Vibration Criteria Research Articles

Remember the DEW Line? The Evolution of Ground-Level Vibration Criteria from the Cold War Years to the Era of Nanoelectronics

Most of my graduate students today do not know about the DEW (Distant Early Warning) Line that was the cornerstone of the United States' air defense arsenal during the Cold War (1947-1991). The DEW Line was the nothernmost of three lines of radar stations across North America designed to provide early detection and characterization of Soviet bombers and land or sea invasions. An advanced design was used for the radar antennae that came with stringent ground motion (i.e., vibration) tolerances.

Ground-borne vibration issues from rail transit near university research buildings

A new light rail transit project being designed and constructed through a university campus presents many potential ground-borne vibration issues. The rail alignment passes near numerous buildings on campus that contain various types of vibration sensitive research equipment. Appropriate vibration criteria for the project are critical to ensure that future operation of the light rail vehicles (LRVs) will not adversely affect activities on campus. Ground-borne vibration criteria are based on equipment sensitivity and the existing vibration environment. Projections of future vibration levels from LRV operations were developed based on field measurement programs. Site specific vibration measurements on campus were conducted to document the soil vibration propagation characteristics and building response characteristics. Additionally, input vibration force characteristics, or vehicle force density levels, of a comparable vehicle were measured and incorporated into the projections. Finally, site specific track design and vibration mitigation measures were modeled and incorporated into the project design.

Evaluation of human response to blasting vibration from excavation of a large scale rock slope: A case study

Ground vibration, as the most critical public hazard of blasting, has received much attention from the community. Many countries established national standards to suppress vibration impact on structures, but a world-accepted blasting vibration criterion on human safety is still missing. In order to evaluate human response to the vibration from blasting excavation of a large-scale rock slope in China, this study aims to suggest a revised criterion. The vibration frequency was introduced to improve the existing single-factor (peak particle velocity) standard recommended by the United States Bureau of Mines (USBM). The feasibility of the new criterion was checked based on field vibration monitoring and investigation of human reactions. Moreover, the air overpressure or blast effects on human beings have also been discussed. The result indicates that the entire zone of influence can be divided into three subzones: severe-annoyance, light-annoyance and perception zone according to the revised safety standard. Both the construction company and local residents have provided positive comments on this influence degree assessment, which indicates that the presented criterion is suitable for evaluating human response to nearby blasts. Nevertheless, this specific criterion needs more field tests and verifications before it can be

Flat Plate–Voided Concrete Slab Systems: Design, Serviceability, Fire Resistance, and Construction

Flat plate–voided concrete slab systems, which have been used for many years in Europe and other parts of the world, are becoming increasingly popular in the United States because of their many inherent benefits. Such benefits include reduced weight, which results in smaller seismic forces and larger superimposed loads for given span lengths; economical longer spans; reduced floor-to-floor heights; accelerated construction schedules; and inherent fire resistance that meets the fire-rating requirements of the International Building Code (IBC). This paper presents (1) the history and recent research on flat plate–voided concrete slab systems, (2) flexural and shear strength design requirements, (3) deflection requirements, (4) vibration criteria for human comfort and sensitive equipment, (5) fire-rating requirements in accordance with the IBC, (6) typical installation sequences, and (7) a summary of the main benefits of flat plate–voided concrete slab systems. The paper shows that such systems can be designed using the provisions of the American Concrete Institute (ACI) for strength and serviceability and can satisfy the minimum requirements for vibration control and fire resistance.

Optimal milling conditions of aeronautical composite material under temperature, forces and vibration parameters

Optimal conditions for milling carbon/epoxy composite material were established by response surface methodology. The combination of cutting parameters such as cutting speed (Vc) and chip thickness (h) was set at various design points of a central composite design. Significant regression models describing the changes of vibration level, delamination of composite, cutting force, workpiece temperature were developed with the coefficient of determination greater than 0.90. Results suggested that beyond a threshold of vibration, the occurrence of delamination is regular. Vibration criterion was defined from the observations of the workpiece according to the delamination defect. The optimum milling conditions were graphically represented using design contour plots. The best combination of process variables was found, according to the cutting conditions. This new technique should help the operator to select the optimum cutting conditions such as cutting speed and feed rate (chip thickness) in order to avoid damage to the carbon/epoxy composite material T800S/M21 and increase machining productivity.

Experimental study on a conduction cooling system for a HTS NMR magnet

A nuclear magnetic resonance (NMR) magnet composed of a high-temperature superconductor (HTS) is expected to contribute to a smaller size and a higher magnetic field (>1 GHz) of the NMR magnet due to its high critical current density under high magnetic field and better mechanical properties. The high operating temperature of HTS NMR magnets also makes conduction cooling by a cryocooler available. The conduction cooling system combined with a cryocooler is compact and user-friendly but has critical issues about the design of conduction cooling passages and the mechanical vibration. The small-scale HTS magnet with the conduction cooling system is fabricated and tested to check the issues and establish the design basis as a preliminary step for the development of a 400-MHz HTS NMR magnet. Thermal analysis for heat loads and thermal resistances at main joints is performed from the temperature distribution of the cooling system. The vibration levels at the crycooler and the vacuum chamber are discussed in comparison to the vibration criterion of NMR magnets. In addition, the design approach to the conduction cooling system for the HTS NMR magnet is discussed.

Measuring, Monitoring and Prediction of Vibration Effects in Rock Masses in Near-Structure Blasting

Blasting and the transmission of vibration involve numerous variables which makes it impossible to predict the levels of vibrations. Therefore an effective blast design and optimization require a multitude of variables be integrated into a single instance. In prior research the existence of the strong relation between PPV and damage to structures has been well established. Besides PPV, the frequency is one of the most important factors controlling the response of structures. This paper presents a case history of Olympic Stadium renovation in Helsinki, Finland with a focus on blasting near the Olympic Stadium Tower. It will be concluded whether the current vibration criteria, measurement and approach are suitable and sufficient for near-structure blasting.

PAL-XFEL 빔라인 허치 구조물 개발

The hutches which are installed in the beamline are largely classified into two, i.e XPP (X-ray pump probe) and CXI (Coherent X-ray image). Laser room is installed on the hutch and provides laser to XPP and CXI simultaneously. And two hutches have heavy crane to install some optics equipments. Safety and reliability of hutch structures should be taken into account for the precise operating of the laser facilities, so vibration analysis is essential to do this. The main purpose of vibration analysis is to install hutch structures with large stiffness. We have changed materials specification several times to install hutch structures having strong stiffness. Now hutch structures were installed and checked vibration status at laser room and XPP hutch. The results of laser table and robot arm satisfy vibration criteria. This paper explains about the design and vibration analysis of hutch structures.

Vibration isolation of large fan array air handling units in healthcare

A new hospital facility constructed in Denver, CO, has all the mechanical equipment that is typically on the roof of the building located directly over all the Operating Rooms (ORs). Many of the ORs are used for procedures involving equipment found in new facilities like high powered microscopes for laser eye surgery or neurosurgery, ceiling mounted high-definition video displays and robotic surgical systems using high resolution cameras. All of which are vibration sensitive. Also, in the future the client wanted flexibility in how the operating rooms are used as the equipment and procedures will change. Because “fan array” mechanical units, produce less vibration than traditional air handling units, they were selected by the design team. The air handling units varied in size from medium with six supply and six return fans to very large with 22 supply and 16 return fans. Because of their size and location in the building, the units were loaded into the facility in multiple modular sections that were then bolted together. This required the development of a vibration isolation solution that allowed for the easy assembly of the mechanical units on site. The rational for the location of the mechanical rooms above the operating rooms will be discussed along with the vibration criteria, analysis, and details of the isolation system. This includes vibration measurements of the final results.

Investigation of deflection and vibration criteria for road bridges

Deflection and vibration play an important role in the serviceability of bridges. Their limits are specified in design codes either for consideration or as requirements. To promote understanding of the role of deflection and vibration limits, a comprehensive literature review is presented and comparison is made to propose the rational method to control bridge vibration for human comfort. To investigate the vibration and deflection criteria and applicability for bridges, actual bridges to represent typical bridge types are selected for experimental tests and theoretical study. Comparisons of the experimental results of deflection, acceleration, and frequency with the theoretical results are performed to verify the validity of the theoretical models. To ensure the applicability of the design code, bridges are redesigned so that they have minimum capacities as required by the design code. Finally, the vibration parameters of actual bridges and bridges using minimum sections are compared with current design limits and proposed criteria.

Assessment of seismic impact on residences during blasting excavation of a large-scale rock slope in China

Reasonable assessment of blast-induced seismic impact on local residences has great significance for reducing social conflicts and ensuring smooth construction. In this paper, a grading and zoning evaluation scheme was introduced to assess the seismic impact caused by surface blasting during excavation of a high rock slope in China. Firstly, based on the one-dimensional seismic wave theory and several worldwide accepted vibration criteria, a specific vibration safety control standard is recommended. Then, a 6-month field investigation was conducted to evaluate the distribution of blasting vibration in the whole influenced residential area, and the attenuation laws of peak particle velocity (PPV) versus scaled distance were also obtained. Combining the presented seismic damage criterion with the monitored PPV distribution, safety distances for preventing cracking of mud-brick houses were derived, and the influenced zone can be divided into three sub-zones: scaled distance D 80 m/kg1/2, which can be defined as the influenced zone, slightly influenced zone and uninfluenced zone, respectively. And this sub-zoning scheme has been verified by the field investigation after blasting. And the result has been used as the main foundation for damage compensation. For this case, this method can also be promoted to other similar projects.

Acceleration Response of Prestressed Cable RC Truss Floor System Subjected to Heel-Drop Loading

AbstractThis paper describes and discusses the vibration serviceability of the innovative prestressed cable-reinforced concrete truss (i.e., prestressed cable RC truss, PCT for abbreviation) floor system subjected to heel-drop impact loading, based on the theoretical and experimental studies. In the theoretical analysis, the PCT floor system is idealized as an anisotropic rectangular plate with four built-in edges and the weighted residual method was used. A field test was carried out to investigate the dynamic characteristics of the PCT floor system and to validate and demonstrate the convergence of the theoretical solution. As a result, the experimental results agree well with the theoretical ones. The decrease of vibration is dramatic in the direction perpendicular to the PCT girder and is at a slower rate along the direction of the girder. The investigated PCT floor system has a low fundamental natural frequency (<4 Hz) with low damping ratio (≈2%). According to one standard of vibration criteria, th...

Comparison of Linear and Nonlinear Vibration Isolation System under Random Excitation

This article studies and compares the efficiency of linear and nonlinear vibration isolation systems. The estimation relies on the value of isolated mass standard deviation due to external oscillation with different spectral densities. The solution of nonlinear differential equation of isolated by nonlinear vibration isolator mass is based on harmonic linearization method. External excitation process is treated as white noise wideband process with different spectral densities. The main interest is attached to the definition of vibration criteria exceedance number for the isolated mass suspended on both types of vibration isolators. The article suggests the application of several practical formulas of exceedance number calculation.

The qualitative assessment of pneumatic actuators operation in terms of vibration criteria

The work quality of pneumatic actuators can be assessed in terms of multiple criteria. In the case of complex systems with pneumatic actuators retained at end positions (with occurrence of piston impact in cylinder covers) the vibration criteria constitute the most reliable indicators. The paper presents an impact assessment on the operating condition of the rodless pneumatic cylinder regarding to selected vibrational symptoms. On the basis of performed analysis the authors had shown meaningful premises allowing an evaluation of the performance and tuning of end position damping piston movement with usage the most common diagnostic tools (portable vibration analyzers). The presented method is useful in tuning of parameters in industrial conditions.

Influence of People Walking on Floor Performance due to Low Level Vibration

Abstract. Vibration in building is one of the important problems which need to consider, especially in designing the floor. Floor vibrations are generally caused by dynamic loads applied particularly by human activity especially walking. Although it is specified as low level amplitude, walking induced vibrations can cause discomfort to human occupants and alarming for a certain items of precision sensitive equipment. This paper investigates the vibration response on floor performance due to one, three and five of people walking. Laser Doppler Vibrometer was used to obtain vibration data when people are walking. Further analysis was carried out by using finite element software package ANSYS to simulate the floor under vibration inputs to obtain natural frequency and mode shapes of the floor structure. The vibration data was then analysed in ModalV analysis to generate the vibration response. Then, the results were checked against the vibration criteria level guideline as a crude tool comparison. As a result, the numbers of people walking were influenced the floor performance, which indicated five peoples walking show the highest response up to ISO level due to vibration compared with one people walking.

Floor Dynamic Assessment on Laboratory due to Ground Borne Vibrations Using ModalV Analysis from Passing Vehicles

High-tech development on laboratory with high resolution and sensitive device is increased nowadays. This equipment requires very sensitive location to accommodate in a special room, because it may cause improper functioning for a certain devise which required low level of vibration. Due to this problem, the aim of this study are to perform the structural response on two story laboratory subjected to ground vibration input due to traffics and to assess the level of vibration at the floor. The vibrations input are measured by using portable equipment called Laser Doppler Vibrometer. The field measurement is done at the laboratory Block E, Faculty of Mechanical and Manufacturing Engineering at Universiti Tun Hussein Onn Malaysia (UTHM). Finite element ANSYS software is fully utilized to model the building structure and perform analysis in order to determine structural modal and transient analysis for the building. Time history response from ANSYS post-processing is transferred into ModalV analysis in MATLAB software in order to evaluate the vibration criteria level of the floor according to specific overseas guideline. It was found that the vibration response on the middle slab of the first floor at level Vibration Criteria, VC-A or maximum particle velocity level at 50μm/s. Vibration Criteria (VC) curve analysis on floor slab indicated the highest vibration will occur at the middle of floor slab and the lowest vibration will occur at the edge of slab which near the column and below VC-E level for ground floor slab.

Analysis of Vibration Effects on Floor of Office Building due to Ground Vibrations from Passing Vehicles

Since the earliest days of ground road transportations and constructions in urban areas, there have been complaints of vibration in building caused by this external source of vibration, known as ground borne vibration. Vibration when it exceeds the recommended threshold could affect the structure of the building and any sensitive equipment housed inside the building, as well as causing discomfort and annoyance to the occupants of the building. The objectives of the study are to determine the level of vibration on each floor of a multi storey building due to ground borne vibration from road traffic, second to numerically investigate the structural response on the multi storey building from vehicles, and lastly to assess the vibration response obtained from both vehicles with the vibration criteria guideline. The selected building for this study is Registrar Office building located in Universiti Tun Hussein Onn Malaysia (UTHM). The scope of study is focused on the effect of ground borne vibration from vehicles on multi storey building and analyzing the data using MATLAB and ANSYSv14. The real inputs of vibration from vehicles were measured and obtained using Laser Doppler Vibrometer (LDV). The vibration level from vehicles and footfalls on the multi storey office building can be determined using Vibration Criteria (VC) guidelines by Gordon. Finally, from the study, the vibration level achieved for this Registrar Office building is above the ISO level which is exceeds the acceptable vibration limit for office building.

Vibration isolation design of railroad tracks within Ankara high speed train station

Ankara serves as a hub for high speed railway operations within Turkey. A new station building of nine stories in total, which also incorporates a shopping mall and a hotel inside, is currently under construction. Need arises for controlling vibrations due to passing trains through the building. Finite element model of the building is developed by commercial software. The interaction of the building with the foundation is represented by a number of spring and damper combinations whose characteristics are obtained from the existing knowledge of soil-structure interactions. The dynamic stiffness characteristics of isolating layer under the railway slabs are sought. The FRF’s between several floors of the building and the base of the track are obtained from the finite element model, to be coupled with FRF’s of the train-track-isolating layer system. Vibration isolation design is carried with respect to vibration criteria in Turkish environmental noise regulations.

Optical Tables Vibration Isolation during Precision Measurements

This article studies dynamic characteristics of the optical table vibration isolation system with quazi – zero stiffness isolators. A numerical model of honeycomb optical table is developed and its deflections subjected to point load are calculated as well as eigenmodes and eigenfrequencies. Modal analysis is performed by means of MSC Patran/Nastran. Numerical model of the optical table is verified by comparing the frequency of its free oscillations and full-scale models. Dynamic analysis is performed due to the base kinematic excitation of different origin and the amplitudes of forced oscillations of the surface of the table with the equipment placed are determined. Amplitudes of forced oscillations are then compared to the regulatory values given by vibration criteria for precision equipment.

Vibration Response on MiNT-SRC Building due to Ground Borne Vibrations from Humans Using Finite Element Modeling

Building structure is naturally exposed to the vibration phenomenon. Vibration in high amplitude may causes big damages to the building structure, while the lower amplitude of vibrations is not causes big effect to the building but it may produce low vibration response to floor structure that can disturbance people comfort and equipment workability. In this study, the vibration response is focusing on low amplitude of vibrations from the ground which due to human activity like footstep or walking. Human activity such as walking will produce low vibration amplitude that can affect the sensitivity of sensitive equipment inside the research or laboratories facilities. Microelectronic and Nanotechnology-Shamsuddin Research Center (MiNT-SRC) building at UTHM is selected to be a location for ground borne vibration measurement due to human activities. The research center is chosen due to sensitivity equipment in the building that prone to vibration effect. Finite element modelling is the method been used to analysed the vibration response distribution to overall building. Vibration data input from field measurement is analysed in ANSYS software based on finite element method, and then further analysis in MATLAB software. A ModalV analysis program in MATLAB is used to produce one third octave velocity spectra and vibration criterion curve for the studied floor. The study shows that the vibration criterion for MiNT-SRC building is classified as VC-E at ground floor and VC-B at the first floor. Thus, based on the result analysis, the sensitive equipment is most suitable to locate at the ground floor of MiNT-SRC building.