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  The Tall Buildings Initiative
Posted by: TAFATNEB - 09-14-2013, 10:27 AM - Forum: Journals, Papers and Presentations - No Replies

The Tall Buildings Initiative

Author: Jack Moehle, PhD, PE; Yousef Bozorgnia, PhD, PE; and T.Y. Yang, PhD Pacific Earthquake Engineering Research Center | Size: 1 MB | Format: PDF | Quality: Unspecified | Publisher: SEAOC 2007 CONVENTION PROCEEDINGS | Year: 2007 | pages: 10

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Several west coast cities are seeing an upsurge in the
construction of high-rise buildings. Many of these buildings
feature framing systems, materials, heights, and dynamic
properties not envisioned by our current building code
prescriptive provisions. Rather than force these buildings to
conform, many jurisdictions are allowing these new designs
to proceed under the alternative procedures provision of the
building code, which allows alternative lateral-force
procedures using rational analyses based on well-established
principles of mechanics in lieu of the prescriptive provisions.
Most designs are opting for a performance-based approach in
which a rational analysis demonstrates serviceability and
safety equivalent to that intended by the code prescriptive
provisions. Several questions arise in a performance-based
design. What is equivalent performance? How should it be
demonstrated? If dynamic analysis is conducted for a range
of anticipated earthquake ground motions, how should the
ground motions be selected and how should the design value
determined? How should performance designs be reviewed?
The Tall Buildings Initiative is funding a range of short to
intermediate-term projects in 2006-2009. The final product
will be a set of written guidelines containing principles and
specific criteria for tall building seismic design. The
document is intended to support ongoing guidelines and
code-writing activities of collaborating organizations, as well
as being a stand-alone reference for designers of high-rise
buildings.


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  DYNAMICS OF BUILDING-SOIL INTERACTION
Posted by: TAFATNEB - 09-14-2013, 10:18 AM - Forum: Scientific journals and Research papers - No Replies

DYNAMICS OF BUILDING-SOIL INTERACTION

Author: PAUL C. JENNINGS AND JACOBO BIELAK | Size: 2 MB | Format: PDF | Quality: Unspecified | Publisher: Bulletin of tile Seismological Society of America. Vol. 63, No. 1, pp. 9-48. February 1973 | Year: 1973 | pages: 40

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In this study of the dynamics of building-soil interaction, the soil is modeled by a
linear elastic half-space, and the building structure by an n-degree-of-freedom
oscillator. Both earthquake response and steady-state response to sinusoidal
excitation are examined. By assuming that the interaction system possesses
n + 2 significant resonant frequencies, the response of the system is reduced to the
superposition of the responses of damped linear oscillators subjected to modified
excitations. The results are valid even though the interaction systems do not
possess classical normal modes. For the special cases of single-story systems and
the first modes of n-story systems, simplified approximate formulas are developed
for the modified natural frequency and damping ratio and for the modified excita-
tion. Example calculations are carried out by the approximate and more exact
analysis for one-story, two-story and ten-story interaction systems.
The results show that interaction tends to decrease all resonant frequencies,
but that the effects are often significant only for the fundamental mode for many
n-story structures and are more pronounced for rocking than for translation.
If the fixed-base structure has damping, the effects of interaction on the earth-
quake responses are not always conservative, and an increase or decrease in the
response can occur, depending on the parameters of the system.


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  Effects of Soil-Structure Interaction on the Seismic Response of Existing R.C. Frame
Posted by: TAFATNEB - 09-14-2013, 10:13 AM - Forum: Civil Engineering MSc and PhD thesis - No Replies

Effects of Soil-Structure Interaction on the Seismic Response of Existing R.C. Frame Buildings

Author: M. Jawad Arefi | Size: 2.7 MB | Format: PDF | Quality: Unspecified | Publisher: Istituto Universitario di Studi Superiori di Pavia Università degli Studi di Pavia | Year: 2008 | pages: 100

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Comprehensive experimental and analytical studies have been carried out to understand the behaviour of existing frame buildings constructed before the introduction of seismic design codes in 1970’s. Different aspects of the response have been investigated and inherent weaknesses have been pointed out. This usually has been done assuming a fixed-base structure while ignoring the flexibility of soil and foundation. In this thesis, the interaction between the super-structure and sub-structure (SSI) is investigated by modelling the soil as simple as possible to capture the overall response of the system.
As new analytical hysteresis rules and more advanced tools of analysis have been developed in recentyears, first the nonlinear response of a single-degree-of-freedom (SDOF) system which can be representative of a broad range of existing or newly designed structures, is investigated while allowing for flexibility of the soil-foundation system and SSI effects.
This simple soil model then is employed to existing nonlinear frame models to quantify the effect of SSI on the overall response of actual structures. The use of flexible base in the analysis can lead to reduction in the structural response and damage consequences in joints and infills. In a further step, the assessed existing frames are retrofitted in beam-column joints area and the effects of flexible base condition on structural demand are examined in more detail.
The results of this study suggest that the compliance of simply modelled soilfor typical building structures have in average beneficial effects in terms of structural demand especially for stiff structures. On the other hand, the governing component of these effects, i.e. rocking of foundation, can result in average to higher absolute deformation of floors which points out to potential pounding problems for structures existing in close vicinity to each other.


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  Distinct Element Method Applied on Old Masonry Structures7
Posted by: TAFATNEB - 09-14-2013, 10:07 AM - Forum: Journals, Papers and Presentations - No Replies

Distinct Element Method Applied on Old Masonry Structures

Author: Marwan Al-Heib | Size: 1.5 MB | Format: PDF | Quality: Unspecified | Publisher: Ineris – Ecole des Mines de Nancy, Parc de Saurupt France | pages: 27

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Masonry structures have specific aspects and different numerical approaches are available
for studying their behavior. The analysis of masonry constructions is a complex task
(Lourenco, 2002), especially under special loads and when the soil-structure interaction
becomes essential for studying the real behavior. Usually, salient aspects are:
Difficult and expensive characterization of the mechanical properties of the materials
used;
Large variability of mechanical properties, due to workmanship and use of natural
materials;
Significant changes in the core and constitution of structural elements, associated with
long construction periods;
Unknown construction sequence;
Unknown existing damage in the structure.
In addition, under the different loading conditions, many experimental studies have shown
that joints or interfaces are the weakest zones of masonry structures. Figure 1 shows some
masonry failure modes, according to Sutcliffe et al., 2001.
Several methods and computational tools are available (Massart et al, 2005) for the
assessment of the mechanical behavior of old constructions. The empirical approaches and
the Eurocode (6) recommendations are generally satisfactory for engineers. The methods
resort to different theories or approaches, resulting in: different levels of complexity (from
simple graphical methods and hand calculations to complex mathematical formulations and
large systems of non-linear equations), different availability for the practitioner (from
readily available in any consulting engineer office to scarcely available in a few researchoriented
institutions and large consulting offices), different time requirements (from a few
seconds of computer time to a few days of processing) and, of course, different costs. Three
approaches (Figure 2) are generally employed by engineers and researchers to model the
masonry element: equivalent medium, discontinuous medium using continuous numerical
approach (finite element and boundary element methods) and discontinuous medium using
distinct element approach (distinct element method). The distinct element code will be
employed herein to model masonry structures.


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  Earthquake Wave-Soil-Structure Interaction Analysis of Tall Buildings
Posted by: TAFATNEB - 09-14-2013, 10:01 AM - Forum: Civil Engineering MSc and PhD thesis - No Replies

Earthquake Wave-Soil-Structure Interaction Analysis of Tall Buildings

Author: Ming Ming Yao B.E., Beijing University of Aeronautics and Astronautics, 1999 M.A.Sc., University of Victoria, 2003 | Size: 1.2 MB | Format: PDF | Quality: Unspecified | Publisher: Ming Ming Yao, 2010 University of Victoria | Year: 2003 | pages: 94

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Earthquakes cause damages to structures and result in great human casualties and economic loss. A fraction of the kinetic energy released from earthquakes is transferred into buildings through soils. The investigation on the mechanism of the energy transferring from soils to buildings during earthquakes is critical for the design of earthquake resistant structures and for upgrading existing structures. In order to understand this phenomena well, a wave-soil-structure interaction analysis is presented. The earthquake wave-soil-structure interaction analysis of tall buildings is the main focus of this research. There are two methods available for modeling the soil-structure interaction (SSI): the direct method and substructure method. The direct method is used for modeling the soil and a tall building together. However, the substructure method is adopted to treat the unbounded soil and the tall building separately. The unbounded soil is modeled by using the Scaled Boundary Finite-Element Method (SBFEM), an infinitesimal finite-element cell method, which naturally satisfies the radiation condition for the wave propagation problem. The tall building is modeled using the standard Finite Element Method (FEM). The SBFEM results in fewer degrees of freedom of the soil than the direct method by only modeling the interface between the soil and building. The SBFEM is implemented into a 3-Dimensional Dynamic Soil-Structure Interaction Analysis program (DSSIA-3D) in this study and is used for investigating the response of tall buildings in both the time domain and frequency domain. Three di.erent parametric studies are carried out for buildings subjected to external harmonic loadings and earthquake loadings. The peak displacement along the height of the building is obtained in the time domain analysis. The coupling between the building’s height, hysteretic damping ratio, soil dynamics and soil-structure interaction e.ect is investigated. Further, the coupling between the structure configuration and the asymmetrical loadings are studied. The findings suggest that the symmetrical building has a higher earthquake resistance capacity than the asymmetrical buildings. The results are compared with building codes, field measurements and other numerical methods. These numerical techniques can be applied to study other structures, such as TV towers, nuclear power plants and dams.


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  Structural Element Approaches for Soil-Structure Interaction
Posted by: TAFATNEB - 09-14-2013, 09:48 AM - Forum: Civil Engineering MSc and PhD thesis - No Replies

Structural Element Approaches for Soil-Structure Interaction

Author: CASELUNGHE ARON & ERIKSSON JONAS | Size: 13.7 MB | Format: PDF | Quality: Unspecified | Publisher: Department of Civil and Environmental Engineering Division of Structural Engineering and GeoEngineering Concrete Structures and Geotechnical Engineering CHALMERS UNIVERSITY OF TECHNOLOGY Göteborg, Sweden 2012 | Year: 2012 | pages: 64

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The emphasis within this study regards structural element models for soil-structure
interaction (SSI). The methods are compared and calibrated against an elastic
continuum modelled with solid elements, which in the study is used as the “correct”
solution. Main interest is the influence on results of simplifications in the method
often used today, with springs representing the subgrade (Winkler model). In the
study this model is modified to better capture the soil’s behaviour.
In a Winkler model the springs act independently of each other, while the soil in
reality is a continuous medium that also transfers shear stresses. To achieve a better
behaviour in a structural element model, different kinds of interaction elements are
included, which couple the springs.
The biggest shortcoming, identified in this thesis, for a Winkler model with uniform
foundation stiffness is that the soil around the superstructure is not taken into account.
This can result in major underestimation of the foundation’s stiffness towards the
superstructure’s edges which normally, at the edges, leads to conservative sectional
forces in the ground slab and unconservative ground pressure. It can also result in a
convex settlement profile, where a concave would be more realistic.
Surrounding soil can be taken into account by increasing the foundation’s stiffness
towards the superstructure’s edges, alternatively the different models described in the
thesis can be implemented. The different models are applied in two simple cases, one
representing a footing and the second a slab. The best correlation to the elastic
continuum was achieved by applying an interaction element between the springs in a
Winkler model that only transfers shear deformations. This shear layer model is also
evaluated in 3D for a case study of “Malmö Konsert, Kongress och Hotell”.
A simple method, for practical use in 2D, to determine this shear layer model’s
parameters is developed by the authors. Analyses indicate that the shear layer’s
stiffness can be determined independently of the superstructure’s geometry. Therefore
only the soil’s properties and depth is needed to determine the shear layer’s stiffness.
A relation for homogenous and elastic soil is presented to determine the stiffness. The
relation is based on 2D analysis and is not verified for 3D. Further study and
verification is needed to make the method complete for practical use.


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  Engineering Viscoelasticity
Posted by: cace-01 - 09-13-2013, 06:17 PM - Forum: Mechanics & Material Technology (Elasticity, Plasticity and Nonlinearity) - Replies (2)

Engineering Viscoelasticity

Author: Danton Gutierrez-Lemini | Size: 4.2 MB | Format: PDF | Quality: Unspecified | Publisher: Springer | Year: 2014 | pages: 380 | ISBN: 1461481384

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Engineering Viscoelasticity covers all aspects of the thermo- mechanical response of viscoelastic substances that a practitioner in the field of viscoelasticity would need to design experiments, interpret test data, develop stress-strain models, perform stress analyses, design structural components, and carry out research work. The material in each chapter is developed from the elementary to the esoteric, providing the background in mathematics and mechanics that are central to understanding the subject matter being presented. This book also examines how viscoelastic materials respond to the application of loads, and provides practical guidelines to use them in the design of commercial, military and industrial applications.

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  Structural Shell Analysis: Understanding and Application
Posted by: cace-01 - 09-13-2013, 06:06 PM - Forum: Analysis & Design - Replies (4)

Structural Shell Analysis: Understanding and Application (Solid Mechanics and Its Applications)

Author: Johan Blaauwendraad and Jeroen H. Hoefakker | Size: ~6 MB | Format: PDF | Quality: Unspecified | Publisher: Springer | Year: 2013 | pages: 250 | ISBN: 9400767005

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The mathematical description of the properties of a shell is much more elaborate than those of beam and plate structures. Therefore many engineers and architects are unacquainted with aspects of shell behaviour and design, and are not familiar with sufficiently reliable shell theories for the different shell types as derived in the middle of the 20th century.
Rather than contributing to theory development, this university textbook focuses on architectural and civil engineering schools. Of course, practising professionals will profit from it as well.

The book deals with thin elastic shells, in particular with cylindrical, conical and spherical types, and with elliptic and hyperbolic paraboloids. The focus is on roofs, chimneys, pressure vessels and storage tanks. Special attention is paid to edge bending disturbance zones, which is indispensable knowledge in FE meshing. A substantial part of the book results from research efforts in the mid 20th century at Delft University of Technology. As such, it is a valuable addition to the body of shell research literature of continuing importance.

This work can be used for university courses. It also shows professionals how to perform manual calculations of the main force flow in shell structures, and provides guidance for structural engineers estimating stresses and deformations.

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  Erectors' Manual (PCI)
Posted by: pelon2040 - 09-13-2013, 02:20 PM - Forum: Archive - No Replies

Hi friends,

Someone can upload the book:

Erector's Manual: Standards and Guidelines for the erection of Precast Cocrete Products
Precast/Prestressed Concrete Institute

Thanks so much

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  SAP2000 V16
Posted by: struceng - 09-13-2013, 07:40 AM - Forum: SAP2000 - Replies (28)

CSI SAP2000 v16.0.0

Size: 358 MB
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SAP2000 V16 Enhancements

Significant enhancements included in SAP2000 v16.0.0, besides bug fixes:

Improved graphics performance
Display of multiple grid systems at the same time
New steel frame design code AISC 360-10
New steel frame design code NTC 2008
New concrete frame design code ACI 318-11
New concrete frame design code NTC 2008
New concrete frame design code NZS 3101-06
New concrete frame design code RCDF 2004
New concrete frame design code Hong Kong CP 2013
Enhanced beam-column capacity check for concrete frame design using Eurocode 2-2004
Stiffness modifiers from the AISC 360 steel frame design direct analysis method are now available in the database table for assigned frame property modifiers
New wind, seismic, and response-spectrum lateral loads for code IBC 2012
New wind lateral loads for code AS/NZS 1170.2-2011
New wind, seismic, and response-spectrum lateral loads for code NTC 2008
New wind, seismic, and response-spectrum lateral loads for codes TSC 2007 and TS 498-97
New response-spectrum lateral loads code AASHTO 2012
New assignment to control area loads transferred to frames
New hybrid U-girder frame section property
New built-in ASTM bridge steel materials
Chinese concrete material and design updated to use characteristic strength rather than grade
New link property for modeling triple-pendulum bearings
External tendons can now be modeled under user control
Plotting of tendon loads, losses, and axial-force response has been enhanced
Ground displacement loading now applies to single-joint links, including distributed spring supports, as well as to springs and restraints
Multiple mass sources can be defined for modeling alternative dynamic behavior
The undeformed shape can now be viewed for various stages of staged construction load case without running the analysis
Response output for staged-construction load cases now is labeled with the stage and step within the stage
Shear stress, von Mises stress, and principal stress response is now available for certain frame sections
Shell stresses can now be displayed normalized by material strength
Bearing pressure on shells from area springs can now be displayed
Display of frame-design D/C ratios can be limited by a specified threshold value
Verification suites are now provided for steel and concrete frame design by most codes
New Open API functions to define section-cuts
New Open API functions to define external load cases for frame results
New Open API functions to get detailed steel frame design results for certain codes
Customizable keyboard shortcuts for menu commands
Support for the import and export of files using the IFC 4 format
Licensing will now support web-activation and virtual servers
Simplified installation using the CSI Installation Wizard
Other minor enhancements

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