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1
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.
Анотація:
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.
2
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.
Анотація:
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.
3
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.
Анотація:
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.
4
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.
5
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.
Анотація:
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.
6
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.
Анотація:
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.
7
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.
Анотація:
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.
8
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.
Анотація:
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.
9
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.
Анотація:
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.
10
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.
Анотація:
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.
11
Zamblauskaitė, Renata, Gintaris Kaklauskas, Darius Bačinskas, and Morten Bo Christiansen. "SHORT-TERM DEFORMATIONAL ANALYSIS OF PRESTRESSED CONCRETE BEAMS USING FLEXURAL CONSTITUTIVE MODEL." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 9, no. 4 (December 31, 2003): 280–83. http://dx.doi.org/10.3846/13923730.2003.10531340.
Анотація:
In this paper, an attempt has been made to extend application of the recently proposed Flexural constitutive model to short-term deformational analysis of flexural prestressed concrete members. The relationship of tensile concrete is based on smeared crack approach and accumulates cracking and the tension stiffening effects. The Flexural constitutive model was applied in a simple engineering technique based on principles of strength of materials and the layered approach. To assess accuracy of the technique, deflections have been calculated for experimental prestressed concrete beams reported in the literature. Comparison has been earned out with the predictions of the well-known design code methods of different countries.
12
Samir, Peter, and George Morcous. "Precast Prestressed Concrete Truss-Girder for Roof Applications." Journal of Structures 2014 (December 14, 2014): 1–13. http://dx.doi.org/10.1155/2014/524156.
Анотація:
Steel trusses are the most popular system for supporting long-span roofs in commercial buildings, such as warehouses and aircraft hangars. There are several advantages of steel trusses, such as lightweight, ease of handling and erection, and geometric flexibility. However, they have some drawbacks, such as high material and maintenance cost, and low fire resistance. In this paper, a precast concrete truss is proposed as an alternative to steel trusses for spans up to 48 m (160 ft) without intermediate supports. The proposed design is easy to produce and has lower construction and maintenance costs than steel trusses. The truss consists of two segments that are formed using standard bridge girder forms with block-outs in the web which result in having diagonals and vertical members and reduces girder weight. The two segments are then connected using a wet joint and post-tensioned longitudinally to form a crowned truss. The proposed design optimizes the truss-girder member locations, cross-sections, and material use. A 9 m (30 ft) long truss specimen is constructed using self-consolidated concrete to investigate the constructability and structural capacity of the proposed design. A finite element analysis of the specimen is conducted to investigate stresses at truss diagonals, verticals, and connections. Testing results indicate the production and structural efficiency of the developed system.
13
Jo, Byung-Wan, Yunn-Ju Byun, and Ghi-Ho Tae. "Structural behavior of cable anchorage zones in prestressed concrete cable-stayed bridge." Canadian Journal of Civil Engineering 29, no. 1 (February 1, 2002): 171–80. http://dx.doi.org/10.1139/l01-087.
Анотація:
Since the cable anchorage zone in a prestressed concrete cable-stayed bridge is subjected to a large amount of concentrated tendon force, it shows very complicated stress distributions which can cause serious local cracks. Accordingly, it is necessary to investigate the parameters affecting the stress distribution, such as the cable inclination, the position of the anchor plate, the modeling method, and three-dimensional effects. The tensile stress distribution in the anchorage zone is compared to the actual design condition by varing the stiffness of spring elements in the local modeling, and an appropriate position for the anchor plate is determined. The results provide elementary data for the stress state in the anchorage zones and encourage more efficient designs.Key words: finite element analysis, bursting stress, spalling stress, cable anchorage zone, cable-stayed bridge.
14
Zhang, Guanhua, Jiawei Wang, Jinliang Liu, Yanmin Jia, and Jigang Han. "Analysis of loss in flexural stiffness of in-service prestressed hollow plate beam." International Journal of Structural Integrity 10, no. 4 (August 12, 2019): 534–47. http://dx.doi.org/10.1108/ijsi-09-2018-0055.
Анотація:
Purpose During service, cracks are caused in prestressed concrete beams owing to overload or other non-load factors. These cracks significantly affect the safety of bridge structures. The purpose of this paper is to carry out a non-linear iterative calculation for a section of a prestressed concrete beam and obtain the change in stiffness after the section cracks. Design/methodology/approach The existing stress of prestressed reinforcement was measured by performing a boring stress release test on two pieces of an in-service 16 m prestressed concrete hollow plate. Considering the non-linear effects of materials, the calculation model of the loss in the flexural stiffness of the prestressed concrete beam was established based on the existing prestress. The accuracy of the non-linear calculation method and the results obtained for the section were verified by conducting a bending destruction test on two pieces of the 16 m prestressed concrete hollow plate in the same batch and by utilising the measured strain and displacement data on the concrete at the top edge of the midspan section under all load levels. Findings The flexural stiffness of the section decreases rapidly at first and then gradually, and structural rigidity is sensitive to the initial cracking of the beam. The method for calculating the loss in the flexural stiffness of the section established with the existing stress of prestressed reinforcement as a parameter is accurate and feasible. It realizes the possibility of assessing the loss in the rigidity of a prestressed concrete structure by adopting the existing stress of prestressed reinforcement as a parameter. Originality/value A method for quickly determining the loss in the stiffness of structures using existing prestress is established. By employing this method, engineers can rapidly determine whether a bridge is dangerous or not without performing a loading test. Thus, this method not only ensures the safety of human life, but also reduces the cost of testing.
15
Mantawy, Islam M., Conner Rusch, Sushil Ghimire, Lucas Lantz, Hari Dhamala, Bipesh Shrestha, Anthony Lampert, et al. "Bridging the Gap between Academia and Practice: Project-Based Class for Prestressed Concrete Applications." Education Sciences 9, no. 3 (July 6, 2019): 176. http://dx.doi.org/10.3390/educsci9030176.
Анотація:
Educational approaches in structural engineering have focused on classical methods for solving problems with manual calculations through assignments, quizzes, and exams. The use of computational software to apply the learned knowledge has been ignored for decades. This paper describes an educational approach to tackle the lack of applicable practical exercises in the structural engineering class “CE 506-Prestressed Concrete” at a university in the western United States during the spring of 2017. The class was designed to provide students with the theoretical concepts of prestressed concrete and the ability to interpret applicable design codes. In their project, students continued to build this knowledge by designing a prestressed bridge superstructure according to a unique state design manual. Students prepared a literature review of their selected state in the U.S.A. and used commercial software to perform an analysis and design of their bridge. Additionally, students were asked to backcheck their design using theoretical methods through manual calculations. By the end of the class, students presented their projects in a head-to-head presentation format, to contrast the differences between their designs in a competitive style. This paper summarizes the class structure, the outcome of the design project, and recommendations for future applications of computer technology in structural engineering education.
16
Morgun, L. V., A. Yu Bogatina, and V. N. Morgun. "MATERIALS AND MODERN STRUCTURAL SOLUTIONS FOR BUILDING STRUCTURES." Herald of Dagestan State Technical University. Technical Sciences 46, no. 4 (January 2, 2020): 167–75. http://dx.doi.org/10.21822/2073-6185-2019-46-4-167-175.
Анотація:
Objectives. The aim of the work is to demonstrate the fundamental difference between fibre-reinforced foam concrete and traditionally-used wall materials in terms of tensile strength.Method. An analysis of the effectiveness of heat-insulating and structural fibre-reinforced concrete in terms of their mechanical and physical properties, including frost resistance, is carried out.Results. The characteristics of the most important operational properties of fibre-reinforced foam concrete for insulating and structural purposes are given. The possibility of expanding the range of prefabricated products in connection with the level of tensile strength of fibre-reinforced foam concrete under bending is substantiated. Empirical data concerning the practical use of original products from fibrereinforced foam concrete in the construction of residential and public buildings in Rostov-on-Don is presented.Conclusion. It is shown that, in order to increase the heat transfer resistance of building envelopes, the use of fibre-reinforced foam concrete in the rehabilitation of existing buildings can ensure their high fire safety subject to the required sanitary and hygienic conditions. Fibre-reinforced foam concrete, being a gas-filled concrete of non-autoclave hardening, allows new design solutions to be offered for heat-insulating and structural purposes in the construction complex of the Russian Federation, which practical application expands the range of factory-made products, reduces energy consumption and contributes to the diversity of the architectural appearance of buildings.
17
Kim, Yail J., Mark F. Green, and R. Gordon Wight. "Flexural behaviour of reinforced or prestressed concrete beams including strengthening with prestressed carbon fibre reinforced polymer sheets: application of a fracture mechanics approach." Canadian Journal of Civil Engineering 34, no. 5 (May 1, 2007): 664–77. http://dx.doi.org/10.1139/l06-161.
Анотація:
This paper describes the application of a fracture mechanics model (Hillerborg 1990) to concrete structures, including strengthening with prestressed carbon fibre reinforced polymer (CFRP) sheets. One benefit of the proposed fracture mechanics model, consisting of a unique combined stress–strain response of concrete, is that it includes the size effect of reinforced concrete beams; however, its application and validation have not been fully investigated. The proposed model is reviewed and further developed to cover prestressed concrete beams including a beam strengthened with a prestressed CFRP sheet. To evaluate the model, various approaches such as finite element analysis, a strength-based model, a conventional design method, and experimental results are compared with the fracture mechanics model. The size-dependent parameter (ε1) significantly affects the predicted behaviour of reinforced or prestressed concrete beams, depending on the contribution of reinforcement. Based on the current assessment, ε1 = 0.005 is recommended as an upper limit for normal strength concrete.Key words: carbon fibre reinforced polymer sheet, flexure, fracture mechanics, prestressed concrete beam, reinforced concrete beam, strengthening, size effect.
18
Nowak, Andrzej S., and Hid N. Grouni. "Calibration of the Ontario Highway Bridge Design Code 1991 edition." Canadian Journal of Civil Engineering 21, no. 1 (February 1, 1994): 25–35. http://dx.doi.org/10.1139/l94-003.
Анотація:
The paper describes the calculation of load and resistance factors for the Ontario Highway Bridge Design Code (OHBDC) 1991 edition. The work involved the development of load and resistance models, the selection of the reliability analysis method, and the calculation of the reliability indices. The statistical models for load and resistance are reviewed. The considered load components include dead load, live load, and dynamic load. Resistance models are developed for girder bridges (steel, reinforced concrete, and prestressed concrete). A reliability analysis is performed for selected representative structures. Reliability indices are calculated using an iterative procedure. The calculations are performed for bridge girders designed using OHBDC 1983 edition. The resulting reliability indices are between 3 and 4 for steel girders and reinforced concrete T-beams, and between 3.5 and 5 for prestressed concrete girders. Lower values are observed for shorter spans (up to 30–40 m). The acceptance criterion in the selection of load and resistance factors is closeness to the target reliability level. The analysis confirmed the need to increase the design live load for shorter spans. Partial resistance factors are considered for steel and concrete. The criteria for the evaluation of existing bridges are based on the reliability analysis and economic considerations. Key words: bridge code, calibration, load factor, resistance factor, reliability index.
19
Rogers, Brandy J., and David V. Jáuregui. "Load Rating of Prestressed Concrete Girder Bridges." Transportation Research Record: Journal of the Transportation Research Board 1928, no. 1 (January 2005): 53–63. http://dx.doi.org/10.1177/0361198105192800106.
Анотація:
In light of the adoption of the load and resistance factor design (LRFD) philosophy by the AASHTO Subcommittee on Bridges and Structures, research efforts are under way to facilitate the transition from load factor rating (LFR) to load and resistance factor rating (LRFR) in New Mexico. Five prestressed concrete girder bridges, courtesy of the New Mexico bridge inventory, were rated with the BRASS-GIRDER and BRASS-GIRDER (LRFD) structural software. The objectives for this study were to evaluate and verify the BRASS (bridge rating and analysis of structural systems) software, to identify the source of dissension between LFR and LRFR rating factors, and to examine any trends in the rating factors as affected by bridge geometry. The comparison of LFR and LRFR focused on both flexure and shear for the strength limit state. The LRFR method generally yielded lower rating factors for flexure, with the longer-span bridges demonstrating a larger deviation between LFR and LRFR. The live load effects were identified as the major factor contributing to the difference in flexure ratings; the dead load effects and flexural resistance had little effect. The LRFR rating factors for shear also were generally lower than those produced by LFR. The discrepancy in the shear ratings was caused by both the live load effects and shear resistance. The dead load effects contributed little to the variation in LFR and LRFR rating factors for shear. Overall, the shear ratings controlled over those based on flexure.
20
Novák, Drahomír, Lukáš Novák, and Ondřej Slowik. "Probabilistic modelling of prestressed concrete roof girders." MATEC Web of Conferences 310 (2020): 00055. http://dx.doi.org/10.1051/matecconf/202031000055.
Анотація:
The paper describes several parts of complex stochastic modelling of precast prestressed concrete girders failing in shear. Experimental studies have been performed on scaled elements as well as on full-scale girders. These tests serve as basis for developing the deterministic nonlinear model and subsequent probabilistic assessment of structural resistance. The combination of nonlinear finite element method and probabilistic analysis is a strong tool for the realistic modelling of structures, but it is extremely time consuming, especially when 3D nonlinear model with many input random parameters is analysed. Therefore, sensitivity analyses have been performed and a surrogate model has been developed. Safety formats are utilized and compared with fully probabilistic approach to determine design value of ultimate capacity of girders.
21
Han, Sun-Jin, Jae-Hoon Jeong, Hyo-Eun Joo, Seung-Ho Choi, Seokdong Choi, and Kang Su Kim. "Flexural and Shear Performance of Prestressed Composite Slabs with Inverted Multi-Ribs." Applied Sciences 9, no. 22 (November 17, 2019): 4946. http://dx.doi.org/10.3390/app9224946.
Анотація:
Half precast concrete slabs with inverted multi-ribs (Joint Advanced Slab, JAS), which enhance composite performance between slabs by introducing shear keys at connections between the slabs and improve structural performance by placing prestressing tendons and truss-type shear reinforcements, have recently been developed and applied in many construction fields. In this study, flexural and shear tests were performed to verify the structural performance of JAS members. Towards this end, two flexural specimens and four shear specimens were fabricated, and the presence of cast-in-place concrete and the location of the critical section were set as the main test variables. In addition, the flexural and shear performance of the JAS was quantitatively evaluated using a non-linear flexural analysis model and current structural design codes. Evaluation results confirmed that the flexural behavior of the JAS was almost similar to the behavior simulated through the non-linear flexural analysis model, and the shear performance of the JAS can also be estimated appropriately by using the shear strength equations presented in the current design codes. For the JAS with cast-in-place concrete, however, the shear strength estimation results differed significantly depending on the way that the shear contributions of the precast concrete unit and cast-in-place concrete were calculated. Based on the analysis results, this study proposed a design method that can reasonably estimate the shear strength of the composite JAS.
22
Tuomala, Markku, Kim Calonius, Arja Saarenheimo, and Pekka Välikangas. "Hard Missile Impact on Prestressed Shear Reinforced Slab." Journal of Disaster Research 5, no. 4 (August 1, 2010): 437–51. http://dx.doi.org/10.20965/jdr.2010.p0437.
Анотація:
The protective concrete walls of nuclear power plants must withstand accidental or intentional missile impact, and structural systems and solutions are being developed in building frameworks and detailed levels requiring sophisticated tools for different design phases such as detailing shear reinforcement. Numerical methods, for example, have been developed and used for predicting prestressed shear reinforced concrete structures response subjected to hard projectile impact. The structural behavior of prestressed impact-loaded walls is predicted analytically and by using nonlinear FE models. Analysis predicts damage mechanisms such as crater formation, penetration, shear cone formation, and perforation. To produce experimental data required to verify the accuracy of numerical models, an experimental setup has been developed at the Technical Research Center of Finland (VTT) for intermediate-scale impact testing enabling force-plate testing with soft missiles and concrete slab impact testing.
23
Yu, Tong-Hua. "Concrete trussed arch bridges in China." Canadian Journal of Civil Engineering 14, no. 6 (December 1, 1987): 820–27. http://dx.doi.org/10.1139/l87-120.
Анотація:
In this paper, the following points are presented: the valuable advantages of the concrete trussed arch bridge; the design consideration and simplified analysis of the bridge; the level of secondary stresses induced in the ends of truss members; the application of prestress to tensile members and bending sections of trusses; and different ways of construction of the bridge.A five-span prestressed concrete trussed arch bridge named the Zhushanlu Road Bridge at Jingdezhen City, Jiangxi Province, is described as an example of medium span bridges of the type popularly adopted in Chinese highway system and the municipal construction since the late sixties. Key words: prestressed concrete, hinged truss, thrust, secondary stress, anchorage, pretensioning, precast.
24
Liu, Shuo, Yi Zhang, Jun Shi, and Baisong Yang. "Internal Forces Analysis of Prestressed Concrete Box Girder Bridge by Using Structural Stressing State Theory." Materials 14, no. 16 (August 19, 2021): 4671. http://dx.doi.org/10.3390/ma14164671.
Анотація:
This paper analyzes the working behavior characteristics of a prestressed concrete transverse large cantilever continuous (PCTLCC) box girder bridge model based on structural stressing state theory and the numerical shape function (NSF) method. At first, the normalized generalized strain energy density (GSED) is established to model the stressing state of the bridge model. Subsequently, the Mann Kendall (M–K) criterion is applied to detect three characteristic loads, respectively, elastic–plastic branch load P (200 kN), failure load Q (300 kN), and progressive failure load H (340 kN), and the failure load Q is found to be the starting load of the damage process of the bridge model, rather than the ultimate load where the structure has been destroyed. Finally, the NSF method is adopted to interpolate the test data, and a detailed analysis for the variation characteristics of the working behavior of the bridge model under loads is performed based on the interpolation results. The characteristic load detection method and experimental data extension method for PCTLCC box girder bridge established in this study can provide valuable references for the design and analysis of such bridges.
25
Kim, Hyun-Gi, and Bum-Joon Kim. "Design Optimization of Conical Concrete Support Structure for Offshore Wind Turbine." Energies 13, no. 18 (September 17, 2020): 4876. http://dx.doi.org/10.3390/en13184876.
Анотація:
Various types of support structures for offshore wind turbine have been developed, and concrete structures have attracted attention due to many advantages. Although many studies have been conducted on the design of the existing steel structures, information and research on the design of concrete support structures are insufficient. Therefore, in this paper, a structural analysis model of conical concrete support structure (CCSS) is established and design optimization is presented. A detailed performance evaluation and the design of prestressed concrete were performed under the marine conditions of Phase 1 test site of southwest offshore wind project in Korea. The fluid–soil–structure interaction (FSI) was applied using the added mass method and soil spring model to represent the effects of water and soil. With the result of quasi-static analysis, a post-tensioning design was implemented by applying prestressing steel, and CCSS showed sufficient rigidity. From the natural frequency analysis, CCSS has a dynamic structural stability, and, in response spectrum and time-history analyses, the CCSS was safe enough under the earthquake loads. The methods and conclusions of this study can provide a theoretical reference for the structural analysis and design of concrete support structures for offshore wind turbines.
26
Wang, Jiawei, Jinliang Liu, Guanhua Zhang, and Yanmin Jia. "Method for computing the shear capacity of prestressed reinforced concrete beams based on truss-arch model." International Journal of Structural Integrity 9, no. 5 (October 1, 2018): 574–86. http://dx.doi.org/10.1108/ijsi-09-2017-0052.
Анотація:
Purpose The calculation of the shear capacity of inclined section for prestressed reinforced concrete beams is an important topic in the design of concrete members. The purpose of this paper, based on the truss-arch model, is to analyze the shear mechanism in prestressed reinforced concrete beams and establish the calculation formula for shear capacity. Design/methodology/approach Considering the effect of the prestressed reinforcement axial force on the angle of the diagonal struts and regression coefficient of softening cocalculation of shear capacity is established. According to the shape of the cracks of prestressed reinforced concrete beams under shear compression failure, the tie-arch model for the calculation of shear capacity is established. Shear-failure-test beam results are collected to verify the established formula for shear bearing capacity. Findings Through theoretical analysis and experimental beam verification, it is confirmed in this study that the truss-arch model can be used to analyze the shear mechanism of prestressed reinforced concrete members accurately. The calculation formula for the angle of the diagonal struts chosen by considering the effect of prestress is accurate. The relationship between the softening coefficient of concrete and strength of concrete that is established is correct. Considering the effect of the destruction of beam shear plasticity of the concrete on the surface crack shape, the tie-arch model, which is established where the arch axis is parabolic, is applicable. Originality/value The formula for shear capacity of prestressed reinforced concrete beams based on this theoretical model can guarantee the effectiveness of the calculation results when the structural properties vary significantly. Engineers can calculate the parameters of prestressed reinforced concrete beams by using the shear capacity calculation formula proposed in this paper.
27
Nathan, Noel D. "Rational Analysis and Design of Prestressed Concrete Beam Columns and Wall Panels." PCI Journal 30, no. 3 (May 1, 1985): 82–133. http://dx.doi.org/10.15554/pcij.05011985.82.133.
28
Lee, Byoung-Jun, and Stephen Pessiki. "Design and Analysis of Precast, Prestressed Concrete, Three - Wythe Sandwich Wall Panels." PCI Journal 52, no. 4 (July 1, 2007): 70–83. http://dx.doi.org/10.15554/pcij.07012007.70.83.
29
Selvachandran, P., S. Anandakumar, and K. L. Muthuramu. "Deflection Behavior of Prestressed Concrete Beam using Fiber Reinforced Polymer (FRP) Tendon." Open Civil Engineering Journal 10, no. 1 (February 29, 2016): 40–60. http://dx.doi.org/10.2174/1874149501610010040.
Анотація:
The application of prestressing steel is restricted in highly corrosive environment area. The behavior of structure changes due to corrosion of prestressing steel, which leads to reduction in strength and it may cause sudden failure. There are many research recommendations to resist corrosion of steel, however the durability of structure shall not be ensured during service life of structure. Fiber Reinforced Polymer (FRP) Tendon is considered as an alternate material due to its corrosive resistance property and high strength. An experimental and numerical analysis carried out to study the deflection behavior of FRP tendon prestressed beam and recommended design guidelines. There are four beam specimens casted and tested in laboratory and 51 experimental results collected from research article to carry out numerical study. The ACI, 2011 [1] recommended generalized deflection calculation for beam by softening the effective moment of inertia curve and also introduced the effect of shift of neutral axis once the member exceeds cracking stress of concrete. Based on experimental and numerical analysis study it is concluded that, the deflection behavior of FRP tendon beam depends on deformability of material, degree of prestressing and bond strength. Design chart proposed for calculation of effective moment of inertia and effective neutral axis distance with respect to deformability index. The error percentage of deflec-tion values as per ACI 2011, is about 10 to 20% has reduced to less than 5% in the proposed method.
30
Li, Hong Jiang, Da Yi Lu, and Qi Feng Wang. "Analysis on Stiff Frame in Replacement of Closure Segment for Prestressed Concrete Cable-Stayed Bridges." Applied Mechanics and Materials 351-352 (August 2013): 1423–31. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.1423.
Анотація:
Stiff frame was the important structural member in construction of replacement of closure segment for prestressed concrete cable-stayed bridges. To establish the design calculation method of it and reveal its variation of internal forces with construction stages of replacement, some configurations and its working process of stiff frame was introduced. Based on construction stage analysis of replacement, calculation methods of its strength and stability were given. Through FEM results, influence of stiff frame to structural dynamic property and global stability of whole bridge were described. Analysis results showed, it was appropriate to consider each section steel of stiff frame as eccentric compression member. During construction, the transversal global property of stiff frame and the security of its link with main girder must be valued. Construction results also proved, the theoretical calculation method could reflect the actual structural state of stiff frame, and its result was conservative. Analysis on stiff frame was an important part of replacement of closure segment, and could provide ways and references for construction control of replacement of closure segment.
31
Park, Young-Ha, Moon-Young Kim, Jong-Myen Park, and Se-Jin Jeon. "An Improved Equation for Predicting Compressive Stress in Posttensioned Anchorage Zone." Advances in Civil Engineering 2020 (February 28, 2020): 1–12. http://dx.doi.org/10.1155/2020/5635060.
Анотація:
Validity of the approximate equation for predicting compressive stress in the posttensioned anchorage zone presented in the AASHTO LRFD Bridge Design Specifications was investigated in this study. Numerical analysis based on the finite element method (FEM) and theoretical analysis showed that the AASHTO formula gives relatively accurate stress values when the effect of duct holes is neglected. However, it was found that the formula can significantly overestimate the stresses in the actual prestressed concrete member with spaces occupied by ducts. Therefore, an improved equation was proposed for the existing AASHTO equation to consider the effect of the duct holes on the stress distribution. This resulted in relatively accurate prediction of the distribution and magnitude of the compressive stresses even with the presence of the duct holes. The proposed equation was also validated by comparing with the stresses measured in the test of a posttensioned full-scale specimen. This study is expected to contribute to the design of the anchorage zone in prestressed concrete structures by suggesting a more reasonable way to assess the appropriateness of anchorage devices.
32
Yang, Jiang Hui, and Gong Sheng Yang. "The Temperature Field Research for Large LNG Cryogenic Storage Tank Wall." Applied Mechanics and Materials 668-669 (October 2014): 733–36. http://dx.doi.org/10.4028/www.scientific.net/amm.668-669.733.
Анотація:
According to the structural characteristic of LNG cryogenic storage tank concrete prestressed wall and heat transfer theory, the paper obtain the calculation formula of the temperature field distribution, emphasis studying the heat flux distribution along the radial and axial and node temperature distribution of the section nodes for a 160,000 m3 capacity LNG cryogenic tank by ABAQUS. The paper also establish a set of method which is suitable for the temperature field analysis, proof the feasibility of finite element analysis technique in the analysis of the LNG cryogenic storage tank, and have a certain reference for the prestressed concrete walls and insulation layer design of the large LNG storage tank.
33
Mante, David M., Robert W. Barnes, Levent Isbiliroglu, Andric Hofrichter, and Anton K. Schindler. "Effective Strategies for Improving Camber Predictions in Precast, Prestressed Concrete Bridge Girders." Transportation Research Record: Journal of the Transportation Research Board 2673, no. 3 (March 2019): 342–54. http://dx.doi.org/10.1177/0361198119833965.
Анотація:
In order to limit construction conflicts in bridges with precast, prestressed concrete girders, it is essential that designers are able to predict midspan girder camber with sufficient accuracy at key stages. This paper describes a study of the effectiveness of various strategies for improving camber predictions when compared with field-measured values from actual bridge girders produced in the southeastern United States. The study also incorporated concrete materials data from nearly 2000 girder production cycles among four regional producers, in addition to a laboratory study of mechanical and time-dependent properties of representative concrete mixtures. A standard incremental time-step analysis software was developed and utilized for the parametric study included in this work. For the girder production cycles monitored in this study, the use of regionally calibrated prediction models for material properties (concrete compressive strength, modulus of elasticity, creep, and shrinkage) resulted in the elimination of approximately 80% of the prediction error associated with current camber prediction practices within the region. As compared with a mean overprediction error of 68% for current design practice, implementation of calibrated prediction models reduced the mean overprediction to approximately 10%. The most effective prediction improvement techniques were determined to be reliance on expected rather than specified concrete compressive strength, the use of an appropriate aggregate correction factor for modulus of elasticity computations, and the use of an incremental time-step analysis method incorporating AASHTO Load and Resistance Factor Design (LRFD) or International Federation for Structural Concrete ( fib) Model Code 2010 creep and shrinkage prediction equations.
34
Ronghe, G. N., and L. M. Gupta. "Parametric Study of Tendon Profiles in Prestressed Steel Plate Girder." Advances in Structural Engineering 5, no. 2 (April 2002): 75–85. http://dx.doi.org/10.1260/1369433021502579.
Анотація:
The concept of prestressing steel structures has only recently been widely considered, despite a long and successful history of prestressing concrete members. Several analytical studies of prestressed steel plate girder were reported in the literature, but much of that work was not studied with reference to different parameters like tendon profile, eccentricity, partial span to full span ratio, prestressing force, load carrying capacity etc. associated with prestressing. This paper examines analytically a comparative study of various tendon configurations and prestressing parameters on over all analysis and design of prestressed steel plate girder. The output from the computer Program for analysis and design of steel plate girder prestressed with different tendon configurations are compared among each other. As a Case-study, a prototype model of Prestressed Steel Testing Frame with straight tendon has been designed, constructed and tested in the laboratory for its safe load carrying capacity and maximum deflection.
35
Hassanain, Mostafa A., and Robert E. Loov. "Cost optimization of concrete bridge infrastructure." Canadian Journal of Civil Engineering 30, no. 5 (October 1, 2003): 841–49. http://dx.doi.org/10.1139/l03-045.
Анотація:
Recent surveys have indicated that between 30% and 40% of all bridges in North America are in various states of deterioration. Funding is limited owing to the existence of other deficient components of the transportation infrastructure. It is clear, therefore, that the return on the available funding needs to be maximized. This paper presents a review of publications on cost optimization of concrete bridge components and systems and then continues with a review of the state-of-the-art in life-cycle cost (LCC) analysis and design of concrete bridges. The main objective of the paper is to encourage bridge engineers to move towards the increased use of advanced analysis and design optimization methods.Key words: bridge, concrete, cost, high-performance concrete, infrastructure, life-cycle cost, optimization, prestressed girders, reliability.
36
Chyzhov, Sergey, Yekaterina Shestakova, Elbek Yakhshiyev, and Anatoliy Antonyuk. "Design principles of prestressed concrete span coponents in the process of despersed reinforcement." Proceedings of Petersburg Transport University, no. 2 (June 20, 2017): 343–53. http://dx.doi.org/10.20295/1815-588x-2017-2-343-353.
Анотація:
Objective: To determine the calculating justification methods of fibre-reinforced spans and scientific evidence of the structural method of dispersed reinforced concrete constructions in drily-hot climate for high-speed mainline railroads, to reveal advantages connected with fibre application in the process of construction, to determine the ways of total costs reduction while providing qualitative reliability characteristics of spans under construction. Methods: Comparative analysis, mathematical modeling. Results: Calculating principles of fibre-reinforced elements of spans were specified. The study was aimed at application solving, with regard to climate in Uzbekistan, and determined the parameters of Lр = 66 m fibre-reinforced concrete span, specified by the objective of scientific study concerning the bridgework for high-speed mainline railroad. Practical importance: Methodological foundation for fibre-reinforced concrete spans calculation was developed.
37
Novak, Drahomir, David Lehky, Ondrej Slowik, and Ladislav Routil. "From Fracture Experiments to Advanced Design and Assessment of Precast Structural Members." Applied Mechanics and Materials 837 (June 2016): 167–74. http://dx.doi.org/10.4028/www.scientific.net/amm.837.167.
Анотація:
An objective reliability analysis of structural members made of advanced cementitious composites must be based on good knowledge of stochastic properties of individual mechanical fracture parameters of utilized material models. The article presents a comprehensive approach to the design and assessment of precast structural elements including: The series of fracture tests of the two concrete mixtures with various ages in two configurations (three point bending and wedge splitting test, subsequent identification of material parameters using effective crack model, work of fracture method and artificial neural networks, execution of destructive tests of scaled structural members and creation of deterministic models of these tests using collected data. In subsequent phases of the project reliability analysis of tested beams will be carried out in order to obtain stochastic parameters of structural response of prestressed elements to shear load. The obtained data will be used to calibrate the analytical equation describing the response of element exposed to both normal and shear forces. The entire process will be concluded by reliability-based optimization of manufactured components.
38
Ghali, Amin, Mamdouh Elbadry, and Sami Megally. "Two-year deflections of the Confederation Bridge." Canadian Journal of Civil Engineering 27, no. 6 (December 1, 2000): 1139–49. http://dx.doi.org/10.1139/l00-050.
Анотація:
A comprehensive research program is currently in progress to monitor and study the behavior and performance of the Confederation Bridge. Part of this program is on monitoring short- and long-term deflections to evaluate the deflection prediction techniques employed in the design of concrete structures in general and this bridge in particular. The investigation comprises measurements of parameters related to the materials used in the bridge. This paper presents some field measurements of vertical deflection as well as the results of computer analysis. Short-term deflections are measured at the time of installation of precast units and also in truck-loading tests. After completion of construction, the deflections are measured at specified intervals. The last readings reported in this paper have been taken 27 months after completion of construction. The computer program CPF (Cracked Plane Frames in prestressed concrete) is employed for analysis of the monitored part of the Confederation Bridge. The bridge is modeled as a plane frame in which the nonprestressed and prestressed steels are considered. Several analyses are performed employing the actual time-dependent concrete properties measured in the field and those calculated from the ACI Committee 209 equations and CEB-FIP Model Code. Comparisons are made between the measured and the predicted deflections. The predicted deflections are found to be in close agreement with the measured values, which indicates that the deflection prediction techniques used in design of this bridge are adequate.Key words: computer analysis, concrete bridges, Confederation Bridge, creep, deflections, field measurements, long-term, prestressed steel, segmental construction, short-term, shrinkage, time-dependent.
39
Balevičius, Robertas, and Eugedijus Dulinskas. "EVALUATION OF CONCRETE LINEAR CREEP IN DETERMINATION OF STRESS STATE AND STEEL PRESTRESS LOSSES IN CONCRETE MEMBERS/BETONO TIESINIO VALKŠNUMO ĮVERTINIMAS, NUSTATANT GELŽBETONINIŲ ELEMENTŲ ĮTEMPIMŲ BŪVĮ IR ARMATŪROS IŠANKSTINIO ĮTEMPIMO NUOSTOLIUS." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 5, no. 6 (December 31, 1999): 364–73. http://dx.doi.org/10.3846/13921525.1999.10531491.
Анотація:
Determination of stress-strain state imposed by concrete linear creep and specification of steel prestress losses in linear prestressed concrete member is discussed in this article. Particularities of regulations of the Code acting in Lithuania [1] and of Eurocode [2] are analysed and a modified method for calculation of steel prestress losses due to concrete linear creep in prestressed concrete linear members suitable for assessment of Code regulations is presented. Also, the method is used for analysis of results of long-term tests of reinforced concrete members. In Lithuania, a code based on investigations of prestressed concrete members is used for calculation of steel prestress losses due to concrete creep. Therefore calculation of losses is associated with stress-strain state of the member in time t in empirical way only and time dependent stress-strain state is adjusted by additional coefficients to take into consideration concrete creep. Analogous calculations of steel prestress losses by Eurocode are presented in a more general form and are based on creep theory. It is clear that in the first [1] and the second [2] cases the same change in stress-state is evaluated by different parameters. Therefore it is important to create a general method based on concrete creep characteristics. General case of eccentrically reinforced prestressed concrete linear member under the action of prestressing forces changing with time in relation to prestress losses due to concrete creep is analysed (Fig 1). Stress-strain time dependent state of such member with the changing concrete stress σ b (t) and σ′ b (t) is determined using well-known equations of equilibrium (1–4) and integral differential equations (7–8) for evaluation of concrete creep deformations [4–8]. These equations are solved by numerical method (9–10) dividing time period considered in intervals. In reference [9] a more particular solution method evaluating variation of interval magnitude in relation to accuracy of solution is presented. In such a way it is possible to assess reduction of concrete stress (13–14) at time moment t when loss of steel prestress due to concrete creep takes place (33–34). There are many experiments performed for investigating concrete creep and determinating time dependent stress-strain state of reinforced concrete members. Various methods are applied for analysis of these data. Assumptions of these methods influence the conclusions of the analysis. In this article there is presented a general method giving opportunity to assess creep of concrete members by the same characteristics, when specific creep (51) or coefficient of creep (52) is determined by tests on eccentrically prestressed linear members (the case of axially prestressed members is presented in [9]). Pure specific creep C* (t,t 0) values determined according to the method proposed in this article and results of experimental investigations [12] of prestress in steel of eccentrically prestressed concrete members and also according to data of analysis [11] of the Code [1] are presented in Fig 2. Using the same creep characteristics method of the Code EC-2 and proposed in this article losses of prestress in steel due to concrete creep were calculated according to EC-2 and the method proposed. Values of these losses and their ratio are presented in Fig 3 and 4. In Fig 5, losses of prestress in steel due to creep predicted after 70 years were calculated in accordance with data of the Code SNiP [1] analysis [11] and regulations of the Code EC-2 [2]. Relationships (62) including (63), (64) formulas are modified EC-2 method for regulation of steel prestress loss due to concrete creep calculation for doubly reinforced members are proposed in the article. Results of analysis of regulations of Eurocode EC-2 and the Code SNiP indicate that design according to Code [2] method for steel prestress loss due concrete creep calculation in all cases gives increased values of stiffness and crack resistance characteristics of the structure, but larger amount of steel is to be used in comparison with the design according to SNiP [1].
40
Li, Xi, Ting Ting Cai, and An Bang Gu. "Test Study on the Influence of Periodical Temperature Stress on the Loss of Structural Prestress." Applied Mechanics and Materials 178-181 (May 2012): 2561–64. http://dx.doi.org/10.4028/www.scientific.net/amm.178-181.2561.
Анотація:
In order to study the prestress loss of the periodical temperature stress on the structure, this test has carried out the temperature stress analysis of 4-piece prestressed rectangular columns. The test takes Baiguodu Bridge in Chongqing Municipality as the supporting engineering to simulate the continuous effect of annual temperature change, for the measurement of prestress loss of the concrete structure. The study has shown that: prestress loss from periodical temperature change exists, and in the present, the design has insufficient estimation on this loss.
41
Li, Dongning, Marc A. Maes, and Walter H. Dilger. "Thermal design criteria for deep prestressed concrete girders based on data from Confederation Bridge." Canadian Journal of Civil Engineering 31, no. 5 (October 1, 2004): 813–25. http://dx.doi.org/10.1139/l04-041.
Анотація:
The evaluation of temperature data recorded on the world's longest bridge built over ice-covered water is presented. The data in question are the hourly recorded temperatures in three girder sections with variable geometry and ambient temperature, solar radiation, and wind speed measured on site from 1998 to 2000. The data were first carefully screened, and problematic records were identified and repaired. The temperatures were then spatially reduced to a set of thermal variables including average, differential, and residual temperatures. Extreme value analysis was performed to obtain 100 year return thermal loads. The results are compared with the provisions in the Canadian highway bridge design code (CAN/CSA-S6-00) and the original design temperatures for the bridge. Temperature distributions for maximum positive vertical differential temperatures during the recording period are plotted for the three girder sections. The observed unrestrained curvatures and nonlinear stresses are compared with those estimated by the Priestley model. Modifications are found to be necessary for extremely deep cross sections.Key words: concrete bridge, thermal response, statistical evaluation, average temperature, differential temperature, curvature, stress.
42
Wang, De Ling, and Jiang Hai Shen. "The Application of CAD Technology on the Design of Reinforced and Prestressed Counterforce Wall System." Advanced Materials Research 214 (February 2011): 397–401. http://dx.doi.org/10.4028/www.scientific.net/amr.214.397.
Анотація:
The counterforce wall and pedestral is a complex system. Computer aided design technology is used to design and analyze this reinforced and prestressed concrete structure. Firstly CAD design program is used to design a representative wall section as a separate component. It helps doing ultimate limit state calculation and serviceability limit state checking computation. The prestress on concrete induced by prestressing steel according to construction method is also computed. Secondly, a finite element program is used to analyze the whole system. The prestress computed by CAD design program is regarded as external load. Simulation technology is also described in this paper. The stress, strain and deformation of the whole prestressed system are calculated and checked. Moreover, dynamic structural analysis is done by finite element program. Then vibration frequencies and modes can be obtained. By combining CAD design with finite element program, this complex system can be designed reasonably and effectively.
43
Jiang, Hai Bo, Yan Song Deng, Yun Qiu, Chun Gen Wei, Li Chen, and Wen Xian Feng. "Numerical Analysis of Mechanical Properties of Precast Segmental Concrete Test Beam with External Tendons." Advanced Materials Research 639-640 (January 2013): 460–69. http://dx.doi.org/10.4028/www.scientific.net/amr.639-640.460.
Анотація:
A finite element model is proposed for numerical analysis of mechanical properties of precast segmental concrete test beam with external tendons. The 3D finite element model of test beam is established by SOLID65 element in ANSYS software, while the dry joint between segments is simulated by contact element, and the attachment between concrete beam and external prestressed tendons is achieved by node coupling method. Numerical simulation analysis reveals structural behavior, stress variations and crack opening cases of joints of the test beam by considering the concrete material and geometric nonlinearity. Influencing factors of the bending mechanical properties of the test beam are researched with different tendon types, secondary effect of external tendons and external tendon slip at deviation. Results of the numerical analysis reveal that the segmental joints are in the compressive state below the 300kN.Crack opening is the key factor of the mechanical properties of the test beam above the 300kN.The results can be used for structural design of precast segmental bridge.
44
Kim, Tae-Hoon. "Hollow precast segmental prestressed concrete bridge columns with a shear resistant connecting element." Canadian Journal of Civil Engineering 44, no. 6 (June 2017): 472–84. http://dx.doi.org/10.1139/cjce-2016-0276.
Анотація:
The purpose of this study was to investigate the performance of hollow precast segmental prestressed concrete (PSC) bridge columns with a shear resistant connecting element. A model of hollow precast segmental PSC bridge columns was tested under a constant axial load and a cyclically reversed horizontal load. The computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology) was used. Non-dimensional P-M interaction diagrams were developed to predict the design resistance of precast segmental PSC bridge columns. Among the numerous parameters, this study concentrates on concrete compressive strength, prestressing reinforcement ratio, effective prestress, diameter of circle passing through tendon centerlines-to-outside diameter of section ratio (Ds/Do) and inside diameter of section-to-outside diameter of section ratio (Di/Do). This study documents the testing of hollow precast segmental PSC bridge columns under cyclic loading and presents conclusions and design recommendations based on the experimental and analytical findings.
45
Wang, Jiawei, Guanhua Zhang, Jinliang Liu, and Yanmin Jia. "Research on destructive test of pretensioning prestressed concrete hollow slab in service." International Journal of Structural Integrity 9, no. 4 (August 13, 2018): 429–41. http://dx.doi.org/10.1108/ijsi-07-2017-0043.
Анотація:
Purpose During service period, the bridge structures will be affected by the environment and load, so the carrying capacity will decline. The purpose of this paper is to research on the bearing capacity of bridge structures with time. Design/methodology/approach Destructive test and non-linear finite element analysis are carried out by utilizing two pretensioning prestressed concrete hollow slabs in service for 20 years; using the structural test deflection value to simulate the stiffness degradation of the service bridge and the finite element calculation results verify the accuracy of the calculation. Findings The flexural rigidity of the main beam when the test beam is destructed is degraded to approximately 20 percent of that before the test, which agrees well with the result of finite element analysis and indicates that the method of deducing the flexural rigidity of the structure according to the measured deflection value can effectively simulate the rigidity degradation law of the bridge in service. The crack resistance property of the test beam degrades obviously and the ultimate bearing capacity of the bending resistance does not degrade obviously. Originality/value The research results truly reflect the destruction process, destructive form, bearing capacity and rigidity degradation law of the old beam of the concrete bridge in service for 20 years and can provide technical basis for optimization design of newly built bridges of the same type and maintenance and reinforcement design of existing old bridges.
46
Shiu, Kwok-Nam, and Henry G. Russell. "Effects of time-dependent concrete properties on prestress losses." Canadian Journal of Civil Engineering 14, no. 5 (October 1, 1987): 649–54. http://dx.doi.org/10.1139/l87-095.
Анотація:
Prestress losses were calculated for a segmental concrete box-girder bridge. Results were based on the time-dependent investigation of the Kishwaukee River Bridge constructed by the balanced cantilever method. Instruments were installed in the bridge during construction to measure the time-dependent deformations. Short- and long-term properties of concrete used in the instrumented segments were measured. With the actual construction schedule and the measured concrete properties, time-dependent nonlinear analyses were performed. Prestress losses were calculated for each construction step. Time-dependent variations of prestress losses during and after construction are presented. Comparisons between design concrete properties and measured values and between analytical prestress losses and design values were made. Key words: mechanical properties, creep properties, shrinkage, prestressing, losses, prestressed concrete bridges, measurement, analysis.
47
Jia, Yu Zhuo, and Li Lin. "Analysis of Two Cross Arm of Reactive Powder Concrete Pole Design with Structure Materials in Civil Engineering." Advanced Materials Research 568 (September 2012): 39–42. http://dx.doi.org/10.4028/www.scientific.net/amr.568.39.
Анотація:
SAP2000 structural analysis software is used to designed two of 500kV partially prestressed reactive powder concrete pole cross arm; moreover, poles of the two cross arm program have been compared. The results show that the triangular truss cross arm has good mechanical properties, improving the main mate’rial of the stress state, the pole reduced height 10m, by the analysis of the structure shows, this cross arm has higher reliability under the operating conditions, which can be used in 500kV transmission line; from economic and technical performance, the pole cost of this program is greatly reduced, while speeding up the construction progress and improving the comprehensive benefits of the poles in the transmission line.
48
Ghali, Amin, Gamil Tadras, and Paul H. Langohr. "Northumberland Strait bridge: analysis techniques and results." Canadian Journal of Civil Engineering 23, no. 1 (February 1, 1996): 86–97. http://dx.doi.org/10.1139/l96-009.
Анотація:
The Northumberland Strait at the Atlantic coast of Canada will be crossed by a 13 km bridge. The major part of the superstructure will consist of 44 spans, each of length 250 m and a box cross section of variable depth 4.5–14 m. The superstructure, divided into units of maximum length 192 m, will be produced in a yard by segmental casting and multistage prestressing. These units will be assembled at their final position on top of the piers. Each pier is composed of two pieces, also produced in the yard and connected on site by cast in situ concrete. This paper describes selected analysis problems and their solutions employed in the structural design. The analysis problems are concerned with (i) dynamic response to ice forces; (ii) movements of pier footings and stiffness of the subgrade; (iii) variation of stresses and deformations during construction and during the life of the structure, considering the effects of creep and shrinkage of concrete and relaxation of the prestressed steel; and (iv) thermal stresses. Key words: bridges, concrete, creep, prestress relaxation, segmental construction, shrinkage, strait crossing.
49
Poloz, Maxim A., Nikolay V. Frolov, Andrey V. Shevchenko, and Jan Jimei. "Analysis of Prestressed Bent Precast-Cast-In-Situ Structures in Vlasov-Mileykovsky Method with Physical Non-Linearity of Material." Materials Science Forum 974 (December 2019): 601–7. http://dx.doi.org/10.4028/www.scientific.net/msf.974.601.
Анотація:
Precast reinforced concrete structures with and without reinforcement pre-stressing are used both as newly designed independent ones and are the result of work to strengthen the existing structures by increasing the section. In both cases, the cross section of such elements is considered as a two-layer section, and the resulting composite element works under load under conditions distributed between the layers of internal forces, the mechanism and actual distribution of which depends on the physical and mechanical characteristics, the design scheme and the layers contact interaction parameters. When calculating and designing prestressed reinforced concrete precast-monolithic elements, the shear seam ductility is usually not paid much attention to, which complicates the structure actual stress-strain state analysis and contains a certain undiscovered potential of its rational design. One of the possible directions in solving the problem, which takes into account the contact seam shift, is the structural mechanics variation principles use in the calculation of structures such as rods of composite section. The questions of a composite reinforced concrete precast-monolithic rod of the variation principles of structural mechanics based on the method of V.Z. Vlasov - I.E. Mileykovsky in the displacements form in combination with the step-iterative method of calculation practical applicability in the structural analysis is considered in this work,. The numerical calculations results according to the proposed method are given. This allows to take into account the precast and monolithic layers shear connections specifics, to take practical account of weld compliance, and also to take into account the material characteristics’ physical non-linearity, which contributes to the precast monolithic structures rational design.
50
Wang, Kun, Zhiyu Zhu, Yang Yang, Kai Yan, Guanpu Xu, and Guanjun Zhang. "Study on shear capacity of prestressed composite joints with concrete-encased CFST columns." Advances in Structural Engineering 24, no. 11 (March 23, 2021): 2457–71. http://dx.doi.org/10.1177/13694332211000558.
Анотація:
Through assuming reasonable constitutive relation of materials, finite element analysis (FEA) models of joints consisting of prestressed concrete-encased steel beams and concrete-encased concrete filled steel tube (CFST) columns were established by soft ABAQUS, and the simulated results were compared with tested ones. On this basis, the nonlinear analysis on the total loading process was conducted, and the stress variation of concrete, profile steel skeleton, steel bar skeleton, and prestressing tendons were observed at yield, peak, and ultimate loads; the influence of axial compressive ratio, steel tube ratio, stirrup ratio, and prestressing level on lateral load-displacement curves at column top and shear force-shear angle in joint core were investigated, and the shear capacity formulae of joint core were developed. It could be concluded that, the lateral peak loads and shear capacity could be improved with the increase of axial compressive ratio, steel tube ratio, stirrup ratio, and prestressing levels in varying degrees, and the ductility of joints will reduce with the increase of axial compressive ratio. Additionally, the shear capacity calculated by proposed practical formula was a little lower than FEA results, which could keep the joints safety and could be used in engineering design.