Author: R. N. Mortimore | Size: 6.6 MB | Format:PDF | Quality:Unspecified | Publisher: Geological Society of London | Year: 2006 | pages: 173 | ISBN: 1862391505
Most of the rocky coastlines around the world are subject to active erosion processes. Because of the growing hazard to local communities from coastal cliff retreat, it is necessary to investigate where, when and how cliffs collapse. The results of these studies are vital for the planners and local authorities responsible for safety and access to cliffs and beaches.
This volume focuses on the coastal chalk cliffs of the English Channel, where a multidisciplinary approach has been used to understand active coastal cliff recession. The book is organized around three main themes: the geological factors controlling cliff instability, the marine parameters influencing coastal erosion and the use of some new tools for hazard assessments. This book will be of use to academics and professionals working on rocky shores, with an interest in sedimentary geology, stratigraphy, tectonics, geomorphology, engineering geology, coastal engineering and GIS.
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3D Periodic Foundation-based Structural Vibration Isolation
Author: Z.B. Cheng, Y.Q. Yan, Farn-Yuh Menq, Y.L. Mo, H.J. Xiang, Z.F. Shi and Kenneth H. Stokoe, II | Size: 938 MB | Format:PDF | Quality:Unspecified | Publisher: Proceedings of the World Congress on Engineering 2013 Vol III, WCE 2013, July 3 - 5, 2013, London, U.K. | Year: 2013 | pages: 06
Guided by the recent advances in solid-state
physics research, a 3D periodic foundation-based structural
vibration isolation is studied. Using construction materials,
concrete, rubber and steel, the three-component periodic
foundation is developed. Frequency band gaps for the specimens
are found to be in low-frequency region (<20Hz). A parametric
study is also conducted to illustrate the influences of the
geometrical and material parameters on the frequency band
gaps. Based on the frequency band gaps analysis, numerical
simulations are performed to verify the efficiency of the periodic
foundation. Harmonic analysis results show periodic foundation
can reduce vibrations in the frequency band gap. Further, a
transient analysis shows that 3D periodic foundations can also
isolate seismic wave effectively.
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Practical Methods for Vibration Control of Industrial Equipment
Author: Andrew K. Costain, B.Sc.Eng. and J Michael Robichaud, P.Eng. Bretech Engineering Ltd | Size: 444 KB | Format:PDF | Quality:Unspecified | pages: 8
The generally accepted methods for vibration control of industrial equipment include; Force Reduction, Mass Addition, Tuning, Isolation, and Damping. This paper will briefly introduce each method, and describe practical methods for their application. Several scenarios and case studies will be presented, with emphasis on pragmatic solutions to industrial vibration problems.
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Vibration from Underground Railways: Considering Piled Foundations and Twin Tunnels
Author: Kirsty Alison Kuo King’s College University of Cambridge | Size: 6.8 MB | Format:PDF | Quality:Unspecified | Publisher: King’s College University of Cambridge | Year: September 2010 | pages: 208
Most engineering courses on vibration begin with a mass on a spring, and then move on to continuous systems such as strings, columns and membranes. These simple systems provide students with a good understanding of the fundamentals of vibration theory, and the physical behaviour of such systems is represented by using well-known equations. However, many vibration problems do not involve such simple systems.
In the past, to solve these problems, engineers would turn to experimental investigations, or would construct simple models that could capture the essential physical behaviour and yet be solved using the available computational techniques. Nowadays, many engineers use commercial software packages that make use of powerful numerical methods such as finite-element or boundary-element methods as their primary tool in constructing models. The difficulty that may arise from the use of such software (that is specially designed to have a user-friendly interface) is that many practitioners lack an awareness of the limitations of these numerical models, and the uncertainty that may be present in the results is often poorly understood
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In this paper mechanical system containing four horizontal blowers with separate frame each is analyzed. The system is fixed on one general foundation. The high level of vibrations is dominating during the work of the system. The results of experimental investigation of mechanical system are represented here. The finite element model of the operation investigated system gives possibility to investigate natural frequencies. The reasons of high level vibrations were identified by comparing the results of experimental data and theoretical calculations. The concept of vibrations reduction based on the results of this investigation was proposed as well.
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Evaluation of dynamic properties of site and Response of Motion Si mulator Foundation
Author: P. Anbazhagan * , T.G. Sitharam + , G.L. Sivakumar Babu and More Ramulu | Size: 122 KB | Format:PDF | Quality:Unspecified | Publisher: Department of Civil Engineering, Indi an Institute of Science, Bangalore | pages: 10
Geotechnical parameters such as shear wave velocity and shear modulus are very important parameters in ground response analysis. The dynamic properties of foundation material below the three axes motion simulator are evaluated using the Block vibration test, Multichannel Analysis of Surface Waves (MASW) and a seismograph. This paper presents the measurements of dynamic properties using Block vibration test and MASW. Paper also present the response of foundation material due to local site condition using SHAKE2000 and vibration measurements for a passive source. Vibration characteristics of foundation material have been monitored by a seismograph with tri-axial sensors to measure the peak particle velocity in all the three directions from the passive sources such
as generator, pump house and industrial Buildings which are located at about 70m to 200m from the proposed motion simulator.
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Foundation impedance ordinates are identified from forced vibration tests conducted on a large-scale model test structure in
Garner Valley, California. The structure is a steel moment frame with removable cross-bracing, a reinforced concrete roof, and a nonembedded
square slab resting on Holocene silty sands. Low-amplitude vibration is applied across the frequency range of 5–15 Hz with a uniaxial
shaker mounted on the roof slab. We describe procedures for calculating frequency-dependent foundation stiffness and damping for horizontal
translational and rotational vibration modes.We apply the procedures to test data obtained with the structure in its braced and unbraced
configurations. Experimental stiffness ordinates exhibit negligible frequency dependence in translation but significant reductions with
frequency in rotation. Damping increases strongly with frequency, is stronger in translation than in rocking, and demonstrates
contributions from both radiation and hysteretic sources. The impedance ordinates are generally consistent with numerical models for a
surface foundation on a half-space, providing that soil moduli are modestly increased from free-field values to account for structural weight,
and hysteretic soil damping is considered.
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Vibrations of machine foundations and surrounding soil
Author: H. van Koten, Zoetermeer, 2 e Stationsstraat 223, the Netherlands 1 P.C.J. Hoogenboom, Delft University of Technology, Delft, the Netherlands | Size: 1.5 MB | Format:PDF | Quality:Unspecified | Publisher: HERON Vol. 57 (2012) No. 1 | Year: 2012 | pages: 26
Rotating or pulsing machines are often placed on concrete foundations supported by soil. The machines cause vibrations in the building and in the surrounding soil. This paper provides information, formulas and calculation examples to predict these vibrations. The formulas have been experimentally tested for both soil foundations and pile foundations. In addition, criteria are provided for evaluating the vibrations.
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Analysis of machine foundation vibrations: state of the art
Author: GEORGE GAZETAS Rensselaer Polytechnic lnstitute, Troy, New York, USA | Size: 3.9 MB | Format:PDF | Quality:Unspecified | Publisher: Soil Dynamics and Earthquake Engineering, 1983, Vol. 2, No. 1 | Year: 1981 | pages: 41
The paper reviews the state-of-the-art of analysing the dynamic response of foundations subjected to machine-type loadings. Following a brief outline of the historical developments in the field, the concepts associated with the definition, physical interpretation and use of the dynamic impedance functions of foundations are elucidated and the available analytical/numerical methods for their evaluation are discussed. Groups of crucial dimensionless problem parameters related to the soil
prot~ile and the foundation geometry are identified and their effects on the response are studied. Results are presented in the form of simple formulae and dimensionless graphs for both the static and dynamic parts of impedances, pertaining to surface and embedded foundations having circular,strip, rectangular or arbitrary plan shape and supported by three types of idealized soil profdes: the halfspace, the stratum-over-bedrock and the layer-over-half space. Consideration is given to the effects of inhomogeneity, anisotropy and non-linearity of soil. The various results are synthesized in a case study referring to the response of two rigid massive foundations, and practical recommendations are made on how to inexpensively predict the response of foundations supported by actual soil deposits.
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