Seismic Retrofit of Existing Concrete Frame Structures Using Viscoelastic Damping Devices: A Research-in-Progress Update PDF Download
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ISBN:
Category :
Languages : en
Pages : 32
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Book Description
The U.S. Army and Air Force have large inventories of concrete frame buildings built before the 1971 San Francisco earthquake, when seismic provisions in U.S. building codes were enhanced. Consequently, many of these buildings may not safely withstand the ground motions associated with large intensity earthquakes. The U.S. Army Construction Engineering Research Laboratories (USACERL) has developed a program to provide improved technologies for mitigating seismic hazards in older military buildings. This study investigated the effectiveness of a nonintrusive rehabilitation technique involving the addition of viscoelastic damping devices to a concrete structure. A one-third scale model of a concrete building was built and placed on the USACERL shaking table. The building was earthquake-tested using two sizes of dampers, and with no dampers in place. Preliminary observations showed that the model with dampers sustained only minimal damage. More detailed analysis continues.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 32
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Book Description
The U.S. Army and Air Force have large inventories of concrete frame buildings built before the 1971 San Francisco earthquake, when seismic provisions in U.S. building codes were enhanced. Consequently, many of these buildings may not safely withstand the ground motions associated with large intensity earthquakes. The U.S. Army Construction Engineering Research Laboratories (USACERL) has developed a program to provide improved technologies for mitigating seismic hazards in older military buildings. This study investigated the effectiveness of a nonintrusive rehabilitation technique involving the addition of viscoelastic damping devices to a concrete structure. A one-third scale model of a concrete building was built and placed on the USACERL shaking table. The building was earthquake-tested using two sizes of dampers, and with no dampers in place. Preliminary observations showed that the model with dampers sustained only minimal damage. More detailed analysis continues.
Author:
Publisher:
ISBN:
Category : Buildings, Reinforced concrete
Languages : en
Pages : 40
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Book Description
Author:
Publisher:
ISBN:
Category : Reinforced concrete construction
Languages : en
Pages : 188
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Book Description
Author: Sachin Kuckian
Publisher: GRIN Verlag
ISBN: 3668992762
Category : Science
Languages : en
Pages : 90
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Book Description
Master's Thesis from the year 2015 in the subject Engineering - Geotechnology, grade: 9.44, , course: Masters (Structural Engineering), language: English, abstract: The present study investigates the seismic behavior of multi-story building using damping devices strategically located within the lateral load resisting elements. It concentrates on a retrofitting strategy with passive energy dissipation device known as Fluid Viscous Damper (FVD) which will be applicable to new design as well as retrofitting existing buildings to ensure seismic safety by fitting damping devices which can transform a wall panel into a damping element. The first study involves analysis of a nine-story model having cut-outs and the use of the dampers of different configuration in these structures. The second study involves the use the diagonal brace configuration dampers provided in the cutout sections of 2D 9, 18, 27 storey structures and 3D 27 storey with core wall structure at three consecutive story levels each. For the second study, the cut out locations is varied depending on their relative positions. The relative position is the ratio of the total height of the structure to the upper edge of the topmost cut-out. These structures were initially modeled and time history analysis was performed on the structure without FVD and the structure retrofitted with FVD. Three different ground motions were used for the analysis. Results of the un- retrofitted structures are then compared with a retrofitted structure in terms of peak story displacements, roof accelerations, and pseudo-spectral accelerations. Study shows that there has been a significant reduction in seismic demands for a structure retrofitted with FVD in terms of peak storey displacements, pseudo-spectral accelerations and roof accelerations when the dampers are placed at lower three cut outs i.e. with high relative position. It is also observed that damping coefficient value obtained is least for upper toggle-brace configuration out of the four different damper configurations and with maximum reduction compared to other configurations. For modeling and analysis purpose the software SAP2000® is used. Through the study it could be concluded that FVD significantly reduces the seismic demands of the structure in terms of peak storey displacements, pseudo-spectral accelerations and roof accelerations. This suggests that FVDs can be efficiently used in retrofitting. Also damping coefficient value obtained is least for upper toggle-brace configuration out of the four different damper configurations suggesting this is the most efficient configuration for retrofitting.
Author: John R. Hayes
Publisher:
ISBN:
Category : Buildings, Reinforced concrete
Languages : en
Pages : 921
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Book Description
The objective of this study was to develop improved understanding of the seismic behavior of a lightly reinforced concrete (LRC) slab-column structure seismically retrofitted with viscoelastic dampers (VEDs). The feasibility of using VEDs to rehabilitate existing LRC slab-column structures was explored, and implications for structural design were considered. A model of a section of a 1950s-era three-story military barracks building was fabricated for testing. A rehabilitation scheme using VEDs was designed and implemented. This section model was subjected to a series of earthquake simulations on the shaking table at the U.S. Army Construction Engineering Research Laboratories (CERL). Experimental measurements included floor and VED displacements, floor accelerations, VED forces, and reinforcement strains. The earthquake simulations comprised a series of gradually increasing intensity replications of two commonly used earthquake records, first on the frame fitted with VEDs, then on the frame without VEDs. Interpretations of the testing results are provided through the use of linear models of the type that might be used in the design office. These analytical models also were used to assess the applicability of the linear modeling procedures that have been recommended in Federal Emergency Management Agency document 273, "NEHRP Guidelines for the Seismic Rehabilitation of Buildings."
Author:
Publisher:
ISBN: 9781642241815
Category :
Languages : en
Pages : 375
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Book Description
Seismic retrofitting is the modification of existing structures to make them more resistant to seismic activity, ground motion, or soil failure due to earthquakes. The planning of changes to existing buildings differs from new planning through an important condition; the existing construction must be taken as the basis of all planning and building actions. The need for seismic retrofitting of an existing building can arise due to several reasons like: building not designed to code, subsequent updating of code and design practice, subsequent upgrading of seismic zone, deterioration of strength and aging, modification of existing structure, change in use of the building, etc. Seismic retrofit is primarily applied to achieve public safety, with various levels of structure and material survivability determined by economic considerations. In recent years, an increased urgency has been felt to strengthen the deficient buildings, as part of active disaster mitigation, and to work out the modifications that may be made to an existing structure to improve the structural performance during an earthquake. Seismic retrofitting schemes can be either global or local, based on how many members of the structures they are used for. Global Retrofit methods include conventional methods (increase seismic resistance of existing structures) or non-conventional methods (reduction of seismic demand). Strengthening and Retrofitting of Existing Structures is a compendium of cutting-edge trends of the research and existing practices in strengthening and retrofitting of structural elements, as well as the findings of a research endeavor initiated by the authors to investigate and develop a robust structural retrofitting scheme by utilizing elastomeric polymers to enhance the resistance of reinforced concrete (RC) structures. It addresses in detail specific techniques for the strengthening of traditional constructions, reinforced concrete buildings, bridges and their foundations. It also presents insight into the key issues relevant to seismic retrofit of concrete frame buildings. Many guidelines are reviewed regarding seismic rehabilitation of school, office, hospital and apartment buildings.
Author: Robert D. Hanson
Publisher:
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 160
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Book Description
The purpose of this monograph is to impart basic concepts of the supplemental energy dissipation technology to design engineers, architects, and building officials so they can understand its benefits and limitations in structural applications. The approach is introductory. References are cited throughout the monograph for readers who wish to study the subject in more depth.Supplemental energy dissipation systems are recent innovations to improve earthquake building performance. Research has led to a better understanding of the effects of supplemental energy dissipation on the earthquake response of buildings. Over the last 20 years, significant progress has been made in developing manufactured systems. They are being reliably designed and installed in new as well as existing buildings.Development of design codes and standards for energy dissipation systems has progressed slowly. This monograph summarizes information on their use in designing new earthquake-resistant buildings and upgrading the seismic performance of existing buildings. The following areas are covered:? The physical consequences of adding energy dissipation systems to a structure for various types of input motion? Summary of generic energy dissipation device characteristics? Summary of pros and cons of specific device characteristics in meeting selected design objectives? Seismic design limits for selecting energy dissipation systems? Design approaches for the limits of elastic or inelastic response
Author: National Center for Earthquake Engineering Research (U.S.)
Publisher:
ISBN:
Category : Earthquake engineering
Languages : en
Pages : 276
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Book Description
Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 776
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Book Description
Author: fib Fédération internationale du béton
Publisher: fib Fédération internationale du béton
ISBN: 9782883940642
Category : Technology & Engineering
Languages : en
Pages : 322
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Book Description
In most parts of the developed world, the building stock and the civil infrastructure are ageing and in constant need of maintenance, repair and upgrading. Moreover, in the light of our current knowledge and of modern codes, the majority of buildings stock and other types of structures in many parts of the world are substandard and deficient. This is especially so in earthquake-prone regions, as, even there, seismic design of structures is relatively recent. In those regions the major part of the seismic threat to human life and property comes from old buildings. Due to the infrastructure's increasing decay, frequently combined with the need for structural upgrading to meet more stringent design requirements (especially against seismic loads), structural retrofitting is becoming more and more important and receives today considerable emphasis throughout the world. In response to this need, a major part of the fib Model Code 2005, currently under development, is being devoted to structural conservation and maintenance. More importantly, in recognition of the importance of the seismic threat arising from existing substandard buildings, the first standards for structural upgrading to be promoted by the international engineering community and by regulatory authorities alike are for seismic rehabilitation of buildings. This is the case, for example, of Part 3: Strengthening and Repair of Buildings of Eurocode 8 (i. e. of the draft European Standard for earthquake-resistant design), and which is the only one among the current (2003) set of 58 Eurocodes attempting to address the problem of structural upgrading. It is also the case of the recent (2001) ASCE draft standard on Seismic evaluation of existing buildings and of the 1996 Law for promotion of seismic strengthening of existing reinforced concrete structures in Japan. As noted in Chapter 1 of this Bulletin, fib - as CEB and FIP did before - has placed considerable emphasis on assessment and rehabilitation of existing structures. The present Bulletin is a culmination of this effort in the special but very important field of seismic assessment and rehabilitation. It has been elaborated over a period of 4 years by Task Group 7.1 Assessment and retrofit of existing structures of fib Commission 7 Seismic design, a truly international team of experts, representing the expertise and experience of all the important seismic regions of the world. In the course of its work the team had six plenary two-day meetings: in January 1999 in Pavia, Italy; in August 1999 in Raleigh, North Carolina; in February 2000 in Queenstown, New Zealand; in July 2000 in Patras, Greece; in March 2001 in Lausanne, Switzerland; and in August 2001 in Seattle, Washington. In October 2002 the final draft of the Bulletin was presented to public during the 1st fib Congress in Osaka. It was also there that it was approved by fib Commission 7 Seismic Design. The contents is structured into main chapters as follows: 1 Introduction - 2 Performance objectives and system considerations - 3 Review of seismic assessment procedures - 4 Strength and deformation capacity of non-seismically detailed components - 5 Seismic retrofitting techniques - 6 Probabilistic concepts and methods - 7 Case studies
