The evaluation of impedance functions in the analysis of foundations vibrations using boundary element method
Author: E. C¸ elebia, *, S. Fıratb , _ I. C¸ ankayac | Size: 2.2 MB | Format:PDF | Quality:Unspecified | Publisher: Applied Mathematics and Computation 173 (2006) 636–667 | Year: 2006 | pages: 32
The basic step in the substructure approach based on discretization of the soil medium
for the soil–structure interaction problems is to determine the impedance functions which are defined as the complex dynamic-stiffness coefficients of the soil-footing system are used in the analysis of foundations vibrations. In this study, the discrete values of impedance functions over wide ranges of frequency-factors are presented for both surface- supported and embedded foundations. The numerical results are obtained by using the substructure approach in the frequency domain which is formulated on basis of the Boundary Element Method derived from the fundamental solution for a homogeneous, isotropic and linear-elastic continuum. To further demonstrate in practical applications and to show the solutions of this type of problems to civil engineers, a comprehensive parametric analysis and systematic calculations are performed with various controlling parameters to evaluate the dynamic response of the vibrating soil–foundation system. In
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DYNAMIC PILE-SOIL-PILE INTERACTION. PART I: ANALYSIS OF AXIAL VIBRATION
Author: National Technical University. Athens. Greece; and Dept Civil Engineering, 212 Kelter Hall, State University of New York, Buffalo, New York 14260. U.S.A | Size: 1 MB | Format:PDF | Quality:Unspecified | Publisher: EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, VOL. 20,115-132 (1991) | Year: 1991 | pages: 18
Simple methods of analysis are developed for computing the dynamic steady-state axial response of floating pile groups
embedded in homogeneous and non-homogeneous soil deposits. Physically-motivated approximations are introduced to
account for the interaction between two individual piles. It is found that such an interaction arises chiefly from the
‘interference’ of wave fields originating along each pile shaft and spreading outward. For homogeneous deposits the wave
fronts originating at an individual pile are cylindrical and the interaction is essentially independent of pile flexibility and
slenderness. For non-homogeneous deposits the wave fronts are non-cylindrical and ray-theory approximations are
invoked to derive pile flexibility-dependent interaction functions.
Results are presented for the dynamic stiffness and damping of several pile groups, as well as for distribution of the
applied load among individual piles. For deposits with modulus proportional to depth, the agreement with the few
rigorous solutions available is encouraging. A comprehensive parameter study focuses on the effects of soil inhomogene-
ity and pile-group configuration. It is demonstrated that the ‘dynamic group efficiency’ may far exceed unity at certain
frequencies. Increasing soil inhomogeneity tends to reduce the respective resonant peaks and lead to smoother
interaction functions, in qualitative agreement with field evidence.
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Machinery Vibration Limits and Dynamic Structural Response
Author: Brian C. Howes, P. Eng., M.Sc. | Size: 0.9 MB | Format:PDF | Quality:Unspecified | pages: 28
Changes in case vibration readings are used to monitor rotating machinery condition. Absolute levels of vibration are indications of condition except where structural resonances (e.g.: bearing
housings, or motor bases) amplify vibrations at certain frequencies (usually integer multiples of shaft speed). Dynamic response at vibration test points can be measured on new installations to assist in establishing standards for absolute vibrations. Also, changes in dynamic response over time can add to understanding of machine condition. Discussion of case history to illustrate points is included.
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- Provides a comprehensive treatment of the behaviour and design of - - FRP-strengthened metallic structures
- Includes descriptions and explanations of basic concepts
- Offers design recommendations and presents design examples
Summary
Repairing or strengthening failing metallic structures traditionally involves using bulky and heavy external steel plates that often pose their own problems. The plates are generally prone to corrosion and overall fatigue. Fibre-reinforced polymer (FRP), a composite material made of a polymer matrix reinforced with fibres, offers a great alternative for strengthening metallic structures, especially steel structures such as bridges, buildings, offshore platforms, pipelines, and crane structures.
FRP-Strengthened Metallic Structures explores the behaviour and design of these structures, from basic concepts to design recommendations. It covers bond behaviour between FRP and steel, and describes improvement of fatigue performance, bending, compression, and bearing forces, strengthening of compression and steel tubular members, strengthening for enhanced fatigue and seismic performance, and strengthening against web crippling of steel sections. It also provides examples of performance improvement by FRP strengthening.
• Summarizes worldwide research on the FRP strengthening of metallic structures
• Contains several topics not generally covered in existing texts
• Presents comprehensive, topical references throughout the book
The book outlines the applications, existing design guidance, and special characteristics of FRP composites within the context of their use in structural strengthening. While the major focus is on steel structures, it also describes others, such as aluminium structures. This book is suitable for structural engineers, researchers, and university students interested in the FRP strengthening technique.
Xiao-Ling Zhao is chair of structural engineering at Monash University, Australia, and is author of Concrete-Filled Tubular Members and Connections, also published by Taylor & Francis.
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This excel will calculate radius of cut for RBS Connection.
This excel are not protected, if you want to modify it's please do not change name who first make it.
Thanks
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This short paper will give you an information about Capital Gate Building System.
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Posted by: ssobhan - 08-29-2013, 11:26 AM - Forum: Archive
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Article/eBook Full Name: Free-Edge Plastic Buckling of Axially Compressed Cylindrical Shells
Author(s): S. C. Batterman
Publish Date: 1968
Published By: ASME
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The design of foundations for tall buildings is a challenging task for geotechnical engineers as they are required to consider all geotechnical aspects of the project, with the aim of identifying and managing the geotechnical risks. In the design of foundations for tall buildings, lateral loadings are of great importance as are the vertical loadings. A small rotation at the foundation will be magnified to a very large magnitude at the top of the structure due to the height of the building, which will affect the serviceability and functionality of the building.
This paper presents the foundation design process for two cases - the 1km high Nakheel Tower in Dubai and the 151 storey Incheon Tower in South Korea. The role of the authors as an internal reviewer of the analyses and an engineer undertaking the numerical analyses during the different project phases will be discussed. Analyses of the proposed foundation were carried out by computer programs using the boundary element method and 2D & 3D finite element methods based on the limit state approach. Key issues, in particular the overall performance of the foundation, will be addressed.
The paper concludes with a summary of the design processes and the basic design criteria for tall buildings.
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Foundation design for the Emirates Twin Towers, Dubai
Author: Harry George Poulos and Andrew J. Davids | Size: 0.81 MB | Format:PDF | Quality:Unspecified | Publisher: Can. Geotech. J. 42: 716–730 (2005) | Year: 8 june 2005 | pages: 15
This paper describes the foundation design process adopted for two high-rise buildings in Dubai, the Emirates Twin Towers. The foundation system for each of the towers was a piled raft, founded on deep deposits of calcareous soils and rocks. The paper outlines the geotechnical investigations undertaken, the field and laboratory testing programs, and the design process and describes how potential issues of low skin friction and cyclic degradation of skin friction due to wind loading were addressed. An advanced numerical computer analysis was used for the design process, which was carried out using a limit state approach. This necessitated analysis of a large number of load cases, and the paper describes how the information was processed to produce design information. A comprehensive program of pile load testing was undertaken, and class A predictions of both axial and lateral load–deflection behaviour were in fair agreement with the load test results. Despite this agreement, the overall settlements of the towers observed during construction were significantly less than predicted. The possible reasons for the discrepancy are discussed.
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