopic LWR models, while the second model couples a second-order microscopic follow-the-leader model with a first-order macroscopic LWR model. Numerical results show that both models are able to catch some second-order (inertial) phenomena such as stop and go waves. Models are calibrated by means of real data measured by fixed sensors placed along the A4 Italian highway Trieste–Venice and its branches, provided by Autovie Venete S.p.A.

scholarly journals Systemic Design for Second-Order Effects

2017 ◽  
Vol 10 (1) ◽  
Author(s):  
Evan Barba
Keyword(s):  
Organizational Change ◽  
Systems Approach ◽  
Core Competency ◽  
Second Order ◽  
Order Effects ◽  
Classroom Intervention ◽  
Second Order Effects ◽  
Design Skills ◽  
Systemic Design

Second-order effects refer to changes within a system that are the result of changes made somewhere else in the system (the first-order effects). Second-order effects can occur at different spatial, temporal, or organizational scales from the original interventions, and are difficult to control. Some organizational theorists suggest that careful management of feedback processes can facilitate controlled change from one organizational configuration to another. Recognizing that skill in managing feedback processes is a core competency of design suggests that design skills are potentially useful tools in achieving organizational change. This paper describes a case study in which a co-design methodology was used to control the second-order effects resulting from a classroom intervention to create organizational change. This approach is then theorized as the Instigator Systems approach.

A case study in bifurcation theory

2017 ◽  
Vol 28 (08) ◽  
pp. 1750104 ◽  
Author(s):  
Youssef Khmou
Keyword(s):  
Dynamical Systems ◽  
Bifurcation Theory ◽  
Chaotic Behavior ◽  
Numerical Study ◽  
Logistic Map ◽  
Logistic Function ◽  
Second Order ◽  
Short Paper ◽  
Chaotic Region

This short paper is focused on the bifurcation theory found in map functions called evolution functions that are used in dynamical systems. The most well-known example of discrete iterative function is the logistic map that puts into evidence bifurcation and chaotic behavior of the topology of the logistic function. We propose a new iterative function based on Lorentizan function and its generalized versions, based on numerical study, it is found that the bifurcation of the Lorentzian function is of second-order where it is characterized by the absence of chaotic region.

scholarly journals ANÁLISE DE SEGUNDA ORDEM DE ESTRUTURAS EM CONCRETO ARMADO

2021 ◽  
Vol 9 (206) ◽  
pp. 1-23
Author(s):  
Ailton Queiroz Junior ◽  
Antonio Ribeiro Santos Junior
Keyword(s):  
Global Stability ◽  
Second Order ◽  
Bending Moments ◽  
Mobile Nodes ◽  
Analysis Software ◽  
Structural Details ◽  
Overall Stability ◽  
Complex Structural ◽  
Bracing System

With the expressive increase in the demand for increasingly tall and robust constructions, plus more and more complex structural details that end up becoming a key element for the projects of the structures of the undertakings, it is important to consider the efforts made by the reinforced concrete structures are subjected. In this sense, the present work has as objective the approach of the parameters of global stability a and Yz followed by the verification of the efforts on the pavements and the displacements of the building caused by the loads acting on the structure. In this work, the use of the global stability parameter a and Yz, which is of fundamental relevance and also prescribed in NBR 6118 (ABNT, 2014), was evaluated. The use of the parameter a considered for the evaluation of the overall stability of the structure, but which is not capable of estimating second order efforts, allows us to classify a structure as being of fixed or mobile nodes. The Yz parameter, on the other hand, can be used to obtain second order efforts. To carry out this work, a case study was launched in the structural analysis software Ftool. The present analysis carried out showed that it is possible to conceive a bracing system for a building with up to 30 floors, using the pillar-wall solution having as a substitute resource for the aforementioned solution the solution of frames formed by beams and columns addressed continuously by tall building literature. Therefore, it is worth mentioning that the solution with wall pillars tends to be more expensive than the solution with frames, a system adopted in the development of this work due to the economic viability of the construction, in view of a higher consumption of materials in the superstructure and also higher costs in the construction. execution of foundations, due to the efforts that will be generated in the building (horizontal forces and bending moments).

The Lift Force on a Cylinder Vibrating in a Current

1990 ◽  
Vol 112 (4) ◽  
pp. 297-303 ◽  
Author(s):  
G. Moe ◽  
Z.-J. Wu
Keyword(s):  
Free Vibration ◽  
Forced Vibration ◽  
Cross Flow ◽  
Reference Frequency ◽  
Average Force ◽  
Vibrational Response ◽  
Uniform Current ◽  
Extensive Program ◽  
Vibration Tests ◽  
Lock In

This paper reports an extensive program of forced and free vibration tests on a single circular cylinder moving mainly perpendicularly to a uniform current. For both free and forced vibration tests, two cases were investigated: one in which the cylinder was restrained in the in-line direction and the other in which it was supported on suitable springs. The cross-flow vibrational response and hydrodynamic forces on the cylinder were measured. Large variations of motion frequency in the “lock-in” range were found from the free vibration tests. This leads to two different definitions of reduced velocity, namely, a so-called nominal reduced velocity based on one reference frequency and the true reduced velocity based on the actual vibration frequency. When different results are compared, the true reduced velocity should be used. The forced vibration tests showed, as may be expected, that the transverse force in the “lock-in” range on the average will add energy to the cylinder at moderate motion amplitudes and subtract energy at large amplitudes. Some conditions resulting in a steady-state vibration of a flexibly mounted cylinder were analyzed. The actual force traces also show very large and apparently random deviations from the average force amplitude. The results from the forced and the free vibration tests are consistent with each other if the true reduced velocity and reduced amplitude are the same.

Free Vibration of Coupled Disk-Hat Structures

1999 ◽  
Author(s):  
Jun-Chul Bae ◽  
Jonathan Wickert
Keyword(s):  
Free Vibration ◽  
Natural Frequencies ◽  
Three Dimensional ◽  
Phase Relationship ◽  
Vibration Modes ◽  
Pure Bending ◽  
Brake Rotors ◽  
Automotive Brake ◽  
Ordered Pairs

Abstract The free vibration of disk-hat structures, such as automotive brake rotors, is investigated analytically and through laboratory experimentation. Of particular interest are the role played by the hat element’s depth in influencing the three-dimensional vibration of the disk, and the manner in which the bending and in-plane modes of the disk alone evolve as a hat of increasing depth is incorporated in the model. The lower vibration modes of disk-hat structures are shown to be characterized by the numbers of nodal circles NC and diameters ND present on the disk, as well as the phase relationship between the disk’s transverse and radial displacements due to coupling with the hat element. Such modes map continuously back to the pure bending and in-plane modes of the disk alone, appear in ordered pairs, and can exist at close frequencies. Those characteristics are explored particularly with respect to sensitivities in the disk’s thickness and the hat’s depth with a view towards shifting particular natural frequencies, or minimizing transverse disk motion in certain vibration modes. Results obtained through analysis and measurement of a prototypical disk-hat structure are applied in a case study with a ventilated automotive brake rotor.

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