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Seismic Performance Of Column To Drilled Shaft Connections In Reinforced Concrete Bridges
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Book Synopsis Seismic Performance of Column-to-drilled-shaft Connections in Reinforced Concrete Bridges by : Michelle Teng Chang
Download or read book Seismic Performance of Column-to-drilled-shaft Connections in Reinforced Concrete Bridges written by Michelle Teng Chang and published by . This book was released on 2021 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Drilled shaft foundations are often used to support reinforced concrete bridge columns founded in soft soils or in locations where a small footprint is desired. Increasingly, the shaft is being built with a diameter larger than that of the column, to allow tolerance in the column placement and to facilitate plastic hinge formation in the column rather than in the shaft. The column-shaft connection, which involves a noncontact splice between the column and shaft bars, is a key component in this structural system. However, there is limited research on the behavior of these connections under seismic loads. In order to understand the force-transfer mechanism of column-shaft connections under seismic loading, one quasi-static cyclic experimental test was conducted on a column-shaft subassembly. Measured results were compared with those from three previous experiments performed at the University of Washington. The study found that the amount of shaft transverse reinforcement in the connection region was critical in determining the failure mode of the connection. In specimens with relatively low amounts of transverse reinforcement, including the specimen tested during this study and a previous specimen tested at the University of Washington, the connection failed through a shaft prying failure mode; the specimens developed large vertical cracks between the confined column core and the annular shaft transition region, and the shaft transverse reinforcement eventually fractured at large drift ratios. Therefore, three methodologies for detailing the shaft transverse reinforcement were evaluated, and a new analysis procedure using a strut-and-tie model was proposed. It is consistent with the measured and observed performance of the tested connections, and is applicable to shafts supporting either precast or cast-in-place columns. The new procedure allows engineers to more accurately predict the behavior of a column-shaft connection and prevent an undesirable below-ground failure in the shaft transition region. Lastly, a set of design equations based on the strut-and-tie findings and existing design models is proposed for use in practice.
Book Synopsis Seismic Performance of Well-confined Concrete Bridge Columns by : Dawn Ellen Lehman
Download or read book Seismic Performance of Well-confined Concrete Bridge Columns written by Dawn Ellen Lehman and published by . This book was released on 1998 with total page 678 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Bond-Slip Behavior and Development of Bridge Column Longitudinal Reinforcing Bars in Enlarged Pile Shafts by : Juan Murcia-Delso
Download or read book Bond-Slip Behavior and Development of Bridge Column Longitudinal Reinforcing Bars in Enlarged Pile Shafts written by Juan Murcia-Delso and published by . This book was released on 2013 with total page 337 pages. Available in PDF, EPUB and Kindle. Book excerpt: Enlarged (Type II) pile shaft foundations are used frequently in reinforced concrete bridges because of the convenience in construction and efficiency in post-earthquake inspection and repair. According to the specifications of the California Department of Transportation (Caltrans), the diameter of a Type II shaft should be at least 610 mm (2 ft) larger than that of the column. Hence, the column reinforcement extended into the pile shaft can be perceived as forming a non-contact splice with the pile shaft reinforcement. Because of the lack of data, the seismic design specifications of Caltrans on the embedment length of column reinforcement in Type II shafts are very conservative for large-diameter columns, which could complicate the construction work and entail high construction costs. This dissertation presents an experimental and analytical investigation to characterize the bond between concrete and reinforcing steel when a reinforced concrete member is subjected to severe cyclic loading, and determine the minimum embedment length required for column longitudinal reinforcement extended into a Type II shaft. Experiments were carried out to investigate the bond strength and cyclic bond deterioration of large-diameter bars (No. 11, 14, and 18) commonly used in large-diameter bridge columns and piles. The experimental results have been used to develop, calibrate, and validate a phenomenological bond-slip model for bars embedded in well-confined concrete. The model successfully reproduces bond deterioration caused by cyclic bar-slip reversals and tensile yielding of the bar, and has been implemented in an interface element in a finite element program. A physics-based dilatant interface model formulated with a multi-surface plasticity concept has also been developed and implemented in the finite element program to simulate bond-slip under a broad range of confinement situations. With the phenomenological bond-slip model, nonlinear finite element analysis has been conducted to extrapolate results of development length tests conducted on large-diameter bars, and assess the reliability of the development lengths required in the AASHTO LRFD Bridge Design Specifications. Finally, two large-scale tests on column-pile shaft assemblies were conducted. The tests were combined with finite element analysis to evaluate the conservatism of the current Caltrans specifications, and provide new design recommendations that can significantly reduce the embedment length required for column reinforcement, while ensuring an appropriate performance of the column-pile shaft connections under severe seismic loads.
Book Synopsis Seismic Performance and Failure Mechanisms of Reinforced Concrete Wide Beam-column Connections by : Hamdolah Behnam
Download or read book Seismic Performance and Failure Mechanisms of Reinforced Concrete Wide Beam-column Connections written by Hamdolah Behnam and published by . This book was released on 2017 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Seismic Performance of Substandard Reinforced Concrete Bridge Columns Under Subduction-Zone Ground Motions by :
Download or read book Seismic Performance of Substandard Reinforced Concrete Bridge Columns Under Subduction-Zone Ground Motions written by and published by . This book was released on 2019 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: A large magnitude, long duration subduction earthquake is impending in the Pacific Northwest, which lies near the Cascadia Subduction Zone (CSZ). Great subduction zone earthquakes are the largest earthquakes in the world and are the sole source zones that can produce earthquakes greater than M8.5. Additionally, the increased duration of a CSZ earthquake may result in more structural damage than expected. Given such seismic hazard, the assessment of reinforced concrete substructures has become crucial in order to prioritize the bridges that may need to be retrofitted and to maintain the highway network operable after a major seismic event. Recent long duration subduction earthquakes occurred in Maule, Chile (Mw 8.8, 2010) and Tohoku, Japan (Mw 9.0, 2011) are a reminder of the importance of studying the effect of subduction ground motions on structural performance. For this purpose, the seismic performance of substandard circular reinforced concrete bridge columns was experimentally evaluated using shake table tests by comparing the column response from crustal and subduction ground motions. Three continuous reinforced columns and three lap-spliced columns were tested using records from 1989 Loma Prieta, 2010 Maule and 2011 Tohoku. The results of the large-scale experiments and numerical studies demonstrated that the increased duration of subduction ground motions affects the displacement capacity and can influence the failure mode of bridge columns. Furthermore, more damage was recorded under the subduction ground motions as compared to similar maximum deformations under the crustal ground motion. Therefore, it is recommended to consider the effects of subduction zone earthquakes in the performance assessment of substandard bridges, or when choosing ground motions for nonlinear time-history analysis, especially in regions prone to subduction zone mega earthquakes.
Book Synopsis Seismic Performance of Circular Reinforced Concrete Columns Under Varying Axial Load by : Gianmario Benzoni
Download or read book Seismic Performance of Circular Reinforced Concrete Columns Under Varying Axial Load written by Gianmario Benzoni and published by . This book was released on 1996 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: The behavior of four circular reinforced concrete bridge columns, with different axial load regimes, is investigated. The first unit was tested under constant compressive axial load corresponding to an axial load ratio of 0.35. The second specimen was subjected to a constant tensile axial force equivalent to 0.087 axial load ratio. Two specimens were tested under varying regime of axial load, ranging between the two previous load limits, in order to simulate realistic seismic conditions of outer columns of multi-column bents. Extended comparison between experimental and predicted shear response, from different current equations, is provided.
Book Synopsis Seismic Performance of Reinforced Concrete Bridge Columns Constructed with Grade 80 Reinforcement by : Tim B. Link
Download or read book Seismic Performance of Reinforced Concrete Bridge Columns Constructed with Grade 80 Reinforcement written by Tim B. Link and published by . This book was released on 2014 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research presented in this thesis assessed the use of high strength steel (HSS) reinforcement for use in reinforced concrete (RC) bridge columns. HSS is not currently allowed in reinforced concrete bridge columns due to a lack of information on the material characteristics and performance information when used in RC bridge columns. Potential benefits in construction, performance, and economics justify the need for research. This research investigated the performance of HSS (ASTM A706 Grade 80 reinforcement) embedded in half-scale RC bridge columns. Column design followed standard design methodologies used by federal and state highway agencies. Six columns were subjected to lateral cyclic loadings, three columns were constructed with Grade 60 reinforcement and three columns were constructed with Grade 80 reinforcement. Results indicate that the columns constructed with Grade 80 reinforcement achieved similar resistances and displacement ductility values when compared with the reference columns constructed with Grade 60 reinforcement. The columns constructed with Grade 60 reinforcement showed larger hysteretic energy dissipation and typically exhbitied larger curvature ductility values than the columns constructed with Grade 80 reinforcement. The effects of the longitudinal reinforcement ratio and moment-shear span ratio on column performance were similar between columns constructed with Grade 60 reinforcement and columns constructed with Grade 80 reinforcement. The results from this research present a promising step towards the implementation of Grade 80 reinforcement in the design and construction of RC bridge columns, within the bounds of the variables used in the testing program.
Book Synopsis Seismic Performance of Square Reinforced Concrete Columns Retrofitted with Titanium Alloy Bars by : Mackenzie M. W. Lostra
Download or read book Seismic Performance of Square Reinforced Concrete Columns Retrofitted with Titanium Alloy Bars written by Mackenzie M. W. Lostra and published by . This book was released on 2016 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt: Large numbers of reinforced concrete (RC) bridges were built in the past that are now considered seismically deficient. The structural members most likely to be considered deficient are the supporting columns. Typical deficient columns contain inadequate transverse reinforcement and poorly detailed lap splice lengths above the foundation. Insufficient lap splice lengths can lead to bond failure and an inability to develop the strength of the longitudinal reinforcement. Deterioration of the mechanical bond between the longitudinal reinforcement bars and the surrounding concrete reduces the stiffness and strength of the column-footing joint and provides limited or no ductility. In addition, widely spaced transverse reinforcement may not adequately confine the base of the column. This permits premature buckling of the longitudinal reinforcement that may occur between transverse bar locations and poor confinement of the concrete core. Complete replacement of these bridges is not practical due to limited resources thus, rehabilitation of existing deficient infrastructure is a practical approach. In this research, titanium alloy bars (TiABs) were explored as an alternative material to retrofit RC columns with poorly detailed reinforcing steel above the footing. The well-defined material properties of TiABs have the potential to provide effective and economical seismic strengthening of deficient RC columns. Compared to conventional reinforcing steel, they have relatively low stiffness, high strength, high ductility, and are fully resistant to corrosion in the operating environment. The proposed installation allows for inspection of the members and the environmental durability of the TiABs make them a viable long-term solution for column strengthening. To evaluate the potential for using TiABs to remediate seismically deficient RC columns with poor lap splice details and inadequate transverse reinforcement that were common in the U.S. prior to 1970, four full-scale columns were tested. One was a control specimen without strengthening and the other three (3) had externally mounted TiABs. The specimens were subjected to fully reversed cyclic lateral loading in the laboratory. The experimental results showed improved ductility and stable cyclic response with minor flexural strength degradation in the specimens retrofitted with TiABs and the failure modes of the columns were altered from non-ductile lap splice failure in the conventionally reinforced column to ductile flexural failure in the retrofitted columns. They demonstrated that TiABs offer a new option for effectively strengthening seismically deficient square bridge columns.
Book Synopsis Seismic Performance of Circular Reinforced Concrete Bridge Columns Under Bidirectional Earthquake Loading by : Mahmoud Mohamad Hachem
Download or read book Seismic Performance of Circular Reinforced Concrete Bridge Columns Under Bidirectional Earthquake Loading written by Mahmoud Mohamad Hachem and published by . This book was released on 2002 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Seismic Behavior of Circular Reinforced Concrete Bridge Columns Under Combined Loading Including Torsion by : Suriya Prakash Shanmugam
Download or read book Seismic Behavior of Circular Reinforced Concrete Bridge Columns Under Combined Loading Including Torsion written by Suriya Prakash Shanmugam and published by . This book was released on 2009 with total page 634 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Reinforced concrete (RC) columns of skewed and curved bridges with unequal spans and column heights can be subjected to combined loading including axial, flexure, shear, and torsion loads during earthquakes. The combination of axial loads, shear force, and flexural and torsional moments can result in complex failure modes of RC bridge columns. This study carried out experimental and analytical studies to investigate the seismic performance of circular RC columns under combined loading including torsion. The main variables considered here were (i) the ratio of torsion-to-bending moment (T/M), (ii) the ratio of bending moment-to-shear (M/V) or shear span (H/D), and (iii) the level of detailing for high and moderate seismicity (high or low spiral ratio). In particular, the effects of the spiral reinforcement ratio and shear span on strength and ductility of circular RC columns under combined loading were addressed. In addition, the effects of torsional loading on the bending moment-curvature, ductility, and energy dissipation characteristics were also considered. The analytical investigation examined the development of existing models for flexure and pure torsion. Interaction diagrams between bending, shear and torsional loads were established from a semi-empirical approach. A damage-based design approach for circular RC columns under combined loads was proposed by decoupling damage index models for flexure and torsion. Experimental and analytical results showed that the progression of damage was amplified by an increase in torsional moment. An increase in the transverse spiral reinforcement ratio delayed the progression of damage and changed the torsional-dominated behavior to flexural-dominated behavior under combined flexural and torsional moments"--Abstract, leaf iii.
Book Synopsis Seismic Performance of Circular Reinforced Concrete Bridge Columns Constructed with Grade 80 Reinforcement by : David Trejo
Download or read book Seismic Performance of Circular Reinforced Concrete Bridge Columns Constructed with Grade 80 Reinforcement written by David Trejo and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This project assessed the use of ASTM A706 Grade 80 reinforcing bars in reinforced concrete columns. Grade 80 is not currently allowed in reinforced concrete columns due to lack of information on the material characteristics and column performance. Six half-scale, circular columns were tested: three constructed with Grade 60 reinforcement and three constructed with Grade 80 reinforcement. Designs followed standard design methodologies used by State Highway Agencies (including AASHTO). Results indicate that columns constructed with Grade 80 reinforcement performed similar to columns constructed with conventional ASTM A706 Grade 60 reinforcement. Computational modeling was performed using OpenSees for all six columns. Results indicate that the columns constructed with Grade 80 reinforcement achieved similar resistance and displacement and curvature ductility values when compared with the reference columns constructed with Grade 60 reinforcement. The columns constructed with Grade 60 reinforcement showed larger hysteretic energy dissipation than the columns constructed with Grade 80 reinforcement.
Book Synopsis Seismic Performance of Damage Resistant Prestressed Precast Concrete Beam-column Connections by : H. A. Spieth
Download or read book Seismic Performance of Damage Resistant Prestressed Precast Concrete Beam-column Connections written by H. A. Spieth and published by . This book was released on 2004 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Seismic Response of Precast Bridge Columns with Energy Dissipating Joints by : Sarira Motaref
Download or read book Seismic Response of Precast Bridge Columns with Energy Dissipating Joints written by Sarira Motaref and published by . This book was released on 2011 with total page 707 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Seismic Evaluation of Bridge Columns with Energy Dissipating Mechanisms by : Mehdi Saiidi
Download or read book Seismic Evaluation of Bridge Columns with Energy Dissipating Mechanisms written by Mehdi Saiidi and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: TRB's National Cooperative Highway Research Program (NCHRP) Research Report 864: Seismic Evaluation of Bridge Columns with Energy Dissipating Mechanisms, Volume 1: Research Overview and Volume 2: Guidelines describes the evaluation of new materials and techniques for design and construction of novel bridge columns meant to improve seismic performance. These techniques include shape memory alloy (SMA), engineered cementitious composite (ECC), fiber-reinforced polymer (FRP), and rocking mechanisms. The guidelines contained in Volume 2 explore a quantitative evaluation method to rate novel columns as well as design and construction methods for SMA-reinforced ECC columns, SMA-reinforced FRP-confined concrete/columns, and FRP-confined hybrid rocking columns. The project explores the behavior of the selected columns and develops proposed design guidelines according to the AASHTO LRFD Bridge Design Specifications and the AASHTO Guide Specifications for LRFD Seismic Bridge Design. Appendices A-I are available online.
Book Synopsis Seismic Evaluation of Bridge Columns with Energy Dissipating Mechanisms by : Mehdi Saiidi
Download or read book Seismic Evaluation of Bridge Columns with Energy Dissipating Mechanisms written by Mehdi Saiidi and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: TRB's National Cooperative Highway Research Program (NCHRP) Research Report 864: Seismic Evaluation of Bridge Columns with Energy Dissipating Mechanisms, Volume 1: Research Overview and Volume 2: Guidelines describes the evaluation of new materials and techniques for design and construction of novel bridge columns meant to improve seismic performance. These techniques include shape memory alloy (SMA), engineered cementitious composite (ECC), fiber-reinforced polymer (FRP), and rocking mechanisms. The guidelines contained in Volume 2 explore a quantitative evaluation method to rate novel columns as well as design and construction methods for SMA-reinforced ECC columns, SMA-reinforced FRP-confined concrete/columns, and FRP-confined hybrid rocking columns. The project explores the behavior of the selected columns and develops proposed design guidelines according to the AASHTO LRFD Bridge Design Specifications and the AASHTO Guide Specifications for LRFD Seismic Bridge Design. Appendices A-I are available online.
Book Synopsis Seismic Retrofit of Circular Reinforced Concrete Bridge Columns by :
Download or read book Seismic Retrofit of Circular Reinforced Concrete Bridge Columns written by and published by . This book was released on 1990 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Inadequate flexural strength and ductility or shear strength of concrete bridge columns has resulted in collapse or severe damage of a number of California bridges in recent moderate earthquakes. In general, these bridges were designed prior to the new seismic design methods which were implemented in the mid-seventies. Bridges constructed in accordance with the new design methods have performed well in recent earthquakes. However, the large number of older bridges that are in service, particularly freeway overpasses designed and constructed in the 1950s and 1970s, are now recognized to have substandard design details and to constitute a cause for major concern. This paper reports the results of a theoretical and experimental program investigating retrofit techniques for circular columns by encasing the critical regions within a steel jacket. The jacket is bonded to the column using grout. Results from six large-scale column tests show that the casing acts efficiently as confinement reinforcement, enabling a displacement ductility factor of greater than 6 to be achieved. The casing also inhibits bond failures at the laps of longitudinal reinforcement in the critical regions of the column by restraining the dilation and spalling of the cover concrete which degenerates into bond failure. Comparisons of 'as-built' and retrofitted columns are presented, and experimental strengths and ductilities are compared with analytical predictions. For the covering abstract of the Conference see IRRD Abstract no. 807839.
Book Synopsis Application of Accelerated Bridge Construction Connections in Moderate-to-High Seismic Regions by :
Download or read book Application of Accelerated Bridge Construction Connections in Moderate-to-High Seismic Regions written by and published by Transportation Research Board. This book was released on 2011 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: TRB’s National Cooperative Highway Research Program (NCHRP) Report 698: Application of Accelerated Bridge Construction Connections in Moderate-to-High Seismic Regions evaluates the performance of connection details for bridge members in accelerated bridge construction in medium-to-high seismic regions and offers suggestions for further research.
