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Author : Adam S. Christopulos
Publisher :
ISBN 13 :
Total Pages : 612 pages
Book Rating : 4.:/5 (622 download)
Download or read book Improved Seismic Performance of Buckling Restrained Braced Frames written by Adam S. Christopulos and published by . This book was released on 2005 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Fokruddin Ahmad
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.3/5 (799 download)
Download or read book Performance Evaluation of Steel Buckling Restrained Braced Frames Subjected to Far-Field, Near-Field, and Long-Duration Earthquakes written by Fokruddin Ahmad and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of Buckling Restrained Brace Frames (BRBFs) has been increasing in recent decades due to their ability to provide superior seismic performance and enhance the resilience of buildings against earthquakes. However, not many studies have extensively and thoroughly investigated the response and resiliency of prescriptively designed BRBF buildings to varying types of earthquake hazards. This study fills that research gap by investigating the seismic performance of two code-designed BRBFs prototype buildings subjected to far-field, near field with pulse and without pulse, and long-duration ground motion sets. The first phase of the study investigated the seismic resiliency of the prescriptively designed BRBF buildings and compared them to identical prototypes designed with mass timber PT-CLT rocking walls using the FEMA P-58 methodology to compare seismic losses. The seismic loss investigation was part of a larger study evaluating the two types of structural systems using multiple criteria decision analysis across four performance categories of seismic resiliency, global warming potential, superstructure cost, and durability. The global warming potential and superstructure cost estimate was completed by others, but this study completed the seismic resiliency assessment and multiple criteria decision analysis.The second phase of this dissertation work analyzed the structural response of the two BRBF prototype buildings across four sets of ground motions representing different hazard levels in Seattle, WA. The two prototype buildings were modeled in 3D using OpenSeesPy to understand the effect of different ground motion types on the structural responses. The analysis results showed that near-field motions increase the deformation demands, such as inter-story drift and maximum ductility in the pulse direction. Though BRBFs are not a self-centering systems, only the upper two floors of the mid-rise building experienced residual drift higher than 0.2%, which is the threshold for expecting minor repair and structural realignment. None of the stories had residual inter-story drift exceeding 0.5% drift for any motion sets. Overall, the code minimum based BRBF buildings showed excellent performance across all the different hazard types. However, the one caveat of this analysis was that long-duration motions had significantly higher cumulative ductility demand than other motion sets.Therefore, the final phase of this dissertation works further investigated the cumulative deformation demand on BRBF braces under long-duration motions. It is important to verify the ductility of the braces through analysis or testing because they act as the primary structural fuse to dissipate the earthquake energy. The final study compared different loading protocols from different countries to the nonlinear modeling results of long-duration motions. It was determined that the long duration motions had over 80% probability of exceeding the current AISC 341 required testing protocol. To rectify these issues, a new loading protocol appropriate for long-duration earthquakes was proposed that accounts for the increased plastic deformation demand and matches the cyclic content of the nonlinear dynamic analyses.In conclusion, these studies have demonstrated that prescriptively designed BRBFs that meet code minimum requirements are a high performing lateral force resisting system to a range of earthquake hazards. They have excellent seismic resiliency, even when not optimized during design through nonlinear time history analysis, as is common in performance-based earthquake engineering. Additionally, the code-designed BRBF buildings were not predicted to have high residual inter-story drifts, which means they are highly likely to be repairable with minor adjustments and re-alignment. However, it was identified that long-duration earthquakes will increase the ductility demand on the braces significantly compared to far-field and near-field earthquakes and that current minimum testing requirements do not account for this increase. A new protocol was proposed to rectify this one challenge with BRBFs.
Author : Subhash Chandra Goel
Publisher :
ISBN 13 : 9781580017145
Total Pages : 261 pages
Book Rating : 4.0/5 (171 download)
Download or read book Performance-based Plastic Design written by Subhash Chandra Goel and published by . This book was released on 2008-01-01 with total page 261 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Yousef Bozorgnia
Publisher : CRC Press
ISBN 13 : 0203486242
Total Pages : 958 pages
Book Rating : 4.2/5 (34 download)
Download or read book Earthquake Engineering written by Yousef Bozorgnia and published by CRC Press. This book was released on 2004-05-11 with total page 958 pages. Available in PDF, EPUB and Kindle. Book excerpt: This multi-contributor book provides comprehensive coverage of earthquake engineering problems, an overview of traditional methods, and the scientific background on recent developments. It discusses computer methods on structural analysis and provides access to the recent design methodologies and serves as a reference for both professionals and res
Author : Pierre Thibault
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (135 download)
Download or read book Development and Numerical Validation of New Hybrid Multi-core Buckling-restrained Braces for Enhanced Seismic Performance written by Pierre Thibault and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contemporary seismic-resistant design of steel structures relies on the dissipation of earthquake energy through significant inelastic deformations. Buckling-restrained braced frames (BRBFs) are a type of concentrically-braced system characterized by braces that yield both in tension and in compression. Thanks to a restraining mechanism that confines a ductile steel core, buckling-restrained braces (BRBs) can take advantage of the cyclic ductility of the steel material. However, BRBs commonly display a low post-yield stiffness, causing substantial interstory drifts and large residual drifts after seismic events. Moreover, yielding of the core is often tied to only a single performance objective, thus making its response at other levels of seismicity largely unpredictable. Hybrid BRB solutions are explored as an alternative to the traditional BRB system to overcome its limitations. The hybrid concept is hinged on harnessing different characteristics from different materials that are carefully combined into one ductile design to achieve a desirable response. This numerical study has three main objectives. Potential core metals are first evaluated to determine the best combinations of two materials with complementary engineering properties. Analysis of experimental data indicates that the post-yield behavior of hybrid BRBs is improved by employing 350WT carbon steel in conjunction with another metal, which possesses a low-yield and high-strain-hardening capacity (e.g., 304L stainless steel, 5083-O aluminum alloy, A36 carbon steel, or LYP-100 low-yield-point steel). Afterwards, two new hybrid BRB systems are designed to accommodate the complex deformation pattern of three core plates connected in parallel. The first proposed option has a restraining mechanism made from concrete-filled steel tubes, while the second hybrid BRB option is fabricated exclusively from metal plate components. Lastly, multiple finite element simulations are carried out on numerical models to quantitatively validate the performance enhancement. Compared to conventional BRBs, hybrid BRBs exhibit an improved strain hardening response, a slight increase in axial stiffness, and a greater energy dissipation capability for an equivalent brace strength.
Author : Stephen A. Mahin
Publisher :
ISBN 13 :
Total Pages : 14 pages
Book Rating : 4.:/5 (123 download)
Download or read book Seismic Performance of Buckling Restrained Braced Frame Systems written by Stephen A. Mahin and published by . This book was released on 2004 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Terri Meyer Boake
Publisher : Walter de Gruyter
ISBN 13 : 3038214825
Total Pages : 184 pages
Book Rating : 4.0/5 (382 download)
Download or read book Diagrid Structures written by Terri Meyer Boake and published by Walter de Gruyter. This book was released on 2014-01-23 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: Diagrids are load-bearing structures made of steel diagonal grids. They were first used in the great buildings of the turn of the millennium, such as the Swiss Re Tower in London (“The Gherkin”) and the Hearst Magazine Tower in New York City. Dagrids owe their ensuing popularity not only to their stunning aesthetic value, but also to their very tangible benefits: lateral loading capacity, a massive saving of material, a significant gain in open, usable floor area, and increased flexibility. At its opening in 2014, the Leadenhall Building in London will be the first skyscraper without a bearing inner core—thanks to a diagrid structure. This book explains comprehensively for the first time all of the aspects involved in this new bearing structure. The author, experienced in teaching, research, and practice (recent publication: Understanding Steel Design. An Architectural Design Manual, 2011), has tracked the development of this technology from its beginnings and employs photographic documentation of the construction phases of many diagrid structures.
Author : Shawn M. Johnson
Publisher :
ISBN 13 :
Total Pages : 632 pages
Book Rating : 4.:/5 (627 download)
Download or read book Improved Seismic Performance of Special Concentrically Braced Frames written by Shawn M. Johnson and published by . This book was released on 2005 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Jacob A. Powell
Publisher :
ISBN 13 :
Total Pages : 386 pages
Book Rating : 4.:/5 (71 download)
Download or read book Evaluation of Special Concentrically Braced Frames for Improved Seismic Performance and Constructability written by Jacob A. Powell and published by . This book was released on 2010 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Chui-Hsin Chen
Publisher :
ISBN 13 :
Total Pages : 342 pages
Book Rating : 4.:/5 (839 download)
Download or read book Performance-Based Seismic Demand Assessment of Concentrically Braced Steel Frame Buildings written by Chui-Hsin Chen and published by . This book was released on 2010 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: The special concentrically steel braced frame (SCBF) system is one of the most effective struc-tural systems to resist lateral forces. Because of its effectiveness and straightforward design, many SCBFs are incorporated in structures throughout the world. However, the highly nonlin-ear behavior associated with buckling and non-ductile fracture of braces reduces the ability of the system to dissipate energy resulting in undesirable modes of behavior. While many studies have investigated the cyclic behavior of individual braces or the behavior of subassemblies, the dynamic demands on the structural system under various seismic hazard levels needs additional study for performance-based earthquake engineering. Archetype buildings of SCBFs and buckling restrained braced frames (BRBFs) were analyzed using the computer program OpenSees (the Open System for Earthquake Engineering Simulation) to improve the understanding of the seismic behavior of braced frame systems, and to assess seismic demands for performance-based design. Numerical models were calibrated using test data determined from testing of conventional buckling braces, buckling restrained braces, and the braced frame specimens. In addition, fiber-based OpenSees models were constructed and compared with results of a sophisticated finite-element model that realistically captured local buckling and local fracture of structural elements. Because the OpenSees models are reasona-bly accurate and efficient, they were chosen to perform set of parametric computer simulations. The seismic demands of the system and structural elements were computed and interpreted for 3-, 6-, and 16-story SCBFs and BRBFs under various hazard levels. The analysis results show large seismic demands for the 3-story SCBF, which may result in unexpected damage of struc-tural and non-structural elements. The median expected probability of a brace buckling at one or more levels in a 3-story SCBF is more than 50% for an earthquake having a 50% probability of exceedance in 50 years (the service-level event). The possible need to replace braces fol-lowing such frequent events due to brace buckling should be considered in performance-based earthquake engineering assessments. In addition, brace fracture in SCBFs is likely for an earthquake having a 2% probability of exceedance in 50 years (the MCE-level event). Analy-ses show that in general, BRBF models had larger drift demands and residual drifts compared to SCBF systems, because of the BRBF's longer fundamental period. However, the tendency to form a weak story in BRBFs is less than that in SCBFs. Evaluation of seismic demand parameters were performed for 2-, 3-, 6-, 12-, and 16-story SCBFs and BRBFs, which demonstrated that short-period braced frame systems, especially SCBFs, had higher probability of collapse than longer-period braced frame systems. Substantially improved response was observed by lowering the response reduction factor of the 2-story SCBF building; this reduced the collapse risk at the hazard level of 2% probability of exceedance in 50 years. For long-period (taller) structures, although the collapse probability was lower compared to the short-period structures, weak story behavior was commonly observed in conventionally designed SCBF. A design parameter related to the ratios of story shear demand and capacity under a pushover analysis is proposed to modify member sizes to reduce weak story behavior efficiently. This is demonstrated for a 16-story SCBF building. Regarding local deformation and force demands, simple methods to estimate out-of-plane buck-ling deformation of braces and column axial force demands are proposed. The investigation of system performance and member behavior provides seismic demands to more accurately assess the socio-economic losses of SCBFs and BRBFs for performance-based earthquake engineering.
Author : Barbara Gwynne Simpson
Publisher :
ISBN 13 :
Total Pages : 298 pages
Book Rating : 4.:/5 (18 download)
Download or read book Design Development for Steel Strongback Braced Frames to Mitigate Concentrations of Damage written by Barbara Gwynne Simpson and published by . This book was released on 2018 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: Steel braced frames are characteristically efficient seismic force-resisting systems. However, multi-story steel braced frames tend to concentrate demands in one or a few stories in response to severe ground shaking. Brace buckling and yielding results in a reduction in story strength and/or stiffness. Unless a mechanism exists to re-distribute the inelastic demands to other stories, demands tend to concentrate in the story where the inelastic response was initiated, indicative of story mechanism behavior. Research has identified the advantages of using pivoting seismic force-resisting systems, herein termed strongback-braced frames, to mitigate story mechanism behavior. Strongback-braced frames employ an essentially elastic truss, or “strongback”, that provides an explicit mechanism of re-distributing demands to adjacent stories. Yielding and energy dissipation is provided through inelastic actions, or fuses (e.g., through brace yielding/buckling and/or beam plastic hinging). Forces and moments developed in these fuses are transferred vertically to adjacent stories by the flexural stiffness and strength of the strongback. As such, strongback-braced frames are expected to result in more uniform drift distributions, reduced peak inelastic demands, and improved design flexibility compared to conventional seismic force-resisting systems. Despite being employed successfully in both research and practice, systematic assessment of the strongback’s behavior and practical design methods have not been developed or validated. Since the behavior of strongback systems is not characterized by the formation of story mechanisms, prior studies have found it difficult to proportion the elastic members in the strongback truss and have recognized detailing issues related to large deformation demands induced in the fuses. As such, a series of investigations were aimed at understanding the dynamic behavior and seismic performance of steel strongback-braced frames. Archetype designs were numerically analyzed to characterize the seismic demands in the strongback elements. A four-story strongback-braced frame was used to benchmark the dynamic behavior observed during nonlinear dynamic analysis. Improved numerical models were calibrated to more realistically simulate the buckling-restrained brace response and to characterize the modeling parameters influencing brace buckling and low-cycle fatigue. The FEMA P695 methodology was used to assess potential design methods based on collapse performance. Extensive parametric studies were carried out on strongback geometries with a range of bracing configurations, ground motion characteristics, and design alternatives. Higher mode effects were identified as the cause of substantial force amplification in the elastic strongback truss. Unlike typical yielding systems where force demands are limited by the capacity of the fuses in every mode, force demands in the strongback are characterized by a yielding first-mode “pivoting” and elastic higher-mode “bending” force demands. Since the strongback is designed to remain elastic in all modes, it can exhibit significant strength and stiffness in higher mode bending. Under the second and higher modes, the strongback truss remains elastic and continues to accumulate force demands after the fuses have yielded and as the ground shaking intensifies. These force demands in the strongback members can be significantly larger than those estimated per traditional capacity design assuming first mode-only demands. The addition of a strongback results in improved dynamic response from typical yielding systems, including a more uniform drift profile compared to reference buckling-restrained braced frames. Based on this research, this study proposes recommendations for the design, analysis, and modeling of strongback-braced frames. Simplified static methods to estimate the dynamic demands in the strongback truss are also proposed, including modal pushover and modal enveloping analysis methods.
Author : Raghu V. Prakash
Publisher :
ISBN 13 : 9789811387685
Total Pages : 826 pages
Book Rating : 4.3/5 (876 download)
Download or read book Structural Integrity Assessment written by Raghu V. Prakash and published by . This book was released on 2020 with total page 826 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains selected papers from the Second Quadrennial International Conference on Structural Integrity (ICONS-2018). The papers cover important topics related to structural integrity of critical installations, such as power plants, aircrafts, spacecrafts, defense and civilian components. The focus is on assuring safety of operations with high levels of reliability and structural integrity. This volume will be of interest to plant operators working with safety critical equipment, engineering solution providers, software professionals working on engineering analysis, as well as academics working in the area. .
Author : Jian Cui
Publisher :
ISBN 13 :
Total Pages : 241 pages
Book Rating : 4.:/5 (127 download)
Download or read book Seismic Performance of Buckling Restrained Braced Frames with and Without Manufacturing Defects Subjected to Combined In-plane and Out-of-plane Loading written by Jian Cui and published by . This book was released on 2021 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 452 pages
Book Rating : 4.X/5 (6 download)
Download or read book NEHRP Guidelines for the Seismic Rehabilitation of Buildings written by and published by . This book was released on 1997 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Peter C. Talley
Publisher :
ISBN 13 :
Total Pages : 115 pages
Book Rating : 4.:/5 (112 download)
Download or read book Capacity Design Methods for Strongback Braced Frames written by Peter C. Talley and published by . This book was released on 2018 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: When subjected to strong earthquake ground motions, conventional steel braced frames are vulnerable to soft-story mechanisms, whereby the weakest story accumulates more damage relative to the rest of the structure. This reduces the overall strength of the structure, increases the cost of repairs, and can cause issues during the design process due to the reduced redundancy of the system. One method for mitigating this behavior is the use of an elastic spine frame. These frames combine a stiff vertical "spine", such as a truss or shear wall, with a more ductile, energy-dissipating system. The spine typically spans the height of the structure and is designed to remain elastic, distributing earthquake demands across the height of the structure and bridging weak stories. One proposed elastic spine frame is the "strongback" braced frame, which merges a steel buckling-restrained braced frame and an elastic truss, using the buckling-restrained braces for energy dissipation and the truss for force distribution. However, strongback braced frames do not have well-established design criteria. Specifically, there is no generally accepted method for ensuring that the strongback remains elastic, and seismic performance factors have not been developed. Additionally, conventional capacity design underestimates the demands on the spine. It is desirous to have a method for design of these frames that hews closely to existing methods utilizing the equivalent lateral force method. This thesis presents the first phase of a study to address these gaps in the design provisions and to better understand the behavior of this system. A suite of building frames which employ the strongback system were designed with the intent of using them as the basis for parametric analytical studies in the second phase. The suite of frames was selected using the requirements of FEMA P695, the state-of-the-art method for determining seismic performance factors. Three alternative capacity design methods were developed and compared to basic capacity design to identify which is best suited to efficiently achieve the performance objectives. The methods were evaluated for efficiency in the design process, and for feasibility of the resulting designs. However, evaluation of performance objectives is the goal of future study.
Author : Victoria R. Wigle
Publisher :
ISBN 13 :
Total Pages : 202 pages
Book Rating : 4.:/5 (318 download)
Download or read book Seismic Behavior and Performance of Buckling-restrained Braced Frame Connections written by Victoria R. Wigle and published by . This book was released on 2008 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Douglas R. Rammer
Publisher :
ISBN 13 :
Total Pages : 2 pages
Book Rating : 4.:/5 (13 download)
Download or read book Development of Heavy Timber Buckling-restrained Braced Frames written by Douglas R. Rammer and published by . This book was released on 2016 with total page 2 pages. Available in PDF, EPUB and Kindle. Book excerpt: Buckling-restrained braced frames (BRBFs) are one of the newer types of seismic-force-resisting systems used in modern building designs. In BRBFs, the primary source of ductility is the axial yielding of the buckling-restrained brace (BRB) cores, and BRBFs have improved ductility in comparison to ordinary or special braced frames. BRBs are incorporated into frame structures to dissipate energy or prevent damage to the surrounding structures. Frame systems employing this type of BRBs have demonstrated improved ductility and are currently an approved seismic-force-resisting system in the ASCE 7-10 code document (ASCE 2010).
