1,721,015 research outputs found
Assessment of seismic design provisions for multi-tiered ordinary concentrically braced frames
Get PDFMulti-tiered braced frames (MT-BFs) are commonly used as lateral force resisting systems in tall single-story buildings such as performing arts and sports centers, industrial warehouses, and airplane hangars. Horizontal members (struts) are used to divide the tall single-story into several bracing panels or tiers, without intermediate floors or out-of-plane supports. Special conditions in MT-BFs during nonlinear seismic response lead to concentration of drifts in the tiers and impose additional flexural demands on the columns. These flexural demands, in combination with axial demands, can cause column instability and compromise the seismic performance of the frames.
The seismic design provisions for multi-tiered ordinary concentrically braced frames (MT-OCBFs) are assessed in this study. MT-OCBFs are intended to achieve modest levels of ductility, and a relatively simple design procedure is used for them. The current design approach, contained in the 2010 AISC Seismic Provisions, requires an axial force amplification for the columns. In contrast, the newest design approach, contained in the 2016 AISC Seismic Provisions, requires an additional axial force amplification to approximately account for imposed flexural demands on the columns. This new requirement leads to larger column sizes, which in turn can dramatically modify seismic response. A set of eighteen frames, with varying total frame height, brace configurations (X, chevron, and split-X), and tier heights, are designed as per both provisions. Their seismic performance is assessed by employing nonlinear static and time history analyses on a three-dimensional, numerical model developed using the OpenSees simulation platform.
The results show that the 2010 AISC Seismic Provisions severely underestimate column demands in MT-OCBFs, leading to significant inelastic drift concentration in one tier and column buckling. The 2016 AISC Seismic Provisions lead to larger columns, which improve redistribution of inelastic drift over the frame height and reduce story drifts, but do not necessarily reduce inelastic drift concentration. Potential for brace loss due to low-cycle fatigue fracture is apparent in both designs. These new provisions reduce the propensity for column buckling, but it is not necessarily prevented. Brace configuration also influences demands on the column. In general, the split-X configuration leads to larger in-plane flexural demands in taller frames and onset of column buckling at small story drift values. In contrast, the shortest frames in this study exhibited relatively better performance with the chevron bracing configuration.Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2017-09-29 without embargo termsThe student, Aradhana Agarwal, accepted the attached license on 2017-07-20 at 13:37.The student, Aradhana Agarwal, submitted this Thesis for approval on 2017-07-20 at 13:45.This Thesis was approved for publication on 2017-07-20 at 17:33.DSpace SAF Submission Ingestion Package generated from Vireo submission #11350 on 2017-09-29 at 11:28:46Made available in DSpace on 2017-09-29T17:56:36Z (GMT). No. of bitstreams: 2
AGARWAL-THESIS-2017.pdf: 97465491 bytes, checksum: 12ab31e68783ad5d26f52a3802c3b33d (MD5)
LICENSE.txt: 4213 bytes, checksum: dad679ad19ce43f0d1a18a92b13c7495 (MD5)
Previous issue date: 2017-07-2
Seismic stability of buckling-restrained braced frames
Get PDFBuckling Restrained Braced Frames (BRBFs) are widely used as a seismic force-resisting system due to their advantageous properties for ductility and energy dissipation. However, because of the modest overstrength and relatively low post-yielding stiffness, BRBFs subjected to seismic loading may be susceptible to concentrations of story drift and global instability triggered by P-Δ effects. Due to the use of simplistic methods that are based on elastic stability, current code design provisions do not address seismic stability rigorously and do not consider the particular inelastic response of a system. As can occur in multistory structures, even for ductile systems, BRBFs tend to develop drift concentration that is intensified by P-Δ effects and may lead to dynamic instability through the formation of story mechanisms. Furthermore, large residual drifts have been observed during numerical and experimental studies of BRBFs. Beyond code provisions, several alternatives that aid in preventing these undesirable response characteristics of BRBFs have been studied before.
This study used the FEMA P-695 Methodology to evaluate the response of current U.S. code-based BRBF designs and to study the effect on seismic stability of additional alternatives. In accordance with the Methodology, the collapse performance was evaluated through nonlinear static and dynamic analyses that were used to investigate the inelastic behavior and determine the collapse fragility of each considered prototype. Several design prototypes, with different number of stories, were developed to study code-based stability provisions, and three alternatives of improvement: strong-axis orientation for BRBF columns, gravity column continuity, and BRBFSMRF dual systems. Furthermore, two design procedures were studied for the BRBF-SMRF dual systems.
In this thesis, results from the collapse performance evaluation process are presented and discussed for the different alternatives to address seismic stability of BRBFs. Results from nonlinear static (pushover) analyses and nonlinear dynamic (response history) analyses allowed assessment of seismic behavior through critical response quantities, such as overstrength, ductility, story drift and BRB demands. Finally, results from collapse performance evaluation permitted quantifying the improvement that is achieved with each alternative and provided a means of comparison.
The well-established negative impact of P-Δ on the seismic stability of BRBFs was demonstrated and the improvement achieved by the use of current code provisions for global stability through the B2 multiplier was shown to be minimal. Since code provisions for global stability are based on elastic stability considerations, essentially the same inelastic behavior was observed whether or not code provisions related to stability were used. In contrast, the increased flexural capacity provided by the use of strong-axis orientation for BRBF columns significantly improved the seismic stability performance of the system. Similarly, the flexural strength contribution provided by continuous gravity columns resulted in considerably improved performance. These two alternatives helped preventing the formation of story mechanisms and distributing inelastic demands more evenly. Finally, BRBF-SMRF dual systems demonstrated superior seismic stability performance compared to all other alternatives. The improvement achieved by the use of these systems is related to the contribution of the SMRF that remains elastic after the BRBs have yielded and later provides restoring forces and additional energy dissipation capacity. Overall, it was observed that the most important condition for seismic stability is reliable positive stiffness at large inelastic drifts, and this is not addressed by current code provisions. The small increase in primary system strength that arises from current code provisions based on elastic stability considerations may in some cases provide a small benefit with respect to seismic stability, but these provisions do not fundamentally address inelastic seismic stability behavior.Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2017-09-29 without embargo termsThe student, Santiago Zaruma Ochoa, accepted the attached license on 2017-07-19 at 13:41.The student, Santiago Zaruma Ochoa, submitted this Thesis for approval on 2017-07-19 at 14:02.This Thesis was approved for publication on 2017-07-19 at 15:10.DSpace SAF Submission Ingestion Package generated from Vireo submission #11535 on 2017-09-29 at 11:32:16Made available in DSpace on 2017-09-29T17:57:09Z (GMT). No. of bitstreams: 2
ZARUMAOCHOA-THESIS-2017.pdf: 4265406 bytes, checksum: 1699579ef434a245b71f22c5f29f535e (MD5)
LICENSE.txt: 4218 bytes, checksum: 8d1ff3cce6059095de493ef58430d26a (MD5)
Previous issue date: 2017-07-1
Performance assessment of special concentrically-braced frames in moderate seismic regions
Get PDFSteel concentrically-braced frames (CBFs) are widely used lateral force resisting systems with high strength, stiffness, and material efficiency. Special concentrically-braced frame (SCBF) systems are a type of CBF commonly used in high seismic regions because they are designed to permit large inelastic drifts. Ductile detailing and capacity design requirements ensure braces are the main source of energy dissipation in the system. While the design of SCBFs in high seismic regions is prevalent and substantiated by previous research, SCBFs are not frequently designed when seismic demands are lower. In moderate seismic regions, it is typical to design low-ductility CBFs because of their design simplicity and economy. Low-ductility CBFs do not have the same detailing or proportioning requirements as SCBFs, which typically results in lighter system weights but has the consequence of non-ductile frame behavior during earthquake response. The lateral force resisting behavior of low-ductility CBFs relies on reserve capacity, or secondary stiffness and strength, following initial brittle limit states.
This study investigates the behavior of SCBFs designed for moderate seismic regions, which is an area unaddressed in previous evaluations of CBFs. The SCBFs designed for this study are compared to recent assessments of the frame behavior and economy of widely used low-ductility CBFs, namely the R=3 CBF and the ordinary concentrically-braced frame (OCBF). Numerical models developed in OpenSees capture the member behaviors and limit states pertinent to multistory CBFs. The suite of frame models analyzed in this work consider variations in frame type, frame height, and brace configuration. Seismic stability of SCBFs is evaluated including the influence of gravity column continuity.
A seismic performance assessment is conducted using the frame models to performing nonlinear static and nonlinear dynamic analyses. Nonlinear static analyses are conducted as a preliminary assessment of the behavior of CBFs, and they are employed to identify the sources of lateral load resistance and ductility.
Nonlinear dynamic analyses are conducted according to the incremental dynamic procedure (IDA) to perform a collapse performance assessment based on the FEMA P965 framework (FEMA, 2009). The numerical models used for the dynamic analyses have the increased capability to model the degradation of components through load reversal.
There are three primary research objectives addressed in this work: (1) to compare the system design, behavior and economy of low-ductility CBFs and SCBFs, (2) to evaluate the collapse performance of SCBFs designed for moderate seismic regions, and (3) to investigate the seismic stability of SCBFs including the influence of gravity column continuity. The results of the nonlinear static analyses highlighted that SCBFs had considerable overstrength beyond the design level as a consequence of the capacity design procedure. The characteristic ductile pushover response for SCBFs was observed and three regions of secondary stiffness were defined and used to evaluate frame behavior. The secondary stiffness term that describes the first region of negative stiffness indicated the predominant behavior for each design variation (e.g. the split-x configuration relying on continuous column contribution more to resist the destabilizing effects of P-Δ). Compared to the low-ductility CBFs, SCBFs exhibited similar levels of elastic stiffness and higher levels of post-elastic stiffness which contributed to the improved ductility capacity.
The dynamic analyses expanded upon the pushover analysis results by capturing structural degradation resulting from cyclic loading, modeling finite ductility capacity of the braces (e.g. the limit state of brace fracture), and the effects of higher modes in the response of the system. The chevron configuration consistently exhibited superior dynamic performance compared to the split-x. While this initially contrasted with the pushover results, the dynamic results were seen as a more realistic inelastic response of the systems. The chevon configurations engaged frame action to provide a combination of lateral resistance from brace inelasticity and column flexural strength, while the split-x distributed inelasticity across the braces of many levels, and did not have the member proportioning to engage frame action. The seismic performance was compared between low-ductility and SCBFs, and all SCBFs exhibited adequate performance for application in moderate seismic regions.Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2018-09-27 without embargo termsThe student, Kelley Grabner, accepted the attached license on 2018-07-17 at 16:07.The student, Kelley Grabner, submitted this Thesis for approval on 2018-07-17 at 16:17.This Thesis was approved for publication on 2018-07-17 at 16:56.DSpace SAF Submission Ingestion Package generated from Vireo submission #12908 on 2018-09-27 at 10:49:00Made available in DSpace on 2018-09-27T16:17:56Z (GMT). No. of bitstreams: 2
GRABNER-THESIS-2018.pdf: 11427442 bytes, checksum: 75de8d86e15080e51ee6db40eed28a83 (MD5)
LICENSE.txt: 4211 bytes, checksum: b7c87a34b7c48d2816854a7e21c8d1c6 (MD5)
Previous issue date: 2018-07-1
Seismic design and analysis of hybrid masonry with fuse connectors
Get PDFHybrid masonry is a new structural system that is composed of reinforced masonry panels within a steel frame; currently, the application of this system has been limited to low seismic regions where wind loads tend to control the design of the lateral force resisting elements. To establish a fundamental understanding of seismic behavior for hybrid masonry structural systems, simple analytical models are developed to predict the ultimate strength of hybrid masonry systems and to illuminate fundamental aspects of system behavior.
The inelastic behavior of hybrid masonry is of great interest when considering the structural response of buildings located in areas dominated by high seismic activity, and it is dictated by the relative capacities of its system components. Thus, two design approaches may be used depending on whether the engineer decides to concentrate yielding in the masonry panels or in the steel connector elements that attach the masonry panels to the steel frame. Typical capacity design principles may be applied to the design of a hybrid masonry system in which the critical yielding elements are detailed to provide adequate ductility while the remaining structural elements are proportioned to remain elastic throughout the duration of a seismic event.
The analytical models that are developed are also used as a basis for designing a suite of representative prototype buildings to help evaluate the feasibility of application of the hybrid masonry structural system for a range of seismic hazard. Numerical models are used to conduct a more detailed study of the inelastic behavior of the Type I system where focus is placed on modeling the inelastic response of the fuse type connectors. The results from the analytical and numerical models are used to understand the sequence of inelastic behavior and discuss implications for seismic performance and system feasibility.
A great deal of effort is then put into further developing the design procedure for this new system. As interest in hybrid masonry grows, the need for an accurate design procedure will increase, especially because no such procedure currently exists. A capacity-based design procedure will be described using simple design examples to explain the major concepts and design methodology. The completion of a full design procedure should serve as a beneficial tool which will further the development of the hybrid masonry system and the range of its application.
It is the hope of the author that the findings summarized in this report help to inspire future research as well as encourage the use of the hybrid masonry system by industry practitioners. Certainly future research efforts are required to further explore the limits of hybrid masonry application and to determine the necessary system response coefficients before this new system can be fully integrated into existing building codes and design specifications.Item withdrawn by Mark Zulauf ([email protected]) on 2013-04-24T20:46:55Z
Item was in collections:
University of Illinois Theses & Dissertations (ID: 1)
No. of bitstreams: 2
Asselin_Robert.docx: 11510863 bytes, checksum: 3c715b078a5142f9d3e68b019ec4ba22 (MD5)
Asselin_Robert.pdf: 2775519 bytes, checksum: 235532557ed24648b6269ce63c1782d8 (MD5)Made available in DSpace on 2013-05-24T21:51:06Z (GMT). No. of bitstreams: 3
Robert_Asselin.pdf: 2775519 bytes, checksum: 235532557ed24648b6269ce63c1782d8 (MD5)
Asselin_Robert.docx: 11510863 bytes, checksum: 3c715b078a5142f9d3e68b019ec4ba22 (MD5)
license.txt: 4064 bytes, checksum: 4013a0c05e0b7e267ce165d56a2780d5 (MD5
Effects of residual stresses and initial imperfections on earthquake response of steel moment frames
No full textThe 2010 AISC Specification establishes the Direct Analysis Method (DM) as the standard stability analysis and design procedure. Although the DM has important benefits over conventional stability design methods, the interface between the DM, the AISC Seismic Provisions and the seismic design requirements in ASCE-7 is not fully established. Since the DM, which was developed for design scenarios that do not contain seismic loading, includes the effects of initial geometric imperfections and inelastic behavior compounded by residual stresses, it is critical to explore the impact of these parameters on the seismic behavior of typical steel buildings before the DM is required for seismic design. To examine these issues, a series of steel special moment-resisting frame models were subjected to monotonic pushover, cyclic pushover and response history analyses. The observed behavior was used to draw comparisons between systems with and without residual stresses and initial imperfections. Cyclic strength degradation at beam-to-column connections was also considered to examine the potential interaction it may have with the other parameters. Whereas the well-known impact of strength degradation on cyclic stability was noted, residual stresses and initial imperfections did not have any appreciable effect on stability behavior for the systems considered. The analyses conducted in this study indicate no clear benefit to using the DM when designing ductile steel systems in high seismic regions and simpler design methods may be equally effective.Item withdrawn by Mark Zulauf ([email protected]) on 2011-04-24T20:30:09Z
Item was in collections:
University of Illinois Theses & Dissertations (ID: 1)
No. of bitstreams: 2
Mathur_Kapil.docx: 5681861 bytes, checksum: 2e8ad50f766747b86a6612db7122135b (MD5)
Mathur_Kapil.pdf: 2491899 bytes, checksum: 3a8307c11c3c8753135535d61490ac70 (MD5)Made available in DSpace on 2011-05-25T15:07:33Z (GMT). No. of bitstreams: 3
Mathur_Kapil.pdf: 2491899 bytes, checksum: 3a8307c11c3c8753135535d61490ac70 (MD5)
license.txt: 4062 bytes, checksum: 62bba0c3d9b40f5121c9e6dd0190c90b (MD5)
Mathur_Kapil.docx: 5681861 bytes, checksum: 2e8ad50f766747b86a6612db7122135b (MD5
Large-scale testing of a steel-concrete composite floor system under column loss scenarios
Get PDFLarge-scale floor system tests concluded a collaborative research project that studied the structural integrity of steel gravity framing systems composed of steel beams and girders with composite concrete slab on steel deck. Steel simple beam-column connection tests were conducted at the University of Washington, steel-concrete composite slab tests were conducted at Purdue University, and complete floor system tests were conducted at the University of Illinois at Urbana-Champaign. The complete floor system tests evaluate gravity systems subjected to severe demands consistent with column loss scenarios, complementing the previously completed component tests. The floor system tests were conducted at half scale on a three-bay square configuration that considers interior, exterior and corner column loss scenarios. The 3-bay by 3-bay configuration was chosen so that multiple tests could be conducted using one structure. For each test, the bays adjacent to the removed column were incrementally loaded with distributed load until the floor could not support more load. These experiments provide valuable data that can be used to validate existing numerical models, identify critical limit states, and determine system capacities under various column loss scenarios.Item withdrawn by Mark Zulauf ([email protected]) on 2014-05-01T20:07:36Z
Item was in collections:
University of Illinois Theses & Dissertations (ID: 1)
No. of bitstreams: 2
Johnson_Eric.docx: 21630463 bytes, checksum: 7dc364774357104e71ed55bfae149ec3 (MD5)
Johnson_Eric.pdf: 20059373 bytes, checksum: bc34dfe1742fb69ad651ae90e8052fe2 (MD5)Made available in DSpace on 2014-05-30T16:44:06Z (GMT). No. of bitstreams: 4
Eric_Johnson.pdf: 20059081 bytes, checksum: dd69d0d4439657ebe7fc860d19fcf2db (MD5)
0_Johnson_Eric.docx: 21634858 bytes, checksum: d0ffefe8f25f2f0697c7c6ad8cf7ed11 (MD5)
1_0_Johnson_Eric.docx: 21634858 bytes, checksum: d0ffefe8f25f2f0697c7c6ad8cf7ed11 (MD5)
license.txt: 4062 bytes, checksum: 9a319610ab51b4328a6c551d50c715ed (MD5
Behavior and performance of steel moment-framed buildings subject to dynamic column loss scenarios
No full textProgressive or disproportionate collapse occurs when localized structural damage leads to widespread collapse or failure of a structure. Although the loss of any structural component in a building has the potential to initiate progressive collapse, structural columns in steel buildings are particularly susceptible to initiating this behavior if their load-carrying capacity is compromised. Steel-framed buildings can possess the capacity to bridge over a single lost column and arrest collapse, but the dynamic and three-dimensional nature of this event prevents simple design-based analysis approaches from providing accurate assessments of collapse resistance.
This research employed a set of two prototype steel moment-framed buildings to study dynamic ground-level column-loss scenarios for a variety of column locations within the structures. One building contained three stories while the other had ten. Both were intended to be representative of typical perimeter moment-frame office buildings built in a low-seismic region of the United States. Three-dimensional finite element models were constructed to model the buildings using shell elements and incorporating the steel deck and composite concrete slab floor system. Nonlinear material models were used along with simplified component models for beam and girder connections. Accurate structural and non-structural masses were used to capture realistic inertial effects. The models were then analyzed using the Abaqus/Explicit finite element analysis engine to simulate instantaneous structural loss of a single ground-level column. This analysis was carried out for twelve individual columns in the three-story building and four individual columns in the ten-story building. Analysis was conducted for a sufficient time following column loss to assess structural collapse or obtain the peak vertical displacement if collapse was arrested. The output was then post-processed to obtain stresses in the steel deck and concrete slab as well as resultant connection forces and load-redistribution behavior.
The three and ten-story building were found to be capable of arresting collapse following the loss of an individual ground-level supporting column for most column locations. Demands were the least severe for perimeter columns within a moment frame, but the structures were also able to bridge over lost interior columns that had no moment connectivity. Connection demands were significant in most column-loss scenarios and adequate moment connection strength and ductility was found to be necessary to ensure successful collapse arrest.Item withdrawn by Mark Zulauf ([email protected]) on 2010-04-29T12:41:48Z
Item was in collections:
University of Illinois Theses & Dissertations (ID: 1)
No. of bitstreams: 2
Hoffman_Seth Thesis_ETD_1st Submission.docx: 64833248 bytes, checksum: 4153fb8f69a6b80f9a044bb9a5093140 (MD5)
Hoffman_Seth.pdf: 21055149 bytes, checksum: 0b84af058376ab13818489271cc41c6e (MD5)Made available in DSpace on 2010-05-19T18:40:42Z (GMT). No. of bitstreams: 3
Hoffman_Seth Thesis_ETD_1st Submission.docx: 64833248 bytes, checksum: 4153fb8f69a6b80f9a044bb9a5093140 (MD5)
Hoffman_Seth.pdf: 21055149 bytes, checksum: 0b84af058376ab13818489271cc41c6e (MD5)
license.txt: 4062 bytes, checksum: 7685715933e2a2a2051e4f1974b61320 (MD5
Behavior of bolted connections in railroad diamond crossings
Get PDFMaintenance and replacement costs of special track work elements are an expensive problem for the railroad industry. In the railroad industry, special track work refers to special railroad elements, including turnouts, switches, and diamond crossings, that are used where rails join or cross. The repeated impact and dynamic loads that diamond crossings are subjected to result in alignment problems and more rapid deterioration of the special track work elements compared to open track. This research project aims to perform finite element analysis of a diamond crossing frog in order to observe the behavior of diamond crossing bolted connections and to provide suggestions for improving their performance.
The ABAQUS environment is used to create and analyze the finite element model. A standard rail joint is modeled with shell elements in order to gain background knowledge on the performance of simple bolted connections in rail. The analysis of one crossing frog in a typical diamond crossing is then performed, again using shell elements. Static, linear elastic analyses were performed using amplified vertical wheel loads to approximate the dynamic effects. The crossing frog model is used to perform a parametric study that evaluates the relative influence of a variety of diamond crossing properties on the behavior of the diamond bolted connections. The results show that the longitudinal rail loads, vertical load position, and foundation stiffness significantly influence the stresses in bolts and connected elements.Item withdrawn by Alexis Thompson ([email protected]) on 2012-04-25T20:47:13Z
Item was in collections:
University of Illinois Theses & Dissertations (ID: 1)
No. of bitstreams: 1
White_Martin.pdf: 3632790 bytes, checksum: 3be691f648dc58fb985c49aff87fa3c1 (MD5)Made available in DSpace on 2012-05-22T00:20:14Z (GMT). No. of bitstreams: 2
White_Martin.pdf: 3661656 bytes, checksum: 53e7d84b97b579aeb98c33ffcbdc3633 (MD5)
license.txt: 4062 bytes, checksum: 77ae6ea25e5e50a4c1010e250a533d23 (MD5
Study of the seismic behavior of steel plate shear walls with coupling through analysis and testing of a small-scale model
Get PDFAs part of a multi-institutional study of seismic analysis, behavior, design and
performance of the steel plate shear wall with coupling (SPSW-WC) system, an integrated
analytical, numerical, and experimental study was conducted on a small-scale, three-story
SPSW-WC specimen. The small-scale specimen’s design was based on the scaling down of one
of the large-scale specimens that will be tested as part of the SPSW-WC program at the
University of Illinois. The concepts of dimensional analysis and similitude were used to scale
down the large-scale specimen. Analytical and numerical models were used to estimate the
small-scale specimen’s ultimate strength and study its behavior under lateral loads. The
experimental study consisted of a cyclic displacement loading test on the small-scale specimen.
The system’s behavior was stable for much of the test, and the specimen was able to undergo
large roof displacements. The analytical, numerical, and experimental results are presented and
discussed.Item withdrawn by Mark Zulauf ([email protected]) on 2013-04-26T14:09:24Z
Item was in collections:
University of Illinois Theses & Dissertations (ID: 1)
No. of bitstreams: 1
Quinonez_Alvaro.pdf: 4554743 bytes, checksum: cec41d1bc00f6b70b4f03bb8da955f69 (MD5)Made available in DSpace on 2013-05-24T21:54:29Z (GMT). No. of bitstreams: 2
Alvaro_Quinonez.pdf: 5450009 bytes, checksum: 6baa5256e197fa24b9a4133b8d036b0b (MD5)
license.txt: 4065 bytes, checksum: 2786ddd64427da13a644afa08d5f54d5 (MD5
Development and experimental validation of self-centering buckling-restrained braces with shape memory alloy
No full textAlthough conventional earthquake-resisting structural systems provide adequate life safety when properly designed, they often rely on significant structural damage to dissipate the seismic energy. The structural damage and the residual drift that may result from the inelastic response can make a building difficult, if not financially unreasonable, to repair after an earthquake. As a result, development of systems that return to their initial position (i.e., “self-center”) following an earthquake and minimize structural damage is a crucial need. The research presented in this thesis aims to address this need by creating an innovative self-centering brace for advanced seismic performance.
In the present study, the seismic behavior and performance of self-centering buckling-restrained braces (SC-BRBs) using shape memory alloys (SMAs) is investigated. The SC-BRBs consist of a typical BRB component, which provides energy dissipation, and pre-tensioned superelastic NiTi shape memory alloy rods, which provide self-centering. The SMA rods are attached to the BRB portion of the brace using a set of concentric tubes and free-floating anchorage plates that cause the SMA rods to elongate when the brace is both in tension and compression. Using a five-story building as context, half-scale SC-BRBs are designed and fabricated for experimental validation. To characterize hysteretic response, the braces are subjected to a cyclic loading protocol adapted from the AISC Seismic Provisions for Structural Steel Buildings. The results of the experiments are used to validate an SC-BRB model in OpenSEES, which is used to conduct further parametric studies of SC-BRB behavior.Item withdrawn by Mark Zulauf ([email protected]) on 2011-07-20T20:48:08Z
Item was in collections:
University of Illinois Theses & Dissertations (ID: 1)
No. of bitstreams: 2
Miller_David.docx: 28179173 bytes, checksum: e9546c930dc1d913ac42e11c4b921dd4 (MD5)
Miller_David.pdf: 11356793 bytes, checksum: 294f29b80f76c7b6e6e42d266ad97104 (MD5)Made available in DSpace on 2011-08-25T22:11:00Z (GMT). No. of bitstreams: 3
Miller_David.pdf: 11356793 bytes, checksum: 294f29b80f76c7b6e6e42d266ad97104 (MD5)
license.txt: 4062 bytes, checksum: c355e93156fb3820721ac4410d7c1e80 (MD5)
Miller_David.docx: 28179173 bytes, checksum: e9546c930dc1d913ac42e11c4b921dd4 (MD5
- …
