Floor vibration due to occupants and reliability-based design guidelines

1995 ◽  
Vol 22 (3) ◽  
pp. 471-479 ◽  
Author(s):  
Ricardo O. Foschi ◽  
Greg A. Neumann ◽  
Felix Yao ◽  
Bryan Folz
Keyword(s):  
Close Agreement ◽  
Analytical Study ◽  
Coupled System ◽  
Design Guidelines ◽  
Vibrational Response ◽  
Reliability Based Design ◽  
Floor Vibration ◽  
Coupled Dynamical System ◽  
Commercial Applications ◽  
Acceptability Criteria

Lightweight floors for residential or commercial applications may exhibit annoying levels of vibration under occupancy loading. This paper presents an experimental and analytical study of the vibrational response of wood floors to impact produced by occupants. The results show that, for the analysis of this type of floors, it is necessary to consider the coupled dynamical system of floor and occupants. It is also shown that occupants may be modelled with simple oscillators, and that the dynamic analysis of the coupled system can produce close agreement with tests. Acceptability criteria are used to study design guidelines, combining the variability in floor stiffness with the variability in human tolerance to vibrations. Floors considered use 2 × 8 SPF joists and I-joists. Key words: vibrations, serviceability, occupancy loads, wood floors, reliability.

Reply: Floor vibration due to occupants and reliability-based design guidelines

1996 ◽  
Vol 23 (2) ◽  
pp. 572-572
Author(s):  
R. O. Foschi ◽  
G. A. Neumann ◽  
F. Yao ◽  
B. Folz
Keyword(s):  
Design Guidelines ◽  
Reliability Based Design ◽  
Floor Vibration

Numerical and Experimental Study on the Dynamic Behavior of an Innovative Steel-Concrete Composite Hollow Waffle Floor

2020 ◽  
Vol 20 (08) ◽  
pp. 2050087
Author(s):  
Xi Zhang ◽  
Qing Li ◽  
Yousan Wang ◽  
Qiming Wang
Keyword(s):  
Experimental Study ◽  
Structural Parameters ◽  
Design Guidelines ◽  
Element Analysis ◽  
Long Span ◽  
Vibration Serviceability ◽  
Floor Vibration ◽  
Walking Tests ◽  
Vibration Performance ◽  
Hollow Beams

The U-shaped steel-concrete composite hollow waffle (CHW) floor is an innovative slender large-span floor composed of a thin slab and bidirectional orthogonal steel-concrete composite hollow beams. Large vibrations may occur under human excitations, and vibration guidelines for CHW floors are still lacking. Thus, this paper undertook a parametric and experimental study to explore the vibration performance of the CHW floors. First, the modal properties and vibration response under walking tests considering the varying frequencies and routes were obtained from the measurements, which validated the accuracy of the finite element analysis (FEA). Then, the influence of the structural parameters on the floor vibration was investigated by numerical modeling. The parametric study shows that the medium-sized long-span (MLS) (28[Formula: see text]m) CHW floors present the best vibration serviceability, the small-sized long-span (SLS) (14[Formula: see text]m) CHW floors vibrate substantially under walking excitation, and the large-sized long-span (LLS) (42[Formula: see text]m) CHW floors are vulnerable to resonance. Finally, this paper provides recommendations for design guidelines for CHW floors and indicates that controlling the span-to-height (SH) value and beam spacing (BS) at a small value are the most effective methods of vibration control.

The Development of Reliability-Based Design Guidelines and Prototype Design of Super Long-Span Bridges

2012 ◽  
Vol 18 (14) ◽  
pp. 1096-1103
Author(s):  
Ho-Kyung Kim ◽  
Myeong-Jae Lee ◽  
ByungHong Yang ◽  
Byeong-Hoon Song ◽  
HaeSung Lee ◽  
...  
Keyword(s):  
Design Guidelines ◽  
Long Span Bridges ◽  
Reliability Based Design ◽  
Long Span ◽  
Prototype Design

scholarly journals Vibration serviceability assessment of office floors for realistic walking and floor layout scenarios: Literature review

2019 ◽  
Vol 23 (6) ◽  
pp. 1238-1255
Author(s):  
Márcio S Gonçalves ◽  
Aleksandar Pavic ◽  
Roberto L Pimentel
Keyword(s):  
Design Guidelines ◽  
Design Criterion ◽  
Embodied Energy ◽  
Human Gait ◽  
Vibration Source ◽  
Structural Elements ◽  
Single Person ◽  
Vibration Serviceability ◽  
Floor Vibration ◽  
Vibration Performance

Over the last two decades, office floors have been built progressively lightweight with increasing spans and slenderness. Therefore, vibration performance of office floors due to walking dynamic loads is becoming their governing design criterion, determining their size and shape, and therefore overall weight and embodied energy of the building. To date, floor design guidelines around the world recommend walking load scenarios in offices featuring some or all of the following standard characteristics: (a) walking loads are assumed to be periodic dynamic excitation represented by the Fourier series, including harmonics corresponding to up to the first four integer multiples of the pacing frequency of which at least one is exciting the floor at a resonant frequency and (b) single person walking. However, the literature surveyed provides evidence that such assessment methodology is potentially an over-simplification which does not reflect real walking load scenarios, since crucial features of the floor vibration source, path and receiver are missing. First, in terms of vibration source, realistic scenarios need to feature (a) moving rather than stationary walking forces, (b) stochastic nature of human gait, (c) simultaneous multi-person walking and (d) human–structure interaction. Second, for the transmission path (i.e. office floor structure), two features are needed to consider: (a) realistic office floor layouts and (b) presence, or absence, of non-structural elements. Finally, for the vibration receivers (i.e. floor occupants), (a) vibrations calculated at floor locations occupied by users (instead of at the potential highest response location which may not be occupied), (b) actual period over which occupants feel vibration due to such excitation and (c) assessment of vibration levels based on their probability of occurrence. This study therefore addresses these seldom considered but increasingly important features and discusses realistic approaches to floor design for vibration serviceability.

Analytical Study of Heat and Mass Transfer in Porous Sheets During Contact Drying Process

2008 ◽  
Author(s):  
Mohammad R. Izadpanah ◽  
Amir R. Ansari Dezfooli
Keyword(s):  
Mass Transfer ◽  
Temperature Distribution ◽  
Moisture Content ◽  
Close Agreement ◽  
Analytical Study ◽  
Numerical Data ◽  
Drying Process ◽  
Governing Equations ◽  
Sturm Liouville ◽  
Contact Drying

Contact drying process has gained wide application in different industries including paper, ceramics and construction industries. Suitable control over temperature distribution will result in required moisture content and its distribution. In the present study, governing equations for a porous sheet are derived using Luikov equation. These equations are then converted into sturm-liouville equations and solved simultaneously. Comparison of temperature and moisture distributions with numerical data shows a close agreement.

Experimental and Analytical Study of Pantograph Dynamics

1991 ◽  
Vol 113 (2) ◽  
pp. 242-247 ◽  
Author(s):  
W. Seering ◽  
K. Armbruster ◽  
C. Vesely ◽  
D. Wormley
Keyword(s):  
Experimental Data ◽  
Dynamic Response ◽  
Coulomb Friction ◽  
Close Agreement ◽  
Analytical Study ◽  
Model Performance ◽  
Nonlinear Effects ◽  
Variable Stiffness ◽  
Response Data ◽  
Lumped Parameter

A nonlinear, lumped parameter pantograph model including geometric and coulomb friction nonlinearities and variable stiffness has been developed. The model performance has been compared with experimental dynamic response data measured on a prototype pantograph. Responses of the model and the experimental data including subharmonic and harmonic resonances are in close agreement for motions excited by comparable forcing functions for input frequencies of 0 to 12 Hz. The model has been used to identify the primary parameters and nonlinear effects which influence dynamic pantograph performance.

Helicopter Ground Resonance Investigation With Dissimilar Nonlinear Lead-Lag Dampers

2015 ◽  
Author(s):  
Aykut Tamer ◽  
Pierangelo Masarati
Keyword(s):  
Dynamic Instability ◽  
Chaotic Behavior ◽  
Linear Time ◽  
Coupled System ◽  
Design Guidelines ◽  
Linear Time Invariant ◽  
Shock Absorbers ◽  
Ground Resonance ◽  
The Stability ◽  
Lag Dampers

This work describes the analysis of helicopter ground resonance when nonlinearity and non-isotropy of the problem are taken into account. Ground resonance is a dynamic instability caused by the interaction between the rotor and the airframe of a helicopter. Sources of nonlinearity can be geometrical (finite blade lead-lag motion) and constitutive (hydraulic lead-lag dampers and shock absorbers). Standard methods use special coordinate transformations that make it possible to cast the problem in linear, time invariant form when considering small oscillations of an isotropic rotor about a reference solution. However, potential non-isotropy of the rotor (e.g. resulting from degraded performance of lead-lag dampers) may turn the problem into linear, time periodic. In such cases, the Floquet-Lyapunov method is normally used to study the stability of the coupled system. In this work the problem is investigated using Lyapunov Characteristic Exponents (LCE). The analysis shows that in some cases, characterized by a marked contribution of the nonlinearity of the blade lead-lag dampers, the problem assumes a nearly chaotic behavior. The stability of the system is investigated, and the sensitivity of the LCEs with respect to system parameters is determined, in an attempt to provide a consistent analysis framework and useful design guidelines.

scholarly journals Predictability of a low-order interactive ensemble

2012 ◽  
Vol 19 (2) ◽  
pp. 273-282 ◽  
Author(s):  
L. Siqueira ◽  
B. Kirtman
Keyword(s):  
Phase Locking ◽  
Coupled Model ◽  
Coupled System ◽  
Ensemble Spread ◽  
The Mean ◽  
Coupled Dynamical System ◽  
Model Phase ◽  
Mean State ◽  
Different Time Scales ◽  
Low Order

Abstract. In this paper, numerical and analytical studies were performed to uncover the mechanisms controlling the changes in ensemble spread of a low-order coupled model with multiple atmospheric realizations. An interactive ensemble approach was applied to a coupled dynamical system based on two versions of the Lorenz 63 model designed in order to imitate the behavior of a coupled system with different time scales. In the dynamic system used in this work the spread of ensemble members is highly dependent on the mean state corresponding to asymmetries in predictability. The slowness of the slow model and the intensity of the boundary forcing anomalies both contribute to the asymmetry and phase locking of both subsystems. The mechanisms controlling the fast model spread were uncovered revealing uncertainty dynamics depending on the location of ensemble members in the fast model phase space and implicitly on the slowness and magnitude of the slow model anomalies.

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