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1
Carver, Kathleen C. "Repurposing Industrial Railroad Bridges: Linking the Past to the Present." Youngstown State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1403195362.
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Butler, Martin A. "Fracture Critical Analysis Procedure for Pony Truss Bridges." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin155351691314481.
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Akin, Tugba. "Structural Monitoring And Analysis Of Steel Truss Railroad Bridges." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614825/index.pdf.
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Railroad bridges are the most important connection parts of railroad networks. These bridges are exposed to heavier train loads compared to highway bridges as well as various detrimental ambient conditions during their life span. The railroad bridges in Turkey are mostly constructed during the late Ottoman and first periods of the Turkish Republictherefore, they are generally close to about 100 years of age
their inspection and maintenance works are essential. Structural health monitoring (SHM) techniques are widely used around the world in order to increase the effectiveness of the inspection and maintenance works and also evaluate structural reliability. Application of SHM methods on railway bridges by static and dynamic measurements over short and long durations give important structural information about bridge members&rsquo
load level and overall bridge structure in terms of vibration frequencies, deflections, etc. Structural Reliability analysis provides further information about the safety of a structural system and becomes even more efficient when combined with the SHM studies. In this study, computer modeling and SHM techniques are used for identifying structural condition of a steel truss railroad bridge in Usak, Turkey, which is composed of six spans with 30 m length each. The first two spans of the bridge were rebuilt about 50 years ago, which had construction plans and are selected as pilot case for SHM and evaluation studies in this thesis. Natural frequencies are obtained by using 4 accelerometers and a dynamic data acquisition system (DAS). Furthermore, mid span vertical deflection member strains and bridge accelerations are obtained using a DAS permanently left on site and then compared with the computer model analyses results. SHM system is programmed for triggering by the rail load sensors developed at METU and an LVDT to collect mid span deflection high speed data from all sensors during train passage. The DAS is also programmed to collect slow speed data (once at every 15 minutes) for determination of average ambient conditions such as temperature and humidity and all bridge sensors during long term monitoring. Structural capacity and reliability indices for stress levels of bridge members are determined for the measured and simulated train loads to determine structural condition of bridge members and connections. Earthquake analyses and design checks for bridge members are also conducted within the scope of this study.
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Borchers, Stephanie. "Parametric analysis of resilient design of steel truss bridges." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99587.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (page 55).
Designing structures to be resilient to extreme loads has become a topic of interest in recent years, which has been triggered by the progressive collapse of structures in the past. Structural failure due to the lack of resilient design has been particularly prevalent in bridges. The failures have been results of a variety of factors that the bridges have been subjected to. The objective of preventing the occurrence of future collapses has encouraged further research into the design of resilient structures. Two main methods to design for resilience have been implemented in this thesis. These methods include the incorporation of robustness or redundancy into the bridge design. Each method is advantageous over the other in certain circumstances. These methods are both based on linear static analysis procedures. A series of 2D truss bridge models with varying parameters have been analyzed for their performance in damaged states. The damage incurred by the bridges include the removal of a pier and the removal of bridge members. The results of this investigation conclude that the cost of designing a bridge to be resilient is relatively low in comparison to the overall cost of the bridge. Robust bridge designs are generally more effective for bridges with longer spans, whereas designs with redundancy are better suited for shorter spans. As the amount of structural damage that is incurred by a bridge increases, the more redundancy should be built into the structure. These results were shared by all three of the truss topologies that were explored.
by Stephanie Borchers.
M. Eng.
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Yahya, Nurul Fadzlina. "Dynamic amplification of metallic truss railway bridges under fatigue loading." Thesis, University of Surrey, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616318.
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The everyday passage of trains over railway bridges produces fatigue damage at critical bridge locations. The amount of fatigue damage accumulated is very sensitive to the stress ranges producing it. The passage of trains produces dynamic amplification of the internal stresses which depends on the train velocity. Therefore, it is imperative to have a reliable estimation of dynamic effects as these directly affect bridge member stresses. Although this topic is well treated in terms of plate girder bridges and dynamic effects considering the ultimate limit state, less literature is available on the case of tlUSS railway bridges and the fatigue limit state. This thesis addresses this gap of quantifying dynamic effects for everyday train passages and their interaction with the accumulation of fatigue damage in tlUSS railway bridges. Three-dimensional finite element (FE) analyses of a typical metallic tlUSS railway bridge are canied out under the passage of railway freight loading and the effect of different modelling parameters on the intemal forces is qhantified. Subsequently, dynamic amplification factors (DAFs) for all the bridge members are estimated from the FE analyses, under different load models and train velocities, and compared with their bridge code counterparts. Statistical analysis of the estimated DAFs is also employed to propose distributions that capture the variability of the DAF among the bridge members which can then be used for the purposes of probabilistic analysis. Lastly, the effect of dynamic amplification on fatigue damage is explicitly quantified by comparing the damage estimates obtained through the use of codespecific DAFs with the ones obtained in this study.
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Cao, Youyou. "System Redundancy Evaluation for Steel Truss Bridge." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/77389.
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In current bridge practice, all tension members in a truss bridge are identified as fracture critical members which implies that a collapse is expected to occur once a member of this type fails. However, there are several examples which show that bridges have remained standing and shown little distress even after a fracture critical member was completely damaged. Due to the high inspection cost for fracture critical members, it would be beneficial to remove fracture critical designation from some tension members. This could be achieved via considering system redundancy. Since there is no clear guidance in existing codified provisions for assessing system redundancy, this research is undertaken to develop simplified analysis techniques to evaluate system redundancy in truss bridges.
The proposed system redundancy analysis in this research starts with the identification of the most critical main truss members whose failure may significantly affect the system redundancy. The system redundancy is then measured by the remaining load capacity of a damaged bridge after losing one of the critical members. The bridge load capacity is checked using 3D models with nonlinear features that can capture the progression of yielding and buckling in a bridge system. The modeling techniques are validated through the case studies of the I-35W Bridge and one test span of the Milton-Madison Bridge. Reasonable correlations are demonstrated between the models and the measured data for these two bridges both in an undamaged and in a damaged state.
The feasibility of the proposed methodology for system redundancy evaluation is examined by applying the methodology blindly to two other simple truss bridges. The application shows that the proposed methodology can efficiently measure the system redundancy. To improve the system redundancy, this research also proposes sample retrofit strategies for the four example bridges.Ph. D.
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Bornet, Lucie. "Influence of the ballast on the dynamic properties of a truss railway bridge." Thesis, KTH, Bro- och stålbyggnad, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-125346.
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To deal with a rapid development of high-speed trains and high-speed railways, constant improvement of the railway infrastructure is necessary and engineers are continuously facing challenges in order to design efficient and optimized structures. Nowadays, more and more railway bridges are built and thus, they require the engineers’ attention both regarding their design and their maintenance. A comprehensive knowledge of the infrastructures and the trains is crucial: their behaviours need to be well known. However, today, the ballast - the granular material disposed on the track and on which the rails lie – is not well known and its effect in dynamic analyses are rarely accounted for. Engineers are still investigating the role played by the ballast in the dynamic behaviour of bridges. This master thesis aims at quantifying the influence of the ballast on the dynamic properties of a bridge. Is the ballast just an additional mass on the structure or does it introduce any additional stiffness? Thus, this project investigates different alternatives and parameters to propose a realistic and reliable model for the ballast superstructure and the track. For the purpose of this study, a simply supported steel truss bridge located in Poland is studied. The bridge was excited by a harmonic force and the interesting point regarding the experiments is that acceleration measurements were collected before and after the ballasted track setting up on the bridge deck. Then, these data are processed through MATLAB in order to obtain the natural frequencies of the bridge at two different times during its construction. The determined natural frequencies for the un-ballasted case are then compared with analytical values obtained with a 3D finite element model implemented in the software LUSAS. This step aims at calibrating the un-ballasted finite element model so that the bridge is represented as realistically as possible. Once it has been done, a model both for the ballast and the track is proposed using solid elements for the ballast superstructure and beam elements for the rails, the guard rails and the sleepers. Different parameters influencing the natural frequencies and modes shapes of the bridge are testing and it appears that the ballast introduces an additional stiffness through a bending stiffness in the ballast and a change in the support conditions. Finally, the contribution of these parameters is assessed and discussed: the stiffness of the ballast increases the stiffness of the bridge by more than 20% for the 2nd vertical bending vibration mode and the support conditions increase the bridge’s stiffness by more than 15% and 30% respectively for the 1stvertical bending the 1st torsional vibration modes.
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Al-Assaf, Adel. "Flutter analysis of open-truss stiffened suspension bridges using synthesized aerodynamic derivatives." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Dissertations/Fall2006/Al_Assaf_122306.pdf.
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Hedric, Andrew C. "Dynamic Behaviors of Historical Wrought Iron Truss Bridges – a Field Testing Case Study." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc822751/.
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Civil infrastructure throughout the world serves as main arteries for commerce and transportation, commonly forming the backbone of many societies. Bridges have been and remain a crucial part of the success of these civil networks. However, the crucial elements have been built over centuries and have been subject to generations of use. Many current bridges have outlived their intended service life or have been retrofitted to carry additional loads over their original design. A large number of these historic bridges are still in everyday use and their condition needs to be monitored for public safety. Transportation infrastructure authorities have implemented various inspection and management programs throughout the world, mainly visual inspections. However, careful visual inspections can provide valuable information but it has limitations in that it provides no actual stress-strain information to determine structural soundness. Structural Health Monitoring (SHM) has been a growing area of research as officials need to asses and triage the aging infrastructure with methods that provide measurable response information to determine the health of the structure. A rapid improvement in technology has allowed researchers to start using new sensors and algorithms to understand the structural parameters of tested structures due to known and unknown loading scenarios. One of the most promising methods involves the use of wireless sensor nodes to measure structural responses to loads in real time. The structural responses can be processed to help understand the modal parameters, determine the health of the structure, and potentially identify damage. For example, modal parameters of structures are typically used when designing the lateral system of a structure. A better understanding of these parameters can lead to better and more efficient designs. Usually engineers rely on a finite element analysis to identify these parameters. By observing the actual parameters displayed during field testing, the theoretical FE models can be validated for accuracy. This paper will present the field testing of a historic wrought iron truss bridge, in a case study, to establish a repeatable procedure to be used as reference for the testing of other similar structures.
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Wang, Liang. "Innovative damage assessment of steel truss bridges using modal strain energy correlation." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/53177/1/Liang_Wang_Thesis.pdf.
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As a part of vital infrastructure and transportation network, bridge structures must function safely at all times. Bridges are designed to have a long life span. At any point in time, however, some bridges are aged. The ageing of bridge structures, given the rapidly growing demand of heavy and fast inter-city passages and continuous increase of freight transportation, would require diligence on bridge owners to ensure that the infrastructure is healthy at reasonable cost. In recent decades, a new technique, structural health monitoring (SHM), has emerged to meet this challenge. In this new engineering discipline, structural modal identification and damage detection have formed a vital component. Witnessed by an increasing number of publications is that the change in vibration characteristics is widely and deeply investigated to assess structural damage. Although a number of publications have addressed the feasibility of various methods through experimental verifications, few of them have focused on steel truss bridges. Finding a feasible vibration-based damage indicator for steel truss bridges and solving the difficulties in practical modal identification to support damage detection motivated this research project.
This research was to derive an innovative method to assess structural damage in steel truss bridges. First, it proposed a new damage indicator that relies on optimising the correlation between theoretical and measured modal strain energy. The optimisation is powered by a newly proposed multilayer genetic algorithm. In addition, a selection criterion for damage-sensitive modes has been studied to achieve more efficient and accurate damage detection results. Second, in order to support the proposed damage indicator, the research studied the applications of two state-of-the-art modal identification techniques by considering some practical difficulties: the limited instrumentation, the influence of environmental noise, the difficulties in finite element model updating, and the data selection problem in the output-only modal identification methods.
The numerical (by a planer truss model) and experimental (by a laboratory through truss bridge) verifications have proved the effectiveness and feasibility of the proposed damage detection scheme. The modal strain energy-based indicator was found to be sensitive to the damage in steel truss bridges with incomplete measurement. It has shown the damage indicator's potential in practical applications of steel truss bridges. Lastly, the achievement and limitation of this study, and lessons learnt from the modal analysis have been summarised.
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Cowled, Craig J. "On the influence of structural complexity on the global vibration characteristics of steel truss bridges." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/115793/1/Craig_Cowled_Thesis.pdf.
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This research focuses on the vibration characteristics of steel truss bridges and how structural complexity influences the chances of successful damage detection (DD). The structural complexity of almost 200 structures from the literature is quantified, highlighting that DD is less successful for experimental structures with high levels of complexity as compared to structures with low levels of complexity. The vibration characteristics of a complex structure were studied under different damage scenarios, revealing that the characteristics most sensitive to damage were also the characteristics with the highest variance. In short, structural complexity makes damage detection difficult.
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Mentes, Yavuz. "Analytical and experimental assessment of steel truss bridge gusset plate connections." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42767.
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The I-35W Bridge over the Mississippi River in Minneapolis, MN had a catastrophic failure in the main span of the deck truss in 2007. This collapse has brought significant attention on the gusset plate connections in steel truss bridges throughout the U.S. Steel truss bridge gusset plate design has not received much focus in the past 40 years, and there is a lack of consensus within the design profession on the procedures to evaluate, design, and rate these critical elements. In the short term, based on the best available information on the gusset plate design, the Federal Highway Administration (FHWA) has issued preliminary guidance. Although some experimental research has been conducted on the ultimate strength of gusset plates, much of this work has been directed toward the performance of tension members and their connections. There has been limited experimental work on the compression capacity and stability of gusset plates, but most of this work is relevant primarily to bracing connections common in building structures. This research focuses on comprehensive experimental and analytical studies on steel truss bridge gusset plate behavior. The studies include comparisons of advanced analytical models with the responses from large-scale experimental tests using discrete and innovative full-field measurements. The calibrated finite element analysis models are then utilized to study a variety of gusset plate configurations. Improved mechanistic idealizations that better capture the observed behavior in the experiments and analytical studies are proposed as the result of this work. The design checks recommended in this thesis present a comprehensive methodology for determining the ultimate gusset plate resistance. This research provides a large database of original results that will be useful for future similar studies. In addition, this research provides modeling procedures that permit the study of steel truss bridge connections and their adjacent framing members using truss bridge sub-assemblies. Based on the comprehensive analytical studies, simple and accurate design calculation procedures to assess the nominal ultimate strength of steel truss gusset plate connections are recommended for steel truss bridge gusset plate connections.
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El-Dabaja, Sarah S. "Analytical Investigation of Welded Gusset Plates Exhibiting Section Loss." Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1399501364.
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Laurendeau, Matthew P. "Live-Load Testing and Finite-Element Analysis of a Steel Cantilever Deck Arched Pratt Truss Bridge for the Long-Term Bridge Performance Program." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/904.
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The Long Term Bridge Performance (LTBP) program is an organization within the Federal Highway Administration that inspects, tests, analyzes, and observes, for an extended period of time, a variety of bridge types throughout the United States. Part of the program includes periodic testing of select bridges of a span of 20 years. The Kettle River Bridge located outside of Sandstone, Minnesota was selected for study due to its unique design.
The Kettle River Bridge is a historical steel cantilevered deck arched Pratt truss bridge. The bridge was instrumented with 151 strain gauges on various floor and truss members along with eight displacement gauges strategically placed along the truss. All gauges were read simultaneously as the bridge underwent non-destructive live loading. The recorded gauge readings were analyzed to determine bridge behavior and then used in the assistance of calibrating a working finite-element model.
After a working model was verified the distribution factors for the interior and exterior floor stringers were determined. By using the controlling distribution factor, a load rating for the bridge was determined for both inventory and operating. The distribution factors and load ratings determined using the working finite-element model were then compared to the AAHSTO LRFD specifications.
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Dickens, Loren E. III. "Structural check of a steel through truss bridge." Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/758.
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Santos, Cody Joshua. "Dynamic Testing for a Steel Truss Bridge for the Long Term Bridge Performance Program." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/894.
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Under the direction of the Federal Highway Administration the Long Term Bridge Performance Program (LTBP) selected Minnesota Bridge number 5718 as a pilot bridge for evaluation. This program focuses on the monitoring of bridges for a 20-year period to understand the structural behavior over time due to the various loads and weathering. In monitoring this bridge a better understanding can be acquired for the maintenance issues related to the nation's deteriorating bridge infrastructure.
Bridge Number 5718, which is located just outside of Sandstone Minnesota, is a steel truss bridge that spans the Kettle River. Constant monitoring of the bridge along with periodic testing of the bridge will allow for the collection of data over a 20-year period. The focus of this work is to establish a baseline for the bridges characteristics through nondestructive dynamic testing. Later tests will be compared to these results and changes can then be tracked.
In order to perform the required testing, two electromagnetic shakers were used to produce the excitation. The bridge was also outfitted with an array of velocity transducers to allow for the response to be recorded. The data was then used to extract the resonant frequencies, mode shapes, and damping ratios. A modal assurance criterion was also performed to solidify the findings. These parameters define the structural identity of the bridge. Through performing these tests the database that is being collected under the Long Term Bridge Performance Program will be used to better the overall health and safety of the nation's bridges.
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Minawi, Ailanto Daniel. "Design of a Long-Span Arch Truss Steel Bridge." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/4289/.
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Radford, Todd C. (Todd Craig) 1977. "The Town lattice truss : an appropriate bridge technology for developing countries." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/57549.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, February 2010.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references.
The Town lattice truss is proposed as an appropriate technology for the Tshumbe Diocese of the Democratic Republic of Congo. This proposal is made based on an understanding of rural transport and appropriate technology and an in-depth analysis of the details of the Town lattice truss. The nature and importance of rural transport and accessibility are presented, and bridges are identified as a key component in rural transport development. The concept of appropriate technology is presented along with a framework consisting of required and desired characteristics of any appropriate technology, including bridges. Structural materials are compared for use in bridges in rural areas of developing countries and timber is selected as the appropriate choice for the Tshumbe Diocese. Three existing timber bridges systems for developing countries are analyzed and compared, and the Town lattice truss is proposed as an alternative to all three. The Town lattice truss is presented and described in detail with reference to a study of forty existing bridges in the northeastern United States that was conducted as a part of this work. Appropriate characteristics of the truss are identified and used to compare the truss with other timber bridge systems. The wooden pegged connections and chord structure are identified as unique components of the Town lattice truss and are the subjects of further analysis. Equations are developed for strength prediction and stiffness estimation for the wooden pegged connections.
(cont.) The chord structure is analyzed for strength and stiffness, which are determined to be combinations of underlying component properties based on the chord termination pattern that is used. A comprehensive set of possible chord termination patterns is developed and the best patterns are proposed for use in design. Finally, truss moment capacity is determined as a function of chord strength and stiffness properties and a simple methodology is proposed for the design of new Town lattice truss bridges.
by Todd Craig Radford.
Ph.D.
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Mya, San Wai. "Robustness Evaluation of Long Span Truss Bridge Using Damage Influence Lines." Kyoto University, 2020. http://hdl.handle.net/2433/253253.
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Orlando, Lorenzo. "Finite Element model calibration of a historical railway steel truss bridge by using dynamic monitoring data." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022.
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This paper proposes a multidisciplinary approach, combining the terrestrial laser scanner and ambient vibration tests to characterize a historical steel truss bridge in Spain: the
Vilagarcia Celosia Bridge. All methods are complemented by advanced numerical simulations and a coarse to fine calibration strategy, based on the Cotter and the non-linear least squares approaches. Results obtained corroborate the robustness of the proposed approach, with a max error in frequencies of 3.6% and an average modal assurance criterion of 0.93.
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Hickey, Lucas James. "Model Validation for a Steel Deck Truss Bridge over the New River." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/32154.
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This thesis presents the methods utilized to model a steel deck truss bridge over the New River in Hillsville, Virginia. These methods were evaluated by comparing analytical results with data recorded from 14 members during live load testing. The research presented herein is part of a larger endeavor to understand the structural behavior and collapse mechanism of the erstwhile I-35W bridge in Minneapolis, MN. Objectives accomplished toward this end include investigation of lacing effects on built up member strain detection, live load testing of a steel truss bridge, and evaluating modeling techniques in comparison to recorded data.
Before any live load testing could be performed, it was necessary to confirm an acceptable strain gage layout for measuring member strains. The effect of riveted lacing in built-up members was investigated by constructing a two-thirds mockup of a typical bridge member. The mockup was then instrumented with strain gages and subjected to known strains in order to determine the most effective strain gage arrangement. Testing analysis concluded that for a built up member consisting of laced channels, one strain gage installed on the middle of the extreme fiber of each channelâ s flanges was sufficient. Thus, laced members on the bridge were mounted with four strain gages each.
Data from live loads were obtained by loading two trucks to 25 tons each. Trucks were positioned at eight locations on the bridge in four different relative truck positions. Data were recorded continuously and reduced to member forces for model validation comparisons. Deflections at selected truss nodes were also recorded for model validation purposes.
The model validation process began by developing four simple truss models, each reflecting different expected restraint conditions, in the hopes of bracketing data from recorded results. Models were refined to frames, and then frames including floor beams and stringers for greater accuracy. The final, most accurate model was selected and used for a failure analysis. This model showed where the minimum amount of load could be applied in order to learn about the bridgeâ s failure behavior, for a test to be conducted at a later time.
Master of Science
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Hamadani, Nabil. "Finite Element Modeling and Health Monitoring of the Ironton Russell Truss Bridge." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1235672296.
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Mutlu, Gunduz. "Dynamic Investigation And Rehabilitation Of Existing Railway Truss Bridge Under High Speed Train Loadings For Passenger Comfort." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609383/index.pdf.
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In Turkey, big investments are made to improve the existing train lines for use of new high speed trains. Most of the bridges on the existing train lines are typical and in this thesis one of the standard types, the classic steel truss bridge is investigated. This thesis presents the dynamic investigation of standard type existing truss bridge for passenger comfort criteria under the high speed train loadings. Two different computational analysis models have been developed to idealize the vehicle-bridge modeling to evaluate the passenger comfort that were influenced by dynamic vibrations on bridges induced by trains. Field tests of this bridge have been conducted by two separate institutes, Middle East Technical University and Turkish State Railways, to determine the state of the bridge under existing low-speed train loadings. Eigenvalue and Time history analysis of the LARSA 4D structural analysis program has been used to investigate the vehicle bridge interactions. The solutions obtained from the analysis have been evaluated with the experimental results. Different rehabilitation options are analytically studied to improve the serviceability of standard steel truss bridges per Eurocode 1990:2002, Eurocode 1991-2:2003, UIC 774-3 and UIC 776-1. The focus of this research is to define a relationship between span weight per meter and passenger comfort as well as the stiffness of this type of bridge.
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Sebastian, Wendel Michael. "The performance of a composite space truss bridge with glass reinforced plastic panels." Thesis, University of Cambridge, 1996. https://www.repository.cam.ac.uk/handle/1810/272273.
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Brunell, Garrett Floyd. "Functionality of a Damaged Steel Truss Bridge Strengthened with Post-Tensioned CFRP Tendons." Thesis, North Dakota State University, 2012. https://hdl.handle.net/10365/26559.
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This research program investigates the performance of a steel truss bridge when subjected to both localized web damage and a subsequent post-tensioned strengthening approach. The investigation utilizes a combined approach involving an experimental scale model bridge and a numerical computer model generated using the commercial finite element software RISA 3-D. The numerical model is validated using test data and further extended to parametric studies in order to investigate the theoretical load rating, strain energy, load redistribution, mode shapes and frequency of the bridge for control, damaged and strengthened states. The presence and severity of damage are found to significantly influence the global safety and reliability of the bridge. Also, higher order modes are more susceptible to changes in shape and frequency in the presence of damage. A recovery of truss deflection and a reduction of member forces are achieved by the proposed strengthening method.
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Hasil, Tadeáš. "Drážní most nad vodotečí." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392120.
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The subject of this master's thesis is a static and structural design of a Load-carrying steel structure of railway bridge with bottom steel deck of the span of 42 + 60 + 42 m over the Labe river in Děčín. A solid steel beam forms the main load-bearing structure of the bridge reinforced with truss-work. The truss-work is made up of an open top chord and diagonal strut without secondary vertical struts. The calculations were done in compliance with valid ČSN EN documents.
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Cleary, John. "FORENSIC INVESTIGATIONS OF THE INNERBELT BRIDGE (CUY-90-1524) IN CLEVELAND, OHIO." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1290457348.
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Rusňák, Marek. "Lávka pro pěší." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372113.
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The main goal of this diploma thesis is a design and verification of a steel footbridge crossing the river Dřevnice in Zlín. As the basic material steel S355 and for selected members steel S235 was chosen. There are two structural variants designed in the introductory part of the thesis. These variants are then compared and in the next part only selected, more favourable variant, is addressed. The selected variant is a truss footbridge with a bridge deck at the bottom and curved top chords. The bridge deck consists of floor beams and steel plate with longitudinal stiffeners. The span of the structure is 35.0 m, the width of the footbridge is 3.9 m and its height in the middle of the span is 4.2 m.
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Häggström, Jens. "Evaluation of the Load Carrying Capacity of a Steel Truss Railway Bridge : Testing, Theory and Evaluation." Licentiate thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-60029.
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A good deal of resources has been invested in building and maintaining existing infrastructure.Many structures are now becoming old and do not meet the requirements of an increasingtraffic load, or are reaching the end of their lifecycle. It is not possible or sustainable to replaceall those structures that have been judged to be obsolete or nearly obsolete. However, in manycases, their specified load carrying capacities are understated, so there is an urgent need toobtain more robust knowledge of their true status. In the design of new structures, a numberof assumptions relating to loading and structural behaviour have to be made, a number that canbe reduced by finding out more about the actual behaviour of the structure. This licentiate thesis describes the structural behaviour of existing unballasted open steel trussrailway bridges in general and methods for assessment in particular, with the aim of keepingthese structures in service for longer. An extensive program, divided into three phases of experimental studies, was carried out toincrease the understanding of existing unballasted steel truss railway bridges. Phase I consisted of instrumentation and monitoring of a 60 year-old railway bridge (ÅbyBridge) while it was still in service. A description of the object and the monitoring in thisphase of measurements is presented in Chapter 3 with some results and analysis in Chapter 4.Some of the findings from Phase I are described in Paper A, from which it was concluded thatthe stringer beams were subjected to large stresses originating from torsion and out-of-planebending. These effects are not normally considered yet may have significant consequences inrelation to fatigue. In Phase II, the former bridge over the Åby River was replaced and put beside the railwaytracks, where the instrumentation from Phase I was extended. The bridge was statically testedin 18 pre-defined load series before reaching failure. Phase II is described in Chapter 3 andsummarized in Paper B. It was found that the bridge could withstand loading corresponding tofour times the highest permitted axle-loading, or twice the design load for new bridges, beforeexhibiting an obvious non-linear behaviour with regard to vertical displacement in the midspan.The peak load was achieved at loading approximately 50% higher than the initial nonlinearbehaviour, where lateral buckling of the top chord limited the structure from carryingmore load. The failure can be concluded as being redundant without brittle failure of any ofthe connections. In Phase III, a different bridge was fitted with instrumentation and monitored while subjectedto live loading: the bridge over the river Rautasjokk. The Rautasjokk Bridge was constructedfive years later than the Åby Bridge, using the same drawings thus making it theoreticallyidentical in terms of geometry and material. It is situated along the “Ore line”, meaning that itis subjected to higher loads compared to the Åby Bridge which was located along the “Mainline”. The program for measurements originated from a code-based assessment which ruled thebridge unsafe to use with regard to fatigue of the stringers due to the gusset plates welded tothe top flange of the stringers. Paper C describes the measurement of local fatigue strains (hotspot)and comparison with nominal strains. In that paper, it was concluded that the hot-spotapproach was only favourable for one out of three studied positions, with regard to fatiguelifespan. This thesis ends with conclusions and suggestions for further research.
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Yucel, Omer Burak. "Calibration Of The Finite Element Model Of A Long Span Cantilever Through Truss Bridge Using Artificial Neural Networks." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609850/index.pdf.
Full textAbstract:
In recent years, Artificial Neural Networks (ANN) have become widely popular tools in various disciplines of engineering, including civil engineering. In this thesis, Multi-layer perceptron with back-propagation type of network is utilized in calibration of the finite element model of a long span cantilever through truss called Commodore Barry Bridge (CBB).
The essence of calibration lies in the phenomena of comparing and correlating the structural response of an analytical model with experimental results as closely as possible. Since CBB is a very large structure having complex structural mechanisms, formulation of mathematical expressions representing the relation between dynamics of the structure and the structural parameters is very complicated. Furthermore, when the errors in the structural model and noise in the experimental data are taken into account, a calibration study becomes more tedious. At this point, ANNs are useful tools since they have the capability of learning with noisy data and ability to approximate functions.
In this study, firstly sensitivity analyses are conducted such that variations in dynamic properties of the bridge are observed with the changes in its structural parameters. In the second part, inverse relation between sensitive structural parameters and modal frequencies of CBB is approximated by training of a neural network. This successfully trained network is then fed up with experimental frequencies to acquire the as-is structural parameters and model updating is achieved accordingly.
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Mazza, Silvia. "Dynamic behaviour of the railway steel bridge crossing Po river at Ostiglia: global and local analysis." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016.
Find full textAbstract:
Structural health monitoring is a very important phase of the maintenance of a civil work. In fact, thanks to the installation of a system able to monitor the conditions of a structure, it is possible to verify how this same structure responds to the loads to which it is subjected and to identify potentially damaged zones. Specifically, a railway bridge crossing a river undergoes stresses and deformations caused by the passage of trains, earthquake events and interactions with water. The INFRASAFE project aims to investigate all these aspects in order to guarantee a total monitoring of a specific structure - the bridge at Revere crossing Po river – in the environmental surrounding where it is placed. This research thesis is part of such project in a sense that it constitutes the preliminary analytical phase prior the experimental campaigns in the site. The truss structure will be modeled in Straus7 and a modal analysis will be performed in order to determine its frequencies and vibration modes. In addition, the axle loads of the real trains passing on the bridge will be considered for a linear static analysis. The results of such analysis will be investigated and the most stressed steel junction will be locally modeled in order to study its fatigue capacity.
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Foster, Patrick. "The development of a feasible expert system model of bridge truss design for use in fifth-grade technology education." Virtual Press, 1993. http://liblink.bsu.edu/uhtbin/catkey/845928.
Full textAbstract:
This study was pursued to determine the essential characteristics of a fifth-grade technology education unit of study utilizing an expert system for bridge design. A panel of artificial intelligence experts was consulted to determine the feasibility of using expert system software to model bridge design, and a panel of education experts was consulted to determine the critical components for the study of bridge design in the fifth grade.It was determined that the most important components of such a study were integration with other curricular areas, most notably mathematics and social studies, and the incorporation of cooperative and group work among students. It was also determined that bridge design is a suitable knowledge domain for expert system consultation.Finally, recommendations for further study were stated.Department of Industry & Technology
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Ferrari, Rosalba (ORCID:0000-0002-3989-713X). "An elastoplastic finite element formulation for the structural analysis of Truss frames with application to ha historical iron arch bridge." Doctoral thesis, Università degli studi di Bergamo, 2013. http://hdl.handle.net/10446/28959.
Full textAbstract:
This doctoral thesis presents a structural analysis of the Paderno d’Adda Bridge, an impressive iron arch viaduct built in 1889 and located in Lombardia region (Italy).
The thesis falls in the context of a research activity started at University of Bergamo since 2005, that is still ongoing and aims to perform an evaluation of the present state of conservation of the bridge. In fact, the bridge is currently still in service and its important position in the context of transport network will soon lead to questions about its future destination, with particular attention to the evaluation of the residual performance capacity.
To this end, an inelastic structural analysis of the Paderno d’Adda bridge has been performed, up to failure. This analysis has been conducted through an autonomous computer code of a 3D frame structure that runs in the MATLAB environment and has been developed within the classical frame of Limit Analysis and Theory of Plasticity.
The algorithm has been developed applying the “exact” and stepwise holonomic step-by-step analysis method. It has shown very much able to track the limit structural behaviour of the bridge, by reaching convergence with smooth runs up to the true limit load and corresponding collapse displacements.
The main characteristic ingredients of its elastoplastic FEM formulation are: beam finite elements; perfectly plastic joints (as an extension of classical plastic hinges); piece-wise linear yield domains; “exact” time integration.
In the algorithm, the following original features have been implemented: treatment of mutual connections by static condensation and Gaussian elimination; determination of the tangent stiffness formulation through Gaussian elimination. These peculiar contributions are presented in detail in this thesis.
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Trachtulcová, Šárka. "Výrobní hala." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372106.
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The subject of this diploma thesis is desigh and assessment of steel structure industrial building. This hall has two bays. The width of the main bay is 30 metres, the width of the second bay is 15 metres. The length of building is 90 metres. Load-bearing system is created of three fixed columns with pin-supported truss beams between. Construction of roof is designed as truss purlin system. There is a bridge crane of 32 tons capacity. The building is situated in area of Uherské Hradiště.
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Trávníček, Jakub. "Lávka pro pěší." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227456.
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The goal of this diploma work is a proposal and structural survey of wooden bridge for pedestrians and cyclists over the water area. The bridge is situated into the area of town Jihlava. A clingy slat wood and steel construction elements have been used for construction proposal. Bridge span is being used as 50 metres. Generally two variations of bridge constructions have been elaborated, variation A and variation B, of which variation A has been elaborated in more details.
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Šarmanová, Iveta. "Železniční most s ocelovou nosnou konstrukcí." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265627.
Full textAbstract:
The subject of master’s thesis is a structural analysis of a bearing structure of an existing historical single-track railway bridge over the Vltava river in a direction from Prague Modřany to Vrané nad Vltavou. The riveted steel bridge carries rail traffic across five fields. A part of the master’s thesis is focused on a disposal of a variant of the longest field by using a modern arch construction.
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Suarez, Sergio. "Parametric Study of the Multi-Objective Particle Swarm Optimization and the Multi-Objective Bee Algorithm Applied to a Simply Supported Flat-Truss Bridge Structure." Thesis, California State University, Long Beach, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=10978095.
Full textAbstract:
Most engineering fields often encounter challenges in material, performance, and time efficiency. Truss design is a subject many structural engineers confront in their careers. Optimization is an effective approach in solving preliminary designs of truss structures. This paper studies two different multi-objective optimization algorithms, the particle swarm optimization (MOPSO) and the bee algorithm (MOBA), to optimize a simply supported flat-truss bridge designed by California State University, Long Beach’s Steel Bridge team for the American Institute of Steel Construction (AISC) Spring 2018 competition. The variables, randomly selected from a continuous domain, are the top chord area, bottom chord area, web member area, and the center-to-center distance between the top and bottom chords. The optimized objectives are the weight and deflections of the bridge for the six load combinations stipulated in AISC’s rules. Both algorithms are calibrated using recommended parameter values derived from the parametric studies conducted. To compare their effectiveness, the recommended parameters were selected so that run-times for both optimization codes were similar. Both algorithms generated optimized solutions to the multi-objective truss problem, but MOPSO exhibited more, and better, solutions in a slightly longer run-time than MOBA.
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Pupík, Antonín. "Lávka pro chodce a cyklisty." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226075.
Full textAbstract:
This thesis deals with the design and assessment of footbridge for pedestrians and cyclists in the city of Hranice, Rybare district. The footbridge will serve as a crossing point over the river Bečva and will conect cycling trail with the street Rybarska. The content of this paper is to propose two different variants of structures. One of these options is selected based on their economic evaluation and further processed. Length of the bridge is 50m.
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Olbert, Jan. "Železniční most přes místní silnici." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240335.
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The thesis deals with the variant design of the steel structure of single-track railway bridge on the line Tišnov – Nové Město na Moravě. The task is bridging the local road by a bridge structure with one field. Length of the bridge is 40 m.
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Malý, Jan. "Objekt pro průmyslovou výrobu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265431.
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The subject of this diploma´s thesis is the design and assessment of steel structure two-bay building for industrial production. The width of the side aisles is 15 meters and the width of the main aisles is 35 meters. The length of industrial building is 90 meters. The height of the building is 17.4 meters. Steel structure of main aisles consists of main truss, the distance is 6 meters. The main truss consists of truss girder and fixed column. In the main aisles traversed, by bridge crane with a capacity of 20 tons. Steel structure of side aisles consists frame construction. The building for industrial production is designed for the area of Blansko.
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PIANA, GIANFRANCO. "Vibrations and Stability of Axially and Transversely Loaded Structures." Doctoral thesis, Politecnico di Torino, 2013. http://hdl.handle.net/11583/2518986.
Full textAbstract:
Modern lightweight and long-span structures are becoming increasingly slender and flexible thanks to continuous improvements in structural analysis techniques, construction methods, and the use of lighter and stronger materials. Modern airplanes, large roofs, and long-span bridges are just some examples of structures for which a design based on vibration and stability is of primary importance.
The thesis aims to investigate into the interplay between vibration and stability phenomena in elastic structures. On the one hand, the concept of stability is intrinsically a dynamic one, and is in general more appropriate to investigate this phenomenon from a dynamic point of view. On the other hand, compressive or compressive-like loads, even if they do not lead to instability, affect the dynamic behaviour of the structure since they influence its natural vibration frequencies.
Three application areas constitute the objective of the present research:
• slender beams subjected to imposed displacements;
• space truss models subjected to dead loads;
• suspension bridges under aerodynamic loads.
Stability and influence of the applied loads on the natural frequencies are studied using analytical, numerical, and experimental tools. The experimental tests were conducted at the Politecnico di Torino in cooperation with the Fluid Dynamics Unit of the National Institute of Metrological Research (INRIM).
The fundamental frequency evolution in slender beams subjected to imposed displacements is analyzed through an experimental study. Different values of geometric imperfections as well as different constraint conditions are investigated, and the natural frequencies are obtained using several methods. The experimental study conducted in the present research leads to recognize two different phases in the bending frequency vs. axial load curves in case of displacement controlled condition, therefore showing a different behaviour with respect to the force controlled case. After, we show how the experimental results can be interpreted and reproduced through numerical simulations.
The influence of dead loads on the natural frequencies of space truss models is investigated through a modal analysis with second-order effects. In particular, the effects of the direction and magnitude of the acting load are studied, leading to show an interesting aspect of the dynamic behaviour due to different effects of the geometric stiffness. In this case, numerical simulations are accompanied by some experiments.
Finally, the effects of steady aerodynamic loads on stability and natural vibration frequencies of suspension bridge decks are analyzed by means of a simplified analytical model. The single (central) span suspension bridge model is considered, and the linearized integro-differential equations describing the flexural-torsional oscillations of the bridge deck are derived. In conclusion, some address on how this study might be integrated into the flutter analysis of long-span suspension bridges is provided.
The quest for stronger, stiffer, and more lightweight structural systems is making the subject studied in this thesis increasingly important in practical applications in the areas of civil, mechanical, and aerospace engineering.
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Vošček, Martin. "Silniční a tramvajový most." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265573.
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The subject of this Diploma Thesis is to develop different alternatives of the road and tram bridge. It is a river bridge with the length of 52,5 m. There are compared two proposals, while in the first proposal it is an arch bridge with the tension bars. The second proposal which is also finalized as the winning proposal is the truss structure. Both proposals have composite deck. The structure is designed from steel S355 and concrete C35/45. The load bearing structure is designed in accordance with applicable technical standards.
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Hurych, Marek. "Lávka přes nádraží." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409851.
Full textAbstract:
The diploma thesis deals with design of loadbearing stell structure of a footbridge across the railway station. Footbridge is situated in the city centre of Brno with total length of 135 meters. For comparison, three bridging variants are predesigned and a varints comparison is made. The selected option was developed in greater detail. It is an arched structure with a semithrough bridge deck and adjacent span with support of oblique column. The main loadbearing structure consists of a pair of pin-supported arches inclited to each other at an angle of 11°. Arches support beams with susperder, the beams are conected by ortotropic steel deck. All load-bearing elements are designed from S355 stell. Spatial rigidity of the structure is ensured by tilting of the arches and by truss bracing at the top of the arch in combination with rigid struts of arch. Spatial rigidity of the superted deck is ensured by ortotropic steel deck.
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Nguyen, Khac Duy. "Structural damage identification using experimental modal parameters via correlation approach." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/117289/2/Khac%20Duy%20Nguyen.pdf.
Full textAbstract:
This research provides a new damage identification strategy using experimental modal parameters via correlation approach. Two damage identification algorithms using modal strain energy-eigenvalue ratio (MSEE) are presented. Firstly, a method using a simplified term of MSEE called geometric modal strain energy-eigenvalue ratio (GMSEE) is developed. Secondly, the original method is modified using the full term of MSEE, proving better capability of damage identification when used with fewer vibration modes. Performance of the proposed damage identification algorithms has been successfully validated with a numerical model and some experimental models of various scales from small to large.
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Ganglbauer, Tereza. "Nosná ocelová konstrukce železničního mostu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-371925.
Full textAbstract:
The master thesis focuses on the design of a Load-carrying steel structure of railway bridge with bottom steel deck of the span of 28 + 45 + 23 m. The bridge is situated in the municipality of Třebestovice. Four variants of solution have been calculated. Two variants are made by plate main beams of variable profile, the next alternative was made by truss structure and the fourth variant consist of a combination of plate main beams with truss stiffener in the middle span. The most optimal solution was processed in detail. The calculations were done in compliance with valid ČSN EN norms.
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Beran, Miroslav. "Výrobní hala." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392241.
Full textAbstract:
The diploma thesis deals with the design and assessment of the steel supporting structure of the production hall. The transverse dimension of the hall is 21,00 m, the longitudinal dimension is 70,00 m, the height of the hall is 17,56 m. S355 steel is used as the main supporting material. The supporting part of the hall consists of columns on which is placed a truss and two crane tracks at two height levels. Three different types of purlins and pillars are considered in the design of the steel structure. For the selected variant, a static calculation of the main bearing elements, including selected details, is drawn up and drawings are drawn up.
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Shih, Hoi Wai. "Damage assessment in structures using vibration characteristics." Thesis, Queensland University of Technology, 2009. https://eprints.qut.edu.au/30319/1/Hoi_Shih_Thesis.pdf.
Full textAbstract:
Changes in load characteristics, deterioration with age, environmental influences and random actions may cause local or global damage in structures, especially in bridges, which are designed for long life spans. Continuous health monitoring of structures will enable the early identification of distress and allow appropriate retrofitting in order to avoid failure or collapse of the structures. In recent times, structural health monitoring (SHM) has attracted much attention in both research and development. Local and global methods of damage assessment using the monitored information are an integral part of SHM techniques. In the local case, the assessment of the state of a structure is done either by direct visual inspection or using experimental techniques such as acoustic emission, ultrasonic, magnetic particle inspection, radiography and eddy current. A characteristic of all these techniques is that their application requires a prior localization of the damaged zones. The limitations of the local methodologies can be overcome by using vibration-based methods, which give a global damage assessment. The vibration-based damage detection methods use measured changes in dynamic characteristics to evaluate changes in physical properties that may indicate structural damage or degradation. The basic idea is that modal parameters (notably frequencies, mode shapes, and modal damping) are functions of the physical properties of the structure (mass, damping, and stiffness). Changes in the physical properties will therefore cause changes in the modal properties. Any reduction in structural stiffness and increase in damping in the structure may indicate structural damage. This research uses the variations in vibration parameters to develop a multi-criteria method for damage assessment. It incorporates the changes in natural frequencies, modal flexibility and modal strain energy to locate damage in the main load bearing elements in bridge structures such as beams, slabs and trusses and simple bridges involving these elements. Dynamic computer simulation techniques are used to develop and apply the multi-criteria procedure under different damage scenarios. The effectiveness of the procedure is demonstrated through numerical examples. Results show that the proposed method incorporating modal flexibility and modal strain energy changes is competent in damage assessment in the structures treated herein.
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Shih, Hoi Wai. "Damage assessment in structures using vibration characteristics." Queensland University of Technology, 2009. http://eprints.qut.edu.au/30319/.
Full textAbstract:
Changes in load characteristics, deterioration with age, environmental influences and random actions may cause local or global damage in structures, especially in bridges, which are designed for long life spans. Continuous health monitoring of structures will enable the early identification of distress and allow appropriate retrofitting in order to avoid failure or collapse of the structures. In recent times, structural health monitoring (SHM) has attracted much attention in both research and development. Local and global methods of damage assessment using the monitored information are an integral part of SHM techniques. In the local case, the assessment of the state of a structure is done either by direct visual inspection or using experimental techniques such as acoustic emission, ultrasonic, magnetic particle inspection, radiography and eddy current. A characteristic of all these techniques is that their application requires a prior localization of the damaged zones. The limitations of the local methodologies can be overcome by using vibration-based methods, which give a global damage assessment. The vibration-based damage detection methods use measured changes in dynamic characteristics to evaluate changes in physical properties that may indicate structural damage or degradation. The basic idea is that modal parameters (notably frequencies, mode shapes, and modal damping) are functions of the physical properties of the structure (mass, damping, and stiffness). Changes in the physical properties will therefore cause changes in the modal properties. Any reduction in structural stiffness and increase in damping in the structure may indicate structural damage. This research uses the variations in vibration parameters to develop a multi-criteria method for damage assessment. It incorporates the changes in natural frequencies, modal flexibility and modal strain energy to locate damage in the main load bearing elements in bridge structures such as beams, slabs and trusses and simple bridges involving these elements. Dynamic computer simulation techniques are used to develop and apply the multi-criteria procedure under different damage scenarios. The effectiveness of the procedure is demonstrated through numerical examples. Results show that the proposed method incorporating modal flexibility and modal strain energy changes is competent in damage assessment in the structures treated herein.
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Hofgård, Daniel, and John Sundkvist. "Climate enhanced concrete in the civil engineering industry." Thesis, KTH, Betongbyggnad, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278216.
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In 2017, the Swedish Parliament stated a new climate law with the goal that Sweden should be climate neutral by 2045. The concrete industry has developed a roadmap on how the goal for 2045 can be achieved, where one way to reduce the carbon emissions from concrete is by replacing a part of the cement clinker with alternative binders in the concrete mix. Ground granulated blast furnace slag (GGBS), fly ash, silica fume and trass are alternative binders that are possible to use in concrete mixes to reduce the amount of ordinary Portland cement (OPC). GGBS, fly ash and silica fume are by-products from other industries, while trass is volcanic ash that can be extracted. Besides the positive environmental impact that comes from using alternative binders and reducing the amount of cement clinker, the alternative binders have other properties, both positive and negative, that affect the concrete. The aim of this thesis was to investigate whether concrete with alternative binders does fulfill the regulations set by Swedish standards and how concrete with alternative binders does affect the material parameters. The concrete mixes were divided into three different types of concrete: concrete for bridges (w/c ratio 0.4), hydropower structures (w/c ratio 0.45) and wind powerplant foundations (w/c ratio 0.55). A total of seven concrete mixes were cast in a laboratory and the concrete mixes were investigated in the three hardening stages of concrete: fresh, young and hardened. The analyzed material parameters were compressive strength, shrinkage, frost resistance, workability, air voids and temperature development. Beyond the experimental testing, a global warming potential (GWP) comparison was made to compare the reduction of GWP for each concrete mix compared to a reference concrete for each usage area. The mix containing a CEM II/A-V fly ash cement and 15% GGBS showed great potential regarding the different material parameters. This mix, however, is according to Swedish standards not possible to certify for structures in exposure class XF4, such as bridges, but is possible to certify for structures in exposure class XF3, such as wind powerplant foundations. The mix containing 30% GGBS and 5% silica fume also showed beneficiary properties, but superplasticizers are required in this mix to ensure good workability. For hydropower structures, the mix containing 35% GGBS showed a great compressive strength but a high temperature development and low workability. The mix containing trass had a notably low temperature development, but with an increase in shrinkage and low workability. Moreover, all concrete mixes showed a frost resistance which, according to standard, is classified as “Very Good”.Sveriges regering antog 2017 ett nytt klimatpolitiskt ramverk med målet att Sverige ska ha noll nettoutsläpp av växthusgaser år 2045. Betongindustrin har tagit fram en färdplan för hur betong kan bli klimatneutralt, där ett sätt att reducera klimatpåverkan från betong är att byta ut en del av cementklinkern mot alternativa bindemedel. Mald granulerad masugnsslagg (GGBS), flygaska, silikastoft och trass är alternativa bindemedel som är möjliga att använda i betongblandningar för att reducera mängden Portlandcement. GGBS, flygaska och silikastoft är restprodukter från andra industrier medan trass är en vulkanisk aska som kan utvinnas. Utöver den positiva miljöeffekten som erhålls när alternativa bindemedel ersätter cementklinker, så har de alternativa bindemedlen andra egenskaper, både positiva och negativa, som påverkar betongen. Målet med denna studie var att undersöka och jämföra om betongblandningar där en del av cementklinkern har ersatts med alternativa bindemedel når upp till de krav som ställs i nuvarande regelverk. Utöver det så undersöktes även hur betongblandningarnas materialparametrar påverkades av alternativa bindemedel. Betongblandningarna delades in i tre olika typer av betong: betong för broar (vct 0.4), vattenbyggnader (vct 0.45) och vindkraftverksfundament (vct 0.55), där totalt sju betongblandningar tillverkades i ett laboratorium. Betongblandningarna undersöktes i de tre olika faserna för hårdnande av betong, vilka är färsk, ung och hårdnad betong. De materialparametrar som analyserades var tryckhållfasthet, krympning, frostresistens, arbetbarhet, luftporhalt och temperaturutveckling. Förutom de experimentella testerna gjordes en jämförelse kring hur mycket koldioxid som kan reduceras för varje betongblandning, jämfört med en referensbetong för varje användningsområde. Betongblandningen med ett CEM II/A-V flygaska-cement och 15% GGBS visade stor potential med avseende på de olika materialparametrarna. Denna blandning är dock enligt svensk standard inte möjlig att certifiera för betongbyggnad i exponeringsklass XF4, exempelvis broar, men kan certifieras för betongbyggnad i exponeringsklass XF3, exempelvis fundament för vindkraftverk. Blandningen med 30% GGBS och 5% silikastoft visade även positiva egenskaper, men flyttillsatsmedel måste användas i denna blandning för att erhålla en god arbetbarhet. För vattenbyggnadsbetong så visade blandningen med 35% GGBS en hög tryckhållfasthet, men samtidigt en hög temperaturutveckling och en låg arbetbarhet. Blandningen med trass hade en noterbart låg temperaturutveckling, men med ökad krympning samt låg arbetbarhet. Avslutningsvis så uppvisade alla blandningar en frostresistens som enligt standard klassificeras som ”Mycket bra”.
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Bartoň, Radek. "Ocelová lávka pro pěší." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227509.
Full textAbstract:
This diploma thesis contains a study of current composite structure of footbridge and in part II design and assessment of steel structure of footbridge for pedestrians and cyclists placed on current footbridge location. Current footbridge is located on "nábřeží Dukelských hrdinů" in Rožnov pod Radhoštěm. In part I, assessment of the current composite structure of footbridge is done, using ČSN and ČSN EN standards for adjusted static behavior of the structure. Comparison of both assessments is made and also with an original assessment from 1988. In part II, design and assessment of steel structure of footbridge placed on currents footbridge location described in part I is done.The structure was designed as two vierendeels trusses connected with cross beams, supporting concrete bridge deck. 9 variants were examined, differing with truss height and the number of verticals. Detailed design and assessment for parts of the structure is done for the chosen variant.