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Seismic Retrofit Of Concrete Columns By Transverse Prestressing
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Book Synopsis Seismic Retrofit of Concrete Columns by Transverse Prestressing by : Amirreza Sabri
Download or read book Seismic Retrofit of Concrete Columns by Transverse Prestressing written by Amirreza Sabri and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Performance of buildings and bridges during past earthquakes has indicated that many of these structures are vulnerable to seismic damage and structural collapse. The deficiencies in pre-1970s design codes have resulted in poor performance of reinforced concrete structures during seismic excitations. The Richter Magnitude 6.6 - 1971 San Fernando Earthquake raised awareness for seismic retrofit needs of existing buildings for the first time. The majority of deficiencies of vulnerable concrete columns can be overcome through seismic retrofits that involve additional transverse reinforcement. This can be done either by providing reinforced concrete, steel, or fibre-reinforced polymer (FRP) jackets around existing columns; or by applying transverse prestressing to columns (RetroBelt System). The research project presented in this thesis involves a seismic retrofit methodology for seismically deficient building and bridge columns, utilizing the use of high-strength packaging straps as external reinforcement for transverse prestressing. The emphasis in the project is placed on experimental research. Three seismically deficient full-size reinforced concrete columns, with a circular, a square and a rectangular cross- section, either critical in shear or flexure, were designed, built and tested under simulated seismic loading. The results indicate that external prestressing of columns in transverse direction with high-strength steel straps improves ductility and energy dissipation capacity of seismically deficient columns. They further indicate that current analytical techniques can be used to predict the force-displacement relationships of columns. A design approach is presented for the retrofit methodology investigated.
Book Synopsis Seismic Retrofit and Repair of Existing Reinforced Concrete Bridge Columns by Transverse Prestressing by : Majid Sadoughi Yarandi
Download or read book Seismic Retrofit and Repair of Existing Reinforced Concrete Bridge Columns by Transverse Prestressing written by Majid Sadoughi Yarandi and published by . This book was released on 2007 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Seismic Retrofit of Concrete Columns with Splice Deficiencies by External Prestressing by : Pascal Beauséjour
Download or read book Seismic Retrofit of Concrete Columns with Splice Deficiencies by External Prestressing written by Pascal Beauséjour and published by . This book was released on 2000 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: According to the current design practice, reinforced concrete columns should have sufficient ductility to resist major earthquakes. The ductility allows a column to maintain its strength during inelastic response to earthquakes. The research project reported in this thesis involves the use of a new retrofit strategy developed for concrete columns at the University of Ottawa. The new procedure consists of external prestressing existing columns with seven wire strands. External prestressing overcomes diagonal tension caused by shear, confines compression concrete, and may improve the behaviour of spliced reinforcement under reversed cyclic loading. Six large scale bridge columns were built and tested under simulated seismic loading. Four long columns with a circular or a square cross-section of approximately 500 mm, and two short circular columns of 610 mm in diameter, were investigated. The columns all had lap spliced longitudinal reinforcement within the potential plastic hinge region. The splice length was equal to twenty times the bar diameter. The reinforcing details were typical of the pre-1970's design practice. The columns were subjected to a constant axial load of 15% of their concentric capacity. (Abstract shortened by UMI.).
Author :Konstantinos G. Megalooikonomou Publisher :Cambridge Scholars Publishing ISBN 13 :1527530361 Total Pages :387 pages Book Rating :4.5/5 (275 download)
Book Synopsis Seismic Assessment and Retrofit of Reinforced Concrete Columns by : Konstantinos G. Megalooikonomou
Download or read book Seismic Assessment and Retrofit of Reinforced Concrete Columns written by Konstantinos G. Megalooikonomou and published by Cambridge Scholars Publishing. This book was released on 2019-02-27 with total page 387 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reinforced concrete columns play a very important role in structural performance. As such, it is essential to apply a suitable analytical tool to estimate their structural behaviour considering all failure mechanisms such as axial, shear, and flexural failures. This book highlights the development of a fiber beam-column element accounting for shear effects and the effect of tension stiffening through reinforcement-to-concrete bond, along with the employment of suitable constitutive material laws.
Book Synopsis Seismic Retrofit of Concrete Columns with Splice Deficiencies by External Prestressing by :
Download or read book Seismic Retrofit of Concrete Columns with Splice Deficiencies by External Prestressing written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Seismic Retrofit of Bridges Supported on Hollow Core Prestressed Concrete Pile-columns by : Samuel Turner
Download or read book Seismic Retrofit of Bridges Supported on Hollow Core Prestressed Concrete Pile-columns written by Samuel Turner and published by . This book was released on 2020 with total page 215 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Washington State Department of Transportation (WSDOT) began a bridge seismic retrofit program in 1991 in order to address the earthquake risks associated with state-owned bridges. The majority of these bridges were constructed in the 1960s, prior to the development of modern seismic design standards during the 1970s and 1980s, and one class of bridges built during that era represents a particular cause for concern. In that class of bridges, circular, hollow-core precast, prestressed concrete piles were driven into the ground, with sufficient length left projecting above ground level to form the columns. Hence, they are referred to in this thesis as "pile-columns." Cap beams were then cast in place on the pile-columns and were connected to them by means of concrete plugs with longitudinal reinforcement cast into the tops of the columns. Many of these hollow pile-column bridges form part of the state's "Lifeline Routes" for seismic events and are consequently slated for retrofit in the near future. Previous, but limited, experimental research have shown that hollow, prestressed concrete specimens show minimal ductility under cyclic lateral loading and fail suddenly, because the wall of the column spalls both inwards and outwards. However, cyclic lateral loading performed during an earlier phase of this research program on an as-built scaled model specimen of the column-to-cap-beam connection showed better ductility than expected. In this portion of the research program, reported in this thesis, experiments were conducted to better understand the behavior of the hollow core pile-columns under pure bending (relevant in the pile region below-grade) as well as combined bending and shear (relevant in the column region above-grade). Finally, a column-to-cap-beam connection retrofitted with a carbon fiber jacket was tested under cyclic lateral loading. Under elastic conditions, the peak moment demand in the pile-column occurs at column-to-cap-beam connection; the moments below-grade are approximately half as large. As a result, the retrofit concept for these bridges is concentrated on that connection. The tested retrofit option involved jacketing the as-built plug region in a carbon fiber wrap on the basis that that procedure is simple and reliable, it slightly lowers the peak moments below-grade, and, if a fiber jacket could be used over only the upper part of the column, it would avoid invoking environmental restrictions for bridges over waterways. Concerns with this, and any other retrofit option, include vulnerability to combined bending and shear failure of the hollow cross section just beyond the end of the plug, as well as susceptibility to pure bending failure of the hollow pile below-grade. Three experimental programs were conducting during this investigation. The first and second were conducted to determine the pure bending, and combined shear and bending, strengths of a hollow pile-column section. The results of these tests aided in calibrating the transverse load capacity of hollow prestressed concrete specimens under two separate load configurations. The third experiment was conducted on a scaled cantilever column-to-cap beam connection, retrofitted with a fiber jacket around the plug region, under reversed cyclic displacement. The results of the third experiment showed that the retrofitted pile-column performed slightly better than the as-built specimen, and that the critical mode of failure was not internal spalling, as suggested by previous researchers, but rather by column cracking, followed by strand debonding. Review of the test results from the as-built specimen concluded that that specimen, too, had failed by strand debonding. Debonding failure proved to be non-ductile, because the strands buckled during the half-cycle following debonding, then fractured as they re-straightened. It was further concluded that the fiber jacket had provided little benefit because strand debonding, and not concrete confinement, was the primary failure mechanism. A third retrofit option was then developed, but limitations on resources prevented it from being tested. Strand debonding can occur only after the column wall cracks, which requires high net tension stress, due primarily to bending. A thick steel jacket, made composite with the concrete components, would increase the flexural stiffness of the region and reduce the bending stress in the concrete column wall, thereby preventing cracking. A methodology for selecting the jacket thickness was developed, and it is recommended that this retrofit option be tested and, if the test is successful, it should be adopted.
Book Synopsis Seismic Retrofitting of Concrete Bridge Columns by External Prestressing by : Derek Mes
Download or read book Seismic Retrofitting of Concrete Bridge Columns by External Prestressing written by Derek Mes and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to recent earthquakes and the ensuing damage, there has been some concern regarding the adequacy of older structures. In particular, there is apprehension as to the adequacy of bridges that were erected prior to the early 1970's. Before this time there was little or no design process which considered seismic behaviour of bridges. Recent codes have been adjusted to compensate for these earlier problems. However, it is not feasible to remove and rebuild all of the previously built bridges. Hence, the only remaining viable approach to improving seismic adequacy of existing bridges is seismic upgrading or retrofitting these structures to improve their strength and/or deformability. The research program presented in this thesis addresses the problem of reinforced concrete bridge column retrofitting. More specifically, the applicability of a new retrofitting technique, developed at the University of Ottawa for columns of different aspect ratios and reinforcement arrangements, will be verified in terms of concrete confinement and shear resistance. The retrofitting technique consists of wrapping and prestressing high strength steel 7-wire strands around the test columns in order to increase their ductility. The specimen's tested were based on pre-1971 design, and hence had larger transverse reinforcement spacing than the present practice. This results in a lack of concrete confinement which translates into columns with poor shear resistance which tend to have a brittle failure mode. By retrofitting with prestressing strands, placed at closer spacing than the original hoops, the concrete confinement is increased, diagonal tension resistance is improved and a more ductile response is attained. Experiments from the first phase of this research program, performed by Yalcin (1997), gave very favourable results for a given aspect ratio and reinforcement arrangement. The present experimental research, forming the second phase, examined columns with different aspect ratios and reinforcement arrangements and also gave favourable results.
Book Synopsis Seismic Assessment and Rehabilitation of Existing Buildings by : S. Tanvir Wasti
Download or read book Seismic Assessment and Rehabilitation of Existing Buildings written by S. Tanvir Wasti and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present volume contains a total of 23 papers centred on the research area of Seismic Assessment and Rehabilitation of Existing Buildings. This subject also forms the core of Project SfP977231, sponsored by the NATO Science for Peace Office and supported by the Scientific and Technical Research Council of Turkey [ TUBIT AK ]. Most of these papers were presented by the authors at a NATO Science for Peace Workshop held in Izmir on 13 - 14 May, 2003 and reflect a part of their latest work conducted within the general confines of the title of the NATO Project. Middle East Technical University, Ankara, Turkey serves as the hub of Project SfP977231 and coordinates research under the project with universities within Turkey, e. g. Istanbul Technical University and Kocaeli University, and with partner institutions in Greece and the Former Yugoslav Republic of Macedonia: A few articles have also been contributed by invited experts, who are all noted researchers in the field. Altogether, the contents of the volume deal with a vast array of problems in Seismic Assessment and Rehabilitation and cover a wide range of possible solutions, techniques and proposals. It is intended to touch upon many of these aspects separately below. Earthquakes constitute possibly the most widely spread and also the most feared of natural hazards. Recent earthquakes within the first six months of 2003, such as the Bingol Earthquake in Turkey and the Algerian earthquake, have caused both loss of life and severe damage to property.
Book Synopsis Seismic Evaluation and Retrofit of Existing Reinforced Concrete Bridge Columns by :
Download or read book Seismic Evaluation and Retrofit of Existing Reinforced Concrete Bridge Columns written by and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Seismic Shear Strength of Reinforced Concrete Columns by : M. J. N. Priestley
Download or read book Seismic Shear Strength of Reinforced Concrete Columns written by M. J. N. Priestley and published by . This book was released on 1993 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Comparative Analysis of Seismic Retrofit Techniques for Reinforced Concrete Bridge Columns by : Jacques Sarrazin
Download or read book A Comparative Analysis of Seismic Retrofit Techniques for Reinforced Concrete Bridge Columns written by Jacques Sarrazin and published by . This book was released on 2004 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Seismic Evaluation of Hollow Core Prestressed Concrete Bridge Column-piles in Washington State by : Tasha Tardieu
Download or read book Seismic Evaluation of Hollow Core Prestressed Concrete Bridge Column-piles in Washington State written by Tasha Tardieu and published by . This book was released on 2019 with total page 225 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Washington State Department of Transportation (WSDOT) began a bridge seismic retrofit program in 1990 in order to address the earthquake risks associated with state-owned bridges. The majority of these bridges were constructed prior to the development of current seismic design standards, and one class of bridges built during that era represents a particular cause for concern. In that class of bridges, hollow precast, prestressed concrete piles were installed in the ground, and they projected above ground level to form the columns. Cap beams were then cast in place, and connected to the column-piles by means of concrete plugs cast into the tops of the columns. Previous, but limited, research experiments have shown that these hollow, prestressed concrete columns and piles show minimal ductility under cyclic lateral loading and fail suddenly, because the wall of the column spalls both inwards and outwards. Jacketing is effective only in preventing the outward spalling. Because many of these hollow-column bridges form part of the state's "Seismic Lifeline Routes", they are slated for retrofit in the near future. This research project was conducted to determine the behavior of both as-built and retrofitted hollow, precast, prestressed concrete column-pile bridges under static and seismic loadings. The findings of the research are intended to inform WSDOT's plans for the retrofit scheme to be used in the field. Under elastic conditions, the peak moment demand occurs at the top of the columns, adjacent to the cap beam; the moments below grade are approximately half as large. Therefore, the proposed retrofit concept for these column-piles involves cutting back the top of the hollow column-pile wall directly below the cap beam to reduce the column moment demand at the top. The exposed plug, and the column corresponding to the plug region, should be jacketed to create a ductile fuse in that location. A simple analytical study of the column-piles considered their behavior under lateral loading and explored the effects of various parameters such as the length of the column, the length of the below-ground pile, the soil stiffness, the presence of a continuous deck and the consequences of inelastic deformation of the plug. The results showed that the potential retrofit would improve the seismic performance of the column-pile system so that it could in most cases withstand the 1000-year design earthquake. Two experimental programs were conducted in order to validate the feasibility of the retrofit concept. The first experimental program was a parametric study to investigate the shear friction strength at the interface between the pile wall and the plug, since the gravity load from the superstructure would have to be transferred to the pile by this mechanism if the pile wall was removed below the cap beam, as suggested in the retrofit method. The second experimental program was a scaled cantilever column bending test of the as-built column-to-cap beam connection, in which the column was subjected to reversed cyclic displacement. The results of the second experimental program showed that the existing column-piles perform better than previous research programs suggest. However, since the existing field conditions differ among the bridges, further study is needed to qualify which conditions lead to the greatest vulnerability, and hence guide the prioritization of bridges in the retrofit program. Further analytical work is needed, using more sophisticated modeling techniques and the geometry and soil properties of particular bridges, to determine more precisely the piles' vulnerability under different earthquake intensities. Further experiments are also needed to verify the choice and effectiveness of the retrofit details.
Author :fib Fédération internationale du béton Publisher :fib Fédération internationale du béton ISBN 13 :9782883940758 Total Pages :234 pages Book Rating :4.9/5 (47 download)
Book Synopsis Retrofitting of Concrete Structures by Externally Bonded FRPs, With Emphasis on Seismic Applications by : fib Fédération internationale du béton
Download or read book Retrofitting of Concrete Structures by Externally Bonded FRPs, With Emphasis on Seismic Applications written by fib Fédération internationale du béton and published by fib Fédération internationale du béton. This book was released on 2006-01-01 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: fib Bulletin 35 is the first bulletin to publish documentation from an fib short course. These courses are held worldwide and cover advanced knowledge of structural concrete in general, or specific topics. They are organized by fib and given by internationally recognized experts in fib, often supplemented with local experts active in fib. They are based on the knowledge and expertise from fib's ten Commissions and nearly fifty Task Groups. fib Bulletin 35 presents the course materials developed for the short course "Retrofitting of Concrete Structures through Externally Bonded FRP, with emphasis on Seismic Applications", given in Ankara and Istanbul in June 2005. The course drew on expertise both from outside Turkey and from the large pool of local experts on this subject. In most countries of the world, the building stock is ageing and needs continuous maintenance or repair. Moreover, the majority of existing constructions are deficient in the light of current knowledge and design codes. The problem of structural deficiency of existing constructions is especially acute in seismic regions, as, even there, seismic design of structures is relatively recent. The direct and indirect costs of demolition and reconstruction of structurally deficient constructions are often prohibitive; furthermore they entail a substantial waste of natural resources and energy. Therefore, structural retrofitting is becoming increasingly widespread throughout the world. Externally bonded Fibre Reinforced Polymers (FRPs) are rapidly becoming the technique of choice for structural retrofitting. They are cleaner and easier to apply than conventional retrofitting techniques, reduce disruption to the occupancy and operation of the facility, do not generate debris or waste, and reduce health and accident hazards at the construction site as well as noise and air pollution in the surroundings. fib Bulletin 35 gives state-of-the-art coverage of retrofitting through FRPs and presents relevant provisions from three recent standardisation milestones: EN 1998-3:2005 "Eurocode 8: Design of structures for earthquake resistance - Part 3: Assessment and retrofitting of buildings", the 2005 Draft of the Turkish seismic design code, and the Italian regulatory document CNR-DT 200/04, "Instructions for Design, Execution and Control of Strengthening Interventions by Means of Fibre-Reinforced Composites" (2004).
Book Synopsis Use of Carbon Fiber Reinforced Polymer Sheets as Transverse Reinforcement in Bridge Columns by : Gamal Elnabelsya
Download or read book Use of Carbon Fiber Reinforced Polymer Sheets as Transverse Reinforcement in Bridge Columns written by Gamal Elnabelsya and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Performance of bridges during previous earthquakes has demonstrated that many structural failures could be attributed to seismic deficiencies in bridge columns. Lack of transverse reinforcement and inadequate splicing of longitudinal reinforcement in potential plastic hinge regions of columns constitute primary reasons for their poor performance. A number of column retrofit techniques have been developed and tested in the past. These techniques include steel jacketing, reinforced concrete jacketing and use of transverse prestressing (RetroBelt) for concrete confinement, shear strengthening and splice clamping. A new retrofit technique, involving fibre reinforced polymer (FRP) jacketing has emerged as a convenient and structurally sound alternative with improved durability. The new technique, although received acceptance in the construction industry, needs to be fully developed as a viable seismic retrofit methodology, supported by reliable design and construction procedures. The successful application of externally applied FRP jackets to existing columns, coupled with deteriorating bridge infrastructure, raised the possibility of using FRP reinforcement for new construction. Stay-in-place formwork, in the form of FRP tubes are being researched for its feasibility. The FRP stay-in-place tubes offer ease in construction, convenient formwork, and when left in place, the protection of concrete against environmental effects, including the protection of steel reinforcement against corrosion, while also serving as column transverse reinforcement. Combined experimental and analytical research was conducted in the current project to i) improve the performance of FRP column jacketing for existing bridge columns, and ii) to develop FRP stay-in-place formwork for new bridge columns. The experimental phase consisted of design, construction and testing of 7 full-scale reinforced concrete bridge columns under simulated seismic loading. The columns represented both existing seismically deficient bridge columns, and new columns in stay-in-place formwork. The existing columns were deficient in either shear, or flexure, where the flexural deficiencies stemmed from lack of concrete confinement and/or use of inadequately spliced longitudinal reinforcement. The test parameters included cross-sectional shape (circular or square), reinforcement splicing, column shear span for flexure and shear-dominant behaviour, FRP jacket thickness, as well as use of FRP tubes as stay-in-place formwork, with or without internally embedded FRP crossties. The columns were subjected to a constant axial compression and incrementally increasing inelastic deformation reversals. The results, presented and discussed in this thesis, indicate that the FRP retrofit methodology provides significant confinement to circular and square columns, improving column ductility substantially. The FRP jack also improved diagonal tension capacity of columns, changing brittle shear-dominant column behavior to ductile flexure dominant response. The jackets, when the transverse strains are controlled, are able to improve performance of inadequately spliced circular columns, while remain somewhat ineffective in improving the performance of spliced square columns. FRP stay-in-place formwork provides excellent ductility to circular and square columns in new concrete columns, offering tremendous potential for use in practice. The analytical phase of the project demonstrates that the current analytical techniques for column analysis can be used for columns with external FRP reinforcement, provided that appropriate material models are used for confined concrete, FRP composites and reinforcement steel. Plastic analysis for flexure, starting with sectional moment-curvature analysis and continuing into member analysis incorporating the formation of plastic hinging, provide excellent predictions of inelastic force-deformation envelopes of recorded hysteretic behaviour. A displacement based design procedure adapted to FRP jacketed columns, as well as columns in FRP stay-in-place formwork provide a reliable design procedure for both retrofitting existing columns and designing new FRP reinforced concrete columns.
Book Synopsis Seismic Column Reinforcement Study by :
Download or read book Seismic Column Reinforcement Study written by and published by . This book was released on 2001 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume I, Chapters 1-6; Volume II, Chapters 7-12.
Book Synopsis Seismic Retrofitting of Concrete Bridge Columns by External Prestressing by :
Download or read book Seismic Retrofitting of Concrete Bridge Columns by External Prestressing written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Seismic Assessment and Retrofit of Existing Multi-column Bent Bridges by : Cole C. McDaniel
Download or read book Seismic Assessment and Retrofit of Existing Multi-column Bent Bridges written by Cole C. McDaniel and published by . This book was released on 2006 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main objective of this research was to assess the seismic vulnerability of typical pre-1975 WSDOT prestressed concrete multi-column bent bridges. Additional objectives included determining the influence of soil-structure-interaction on the bridge assessment and evaluating the effects of non-traditional retrofit schemes on the global response of the bridges. Overall this research highlighted the vulnerability of non-monolithic bridge decks and shear-dominating bridge columns in pre-1975 WSDOT prestressed concrete multi-column bent bridges as well as the importance of including soil-structure-interaction, calibrating the force/displacement characterization of the columns to experimental test data and detailed modeling of the bridges such as expansion joint/girder interaction. In the end, the seismic assessment of bridges is a cost/efficiency issue. Each bridge is different, therefore, investing in improved analyses up front will enable an efficient use of the limited funds for bridge improvement, resulting in a significant savings overall.
