Probabilistic evaluation of performance point in structures and investigation of the uncertainties
Author: F. Azhdary* and N. Shabakhty Department of Civil Engineering, University of Sistan and Baluchestan, Zahedan, Iran. | Size: 216 KB | Format:PDF | Quality:Unspecified | Publisher: Journal of Mechanical Engineering Research Vol. 3. (6), pp. 197-208, June 2011 | Year: 2011 | pages: 12
The main goal of the performance based design of structures is to rationally predict the structures’
performance during earthquakes which may occur during the lifetime of the structure. In this sort of
design, a specific displacement is defined as target displacement and the structure is subjected to a
force in order to reach this target displacement. This design process includes uncertainties in loading,
materials and analysis methods of the performance point. Therefore, statistical and probabilistic
analysis should be considered. In this paper, uncertainty sources for determining the performance
point are defined and then the procedures suggested in the codes are introduced. In the next step, an
appropriate probability distribution function is defined for uncertainty parameters and finally the
performance point of the structure is determined regarding these parameters in accordance with the
codes. In addition, the sensitivity of the performance point with respect to the mentioned parameters is
investigated. Results indicate that sensitivity of the performance point to geometric characteristics is of
great importance and other parameters such as dead and live load stand in the second level in terms of
sensitivity. An appropriate lateral loading pattern with the least uncertainty is also proposed for
buildings.
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CAPACITY SPECTRUM METHOD BASED ON INELASTIC DEMAND SPECTRA
Author: PETER FAJFAR* Faculty of Civil and Geodetic Engineering, University of Ljubljana, Ljubljana, Slovenia | Size: 156 KB | Format:PDF | Quality:Unspecified | Publisher: EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS Earthquake Engng. Struct. Dyn. 28, 979}993 (1999) | Year: 1999 | pages: 15
By means of a graphical procedure, the capacity spectrum method compares the capacity of a structure with
the demands of earthquake ground motion on it. In the present version of the method, highly damped elastic
spectra have been used to determine seismic demand. A more straightforward approach for the determination
of seismic demand is based on the use of the inelastic strength and displacement spectra which can be
obtained directly by time-history analyses of inelastic SDOF systems, or indirectly from elastic spectra.
The advantages of the two approaches (i.e. the visual representation of the capacity spectrum method and
the superior physical basis of inelastic demand spectra) can be combined. In this paper, the idea of using
inelastic demand spectra within the capacity spectrum method has been elaborated and is presented in an
easy to use format. The approach represents the so-called N2 method formulated in the format of the
capacity spectrum method. By reversing the procedure, a direct displacement-based design can be performed.
The application of the modi"ed capacity spectrum method is illustrated by means of two examples.
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I would like to know what are the minimal legal requirements for getting a PhD degree, to become an associate professor and professor in the field of structural engineering? By requirements I mean are there any minimal number of published articles, how many of them must be in refereed journals, how many in journals with impact factor, how many books must have been published, in how many scientific projects somenone has to be participated, etc. It will be interesting for me to know what are these requirements in different countries.
It has been observed that most of the bridges damaged in earthquakes were constructed before 1971 and had little or no design consideration to seismic resistance. Since the 1971 San Fernando earthquake in California, the standards for earthquake design have been strengthened considerably, and bridge structural behavior has been more accurately evaluated. Since then, structural ductility, a crucial element for the survival of bridges under severe earthquakes has become a key consideration in structural analysis and design. However, bridges that were constructed prior to 1971 are still in use and play important roles in our transportation systems, which may be susceptible to failure due to their structural deficiencies. To ensure safety and performance of these bridges, a seismic retrofit and strengthening program has been one of the major efforts of the Washington Department of Transportation and the Federal Highway Administration, aiming at improving seismic performance of older bridges. Retrofitting methods such as restrainers and column jacketing have proven to be effective in recent earthquakes. Techniques to retrofit other bridge members have also been developed such as soil anchors, footing retrofit involving increased plan dimension and reinforced overlay, construction of link beams, and system isolation and damping device. The goal of seismic retrofit is to minimize the likelihood of structural failure while meeting certain performance requirements. This allows engineers to design repair strategies based on performance needs. As a consequence, some level of damage may be acceptable during a design-level earthquake. The California Department of Transportation (Caltrans) has required that bridge retrofits provide survival limit-state protection at seismic intensities appropriate for new bridges. This makes possible the proposition of efficient and effective strengthening measures with optimized retrofitting schemes, and the adoption of the plan that is the most economical for the acceptable damage level. One of the ways of implementation the retrofit program for the structures is providing a nonlinear static analysis.
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seismic performance of flexible concrete structures
Author: habib labib fighali | Size: 6.6 MB | Format:PDF | Quality:Unspecified | Publisher: the universitu of texas at austin | Year: december 1999 | pages: 277
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Seismic Behaviour and Retrofit of Historic Masonry Minaret
Author: Prof. Ahmet Murat Turk, Ph.D. (Civ.Eng.) Istanbul Kultur University Civil Engineering Department.Cumhur Cosgun, B.Sc. (Civ.Eng.) Istanbul Kultur University Civil Engineering Department | Size: 0.73 MB | Format:PDF | Quality:Unspecified | Year: 2012 | pages: 07
The dynamic behaviour of block masonry minaret of a historical mosque in Istanbul is analyzed, and a seismic retrofit method is proposed. Due to high seismicity of the region, a 3D finite element model is used to determine lateral displacements and
failure modes under seismic load. The analyses show that the highest damage usually occurs at the base and the lower part of the minaret, and that lateral behaviour can be
improved by strengthening these sections with fiber reinforced polymer (FRP) sheets. The results obtained are promising in terms of seismic protection.
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"APPROXIMATE BUCKLING CRITERIA FOR MULTI-STIFFENED RECTANGULAR PLATES UNDER BENDING AND COMPRESSION"
Author: B RICHMOND
Source: ICE Proceedings, Volume 20, Issue 1, 01 September 1961 , pages 141 –150
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The “Residential Code Requirements for Structural Concrete” cover the design and construction of cast-in-place concrete for one- and two-family dwellings and multiple single-family dwellings (townhouses), and their accessory structures.
Among the subjects covered are the design and construction requirements for plain and reinforced concrete footings, foundation walls, and slabs-on-ground, and requirements for concrete, reinforcement, forms, and other related materials.
The quality and testing of materials discussed in this document are covered by reference to the appropriate ASTM standards.
The Code is written to allow for reference by adoption in a general building code without changing its language. Background details or suggestions for carrying out the requirements or intent of the Code are provided in the commentary. The commentary discusses some of the considerations of the committee in developing the Code with emphasis given to the explanation of provisions that may be unfamiliar to code users or where significant departure exists from other concrete codes. Commentary provisions begin with an “R,” such as “R.1.1.1,” and commentary text is shown in italics.
Relevant resource documents are cited for the user desiring more detailed study of individual issues.
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This publication contains a comprehensive summary of the seismic detailing requirements contained in Chapter 21 of Building Code Requirements for Structural Concrete (318-05) and Commentary (318R-05), which is adopted by reference in the 2006 International Building Code.
Numerous tables and figures explain and illustrate the provisions for the following components in buildings located in regions of moderate and high seismic risk:
- Flexural members of special moment frames
- Special moment frame members subjected to bending and axial load
- Joints of special moment frames
- Special reinforced concrete structural walls and coupling beams
- Structural diaphragms and trusses
- Foundations
- Frame members not proportioned to resist forces induced by earthquake motions
-Intermediate moment frames.
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