NUMERICAL MODELS FOR THE SEISMIC ASSESSMENT OF AN OLD MASONRY TOWER
Author: Paulo B. Lourenço;Fernando Peña ;Daniel V. Oliveira; | Size: 1.8 MB | Format:PDF | Quality:Unspecified | Publisher: SEISMIC ASSESSMENT OF AN OLD MASONRY TOWER F. Peña, P.B. Lourenço, N. Mendes & D.V. Oliveira | Year: | pages: 20
The present paper describes the seismic assessment of the Qutb Minar in Delhi, India. Three models with different levels of complexity and simplifications were developed. The use of these models allows to overcome the complexity on the study of the seismic behavior of ancient masonry structures; by combining the results of the different models it is possible to obtain a better and more comprehensive interpretation of the seismic behavior. The models were used for non-linear static (pushover) and non-linear dynamic analyses. The static and dynamic analyses give different behaviors, indicating that push-over analysis should be used carefully in the seismic assessment of masonry structures. For the static analysis, the base of the tower is the most vulnerable part; while according to the dynamic analysis, it is the upper part of the tower. This last behavior is according to the historical damage suffered by the tower due to earthquakes. The different behaviors can be explained by the influence of the higher modes of vibration.
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Author: Prof. Davide Bigoni | Size: 17.1 MB | Format:PDF | Quality:Unspecified | Publisher: UNIVERSITY OF TRENTO Modeling, Preservation and Control of Materials and Structures Ph. D. | Year: 08/04/2011 | pages: 172
This study is dedicated to simplified vulnerability assessment of
masonry towers, in particular to the definition of collapse mechanism geometry.
After a preliminary analysis on damages and collapse mechanisms
caused to towers by the earthquakes and a review of analysis
methods in literature, a model to determine the plane of fracture that defines the kinematic blocks of an overturning mechanism was proposed, based on simple equilibrium conditions.
According to the Italian codes, in fact, tower structures are classified as one of the churches macroelements, characterized by peculiar collapse mechanisms; respect to other macroelements, for towers a slight variation in mechanism geometry implies relevant variation in collapse multiplier values; this is mainly due to the importance of mass and height in these structures. Hence a correct definition of kinematism geometry results very important.
The proposed method was applied also including a limit on masonry compressive strength, despite traditional limit analysis method that usually assumes as infinite masonry compressive strength.
For the use in common practice, the curve of fracture was evaluated through parametric analyses for different geometrical configurations, to which many existing towers can be assimilated. Finally, besides a comparison with real collapse mechanisms surveyed on towers after earthquakes, the proposed method was applied also in the vulnerability assessment of a medieval masonry tower, the Ghirlandina in Modena.
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Seismic vulnerability assessment to slight damage based on experimental modal parameters
Author: Clotaire Michel , Philippe Gueguen , Matthieu Causse | Size: 1 MB | Format:PDF | Quality:Unspecified | pages: 50
The aim of this paper is to adjust behaviour models for each class of structure for vulnerability assessment by using ambient vibration. A simple model based on frequencies, mode shapes and damping, taken from ambient vibrations, allows computation of the response of the structures and comparison of inter-storey drifts with the limits found in the literature for the slight damage grade, considered here as the limit of elastic behaviour. Two complete methodologies for building fragility curves are proposed: (1) using a multi-degree of freedom system including higher modes and full seismic ground motion, (2) using a single-degree of freedom model considering the fundamental mode f0 of the structure and ground motion displacement response spectra SD(f0). These two methods were applied to the city of Grenoble, where 60 buildings were studied. Fragility curves for slight damage were derived for the various masonry and reinforced concrete classes of buildings.
A site-specific earthquake scenario, taking into account local site conditions, was considered, corresponding to an ML=5.5 earthquake at a distance of 15km. The results show the benefits of using experimental models to reduce variability of the slight damage fragility curve. Moreover, by introducing the experimental modal model of the buildings, it is possible to improve seismic risk assessment at an overall scale (the city) or a local scale (the building) for the first damage grade (slight damage). This level of damage, of great interest for moderate seismic prone
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American Petroleum Institute API RP 2A- WSD Recommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms—Working Stress Design 2000
Author: American Petroleum Institute | Size: 1 MB | Format:PDF | Quality:Unspecified | Publisher: American Petroleum Institute | Year: 2000 | pages: 243
This Recommended Practice for Planning, Designing, and Constructing Fixed Offshore Platforms containsengineering design principles and good practices that have evolved during the development of offshore oilresources. Good practice is based on good engineering; therefore, this recommended practice consists essentiallyof good engineering recommendations. In no case is any specific recommendation included which could not beaccomplished by presently available techniques and equipment. Consideration is given in all cases to the safety ofpersonnel, compliance with existing regulations, and antipollution of water bodies.
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Author: William D. Callister, Jr. | Size: 31.3 MB | Format:PDF | Quality:Unspecified | Publisher: John Wiley & Sons, Inc | Year: 2007 | pages: 975 | ISBN: 978-0-471-73696-7
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Posted by: amiboyz - 11-18-2013, 08:43 AM - Forum: Archive
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ACCEPTANCE CRITERIA FOR CONCRETE AND REINFORCED AND UNREINFORCED MASONRY STRENGTHENING USING FIBER-REINFORCED, COMPOSITE SYSTEMS
Size: 72 KB | Format:PDF | Quality:Unspecified | Publisher: International Conference of Building Officials | Year: 1997 | pages: 8
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Evaluation reports issued by the ICBO Evaluation Service, Inc. (ICBO ES), are based upon performance features of the
Uniform Building Code, ICBO Uniform Mechanical Codeand related codes.
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Here I share for Steel Table section properties with metric unit
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DEVELOPMENT OF SEISMIC VULNERABILITY ASSESSMENT METHODOLOGIES OVER THE PAST 30 YEARS
Author: G.M. Calvi*, R. Pinho**, G. Magenes*, J.J. Bommer***, L.F. Restrepo-Vélez**** and H. Crowley** *Department of Structural Mechanics, University of Pavia, Pavia, Italy **European Centre for Training and Research in Earthquake Engineering (EUCENTRE), Pavia, Italy ***Department of Civil and Environmental Engineering, Imperial College London, U.K.Solingral S.A., Medellin, Colombia | Size: 0.87 MB | Format:PDF | Quality:Unspecified | Year: 2009 | pages: 30
Models capable of estimating losses in future earthquakes are of fundamental importance for
emergency planners and for the insurance and reinsurance industries. One of the main ingredients in loss model is an accurate, transparent and conceptually sound algorithm to assess the seismic vulnerability of the building stock and indeed many tools and methodologies have been proposed over the
past 30 years for this purpose. This paper takes a look at some of the most significant contributions in the
field of vulnerability assessment and identifies the key advantages and disadvantages of these procedures
in order to distinguish the main characteristics of an ideal methodology.
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Seismic Response of Reinforced Concrete Structures Affected by Reinforcement Corrosion
Author: Paola Simioni | Size: 5.4 MB | Format:PDF | Quality:Unspecified | Publisher: Faculty of Architecture, Civil Engineering and Environmental Sciences University of Braunschweig – Institute of Technology | Year: 2009 | pages: 186
Durability of RC structures is a well known critical issue, requiring a time-dependent assessment of the structural performance. In fact, the progressive deterioration of the materials properties may significantly affect the response of the whole structural system, compromising the capability of the structure to withstand the loads for which it was designed. Thus, civil engineers are concerned not only with the need for durable design, but also with the importance of maintenance, inspection and, if necessary, reparation/rehabilitation interventions during the structure’s service life.
Experience shows that corrosion of reinforcing steel may be cited as the major source of degradation, increasing the structural vulnerability to extreme loads and natural hazards. In particular, the variation of the mechanical properties of steel, concrete and their interfacial layer induced by corrosion may result in the reduction of the load bearing capacity and, in some cases, also the shift of the failure mechanism from the ductile to the fragile type. These aspects become a main issue in safety assessment, with noteworthy implications in seismic prone areas, where the ductility characteristics of the structure are of primary importance for a good seismic behaviour. In order to support decision makers with a better comprehension of the matter of safety assessment, the concept of risk management has recently become of great concern also in civil engineering, being already popular in other disciplines. The general procedure developed within the International Graduate College IGC 802 allows managing risk in any situation or field in which an undesired or unexpected event could be significant, providing a greater insight of its possible outcomes and thus giving the possibility to control its impacts. In the submitted dissertation a methodology is presented to investigate the effects induced by increasing levels of environmental degradation on the seismic response of RC structures, focusing on the consequences of reinforcement corrosion on the local and global structural behaviour. Referring to the risk management procedure, both seismic shaking and reinforcement corrosion were identified as the hazards endangering the system. Within the risk analysis phase, a new module for the specific management of steel corrosion was proposed (“corrosion risk management chain”). The evaluation of the structural vulnerability was carried out at two different levels of investigation. A “micro” level approach allowed describing the influence of corrosion on the bond-slip behaviour between reinforcing bars embedded in concrete and concrete itself. A new bond law was developed, able to describe the degradation of bond strength due to environmental attacks, in pull-out and beam tests. By means of the “macro” level approach it was possible to describe the variation of the seismic performance of a RC building at the end of its service life respect to the time of construction. It was assumed that, in accordance to the climatic characteristics of the site, the structure suffered of a moderate corrosion attack due to carbonation, resulting in the reduction of load bearing capacity and structural ductility.
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