Artykuły w czasopismach: „Bridal creeper”

1

Turner, Peter J., John K. Scott i Helen Spafford. "Bridal Creeper (Asparagus asparagoides)–Invaded Sites with Elevated Levels of Available Soil Nutrients: Barrier to Restoration?" Invasive Plant Science and Management 4, nr 2 (kwiecień 2011): 212–22. http://dx.doi.org/10.1614/ipsm-d-10-00032.1.

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AbstractBridal creeper has become a serious environmental weed in southern Australia. Historically the invaded areas had low soil nutrient levels. However, our field surveys indicate that soils in bridal creeper–invaded areas have higher phosphorus and iron levels than soils in nearby native reference areas regardless of the proximity to agriculture or other disturbances. A glasshouse experiment was undertaken to determine the influence of increased nutrients on plants that co-occur with bridal creeper in order to (1) assess the impact of changed soil conditions and (2) predict the response of dominant species following the biological control of bridal creeper. The relative growth rate (RGR) of bridal creeper, two native shrubs (narrow-leaved thomasia [Thomasia angustifolia] and bluebell creeper [Billardiera heterophylla]), and an invasive exotic grass (annual veldt grass [Ehrharta longiflora]) were determined in three soil types: soil collected within a bridal creeper stand, soil collected from a nearby reference area, and a potting mix with nutrient levels higher than that recorded in the field. The plant species were chosen due to their association with bridal creeper. For example, the native species narrow-leaved thomasia was identified in a previous survey as the most abundant shrub at the invaded site where the soil was collected. The two other species, bluebell creeper and annual veldt grass, were identified from a previous seedbank trial as being abundant (in the seedbank) and able to readily germinate in invaded areas. When grown in either the bridal creeper–invaded soil or reference soil, bluebell creeper had significantly lower RGRs than narrow-leaved thomasia and annual veldt grass. However, as all these species showed increases in RGRs between reference soil and bridal creeper soil, this study indicates that for at least these three species the impact of increased nutrients may not be a barrier to the recovery of invaded areas following the control of bridal creeper.

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Harman, H. M., N. W. Waipara, C. J. Winks, L. A. Smith, P. G. Peterson i J. P. Wilkie. "Natural enemies of bridal creeper Asparagus asparagoides in New Zealand". New Zealand Plant Protection 61 (1.08.2008): 362–67. http://dx.doi.org/10.30843/nzpp.2008.61.6884.

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Bridal creeper is a weed of natural and productive areas in the northern North Island of New Zealand A classical biocontrol programme was initiated in 20052007 with a survey of invertebrate fauna and pathogens associated with the weed in New Zealand Although bridal creeper was attacked by a wide range of generalist invertebrates their overall damage affected

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Waipara, N. W., E. H. C. McKenzie, H. M. Harman, C. J. Winks i D. Park. "First record of bridal creeper rust,Puccinia myrsiphylli, a classical biocontrol agent of the environmental weed bridal creeper,Asparagus asparagoides, in New Zealand". Australasian Plant Disease Notes 1, nr 1 (2006): 23. http://dx.doi.org/10.1071/dn06010.

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Morin, Louise, i Penelope B. Edwards. "Selection of biological control agents for bridal creeper: a retrospective review". Australian Journal of Entomology 45, nr 4 (listopad 2006): 287–91. http://dx.doi.org/10.1111/j.1440-6055.2006.00552.x.

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Harman, H. M., N. W. Waipara, C. J. Winks, L. A. Smith, P. G. Peterson, A. Jones i J. Stanley. "Distribution of bridal creeper rust (Puccinia myrsiphyllii) In New Zealand". New Zealand Plant Protection 60 (1.08.2007): 320. http://dx.doi.org/10.30843/nzpp.2007.60.4667.

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Jusaitis, Manfred. "Herbicidal control of bridal creeper (Asparagus asparagoides) in an ecologically sensitive environment". Pacific Conservation Biology 24, nr 1 (2018): 3. http://dx.doi.org/10.1071/pc17010.

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Asparagus asparagoides (bridal creeper) is a highly invasive noxious environmental weed in southern Australia. It poses a severe threat to biodiversity and conservation in temperate natural ecosystems. Pterostylis arenicola, a threatened terrestrial orchid endemic to South Australia, is directly imperilled by this weed in most of its remnant populations. The coincident growth phenologies of orchid and weed make for an ecologically sensitive environment when considering methods of weed control or eradication. To minimise impact on the orchid and its ecosystem, this paper examines the efficacy of herbicide application for A. asparagoides control using the weed wiping technique, comparing it to the conventional spray application method. The most prolonged control of A. asparagoides was achieved after a single wipe-application of 1.5 g a.i. (active ingredient) L−1 metsulfuron methyl, either alone or in combination with 120 g a.i. L−1 glyphosate, both treatments giving significantly better weed control five years after treatment than comparable spray applications. An investigation of the effect of glyphosate on cultures of the mycorrhizal fungus isolated from P. arenicola indicated a significant decline in mycelial growth with increasing herbicide concentration over the range 0.5–3.0 kg a.i. ha−1. These results provide further incentive for the use of ecologically sensitive herbicide application techniques, such as weed wiping, in areas of high conservation concern.

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Stansbury, C. D. "Dispersal of the environmental weed Bridal Creeper, Asparagus asparagoides, by Silvereyes, Zosterops lateralis, in south-western Australia". Emu - Austral Ornithology 101, nr 1 (marzec 2001): 39–45. http://dx.doi.org/10.1071/mu00069.

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Willis, Anthony J., Rachel McKay, John A. Vranjic, Marion J. Kilby i Richard H. Groves. "Comparative seed ecology of the endangered shrub,Pimelea spicataand a threatening weed, Bridal Creeper: Smoke, heat and other fire-related germination cues". Ecological Management & Restoration 4, nr 1 (kwiecień 2003): 55–65. http://dx.doi.org/10.1046/j.1442-8903.2003.00131.x.

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TURNER, PETER J., JOHN K. SCOTT i HELEN SPAFFORD. "The ecological barriers to the recovery of bridal creeper (Asparagus asparagoides(L.) Druce) infested sites: Impacts on vegetation and the potential increase in other exotic species". Austral Ecology 33, nr 6 (wrzesień 2008): 713–22. http://dx.doi.org/10.1111/j.1442-9993.2008.01839.x.

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Stansbury, C. D., i J. K. Scott. "The history, distribution and rate of spread of the invasive alien plant, bridal creeper, Asparagus asparagoides (L.) Wight, as determined from a questionnaire survey of landholders in south-western Australia". Diversity Distributions 5, nr 3 (maj 1999): 105–16. http://dx.doi.org/10.1046/j.1472-4642.1999.00030.x.

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11

Lin, Sheng, Xian Fen Xu, Cheng Wang i Jian Xin Ye. "Analysis of Creep and Shrinkage Mechanism of Bridge Considering the Effect of Shrinkage on Creep Stress Reduction". Advanced Materials Research 255-260 (maj 2011): 781–85. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.781.

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The effect of concrete shrinkage and creep on the deformation of the bridge structure is posing a serious issue with increasing numbers of large-span bridges are being built. At the moment, only the creep coefficient is usually considered for calculating bridge creep, without taking other factors into consideration. This paper, based on aging theory, considers the influence of shrinkage on creep stress reduction, by simplifying the formula of creep strain under discrete load by using the integral mean-value theorem and deriving the formula of concrete creep strain. Taking a continuous rigid frame bridge for example, the paper calculated the creep considering creep stress reduction under shrinkage, which showed that the method can well predict the final shrinkage and creep values of large-span concrete bridge.

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Peng, Keke, i Fangzhen Wen. "Analysis of shrinkage and creep effect for bridge widening based on TB-FEM method and experimental research". MATEC Web of Conferences 277 (2019): 02015. http://dx.doi.org/10.1051/matecconf/201927702015.

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Based on TB-FEM method and laboratory test, the influence of shrinkage and creep on the structure of widened bridge is studied. The shrinkage test uses C50 concrete and C50 double-mixture (steel polyester fiber) concrete to prepare the standard prism specimen, and the creep test uses the 15m hollow slab which exactly has the same material, size, prestress and construction method of a real bridge as the creep test specimen. The strain-time curve obtained by shrinkage and creep is used to define the shrinkage and creep characteristics of the material, and Trost-Bazant is combined with finite element method to analyze the mechanical response of the new and old bridge splicing structure caused by shrinkage and creep. The result shows that under the condition of rigid splicing, the new bridge should be supported by the simply supported structure, and it is not suitable to use the same simply supported and continuous hollow slab as the original bridge. Theoretical analysis and example study show that combination of laboratory test and TB-FEM method can reasonably analyze the effect of shrinkage and creep on bridge widening, and provide a theoretical basis for the type selection of widening structure.

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13

Lu, Zhi Fang, i Mu Yu Liu. "Stochastic Finite Element Analysis for Shrinkage and Creep of a Concrete Bridge Based on LHS". Advanced Materials Research 163-167 (grudzień 2010): 1744–48. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.1744.

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Shrinkage and creep are the inherent properties of concrete bridge. According to Latin Hypercube Sampling method (LHS) and concrete bridge shrinkage and creep uncertainty parameters, this paper promotes stochastic finite element method based on LHS for concrete bridge shrinkage and creep uncertainty analysis in ANSYS random analysis model. Based on this stochastic finite element method, internal force and long-term deformation of a continuous rigid frame bridge with density gradient concrete is analyzed. Result show, internal force and deformation of continuous rigid frame bridge after completing are reasonable and satisfy Code requirement, and are various in previous 3 years at service stage and trend to steadily after 3 years. Research result provides theoretical basis for shrinkage and creep uncertainty further analysis in concrete bridge.

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14

Xia, Guo Ping, i Zhe Zhang. "Static Analysis of Cable-Stayed Suspension Bridge under Concrete Shrinkage and Creep". Advanced Materials Research 189-193 (luty 2011): 4409–13. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.4409.

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The paper studye the effect of shrinkage and creep on the cable-stayed suapension bridge. In order to research the static action of cable-stayed suspension bridge, two plane models of Jinzhou Bay Bridge is analyzed under shrinkage and creep by using general FEM software. One is a self-anchored bridge and the other is an earth-anchored bridge. The differences in static behavior between the two bridges are compared in detail. The results indicated that the shrinkage and creep effects have great influences on both bridges, and the effects have greater influences on self-anchored system than earth-anchored system. In addition, the author analyzes the causes of these differences between the two bridges. In conclusion，shrinkage and creep have some effect on the bridge displacements and internal forces. It is an important factor which can not be ignored in the design.

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Yuan, Fang. "Mortar Thickness Calculation of Bonding Layer in Large-Scale Bridge Construction". Applied Mechanics and Materials 651-653 (wrzesień 2014): 1188–91. http://dx.doi.org/10.4028/www.scientific.net/amm.651-653.1188.

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The traditional calculation methods of mortar thickness without considering creep of the bridge caused by the mortar thickness, affects the safety and quality of the bridge. This paper proposes a mortar thickness calculation method of bonding layer in large-scale bridge construction based on Kalman filtering. The method uses the mortar creep impact indicators system, selects the creep test data as sample, and analyzes its sensitivity to the thickness to get the intensity of factors affecting mortar creep. It also filters the interface of amount of cement, aggregate content, water-cement ratio and components, and effectively computes the thickness which reduces the cost while improving the quality of bridge construction.

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Wu, Hai Jun, Yu Gao i Ping Lu. "Analysis of Shrinkage and Creep Effect on Improved Truss Composite Arch Bridge". Advanced Materials Research 255-260 (maj 2011): 906–10. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.906.

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In order to study the shrinkage and creep effect on improved truss composite arch bridge , this paper analyzed and compared different parameters' influence on the truss composite arch bridge by changing parameters such as shrinkage days, the age of loading, computation theory and diagonal web member forms. It was based on Shiqiaohe bridge, the result showed that shrinkage days and the age of loading were the key parameters; the longer the shrinkage days makes the effects of creep bigger; the longer the age of loading makes the effects of creep smaller. The effect of shrinkage of rigid diagonal web member was larger than that of cables, the applied computation theory has little influence to shrinkage and creep effect on truss composite arch bridge.

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17

Yin, Jian, Yi Jin Li, Ke Ren Zheng, Shi Dong Luo, Ai Guo Yan i Zhen Biao Liu. "Research on Creep Performance of C60 High Performance Concrete". Key Engineering Materials 405-406 (styczeń 2009): 400–404. http://dx.doi.org/10.4028/www.scientific.net/kem.405-406.400.

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It was tested creep performance of C60 high strength concrete and C60 HPC to calculate the long-term creep of C60 HPC accurately, which was combined with engineering construction of Yichang Chang Jiang Railway Bridge. It was concluded the creep degree and creep coefficient of C60 HPC by means of optimization fit calculation, which gives scientific foundation for the design and construction of this bridge.

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18

Zhang, Yun Tao. "Experimental Research on Concrete Shrinkage and Creep for Main Girder of Sutong Continuous Rigid-Frame Bridge". Advanced Materials Research 594-597 (listopad 2012): 1547–51. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.1547.

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In order to obtain shrinkage and creep of HPC used in Sutong continuous rigid-frame bridge, shrinkage and creep of plain concrete and RC are investigated under natural environment over two years. Reinforcement ratio 0.76% is close to that of the middle span. Loading stress of creep test is about 15MPa, which is near the maximum stress of the bridge. Four loading ages, 7d, 14d, 21d and 28d, were used to simulate different loading ages in construction. The curves of creep and shrinkage were fitted from test values. The results show the test values of creep and shrinkage were less than the current Chinese bridge code JTG D62-2004, and the creep and shrinkage of RC is less than plain concrete. If the reinforcement ratio is low, reinforcement exerts less influence on creep and shrinkage, and the influence of reinforcement can be neglected in engineering application. Reinforcement can effectively reduce creep and shrinkage if the reinforcement ratio is high.

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Wang, Yongbao, Renda Zhao, Yi Jia i Ping Liao. "Creep Characteristics Of Concrete Used In Long-Span Arch Bridge". Baltic Journal of Road and Bridge Engineering 14, nr 1 (28.03.2019): 18–36. http://dx.doi.org/10.7250/bjrbe.2019-14.431.

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The reinforced concrete arch bridge with concrete-filled steel tubular stiffened skeleton is extensively used in the mountainous area of southwest China due to their long span and high stability. Beibanjiang Bridge located in Shanghai- Kunming high-speed railway, which had a record span of 445 m, has recently been completed in 2016. However, concrete creep and shrinkage have pronounced effects on the long-term deflection and stress redistribution of this bridge. Several concrete creep and shrinkage specimens in the natural environment were made to predict the long-term behaviour of this bridge accurately. They were used to measure the concrete creep and shrinkage of the core concrete and surrounding concrete used in the arch bridge. The test results were compared to ACI209 R-92 Prediction of Creep, Shrinkage and Temperature Effects in Concrete Structures model, 1990 CEB-FIP Model Code 1990: Design Code model, fib Model Code for Concrete Structures 2010 model and Creep and Shrinkage Prediction Model for Analysis and Design of Concrete Structures-Model B3. Based on the numerical fitting method, the fib Model Code for Concrete Structures 2010 model was modified to suit the concrete creep and shrinkage experimental results. Then, the modified fib Model Code for Concrete Structures 2010 model was used to predict the timedependent behaviour of a concrete arch bridge.

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Luo, Jun Li, Zhi Sheng Xu, Jun Li i Ji Hao Yang. "Study on Prediction Model of Shrinkage and Creep of Prestressed Concrete Beam in Passenger Dedicated Line". Advanced Materials Research 255-260 (maj 2011): 3998–4002. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.3998.

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To improve the calculation precision of deformation in prestressed concrete bridge in passenger dedicated line and accurately predict the development of shrinkage and creep in bridge, a universal applicable modified model was put forward in this paper based on ACI 209R(1992) shrinkage and creep model. In the modified model, three influence factors-slump, strength and reinforcement - are corrected. And the modified model results were compared with the experimental results. It shows that the modified model can more accurately predict the development of shrinkage and creep of high-speed railway bridge and better accord with the law of it.

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Guo, Fei, Hong Gen Qin, Peng Fei Cao, Guan Guo Liu i Yun Sheng Zhang. "Analysis on Creep Property and Model of Bridge Girder Concrete with Various Mix Proportions". Applied Mechanics and Materials 368-370 (sierpień 2013): 1487–94. http://dx.doi.org/10.4028/www.scientific.net/amm.368-370.1487.

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Combined with the construction of Jinghang Canal Bridge of Jiangliu highway, shrinkage and creep property of the cast-in-situ high performance concrete of bridge girder was researched. The results showed early shrinkage and creep development of the high performance concrete was relatively rapid, and creep tended to be stable 120 days later. With the admixture increasing, shrinkage and creep of the concrete were reduced. Meanwhile, early creep rate deceased. Similar results applied to the reduction of sand rate and water-cement ratio. Based on creep prediction models both at home and abroad, hyperbolic power function and exponential function model were put forward, taking the influence of material parameter and environmental factors on shrinkage and creep into consideration. In accordance with the model, concrete creep formula was given out and would provide a relatively scientific basis for practical prediction of concrete creep.

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Niu, Yanwei, i Yingying Tang. "Effect of Shear Creep on Long-Term Deformation Analysis of Long-Span Concrete Girder Bridge". Advances in Materials Science and Engineering 2019 (13.12.2019): 1–10. http://dx.doi.org/10.1155/2019/4382904.

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The purpose of this paper is to report on the development of a three-dimensional (3D) creep calculation method suited for use in analyzing long-term deformation of long-span concrete girder bridges. Based on linear creep and the superposition principle, the proposed method can consider both shear creep and segmental multiage concrete effect, and a related program is developed. The effects of shear creep are introduced by applying this method to a continuous girder bridge with a main span of 100 m. Comparisons obtained with the nonshear case show that shear creep causes long-term deformation to increase by 12.5%. Furthermore, the effect of shear creep is proportional to the shear creep coefficient; for a bridge with different degrees of prestress, the influence of shear creep is close. Combined with the analysis of a continuous rigid bridge with a main span of 270 m, the results based on the general frame program suggest that shear creep amplification is multiplied by a factor of 1.13–1.15 in terms of long-term deformation. Moreover, the vertical prestress has little effect on shear creep and long-term deformation. The 3D creep analysis shows a larger long-term prestress loss for vertical prestress at a region near the pier cross section. The relevant computation method and result can be referenced for the design and long-term deformation analysis of similar bridges.

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Gao, Heng Shan, i Tie Ying Li. "Shrinkage and Creep of Concrete on the Mechanical Properties of Cable-Stayed Bridge". Advanced Materials Research 594-597 (listopad 2012): 1498–503. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.1498.

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In this paper, using the universal finite element analysis software SAP2000 to build a large span cable-stayed bridge with finite element model, using a stepwise analysis finite element method to study the concrete shrinkage and creep efforts on the main beam inner force and deformation, cable tension during the cable-stayed bridge construction process and after the bridge. Research results show that the effects of shrinkage and creep in the finished bridge cannot be ignored, and the results can be used as reference for the design of similar projects.

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Zeng, Qing Xiang, i Da Jian Han. "A Simplified Concrete Creep and Shrinkage CEB-FIP90 Model in Long-Span Bridge Design". Applied Mechanics and Materials 638-640 (wrzesień 2014): 1059–62. http://dx.doi.org/10.4028/www.scientific.net/amm.638-640.1059.

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The concrete shrinkage strain and creep coefficient calculation method in CEB - FIP MC90 model is briefly introduced. For application convenience in bridge design, a simplified formula for calculation of the concrete shrinkage strain and creep coefficient is derived. Considering the varying range of every influence factor, a correlation analysis for the factor is carried out. And the weights of those factors related to concrete shrinkage and creep coefficient are discussed. Considering the climate characteristics and the bridge structure features in the Pearl River Delta area, the variation ranges of concrete nominal shrinkage strain and nominal creep coefficient are calculated respectively.

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Wang, Xiao Ping. "Influences of Concrete Creep and Temperature Deformation on Vehilce Travelling across Bridge". Applied Mechanics and Materials 556-562 (maj 2014): 655–58. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.655.

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When long-span pre-stressed concrete bridges are subjected to concrete creep and temperature load , bridge deck deformation will be aroused. Then the additional track irregularity will be generated. It brings about the result that the dynamic response of train-track-bridge system will be influenced. In this paper, with the train-track-bridge coupling vibration theory, a (90+180+90) m continuous beam-arch combination bridge located on a certain passenger line is analysised comparatively, by considering the effect of concrete creep and temperature deformation. The results show that, the track irregularity caused by the concrete creep and temperature deformation influence the wheel unloading rate and the vertical accelararion of the train so obviously with the speed increasing. It can be concluded that the track irregularity need to be considered, especially for high-speed trains.

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Li, Wen Qiu, Yan Zhu i Xiao Zhen Li. "Dynamic Response of Bridges to Moving Trains: A Study on Effects of Concrete Creep and Temperature Deformation". Applied Mechanics and Materials 193-194 (sierpień 2012): 1179–82. http://dx.doi.org/10.4028/www.scientific.net/amm.193-194.1179.

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In this paper, a great deal of research undertaken to study the dynamic responses of a high-speed railway bridge subjected to moving trains. Based on coupling vibration analysis of a rigid frame-continuous bridge, the effect on the kinetic characteristics induced by track irregularities, temperature and creep is discussed. The results show that great changes occur in parameters of trains such as rate of wheel load reduction, the vertical acceleration and the vertical Sperling index when considering the effect of temperature and creep compared with regarding track irregularities only. It is recommended that the combination of track irregularities, temperature and creep is essential to evaluate dynamic feature of train-bridge coupled system for high-speed railways.

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Li, Lei, Yan Xiao i Rui Zhen Yang. "Experimental Study on Creep and Mechanical Behavior of Modern Bamboo Bridge Structure". Key Engineering Materials 517 (czerwiec 2012): 141–49. http://dx.doi.org/10.4028/www.scientific.net/kem.517.141.

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A full-scale testing model of laminated bamboo truck load bridge was made based on the original structure. The mid-span deflection of CFRP-reinforced bamboo girders, temperature and relative air humidity were obtained through over three years creep test under self-weight, and the analysis based on experimental results was finished. The results indicate that the average creep deflection of the girders after three years is approximately 8-mm. In addition, the increase in temperature and humidity may contribute to creep. On the basis of creep test, a short-term loading test was carried out applied with dead load, and the bridge collapsed under the load of 18.5-t. By the analysis of the experimental results, it is realized that long span CFRP-reinforced bamboo girders have sufficient capacity to meet the strength and durability needs of practical use. Although CFRP layers could improve the performance of bamboo girders effectively, there is a decrease in strength and stiffness when considering the long-term performance. All these studies may contribute to improving the design of bamboo bridge structures, and some construction measures are suggested for the bamboo bridge according to the results of the experimental and analysis results.

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Lu, Zhi Fang, i Mu Yu Liu. "Shrinkage and Creep Analysis of a Continuous Rigid-Frame Bridge with Density Gradient Concrete". Advanced Materials Research 250-253 (maj 2011): 2506–9. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.2506.

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In consideration of the excessive mid-span deflection and box girder cracks of continuous rigid-frame bridges, this paper analyzes the maximum first principal stress and mid-span deflection increment of a continuous rigid-frame bridge with density gradient concrete under shrinkage and creep effect. The maximum first principal stress increment at main span is 0.084MPa and mid-span deflection increment is 73mm after 10 years for continuous rigid-frame bridge with density gradient concrete, which are smaller than a continuous rigid-frame bridge with normal concrete. All of that show that continuous rigid-frame bridge with density gradient concrete reduces effect of shrinkage and creep. The research provides a theoretical basis for the successful application of continuous rigid-frame bridge with density gradient concrete.

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Wen, Lina, Qiangong Cheng, Qiang Cheng, Xifeng Guo i Bin Zhang. "In Situ Creep Model Testing for the Tunnel Anchor Foundation of Xingkang Suspension Bridge in Luding of China". Advances in Civil Engineering 2020 (7.09.2020): 1–19. http://dx.doi.org/10.1155/2020/8898777.

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Due to the limitations of geography and geology, cast concrete tunnel anchors were used to provide counterforces for Xingkang Suspension Bridge foundation at the left bank of Daduhe River. In this study, the in situ creep tests were conducted on two model tunnel anchors at a scale of 1:10 near the real working anchor site. Thus, the long-term deformation of the real working tunnel anchors installed at the bridge foundation could be determined from the creep test of model tunnel anchors. The creep tests were conducted under three different loads and lasted for 102.2 h, 167.5 h, and 189.4 h, respectively. The model anchor, the surrounding rock, and their interface were all monitored and measured during the creep testing. In addition, the numerical calculation, in which the Burger creep constitution was used for describing the surrounding rock and the Mohr–Coulomb criterion for describing the concrete anchor, was performed to further evaluate the long-term stability of the real working tunnel anchors. The numerical calculations are in good agreement with the laboratory testing results, and the creep deformations of the anchor and the surrounding rock have the same order of magnitude. The results show that the tunnel anchor and surrounding rock of Xingkang Bridge are in a stable creep state under the three different loads.

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Xiang, Ping, Minglong Wei, Mengmeng Sun, Qiusheng Li, Lizhong Jiang, Xiang Liu i Jianying Ren. "Creep Effect on the Dynamic Response of Train-Track-Continuous Bridge System". International Journal of Structural Stability and Dynamics 21, nr 10 (10.06.2021): 2150139. http://dx.doi.org/10.1142/s021945542150139x.

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The influence of track irregularity and deck deformation on the running safety of high-speed railway (HSR) trains is investigated, with emphasis placed on those caused by the creep of continuous prestressed bridges. A bridge model is established with CRTS II ballastless track to account for a train-track-bridge (TTB) system. The creep effect is calculated by the finite element software MIDAS/Civil. The accuracy of the numerical simulation is confirmed by comparing the numerical predictions with field measurements. Considering the stability index of the moving train, the deformation threshold for safe operation of the train is determined. The results show that the initial prestressing stress has a great impact on the residual deformation of the bridge, but the deformation of the rail is less affected by the stiffness of the fastener. Creep irregularity has a great influence on the comfort of the moving train, but does not affect its running safety. When the creep amplitude is greater than 4[Formula: see text]mm, the increase in the amplitude of the creep irregularity has a greater effect on the acceleration of the car body.

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Wu, Chong, Zu Lin He, De Fu He, Wan Jun Zhang, Rui Wang i Guo Tao Yang. "Influence of Shrinkage and Creep of the Concrete Slab on the Mechanical Behavior of Steel Arch Bridge". Advanced Materials Research 374-377 (październik 2011): 2484–87. http://dx.doi.org/10.4028/www.scientific.net/amr.374-377.2484.

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Steel and concrete composite structures are widely used in bridge engineering, for it can fully utilize the compression property of concrete and tensile behavior of the steel. However, the coupled behavior of shrinkage and creep exist in concrete. The creep behavior is dependent on the initial stress, while shrinkage is not. The shrinkage and creep of the concrete have a significant influence on the internal force and deformation and it may cause the cracking or even the failure of the structure. Nowadays, precast concrete slab is widely adopted in the composite bridges to reduce the effect of shrinkage and creep. Storage time is a critical parameter for the precast concrete slab to reach the best economic benefit and mechanical behavior of the structure. Therefore, in this paper, the finite element model of Xinshiji Bridge with the consideration of the relative slip between the steel and concrete was established to investigate the influence of loading age of the concrete on the mechanical behavior of the composite bridge, and the optimal storage time was determined.

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Wu, Xun, Jie Li, Xian Shui Yi i Zhi Chao Zhang. "Numerical Analysis of Creep and Longitudinal Cracks Effection on PC Bridge Deflection". Applied Mechanics and Materials 638-640 (wrzesień 2014): 969–72. http://dx.doi.org/10.4028/www.scientific.net/amm.638-640.969.

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This paper presents a three-dimensional entity model to analyze the creep effection of PC continuous rigid frame bridge and simulate the impact of longitudinal cracks at the bottom of mian span on the deflection briefly with ANSYS software. The result shows that creep amplifies the deflection of bridge and makes the position of maximum deflection move to the center of mian span. And the longitudinal cracks of mian span don’t make great contribution to the deflection of PC continuous rigid frame bridge directly. Actually, the cracks change the stress state of the bridge’s section, which results in the risk of web cracking and further the stiffness degradation of structure. The stiffness degradation increases the defection of bridge to a great degree finally.

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Zhang, Liang Liang, Li Qun Wu, Jian Xin Yang i Kang Zhang. "Effect of Fly Ash on Creep of High Performance Concrete Used in Bridge". Applied Mechanics and Materials 204-208 (październik 2012): 2192–95. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.2192.

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W/C ratio and the quantity of fly ash added have obvious influence on creep of high performance concrete. Effect of different quantities of fly ash on creep of high performance concrete of different W/C ratios used in bridge is studied in this research whose results reflect that creep value reduces along with reduction of W/C ratio at a certain quantity of fly ash added. Adding fly ash restrains creep on the whole, however, the degree depends on the quantity of fly ash added. Creep value of high performance concrete mixed with class-I fly ash at blend ratio of 12~40% is lower than that of standard concrete and fly ash at blend ratio of 18% has the best effect. Creep value in 365d is 51% of that of standard concrete at fly ash blend ratio of 18%, while at fly ash blend ratio of 40%, creep value in 365d is lower than that of standard concrete but higher than that of concrete at other blend ratios. It is generally considered that inhibition of creep of high performance concrete begins to fall beyond blend ratio of 30%.

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Wang, Rong Xia, Fan Li, Rong Guo i Shao Wei Zhao. "The Influence of Concrete Creep on Deflection of Box Beam with Sectional Joints in Continuous Rigid Frame Bridge". Advanced Materials Research 446-449 (styczeń 2012): 1063–66. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.1063.

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Over-deflection of beam in continuous rigid frame bridge has become an serious problem in recent years. The reason is complex. Some reseachers think that the bad quality of sectional joints in cantilever construction will cause additional shearing deformation and affect the beam deflection, this idea need to be further studied. In the paper, two three-dimensional models are built up based on a factual bridge, the simulation method of sectinoal joints is studied. The influence of concrete creep on the deflection of box beam with sectional joints is analysed being compared to beam without sectional joints . In order to simulate concrete creep, a method of effective elastic modulus adjusted with concrete age was applied. The study shows that the shearing deformation of sectional joints has obvious influence on the long-term deflection , and different calcultion method of concrete creep has different effect on it. It shouldn’t be ignored in the bridge design.

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Hu, Xu Hui, Ning Zhong i Shi Hong Jing. "Influence of Concrete Shrinkage and Creep on Composite Beam of Cable-Stayed Bridge". Advanced Materials Research 671-674 (marzec 2013): 1040–44. http://dx.doi.org/10.4028/www.scientific.net/amr.671-674.1040.

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Based on the shrinkage and creep theory model of the JTG D62-2004 and trough the finite element analysis software, it is to respectively calculate the main span displacement and the upper and lower edge stress of the steel beam and the concrete slab under the impacts of concrete shrinkage and creep at the initial stage and the normal operation stage (with 10 years of shrinkage and creep calculated) for the steel-concrete composite deck system of the cable-stayed with a main beam of 436m.The results show that the effects of the shrinkage and creep can’t be ignored.

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Liu, Jin Yu, Yang Zou i Peng Peng Zheng. "Time-History Analysis of Pre-Stress Loss of Four-Spans Pre-Stressed Continuous Rigid Frame Bridge". Applied Mechanics and Materials 587-589 (lipiec 2014): 1462–67. http://dx.doi.org/10.4028/www.scientific.net/amm.587-589.1462.

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Taking Guizhou Hezhang Bridge as the engineering background, this paper used Midas/Civil FEM platform to study the pre-stress loss and deformation of main girder in bridge construction stage and completion stage on the basis of concrete creep and shrinkage formulas provided by “Highway reinforced concrete and pre-stressed concrete bridge design code (JTG D62-2004)” and the US bridge standard – AASHTO LRFD – published in 2005. The results showed that the pre-stress pipeline friction losses calculated according to the two standards are basically the same. The loss of the anchor deformation, elastic compression and tendon relaxation obtained by AASHTO LRFD is slightly greater than that obtained by JTG D62-2004. However, due to the different computing models, both pre-stress loss and the main beam deflection caused by concrete creep and shrinkage obtained by AASHTO LRFD are larger than that by JTG D60-2004.

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Wang, Jie Jun, Qing Liang Zhu i Xiao Liang Peng. "Research of Deformation and Stress of Long-Span Arch Bridge under the Effect of Shrinkage and Creep in the Construction Process". Applied Mechanics and Materials 178-181 (maj 2012): 2273–76. http://dx.doi.org/10.4028/www.scientific.net/amm.178-181.2273.

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Considering the transformation of the system and the increasing of the load in the construction process of long-span arch bridge, combining with the definite engineering example and calculating the construction process of arch bridge by using finite element method,focusing on the analysis of deformation and stress of arch bridge under the effect of shrinkage and creep in the process of construction.

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Huo, Xiaoming (Sharon), i Maher K. Tadros. "Structural Design of High-Performance Concrete Bridge Beams". Transportation Research Record: Journal of the Transportation Research Board 1696, nr 1 (styczeń 2000): 171–78. http://dx.doi.org/10.3141/1696-59.

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Recently high-performance concrete (HPC) has been used in highway bridges and has gained popularity for its short-term and prospective long-term performances. Benefits of using HPC include fewer girder lines required, longer span capacity of girders, reduced creep and shrinkage deformation, less prestress losses, longer life cycle, and less maintenance of bridges. Research has been conducted on several issues of structural design of HPC bridge beams. The topics discussed include the effects of section properties of prestressed concrete girders, allowable tensile and compressive stresses, creep and shrinkage deformations of HPC, and prediction of prestress losses with HPC. The results from a parametric study have shown that a section that can have a large number of strands placed in its bottom flange is more suitable for HPC applications. The use of 15-mm-diameter prestressing strands allows the higher prestressing force applied on sections and can provide more efficiency in HPC bridges. The research results also indicate that the allowable compressive strength of HPC has a major effect on the structural design of bridges, whereas the allowable tensile stress has a minor effect on the design. Equations for predicting prestress losses based on the experimental and analytical results are recommended. The recommended equations consider the effects of lower creep and shrinkage deformations of HPC.

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Peng, Long Fan, i Zhi Da Li. "Analysis on the Deflection of Cantilever Construction Based on Viscoelasticity". Advanced Materials Research 1030-1032 (wrzesień 2014): 1078–81. http://dx.doi.org/10.4028/www.scientific.net/amr.1030-1032.1078.

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The creep of concrete in the construction process of deformation influential, especially in the cantilever pouring construction, short age of concrete, creep effect more apparent. Meaning for cantilever construction of Bridges, creep analysis must be properly considered section at different time of loading values and the concrete ages of different segments. In this paper, based on the viscoelastic problem of cantilever construction of concrete creep analysis method, analyzes the deflection of cantilever construction process of a rigid-frame bridge, and compared with the actual measured value.

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Zhang, Rong Ling, Liang Wang, Chang An Yang, Bing Yang, Chang Yue Zhu i Qiang Jian Hao. "Simulation Analysis of Shrinkage and Creep for Bowstring Arch Bridge Steel Tube Concrete in Different Specification". Applied Mechanics and Materials 178-181 (maj 2012): 2219–23. http://dx.doi.org/10.4028/www.scientific.net/amm.178-181.2219.

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The actual bowstring arch CFST is taken as the background,the paper using finite element analysis method, researched the shrinkage and creep of combination of steel and concrete structure. Through the use of different countries regulation of shrinkage and creep of concrete, the effects of the structure deflection separately were studied ,then explain the different influence degree of different norms in the calculation of the creep and shrinkage of concrete; The paper also has also put forward the doubt about accurate calculation concrete filled steel tubular structure shrinkage and creep of concrete, it puts forward new requirements for the research and standards about steel tube concrete shrinkage and creep at last.

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41

Rao, Rui, Ji Yang Fu i Ai Rong Liu. "The Effect of the Varied Temperature and Humidity on Creep Deflection in Service Stage of Bridges". Advanced Materials Research 163-167 (grudzień 2010): 1474–79. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.1474.

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The creep deflections in service stage of bridges are discussed with the effect of the variable temperature and humidity on creep. A coefficient of equivalent duration of loading (CEDL) is proposed, which is an indicator of the effect of the variable temperature and humidity. According to the periodicity of the climate and based on the recorded and collected daily average temperature and humidity in five cities in Pearl River delta from 2002 to 2006, the monthly average CEDL and the yearly average CEDL are thus given to study the effect of the variable temperature and humidity on the creep deflection of a five spans single plane cable-stayed bridge. It is demonstrated that the effect of the variable temperature and humidity is notable in the early phase but inapparent in the later phase of the service stage of the bridge.

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42

Soleymani, Hamid R. "Structural design properties of concrete for a bridge in Alberta". Canadian Journal of Civil Engineering 33, nr 2 (1.02.2006): 199–205. http://dx.doi.org/10.1139/l05-092.

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In this investigation, the structural design properties of concrete were characterized. Compressive, tensile, and flexural strengths were measured at different ages. In addition, modulus of elasticity, Poisson's ratio, creep, shrinkage, and various other properties were measured. Laboratory results were compared with several structural codes used by engineers for bridge and structural design. The results serve as a reminder that assumed code values can be significantly in error and must be used only in the absence of better data.Key words: concrete, creep, shrinkage, modulus of elasticity, strength, design.

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Shan, Cheng Lin, i Ling Yan. "Creep Stress Analysis of PC Composed Box Girder Bridge with Corrugated Steel Webs". Advanced Materials Research 163-167 (grudzień 2010): 1987–90. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.1987.

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According to the forced load-bearing characteristics of the prestressed concrete girder bridge with corrugated steel webs, the cross-section internal forces and stress redistribution of box-girder were studied under the influence of concrete creep. And the internal force redistribution formula on concrete creep was derived through the establishment of the compatibility equation of bending deformation; the stress redistribution formulas of the top slab and the bottom slab of box-girder at any time were also derived, through the establishment of the compatibility equation of the axial displacement and angular deformation of the top slab and the bottom slab of box-girder under the influence of concrete creep at any time. These show that the creep stress is only related to the box height and it’s the geometric properties of top slab and bottom slab concrete section, but not to the steel web’s size.

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Wang, Yongbao, Renda Zhao, Yi Jia i Ping Liao. "Time-dependent Behaviour Analysis of Long-span Concrete Arch Bridge". Baltic Journal of Road and Bridge Engineering 14, nr 2 (27.06.2019): 227–48. http://dx.doi.org/10.7250/bjrbe.2019-14.441.

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This paper continues the previous study on clarifying the time-dependent behaviour of Beipanjiang Bridge ‒ a reinforced concrete arch bridge with concrete-filled steel tubular stiffened skeleton. The obtained prediction models and the Finite Element Models were used to simulate the long-term behaviour and stress redistribution of the concrete arch bridge. Three-dimensional beam elements simulated the stiffened skeleton and surrounding concrete. Then, a parameters study was carried out to analyse the time-dependent behaviour of the arch bridge influenced by different concrete creep and shrinkage models. The simulation results demonstrate that concrete creep and shrinkage have a significant influence on the time-dependent behaviour of the concrete arch bridge. After the bridge completion, the Comite Euro-International du Beton mean deviation of displacements obtained by 1990 CEBFIP Model Code: Design Code model and fib Model Code for Concrete Structures 2010 model are 3.4%, 31.9% larger than the results predicted by the modified fib Model Code for Concrete Structures 2010 model. The stresses between the steel and the concrete redistribute with time because of the concrete long-term effect. The steel will yield if the fib Model Code for Concrete Structures 2010 model is used in the analysis. The stresses in a different part of the surrounding concrete are non-uniformly distributed.

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45

Harrison, Alex, i N. David LeBlanc. "Design and Construction of a Full-Width, Full-Depth Precast Concrete Deck Slab on Steel Girder Bridge". Transportation Research Record: Journal of the Transportation Research Board 1907, nr 1 (styczeń 2005): 54–66. http://dx.doi.org/10.1177/0361198105190700107.

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The West Sandusky Street Bridge over I-75 in Findlay, Ohio, consisted of a single 170-ft-span hybrid steel plate girder bridge with a concrete deck. To minimize closure times on West Sandusky Street and reduce traffic delays on I-75 during the bridge's replacement, full-width, full-depth precast concrete deck panels were proposed for the bridge deck construction. The precast deck panels are posttensioned both longitudinally and transversely to minimize cracking and improve durability and are constructed with shear stud pockets to allow for the installation of shear studs after erection and posttensioning. During detail design, a finite element analysis of the bridge deck was carried out to determine the required level of prestress in the deck. A time-dependent analysis was subsequently completed to determine the long-term creep effects and posttensioning losses, including the effects of restraint from the steel girders. A sensitivity analysis determined the optimum curing time required before stressing the longitudinal posttensioning tendons and grouting the shear pockets. The steel plate girders were designed for the long-term creep effects due to the posttensioning of the deck, which imposed additional axial loads and moments on the steel girders. The replacement deck panels were fabricated before bridge demolition and road closure. Bridge construction was completed in fall 2004.

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Chen, Zhaowei. "Evaluation of longitudinal connected track under combined action of running train and long-term bridge deformation". Journal of Vibration and Control 26, nr 7-8 (13.12.2019): 599–609. http://dx.doi.org/10.1177/1077546319889855.

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With long-term operation of high-speed railways, bridge deformation is hard to avoid, which directly affects the mechanical property of longitudinal connected track. To ensure the structural stability of longitudinal connected track and operation safety of train, this work proposes a work to evaluate longitudinal connected track under combined action of running train and long-term bridge deformation. First, the methodology of evaluating longitudinal connected track subject to train load and long-term bridge deformation has been proposed, in which an accurate train–track–bridge dynamic model and the method to determine long-term bridge deformation are settled. Then, the long-term bridge deformations caused by concrete creep, shrinkage, temperature, and pier settlement are investigated. On this basis, the evaluation of longitudinal connected track subject to long-term bridge deformation and running train is conducted, and the safety value of pier settlement for Chinese high-speed railways with longitudinal connected track is suggested. Results show that the long-term bridge deformations are even larger than the amplitude of random rail irregularity. With smaller settlement, influences of creep, shrinkage, and temperature play the leading role in affecting the mechanical behavior of longitudinal connected track, while influence of pier settlement occupies the dominant position with larger settlement. It is suggested that the pier settlement for Chinese high-speed railways with longitudinal connected track should be less than 7.7 mm to ensure structural stability of track and operation safety of train.

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George, Norine, Kiran Umachagi i Sunil Kumar Tengli. "Effect of Time Dependent Variables on Different Types of PSC Box Girder Bridges." SAMRIDDHI : A Journal of Physical Sciences, Engineering and Technology 11, nr 02 (25.12.2019): 123–28. http://dx.doi.org/10.18090/samriddhi.v11i02.6.

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Time dependent variables such as temperature gradient, effective temperature, creep, and shrinkage lead to long term deflection in prestressed concrete girders. This in turn effects the serviceability and sustainability of the bridge in the long run. Therefore, research and analysis is of paramount importance before deciding the type of girder to be used. A parametric study was carried out in order to determine the most desirable and efficient type of box girder to be used for a prestressed concrete bridge having a continuous span. Three prestressed concrete box girder bridge models of single, multi-cell rectangular and multi-cell trapezoidal cross section, having similar span, width and depth were taken into consideration. The finite element models were analysed using MIDAS Civil. The behaviour of the box girder cell types under various time dependent properties such as temperature, creep and shrinkage are presented in this paper. The results show that the prestressed concrete box girder bridge of multi-cell rectangular cross section exhibits greater forces and moments due to time dependent variables in comparison to the other two box girder cell types.

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Lu, Xiao Jun, Zhi Da Li i Ping Zhang. "Experimental Study on C60 High Performance Concrete with High Content Mineral Additives and Low Shrinkage Creep". Advanced Materials Research 1030-1032 (wrzesień 2014): 978–82. http://dx.doi.org/10.4028/www.scientific.net/amr.1030-1032.978.

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Shrinkage and creep behavior of concrete are keys that affect bridge construction and usage. The C60 high performance concrete was prepared by adding high content mineral additives and reducing water-binder ratio. This kind of concrete has good work performance and higher pumpability. It also has a low shrinkage and creep feature. Experiments were carried out to compare performance to concrete without mineral additives. Results show that its shrinkage and creep value decrease about 30% to 50% within long age of 360 days.

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Ghali, Amin, Gamil Tadras i Paul H. Langohr. "Northumberland Strait bridge: analysis techniques and results". Canadian Journal of Civil Engineering 23, nr 1 (1.02.1996): 86–97. http://dx.doi.org/10.1139/l96-009.

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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.

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Xihua, Dai, Liu Liangfang i Xian Rong. "Creep behavior of precast segmental box girder bridge". IOP Conference Series: Earth and Environmental Science 81 (sierpień 2017): 012138. http://dx.doi.org/10.1088/1755-1315/81/1/012138.

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