Seismic Response Of Buildings That Utilise Unbonded Post Tensioned Concrete Walls
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Seismic Response Of Buildings That Utilise Unbonded Post Tensioned Concrete Walls
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Author : Jonathan Watkins (‡c (PhD))
language : en
Publisher:
Release Date : 2017
Seismic Response Of Buildings That Utilise Unbonded Post Tensioned Concrete Walls written by Jonathan Watkins (‡c (PhD)) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with Concrete walls categories.
Unbonded post-tensioned precast concrete walls are a low-damage seismic resisting system that resist lateral loads by rocking at the wall base. This thesis addresses the uncertainty that wall-to-floor interaction can have on the seismic response and performance of buildings that use such wall systems. A computational model was developed and verified to accurately calculate the bi-directional lateral-load response of isolated post-tensioned concrete walls. The wall model was extended to represent a previously tested full scale, four storey building with post-tensioned concrete walls. The building model accurately captured the measured response of the test building that was subjected to increasing intensities of earthquake motion on a tri-directional shake-table. To accurately capture the seismic response of the building the model must represent the in-plane and out-of-plane floor behaviour, account for cracking of the floor, and represent the stiffness of the precast concrete floor units. Wall-to-floor interaction resulted in deformations that were concentrated in the link slab between the wall and adjacent precast floor unit of the test building. This deformation resulted in significant over-strength demands on the wall and column, which the dynamic loading further increased. During the 1995 Kobe earthquake motion the peak wall base shear from the building model was 110% greater compared to the same building model that did not account for wall-to-floor interaction or dynamic loading. A parametric study of the building model found that increasing the rib depth of the precast floor elements or the thickness of the floor resulted in significantly greater over-strength demands compared to the original building. The results of the parametric study confirmed that if the effects of wall-to-floor interaction are not considered as part of the design process, the inelastic mechanisms that develop when a building is subjected to an earthquake may be different than predicted and result in undesirable failure modes An innovative wall-to-floor connector that could eliminate the adverse effects of wall-to-floor interaction was experimentally subjected to the combination of vertical displacement and shear forces they would experience in a major earthquake. Within their design limits the connectors performed well and effectively isolated the floor from the walls vertical displacement while transferring shear force from the floor to the wall.
Dynamic Response Of Unbonded Post Tensioned Concrete Walls For Seismic Resilient Structures
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Author : Kimberley M. Twigden
language : en
Publisher:
Release Date : 2016
Dynamic Response Of Unbonded Post Tensioned Concrete Walls For Seismic Resilient Structures written by Kimberley M. Twigden and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Concrete walls categories.
The research in this thesis was conducted with the primary aim of advancing the current state of knowledge of unbonded Post-Tensioned (PT) precast concrete rocking walls. Emphasis was placed on systematically investigating both the static and dynamic experimental response of Single Rocking Wall (SRW) and Precast Wall with End Columns (PreWEC) systems. Using the experimental data generated, simple numerical modelling techniques were investigated and the Direct Displacement Based Design (DDBD) process was verified. The experimental programme consisted of component tests on modified energy dissipating Oconnectors and pseudo-static cyclic, snap back, and shake table testing on a selection of SRW and PreWEC systems. The unique experimental investigation into the cyclic response of an improved O-connector confirmed the suitability of the O-connector as a cost effective energy dissipater that is able to demonstrate stable hysteretic behaviour while being easy to install and replace. The focus of the wall tests was on assessing the general wall response and design, the influence of the O-connectors on the wall panel, initial stiffness and fundamental frequency, equivalent viscous damping and residual drifts from different loading types. During the wall tests only minor damage and negligible residual drifts were observed which confirmed the desirable seismic behaviour of SRW and PreWEC systems under both static and dynamic loads. An investigation was performed using a simple single degree of freedom numerical model to provide recommendations on appropriate damping schemes that are able to emulate the seismic response of SRW and PreWEC systems that were validated using the shake table test results. The numerical analyses indicated that good estimation of the seismic response could be attained when using 2% tangent stiffness proportional damping in combination with a hysteretic behaviour calibrated to the cyclic hysteresis. Lastly, an assessment of current methods used for determining the equivalent viscous damping for unbonded PT walls systems in the current DDBD framework was performed. A current method based on the weighted contribution of an unbonded PT only system and a purely dissipative system was found to produce good results when used with the proposed bilinear force-displacement idealisation based on an effective stiffness.
Seismic Performance And Modeling Of Reinforced Concrete And Post Tensioned Precast Concrete Shear Walls
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Author : Ahmet Can Tanyeri
language : en
Publisher:
Release Date : 2014
Seismic Performance And Modeling Of Reinforced Concrete And Post Tensioned Precast Concrete Shear Walls written by Ahmet Can Tanyeri and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
Past earthquakes have shown examples of unsatisfactory performance of buildings using reinforced concrete structural walls as the primary lateral-force-resisting system. In the 1994 Northridge earthquake, examples can be found where walls possessed too much overstrength, leading to unintended failure of collectors and floor systems, including precast and post-tensioned construction. In the 2010 Maule Chile earthquake, many structural wall buildings sustained severe damage. Although Chilean design standards result in different reinforcement detailing than is common in U.S. walls, the failure patterns raise concerns about how well conventionally reinforced structural walls in U.S. buildings will perform during the next earthquake. Alternative wall design philosophies that offer more predictable response, with better damage control, should be investigated. After the Mw 8.8 Chile earthquake, the 15-story Alto Rio building in Concepción sustained failures near the base, overturned, and came to rest on its side. The collapse of the Alto Rio building was significant because it was designed using the Chilean Building Code NCh433. Of96, which requires the use of ACI 318-95 for design of reinforced concrete structural elements intended to resist design seismic forces. The failure of the Alto Rio building is significant for many reasons. It is the first modern shear wall building of its type to collapse by overturning during an earthquake. The building is studied using forensic data and structural models of the framing system subjected to earthquake shaking. The study identifies the likely failure mechanism and suggests areas for which design and detailing practices could be improved. The capabilities and shortcomings of the analyses to identify details of the failure mechanism are themselves important outcomes of the study. A second study explores the behavior of structural wall buildings using unbonded post-tensioned structural walls. Such walls offer the opportunity to better control yielding mechanisms and promote self-centering behavior. The study focuses on the measured responses of a full-scale, four-story building model tested on the E-Defense shaking table in Japan. The seismic force-resisting system of the test building comprised two post-tensioned (PT) precast frames in one direction and two unbonded PT precast walls in the other direction. The building was designed using the latest code requirements and design recommendations available both in Japan and the U.S., including the ACI ITG-5.2-09. The test building was subjected to several earthquake ground motions, ranging from serviceability level to near collapse. Analytical studies were carried out to test the capability of the structural models to replicate behaviors important to structural engineers, and to assess whether available analysis tools are sufficient to model dynamic behavior that results when a full-scale building is subjected to realistic earthquake ground shaking. Measured response data from such an outstanding test provides an opportunity to fully understand the response characteristics of PT walls and assess the ability of nonlinear analytical models to reproduce important global and local responses, including three-dimensional system interactions, both prior to and after loss of significant lateral strength. Moreover, this study to assess behavior and system interaction of PT walls leads to improvements of the current design ideas and performance expectations. The present study examines both the collapse of the Alto Rio building in Chile and the shaking table tests of the unbonded post-tensioned wall building in Japan. The collapse study suggests areas of improvement in current design and detailing practice. The shaking table study suggests an alternative approach to design of shear walls in buildings. Both studies demonstrate the use of modern structural analysis tools to interpret building responses to earthquake shaking. Taken together, the studies provide added confidence in earthquake simulation capabilities and demonstrate alternatives for designing earthquake-resistant buildings that use structural walls.
Seismic Design Of Precast Concrete Building Structures
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Author : fib Fédération internationale du béton
language : en
Publisher: fib Fédération internationale du béton
Release Date : 2003-01-01
Seismic Design Of Precast Concrete Building Structures written by fib Fédération internationale du béton and has been published by fib Fédération internationale du béton this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003-01-01 with Technology & Engineering categories.
The aim of this state-of-art report is to present current practices for use of precast and prestressed concrete in countries in seismic regions, to recommend good practice, and to discuss current developments. The report has been drafted by 30 contributors from nine different countries. This state-of-art report covers: state of the practice in various countries; advantages and disadvantages of incorporating precast reinforced and prestressed concrete in construction; lessons learned from previous earthquakes; construction concepts; design approaches; primary lateral load resisting systems (precast and prestressed concrete frame systems and structural walls including dual systems) diaphragms of precast and prestressed concrete floor units; modelling and analytical methods; gravity load resisting systems; foundations; and miscellaneous elements (shells, folded plates, stairs and architectural cladding panels). Design equations are reported where necessary, but the emphasis is on principles. Ordinary cast-in-place reinforced concrete is not considered in this report. This fib state-of-the-art report is intended to assist designers and constructors to provide safe and economical applications of structural precast concrete and at the same time to allow innovation in design and construction to continue. This Bulletin N° 27 was approved as an fib state-of-art report in autumn 2002 byfib Commission 7, Seismic design.
Seismic Response Of Unbonded Post Tensioned Precast Concrete Walls With Ductile Vertical Connections
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Author : James Roland Conley
language : en
Publisher:
Release Date : 2000
Seismic Response Of Unbonded Post Tensioned Precast Concrete Walls With Ductile Vertical Connections written by James Roland Conley and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with categories.
Seismic Analysis And Design Of Buildings Equipped With Propped Rocking Wall Systems
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Author : Afsoon Nicknam
language : en
Publisher:
Release Date : 2015
Seismic Analysis And Design Of Buildings Equipped With Propped Rocking Wall Systems written by Afsoon Nicknam and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Propped Rocking Wall (PRW) is an innovative technology which combines passive damping with unbonded post-tensioned rocking concrete walls. This system has been proposed to reduce economic losses associated with earthquakes by returning a building to a functional state following a design seismic event. The proposed seismic force-resisting system consists of a slender unbonded post-tensioned concrete wall which is "propped" near the top with multi-story diagonal steel braces equipped with passive supplemental damping devices. In this study, a closed-form solution was derived for the global hysteretic response of the PRW system and a parametric study was conducted to evaluate the effect of different structural parameters involved. A seismic Direct Displacement-Based Design (DDBD) procedure for buildings equipped with PRW systems was then developed. The proposed design procedure was first evaluated through a comparative study between the seismic performance of the introduced system as opposed to a similar system called Propped Shear Walls (PSW) from which the proposed system was originally inspired. The adequacy of the proposed DDBD procedure and further the performance of PRWs were then evaluated through a shake table testing program. Detailed modeling of the PRW test model was developed and validated with shake table test results. Numerical modeling of the PRW on the prototype scale was further adopted and used in a seismic vulnerability assessment study based on the Methodology presented in FEMA P695. Design verifications were then extended to taller buildings equipped with the proposed Propped Rocking Wall (PRW) system. For this purpose, the seismic response of an 8-story building was evaluated against the predetermined performance objectives set in the beginning of the design procedure. In addition, the sensitivity of the response parameters under consideration to three main design parameters was studied.
Seismic Design And Analysis Of Unbonded Post Tensioned Precast Wall Systems
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Author : Sriram R. Aaleti
language : en
Publisher:
Release Date : 2005
Seismic Design And Analysis Of Unbonded Post Tensioned Precast Wall Systems written by Sriram R. Aaleti and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.
Following the satisfactory response of the unbonded post-tensioned precast concrete jointed wall system tested for seismic performance as part of the PREcast Seismic Structural Systems (PRESSS) test building, a set of design guidelines was published. Based on these guidelines, Thomas & Sritharan (2003) developed a procedure to analyze the unbonded jointed wall systems. The primary objective of this research is to improve this analysis procedure so that it can be applied to analyze both unbonded post-tensioned single walls and jointed wall systems. Using the experimental data from PRESSS test building, ATLSS research center single wall tests, the accuracy of this analysis procedure and that based on the monolithic beam analogy (MBA) are examined. It was found that both the analysis methods predicted the moment resistance of the walls adequately at the given base rotation. Based on these analysis procedures, revised set of design guidelines are proposed for design of precast jointed wall systems with unbonded post-tensioning steel. A detailed investigation on the influence of several wall parameters on the lateral load behavior of jointed wall system is conducted and a new jointed wall concept refer to as the "jointed wall-column (JWC) system" is proposed. It is shown by analysis that, the JWC system will be more economical than that of an equivalent jointed wall system tested in the PRESSS building.
Shake Table Testing And Analytical Modeling Of A Full Scale Four Story Unbonded Post Tensioned Concrete Wall Building
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Author : Sofia Gavridou
language : en
Publisher:
Release Date : 2015
Shake Table Testing And Analytical Modeling Of A Full Scale Four Story Unbonded Post Tensioned Concrete Wall Building written by Sofia Gavridou and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
The level of structural damage and the associated economic impact caused by recent earthquakes worldwide have spurred an increased interest in high performance seismic resisting systems that can sustain severe earthquakes with minimal damage. A particularly efficient high performance wall system consists of precast concrete panels vertically post-tensioned to the foundation with unbonded post-tensioning steel. The system relies on the vertical unbonded post-tensioning steel for flexural strength and re-centering, while mild bonded steel bars provide energy dissipation and additional flexural strength. Under lateral loading, the traditional plastic hinge mechanism, associated with structural damage and the potential for large residual deformation, is replaced by a controlled rocking mechanism at the wall-to-foundation interface that allows the system to undergo large nonlinear displacements with minimal damage and minor residual deformations. This thesis presents experimental results from a dynamic test on a full-scale, four-story precast concrete building that utilized unbonded post-tensioned (UPT) walls in one principal direction of response and bonded post-tensioned concrete frames in the orthogonal direction. The building was subjected to simultaneous three-dimensional shaking using recorded ground motions from the 1995 Kobe earthquake. The excellent performance of the test building in the wall direction of response, exhibiting minimal damage and no residual deformations, confirms that UPT walls are a viable alternative to conventional reinforced concrete (RC) structural walls. In addition to providing experimental evidence of seismic performance of UPT walls incorporated into a building system, the tests provided valuable insight into issues typically not addressed in component-level experimental studies, such as the role of the floor diaphragm, influence of component interactions, and contributions of three-dimensional responses and torsion. As evidenced by the E-Defense test building, these effects need to be considered to obtain realistic estimates of lateral resistance and displacement demands. The tests also provided a wealth of data against which design methodologies and analytical models for UPT systems can be benchmarked. Based on a detailed assessment of the E-Defense UPT walls in accordance with ACI ITG-5.2 (2009), and the performance of the UPT walls in the tests, design implications were identified and some revisions to ACI ITG-5.2 were suggested. Finally, an analytical model of the building in the wall direction was developed. Experimental results in this direction were used to assess the ability of the model to capture the dynamic responses and interactions of unbonded post-tensioned structural systems. Correlations between analytical and experimental results were satisfactory for a range of global and local responses, and key aspects of the interaction between components such as framing action and beam elongation effects were adequately reflected in the model.
Advances In Building Technology
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Author : M. Anson
language : en
Publisher: Elsevier
Release Date : 2002-11-14
Advances In Building Technology written by M. Anson and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002-11-14 with Technology & Engineering categories.
This set of proceedings is based on the International Conference on Advances in Building Technology in Hong Kong on 4-6 December 2002. The two volumes of proceedings contain 9 invited keynote papers, 72 papers delivered by 11 teams , and 133 contributed papers from over 20 countries around the world. The papers cover a wide spectrum of topics across the three technology sub-themes of structures and construction, environment, and information technology. The variety within these categories spans a width of topics, and these proceedings provide readers with a good general overview of recent advances in building research.
Advances In Seismic Performance And Risk Estimation Of Precast Concrete Buildings
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Author : Andrea Belleri
language : en
Publisher: Frontiers Media SA
Release Date : 2022-02-09
Advances In Seismic Performance And Risk Estimation Of Precast Concrete Buildings written by Andrea Belleri and has been published by Frontiers Media SA this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-02-09 with Technology & Engineering categories.