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Статті в журналах з теми "Prestressed concrete, autoclave, structural design, structural analysis":
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Bezgin, Niyazi Özgür. "An insight into design of prefabricated and prestressed concrete monoblock railway ties for service loads." Challenge Journal of Structural Mechanics 4, no. 4 (December 5, 2018): 126. http://dx.doi.org/10.20528/cjsmec.2018.04.001.
Ballasted railway track ties support the wheel forces of a train that are transferred by the rails, maintain the track gauge and provide track stability. Prestressed concrete ties provide the required track bearing to the applied wheel loads and constitute a major part of the track self-weight. Design of prestressed concrete ties involves an evaluation of their structural interaction with the ballast and an understanding of prestressed concrete design for service loads and ultimate loads. This paper aims to provide an insight for the design of a prestressed concrete ballasted railway tie under service loads and highlight the genuine qualities of tie design in terms geotechnical engineering, materials engineering and structural engineering. Through the analysis of a finite element model, this paper presents estimations for bending moment values under service conditions for a prestressed concrete high-speed railway tie under varying track support conditions. The paper then compares the estimated values with those suggested by the relevant design guidelines for railway ties.
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Shahawi, M. El, and B. deV Batchelor. "Design methods for partially prestressed concrete—a review." Canadian Journal of Civil Engineering 14, no. 2 (April 1, 1987): 269–77. http://dx.doi.org/10.1139/l87-039.
Methods for use in the flexural analysis and design of a partially prestressed concrete section are outlined. A typical design example is presented and the results obtained by different design methods are compared. Methods proposed by Moustafa, Naaman and Siriaksorn, Bachmann, and Nilson are all suitable for design purposes. The graphs developed by Moustafa are useful in expediting design. The method proposed by Abeles, which is based on the use of a fictitious tensile stress in the concrete, is generally not recommended. Key words: concrete (prestress), design, flexure, partial prestressing.
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Wang, Qian, Wen-liang Qiu, and Sheng-li Xu. "Structural Optimization of Steel Cantilever Used in Concrete Box Girder Bridge Widening." Mathematical Problems in Engineering 2015 (2015): 1–14. http://dx.doi.org/10.1155/2015/105024.
The structural optimization method of steel cantilever used in concrete box girder bridge widening is illustrated in this paper. The structural optimization method of steel cantilever incorporates the conceptual layout design of steel cantilever beam based on the topological theory and the determination of the optimal location of the transverse external prestressed tendons which connect the steel cantilever and the box girder. The optimal design theory and the analysis process are illustrated. The mechanical model for the prestressed steel cantilever is built and the analytical expression of the optimal position of the transverse external tendon is deduced. At last the effectiveness of this method is demonstrated by the design of steel cantilevers which are used to widen an existing bridge.
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Priestley, M. J. N. "Analysis and Design of Circular Prestressed Concrete Storage Tanks." PCI Journal 30, no. 4 (July 1, 1985): 64–85. http://dx.doi.org/10.15554/pcij.07011985.64.85.
Elbadry, Mamdouh M., and Amin Ghali. "Analysis of time-dependent effects in concrete structures using conventional linear computer programs." Canadian Journal of Civil Engineering 28, no. 2 (April 1, 2001): 190–200. http://dx.doi.org/10.1139/l00-093.
Analysis of the time-dependent changes in displacements, internal forces, and reactions at the supports in continuous reinforced concrete structures cast, prestressed, and loaded at different stages is frequently needed in design to satisfy the serviceability requirements. The time-dependent parameters considered in the analysis are creep and shrinkage of concrete, relaxation of prestressed steel, sequence of construction, and changes in structural system and support conditions. A procedure of analysis is presented using conventional linear analysis computer programs. The analysis procedure is explained through examples to demonstrate its simplicity and applicability.Key words: analysis, computer program, creep, displacement, frames, precast concrete, prestressed concrete, relaxation, shrinkage, time-dependent.
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Huang, Dongzhou, and Mohsen Shahawy. "Analysis of Tensile Stresses in Transfer Zone of Prestressed Concrete U-Beams." Transportation Research Record: Journal of the Transportation Research Board 1928, no. 1 (January 2005): 134–41. http://dx.doi.org/10.1177/0361198105192800115.
Prestressed U-beam bridges compare favorably in cost and appearance to traditional concrete I-beam bridges. Consequently, U-beam bridges are gaining in popularity and usage, especially when aesthetic issues are deemed important. U-beam bridges first appeared in Florida in 2000; however, during construction, cracks developed in the webs of the U-beams. This paper presents results of an analysis of representative cracking of U-beams and proposes a practical method for the transfer zone stirrup design. For the purpose of the analysis, the U-beam is divided into a series of finite shell-plate elements, and the prestressing tendons are simulated as a number of concentrated forces. Two different mechanical models of the U-beams are developed on the basis of the stages of construction. Analytical results show that high tensile stresses occur in the end zone of the U-beam because of the prestressing tendons and that these tensile stress must be properly considered in bridge design. The research results are applicable to the design of prestressed U-beams and similar types of prestressed girders.
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Yi, Lu Ping, and Jing Ji. "Analysis and Design of Concrete Cylindrical Shell Roof Structure." Advanced Materials Research 549 (July 2012): 866–70. http://dx.doi.org/10.4028/www.scientific.net/amr.549.866.
Combined with the roof of a warehouse the arched shell roof structure is select, simulation Numerical simulation is carried out for the arched shell roof structure system by the ANSYS finite element method, the deformation and stress are obtained which meet the specification requirements. So it is reasonable to select the thin vaulted roof. Finally, the arrangements of the two prestressing tendons of prestressed concrete beams in the framework and the matter which needs to be paid attention to during designing are given, and these can provide reference for similar finite element solution and design of the structural system.
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Shi, Jun, Jiyang Shen, Guangchun Zhou, Fengjiang Qin, and Pengcheng Li. "STRESSING STATE ANALYSIS OF LARGE CURVATURE CONTINUOUS PRESTRESSED CONCRETE BOX-GIRDER BRIDGE MODEL." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 25, no. 5 (May 2, 2019): 411–21. http://dx.doi.org/10.3846/jcem.2019.9869.
This paper experimentally analyzes the working behavior characteristics of a large-curvature continuous prestressed concrete box-girder (CPCBG) bridge model based on structural stressing state theory. First, the measured strain data is modeled as generalized strain energy density (GSED) to characterize the stressing state of the bridge model. Then, the Mann-Kendall (M-K) criterion is adopted to detect the stressing state leaps of the bridge model according to the natural law from quantitative change to qualitative change of a system, which derives the new definition of structural failure load. Correspondingly, the stressing state modes for the bridge model’s sections and internal forces are proposed to verify their changing characteristics and the coordinate working behavior around the characteristic loads. The analytical results reveal the working behavior characteristics of the bridge mode unseen in traditional structural analysis, which provides a new angle of view to conduct structural analysis and a reference to the improvement of design codes.
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Guan, Hua, and De Wei Chen. "Stochastic Analysis of Prestressed Concrete Cable-Stayed Bridges Considering Construction Errors." Advanced Materials Research 255-260 (May 2011): 1023–28. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.1023.
There is a deviation between finished bridge and design requirement of prestressed concrete (PC) cable-stayed bridge due to the construction errors in construction process. Besides, the randomness of construction errors will cause the variability of structure system in construction state. However, the most common analyses considering construction errors are based on deterministic analysis method, which concern the mean errors effect merely. These are inadequate obviously. In this paper the main construction errors of PC cable-stayed bridge and corresponding distributions are outlined firstly. Also several common stochastic analysis methods are introduced. Using Monte-Carlo method with ANSYS finite element analysis (FEA) software, then, a stochastic analysis of a single tower PC cable-stayed bridge considering construction errors is completed, and the probability characteristics of structural response under dead load are obtained. Finally, from the reliability point of view, the influence of randomness of construction errors on structural safety and the necessity of stochastic analysis for PC cable-stayed bridges are discussed.
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Lwin, M. Myint, and Bijan Khaleghi. "Time-Dependent Prestress Losses in Prestressed Concrete Girders Built of High-Performance Concrete." Transportation Research Record: Journal of the Transportation Research Board 1594, no. 1 (January 1997): 64–72. http://dx.doi.org/10.3141/1594-07.
The Washington State Department of Transportation is one of several state departments of transportation involved in demonstration projects to acquire information and data on the design, fabrication, and construction of prestressed concrete bridges with high-performance concrete (HPC). Predicting the time-dependent prestress losses due to the creep and shrinkage of HPC and the relaxation of prestressing steel is difficult because of the limited experience with and data on the creep and shrinkage properties of HPC. The AASHTO load resistance factor design specification approach to estimating prestress losses is discussed, and the time-step method and the modified rate-of-creep method are introduced as ways of predicting more accurately the time-dependent prestress losses. A design example is used to compare and discuss numerically the prestress losses computed by the various methods. The modified rate-of-creep analysis method yields the lowest losses. The modified rate-of-creep method is a desirable, comprehensive, applicable, and practical method for estimating time-dependent prestress losses in composite and noncomposite prestressed concrete girders with HPC. This method is suitable for manual and electronic computation.
Також вас можуть зацікавити розширені добірки на тему "Prestressed concrete, autoclave, structural design, structural analysis" для конкретних типів джерел:
Дисертації з теми "Prestressed concrete, autoclave, structural design, structural analysis":
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Carboni, Munoz Alvaro Antonio. "Prestressed concrete aerospace autoclave ovens: feasibility and opportunities for the industry." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23456/.
With the current and future growth of composites in the aeronautic industry, market pressure is increasing for fabricants to obtain the largest possible composite sections, in order to reduce the use weight and complexity of the final product. In this scenario, autoclaves remain as the main constraint to determine the maximum size of a composite element that can be produced and thus, the question on how larger autoclaves can be built is ever more relevant.
This research aims to explore the possibilities, strengths and weaknesses that prestressed concrete presents as a possible material for a new generation of super large autoclaves. To determine the feasibility of the concept, the current state of the art in prestressed structures was studied to determine a viable design scope and the behavior of the structure in key areas, such as fatigue and comparative material consumption. Then, estimations were performed in consideration to the applicable construction codes as well as simplified numerical models, in order to obtain a rough estimate in terms of stresses and material demand.
Finally, a study case was considered for an ultra large autoclave (10m diameter, 84m length) using the previously estimated designs, to study the static and dynamic behavior of the structure.
2
Wang, Naiyu. "Reliability-based condition assessment of existing highway bridges." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34835.
Condition assessment and safety verification of existing bridges and decisions as to whether bridge posting is required are addressed through analysis, load testing, or a combination of methods. Bridge rating through structural analysis is by far the most common procedure for rating existing bridges. The American Association of State Highway and Transportation Officials (AASHTO) Manual for Bridge Evaluation (MBE), First Edition permits bridge capacity ratings to be determined through allowable stress rating (ASR), load factor rating (LFR) or load and resistance factor rating (LRFR); the latter method is keyed to the AASHTO LRFD Bridge Design Specifications, which is reliability-based and has been required for the design of new bridges built with federal findings since October, 2007. A survey of current bridge rating practices in the United States has revealed that these three methods may lead to different ratings and posting limits for the same bridge, a situation that carries serious implications with regard to the safety of the public and the economic well-being of communities that may be affected by bridge postings or closures.
To address this issue, a research program has been conducted with the overall objective of providing recommendations for improving the process by which the condition of existing bridge structures is assessed. This research required a coordinated program of load testing and finite element analysis of selected bridges in the State of Georgia to gain perspectives on the behavior of older bridges under various load conditions. Structural system reliability assessments of these bridges were conducted and bridge fragilities were developed for purposes of comparison with component reliability benchmarks for new bridges. A reliability-based bridge rating framework was developed, along with a series of recommended improvements to the current bridge rating methods, which facilitate the incorporation of various in situ conditions of existing bridges into the bridge rating process at both component and system levels. This framework permits bridge ratings to be conducted at three levels of increasing complexity to achieve the performance objectives, expressed in the terms of reliability, that are embedded in the LRFR option of the AASHTO Manual of Bridge Evaluation. This research was sponsored by the Georgia Department of Transportation, and has led to a set of Recommended Guidelines for Condition Assessment and Evaluation of Existing Bridges in Georgia.
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Tylčer, Jan. "Návrh předpjaté mostní konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226959.
This thesis describes the design of a road bridge in Trutnov through local communication. It is designed prestressed dvoutrámová construction of two fields with twin inclined struts. It developed a detailed static analysis and the bridge is considered to I. and II. limit state according to European standards - Eurocode. It is prepared detailed drawings.
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Luberová, Lucie. "Návrh mostní konstrukce dálničního mostu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265249.
The subject of this bachelo r’s thesis is the design a new supporting bridge construction in Prešovský kraj, district Levoča the territory of Slovak Republic. This object is located on the highway D 26,5/120, at kilometer 13,499 795 and communication of third class – 131-00 bridges. The objective is the design of a perpendicular four-span construction, which is proposed in three variants. The first variant is a chamber girder with inclined walls from post-tensioned concrete height 2,480 m. The second variant is composed of two beamed cross-section and the third variant is composed of one beamed cross-section. For detailed assessment the first variant was chosen with a length of bridging of 166,000 m. The calculation of load effects is done by software Scia Engineer and compared with a manual calculation according to current standards. This bridge is designed according to limit states, construction´s influence on design is taking into consideration. Structural analysis, well arranged drawings and visualization are elaborated in this thesis too.
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Pírková, Barbora. "Dálniční most přes hluboké údolí." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265632.
The subject of this diploma thesis is the design and the assessment of post-tensioned bridge structure over deep wally, which transfer road D26,5/100 on D1 in Slovakia between Hubová – Ivachnová. Three variants were designed and compared. The most suitable variant of two identical bridges with box cross-section and constant height was further assess in detail.
Книги з теми "Prestressed concrete, autoclave, structural design, structural analysis":
1
O'Brien, Eugene J. Reinforced and prestressed concrete design: The complete process. Edited by Dixon Andrew S. 1968-. Harlow, England: Longman Scientific & Technical, 1995.
Singh, Tarvinder. Axisymmetric global structural analysis of BARC prestressed concrete containment model for beyond design pressure. Mumbai: Bhabha Atomic Research Centre, 2008.
Singh, Tarvinder. Axisymmetric global structural analysis of BARC prestressed concrete containment model for beyond design pressure. Mumbai: Bhabha Atomic Research Centre, 2008.
Тези доповідей конференцій з теми "Prestressed concrete, autoclave, structural design, structural analysis":
1
Wang, Shen, and Javeed A. Munshi. "Evaluation of Tendon Anchorage Zone Stresses in Prestressed Concrete Nuclear Containment Using Detailed Finite Element Analysis." In 2012 20th International Conference on Nuclear Engineering and the ASME 2012 Power Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icone20-power2012-54014.
Nuclear containments serve the critical function of providing a leak proof boundary for containment of radiation in nuclear power plants. The containments are, generally, steel, reinforced concrete or prestressed concrete depending upon the diameter and internal design pressure. Prestressed concrete containments are used in large nuclear containments with significant design internal pressure. In these situations, the externally applied prestressing serves to counter internal design pressure due to LOCA (loss of coolant accident) and other accident loads thus reducing the required thickness and reinforcement demand. The prestressing tendons are placed in sheathing within the concrete. After the concrete achieves its required strength, the tendons are stretched and locked off against the ends of the concrete called anchorage zones. These anchorage zones are thus subjected to substantial compressive and splitting stresses and need to be properly designed and detailed. Since anchorage zones are the primary location of the prestressing force transfer to concrete, they experience very large and localized bearing and splitting stresses which can have significant safety and structural consequences for the containment integrity. Simple analysis based on strut-and-tie model is generally used for design of prestressed concrete anchorage zones. But because of the stress concentrations and potential impact to structural integrity, it is prudent to utilize detailed finite element method to verify and/or substantiate the results from simple analysis. The finite element (FE) analysis of tendon anchorage zone requires a refined mesh in order to capture the geometry of details surrounding tendons. This paper presents a detailed and practical finite element model used to perform a comprehensive stress analysis of an anchorage zone of a large post-tensioned containment. Both local and general anchorage zones are evaluated. A fictitious case of tendon anchorage zone is established as an example case based on typical parameters of nuclear plants. A 3D finite element model is then developed using ANSYS Version 13.0, in which the effect of tendon sleeve / sheathing into concrete is modeled explicitly. This paper also discusses anchorage zone analysis approaches in various state-of-the-practice codes and standards using hand calculations. The result of finite element analysis are compared with analyses using various hand calculation approaches. In particular, importance of adequate reinforcement design and detailing in anchorage regions is discussed based on the stress profiles from FE analysis and compared with hand calculation methods. It is concluded that a detailed finite element evaluation of anchorage regions is necessary to develop a level of confidence required for ensuring safety and integrity of nuclear containments. The FE modeling also serves as verification for results from simple hand calculation methods.
2
Wu, Wenpeng, Shiguo Long, and Huihui Li. "Seismic Performance of Self-Centering UHPC Retainers Applied to Medium-Small Span Concrete Bridges." In IABSE Congress, New York, New York 2019: The Evolving Metropolis. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2019. http://dx.doi.org/10.2749/newyork.2019.2043.
<p>Seismic resistant retainer is an important component for seismic design of the medium‐small span bridges. However, it’s difficult for the bridge engineers to design a reasonable transverse retainer due to deficiency of design detail in most of current seismic design specifications. Therefore, this paper proposed a prestressed prefabricated concrete retainer that utilize the ultra‐high performance concrete (UHPC). Firstly, the structural characteristics and the seismic design method of the new proposed retainer is illustrated. The OpenSEES model of the case‐study bridge were simulated by considering three different types of seismic resistant retainers. A total of ten high intensity ground motions were selected to conduct the nonlinear time history analysis (NTHA). Subsequently, to investigate the seismic performance of the proposed UHPC retainer, this paper performs the comparative study of seismic responses for different bridge components. It is concluded that, the proposed retainer can provide excellent displacement capacity and help to reduce the seismic damage of bridge piers significantly. In addition, the new retainer has strong ability to keep self‐centering to help the bridge reducing the residual displacement of superstructure under strong seismic events. The proposed UHPC retainer is applicable to the rapid prestressed prefabricated construction process and has a clear load transfer mode under earthquake actions. Therefore, it is a good candidate to the multi‐level performance‐based seismic design of the medium‐small span bridges.</p>
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Toumpanaki, Eleni, Janet M. Lees, and Giovanni P. Terrasi. "Effect of bond in the development length of CFRP pretensioned beams." In IABSE Symposium, Guimarães 2019: Towards a Resilient Built Environment Risk and Asset Management. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2019. http://dx.doi.org/10.2749/guimaraes.2019.0635.
<p>Carbon Fibre Reinforced Polymer (CFRP) tendons present an alternative material that can mitigate steel corrosion problems in concrete bridges. The use of CFRP prestress tendons can result in more durable prestressed concrete structures. However, the potential matrix plasticisation of CFRP tendons in humid environments and their inherent lack of ductility need to be considered in the design process. A tension stiffening analysis is undertaken to study the effect of variations in bond strength parameters on the cracking behaviour, deformability and structural performance of CFRP prestressed beams. The bond strength scenarios under consideration reflect either low or high bond conditions. The former could be associated with epoxy plasticisation and bond degradation due to moisture ingress at a crack location. A low bond performance results in a smaller number of cracks and higher deflections at failure compared with high bond tendons.</p>
