土木工程期刊论文英文文献怎么写

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SCC formwork pressure: Influence of steel rebars　　Abstract　　The formwork pressure exerted by a given Self Compacting Concrete (SCC) depends on its thixotropic behavior, on the casting rate and on the shape of the It can moreover be expected that, in the case of a formwork containing steel rebars, these should also play a In first part, the specific case of a cylindrical formwork containing a single cylindrical steel rebar is In second part, a comparison of the theoretical predictions to the experimental measurements of the pressure drop, after the end of casting SCC, was determined and the proposed model was Finally, an extrapolation is suggested of the proposed method to the case of a rectangular formwork containing a given horizontal section of steel rebars, which could allow the prediction of the formwork pressure during 　　Keywords: Fresh concrete; Rheology; Workability; Formwork presure; Thixotropy　　 Introduction　　In most of the current building codes or technical recommendations [1], [2], [3] and [4], the main parameters affecting formwork pressure during casting are the density of concrete, the formwork dimensions, the pouring rate of concrete, the temperature, and the type of 　　However, it was recently demonstrated that, in the case of SCC, the thixotropic behaviour of the material played a major role [5] P Billberg, Form pressure generated by self-compacting concrete, Proceedings of the 3rd International RILEM Symposium on Self-compacting Concrete, RILEM PRO33 Reykjavik, Iceland (2003), 271–[5], [6], [7] and [8] It can be noted that this influence is in fact indirectly taken into account in the above empirical technical recommendations via the effect of temperature and type of the binder, which are both strongly linked to the ability of the material to build up a structure at rest [9], [10] and [11]　　During placing, the material indeed behaves as a fluid but, if is cast slowly enough or if at rest, it builds up an internal structure and has the ability to withstand the load from concrete cast above it without increasing the lateral stress against the It was demonstrated in [7] and [8] that, for a SCC confined in a formwork and only submitted to gravity forces, the lateral stress (also called pressure) at the walls may be less than the hydrostatic pressure as some shear stress τwall is supported by the It was also demonstrated that this shear stress reached the value of the yield stress, which itself increased with time because of Finally, if there is no sliding at the interface between the material and the formwork [8], the yield stress (not less or not more) is fully mobilized at the wall and a fraction of the material weight is supported (vertically) by the The pressure exerted by the material on the walls is then lower than the value of the hydrostatic 　　Based on these results, the model proposed by Ovarlez and Roussel [7] predicts a relative lateral pressure σ′ ( ratio between pressure and hydrostatic pressure) at the bottom of the formwork and at the end of casting equal to:　　(1)and a pressure drop Δσ′(t) after casting equal to:　　(2)where H is the height of concrete in the formwork in m, Athix the structuration rate in Pa/s [10], R is the casting rate in m/s, e is the width of the formwork in m, g is gravity, t is the time after the end of casting and ρ is the density of the 　　As it can be seen from the above, the key point for the pressure decrease is that the shear stress on each vertical boundary of the formwork equals the static yield stress of the It can then be expected that, in the case of a formwork containing steel rebars, the stress at the surface of the rebars should also play a It is the objective of this paper to start from the model developed by Ovarlez and Roussel [7] and extend it to the case of reinforced As the steel rebars should have a positive effect on formwork design ( decreasing the formwork pressure), this could allow for a further reduction of the formwork 　　In first part, the specific case of a cylindrical formwork containing a single cylindrical steel rebar is In second part, a comparison of the theoretical predictions to the experimental measurements of the pressure drop, after the end of casting SCC, is determined and the proposed model is Finally, an extrapolation is suggested of the proposed method to the case of a rectangular formwork containing a given horizontal section of steel rebars, which could allow the prediction of the formwork pressure during 　　 Influence of a vertical steel bar on the pressure decrease inside a cylindrical formwork　　In this paper, SCC is considered as a yield stress material (in first step, thixotropy is neglected), and, for stresses below the yield stress, SCC behaves as an elastic material [7] In the following, cylindrical coordinates are used with r in the radius direction; the vertical direction z is oriented downwards (see F 1) The top surface (upper limit of the formwork) is the plane z = 0; the formwork walls are at r = R The bottom of the formwork is located at z = H An elastic medium of density ρ is confined between the cylindrical formwork and an internal cylindrical steel rebar defined by the boundary (r = rb) For the boundary condition, the Tresca conditions are imposed everywhere at the walls ( it is assumed that the shear stress at the walls is equal to the yield stress τ00 as argued by Ovarlez and Roussel [7] and demonstrated in [8]) In order to compute the mean vertical stress σzz(z) in the formwork, the static equilibrium equation projected on the z axis on an horizontal slice of material confined between two coaxial rigid cylinders can be written:　　 Evaluation of the structuration rate of SCC at rest　　 The vane test　　The yield stress of the studied SCC was measured using a concrete rheometer equipped with a vane The vane geometry used in this study consisted of four 10 mm thick blades around a cylindrical shaft of 120 mm The blade height was 60 mm and the vane diameter was 250 The gap between the rotating tool and the external cylinder was equal to 90 mm which is sufficiently large to avoid any scaling effect due to the size of the gravel (Dmax = 10 mm here)　　Tests were performed for four different resting times after mixing on different samples from the same Of course, working with the same batch does not allow for the distinction between the non-reversible evolution of the behavior due to the hydration of the cement particles and the reversible evolution of the behavior due to thixotropy [9] and [10] It can however be noted that the final age of the studied system ( from the beginning of the mixing step to the last vane test measurement) was of the order of 70 Although Jarny et [13] have recently shown, using MRI velocimetry, that a period of around 30 min exists, for which irreversible effects have not yet become significant compared to reversible ones, the final age of the system in the present study was over this However, no strong stiffening nor softening of the sample was visually spotted nor measured as it will be shown Finally, the data analysis proposed by Estellé et [14] was used for the yield stress 　　 The plate test　　The plate test appears to be a very convenient method to monitor the apparent yield stress evolution of a thixotropic material with It was first developed and used in [8] but more details about its application to other materials than cement can be found in [15]　　The device is composed of a plate rigidly attached below a The plate is lowered into a vessel containing the SCC ( F 2) The apparent mass of the plate is continuously monitored versus time by recording the balance output with a The balance measurements have an uncertainty of ± 01 The vessel was made of smooth PVC and was cylindrical with a diameter of 200 mm and 200 mm in The plate was placed along the cylinder During the tests, the vessel was filled with material to a height of 200 The plate used was 3 mm thick, 75 mm wide and 100 mm It was covered with sand paper with an average roughness of 200 µ The sand paper was used to avoid any slippage between the material and the plate [8] The distance between the plate and the vessel walls was large enough compared to the size of the constitutive particles that the material can be considered as homogeneous [16] and [17] The height H of the immersed portion of the plate was measured before the start of the To ensure that all tests start with the suspension in similar condition, vibration was applied (frequency of 50 Hz, amplitude of 5 mm) for 30 This step is critical in order to ensure tests Variations between tests performed on the same material in the same experimental conditions were then less than 5%　　--------------------------------------------------------------------------------　　Full-size image (22K)　　F Schematic of the plate 　　View Within Article　　The plate test analysis is based on the fact that the slight deformation of the cement paste under its own weight allows for the transfer of a part of this weight to the plate by the mobilization of a shear stress on the This shear stress is equal to the maximum value physically acceptable, which is the yield stress (more details were given in [8], [15], [16] and [17]) The variation in apparent yield stress with time can then be calculated from the measured apparent mass evolution of the plate with time using the following relation:　　(9)Δτ0(t)=gΔM(t)/2Swhere ΔM(t) is the measured variation in the apparent mass of the plate and S is the immerged 　　 Laboratory cylindrical formworks　　Two columns were simultaneously filled with the studied SCC The columns were made of the same PVC covered with the same sand paper as the plate The columns inner diameters were equal to 100 Each column was 1300 mm The thickness of the plastic wall was 3 A 25 mm diameter steel bar was introduced in the second column (F 3)
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yangwenmoney
207 评论

红色高跟鞋H

土木工程civil Engineering 开题报告Thesis proposal 文献综述Review of the literature
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天生我翔2011

English is the Civil Engineering Civil Engineering, civil engineering is literally, it is the construction of the project It means building objects that the construction on the ground, underground, water works facilities, equipment and materials to use in surveying, design construction, maintenance, repair and other professional Civil Engineering with the progress of the human society, has been transformed into large integrated disciplines, it has a number of branches, such as : construction, rail projects, road projects, bridge projects, special project structure, water drainage works, the port project, water, environmental engineering A total of six professional Civil Engineering : architecture, urban planning, civil engineering, construction and environmental engineering equipment, water drainage works and road bridge Civil Engineering as an important foundation subjects, its important attribute : an integrated, social, practicality, Civil Engineering for the development of the national economy and improve the living standards of the people provided important material and technological foundation for the revitalization of many industries played a catalytic role in the construction of fixed assets is a basic production process, the construction and real estate in many countries and regions become a pillar of the economyAncient Civil Engineering has a long time span, roughly 500 years before Christ from the original date in civil engineering activities to the 16 century Italian Renaissance, resulting in the rapid development of the Civil Engineering on the road today, and has experienced more than 2,000 During this period, due to the development of scientific theories and slow, there is no breakthrough in civil engineering Century from 17 pages to 40 years in the 20th century end of the Second World War 300 years, foreign construction made great Civil Engineering has entered a phase of quantitative Some theoretical development, the emergence of new materials, new tools of invention, the Civil Engineering Science is perfection and In modern times, after the end of World War II, many countries economic takeoff, the increasing advances of modern science, so as to provide a powerful impetus to further development and material People's living conditions continue to improve, more and more comfortable living environment for the inevitable in the circumstances, the construction of development directly to the Civil Engineering 土木工程的英文是Civil Engineering ,直译是民用工程，它是建造各种工程的统称。它既指建设的对象，即建造在地上，地下，水中的工程设施，也指应用的材料设备和进行的勘测，设计施工，保养，维修等专业技术。土木工程随着人类社会的进步而发展，至今已经演变成为大型综合性的学科，它已经出许多分支，如：建筑工程，铁路工程，道路工程，桥梁工程，特种工程结构，给水排水工程，港口工程，水利工程，环境工程等学科。土木工程共有六个专业：建筑学，城市规划，土木工程，建筑环境与设备工程，给水排水工程和道路桥梁工程。土木工程作为一个重要的基础学科，有其重要的属性：综合性，社会性，实践性，统一性。土木工程为国民经济的发展和人民生活的改善提供了重要的物质技术基础，对众多产业的振兴发挥了促进作用，工程建设是形成固定资产的基本生产过程，因此，建筑业和房地产成为许多国家和地区的经济支柱之一。古代的土木工程有很长的时间跨度，大致从公元前500年新石器时代出现原始的土木工程活动到16世纪末意大利的文艺复兴，导致土木工程走上迅速发展的道路为止，前后经历了两千多年。在这段时间内，由于科学理论发展及其缓慢，土木工程也没有突破习惯的发展。从17世纪中页开始到20 世纪40年代第二次世界大战结束为止的300年间，国外的建筑取得了长足的进步。土木工程进入了定量分析阶段。一些理论的发展，新材料的出现，新工具的发明，都使土木工程科学日渐完善和成熟。到了近代，二战结束之后，许多国家经济起飞，现代科学日益进步，从而为进一步发展提供了强大的动力和物质基础。人们生活水平的不断提高，必然要求越来越舒适的居住环境，在这种情况下，建筑的发展直接推动了土木工程的发展。总的来说土木工程是一门古老的学科，它已经取得了巨大的成就，未来的土木工程将在人们的生活中占据更重要的地位。地球环境的日益恶化，人口的不断增加，人们为了争取生存，为了争取更舒适的生存环境，必将更加重视土木工程。在不久的将来，一些重大项目将会陆续兴建，插入云霄的摩天大楼，横跨大样的桥梁，更加方便的交通将不是梦想。科技的发展，以及地球不断恶化的环境必将促使土木工程向太空和海洋发展，为人类提供更广阔的生存空间。近年来，工程材料主要是钢筋，混凝土，木材和砖材，在未来，传统材料将得到改观，一些全新的更加适合建筑的材料将问世，尤其是化学合成材料将推动建筑走向更高点。同时，设计方法的精确化，设计工作的自动化，信息和智能话技术的全面引入，将会是人们有一个更加舒适的居住环境。一句话，理论的发展，新材料的出现，计算机的应用，高新技术的引入等都将使土木工程有一个新的飞跃
296 评论

杜佳妮625

Research on the construction safety management of Civil EngineeringIn recent years, the construction accident in civil engineering in our country often This not only caused casualties, also caused great loss of national property, and resulting in a very bad social Therefore, in our country, the construction units in the civil engineering construction projects, shouldstrengthen the construction safety management, all aspects ofsecurity control for engineering, to prevent dangerous accidentsin the end it The cause of the civil engineering constructionaccidents are in many In order to enhance security,should be combined with the characteristics of construction projects and the enterprise's internal and external conditions, the rational allocation of production factors, optimization of management In order to realize the construction safetymanagement, construction units should establish a safety management system of a project, it should be carried out from the following aspects:A construction safety consciousness, cultivate the modern safety science theory, occurrence of unsafe human behavior To implement safety management, it should becombined with psychology, behavioral science to strengthen the education and training of employees in production safety,improve the consciousness of safe production, so as to guide the safety production behavior of For the construction enterprises should strengthen safety awareness and educationproject personnel, developing the regular safety education to the construction personnel involved in the project, and to carry outsecurity Three level education to the new participate in the work of the operating personnel; often transform types of employees, should be safety training for new types of work, makeoperation personnel matters needing attention can be familiar with the safe operation of In order to make safe productionconsciousness win support among the people, enterprisemanagement personnel but also in engineering project, using a variety of promotional tools to start a variety of education,cultivate the construction personnel safety Andin the management of enterprises, the production safety systemthought Leaders at all levels and enterprises in issuing the project production task, should also carry out safety Such as the production safety requirements to the construction personnel, so conducive to safe thought into the production of management, let each employee has consciously in the psychological sense of Two, the establishment of management system for safety in production in addition to strengthen production safety education and awareness of construction project staff, should alsoestablish a safety management system, protect the system from the construction enterprise safety in production In order toavoid the frequent occurrence of sudden accident, the construction enterprise should according to the project, to develop a comprehensive, the system of safety management,and invest the necessary manpower and funds to ensure the implementation of the Ensure the production safetyconstruction from the system implementation, the project section of construction enterprises should establish the safety inspectionsystem, and regularly to the project construction of the security Make a clear record of project construction process,record the dangerous post, and regularly check the Self evaluation and construction team every week to organize asafety activities, the project department to make regular safetyevaluation for project Construction enterprises in theconstruction of civil engineering, in order to establish a safety management system, need to make corresponding technical measures for safety management system, a comprehensivescientific standard for Therefore, the safety work of construction enterprise project technical measures should be prior to commencement of As for engineering and technical measures should be strict examination and approval, the approval before If the design changes during construction, corresponding safety technical measures should be coordinated with the adjustment,will The safety technical measures enacted personnel andparticipation, should fully understand the project as the construction scheme, construction environment, the actualoperation has, and combined with relevant laws and regulations or the security policy to establish safety technical measures,which can ensure the safety In civil engineering construction of large, corresponding safety technical measuresshould be formulated more comprehensive and more specific,must be carried out through the whole process of construction,and mainly covers to other engineering To establish the system of safety management, construction enterprises should also be strict safety As before the construction of the project, technical personnel should to the technical measures for the construction Such as technical personnel issue written materials relatedto the construction personnel, and the implementation of safety technical measures of construction workers to regularly check;when technicians found construction personnel in violation oftechnical measure behavior, to give timely When theconstruction personnel technical mistakes when amended and supplemented In order to ensure the safety ofconstruction enterprises to implement, should take theseinspection of production safety measures the formation of rules and regulations, require employees to strictly abide by, so to ensure safety production At the same time, the construction enterprises can also follow the specific constructiondevelopment situation, formulate a set of safety technical measures linked to reward and punishment system, to strictly abide by the department or individual production safety, strictsecurity checks to reward, and if there are penalties for violations of the At the same time should have a goodproduction safety supervision work, and sent to the specialized production safety supervision When there is potential safety hazard factors in project development, should be timely analysis and inspection and make treatment immediately, so thatthe safety management to implement, implement the specificsystem, ensure the feasibility of production The range ofcivil engineering projects involved in the construction processmore widely, because the factors which affect the engineering safety But in the construction process, the occurrence of safety accidents is often unexpected, with occasional andunexpected These come unexpectedly accidents, serious damage often caused casualties and Three, strengthen the safety production and environment management in civil engineering construction process,environment is an important factor influencing the construction So in order to guarantee safety in production, enterprises should be to strengthen the management of construction As in the construction site, the unnecessary equipment and surplus materials, should be timely In the pile construction materials in order to keep the construction site, the patency of the road accident, ensure to timely rescue, this is to protect the safety measures to And construction enterprises shouldstrictly abide by the rules and regulations, which occurred on theconstruction site of the waste, garbage bag, cement, waste materials and other items should be clear, it can keep the siteclean, to create a civilized construction environment for safe Create a safe production environment construction enterprises, should also be reflected in the risk disposal of For some such as the construction of Electricity,dangerous equipment, cloth rod is used, should by the competent department of enterprise safety approval approval,the approval before they can be put into use And in the process of construction of civil engineering, a comprehensive analysis of the conditions of construction Some of the effects of environmental factors of the quality of construction, totake timely measures, and to conduct a comprehensivespecification, so that can realize the safe construction quality engineering to create good

296 评论

半夜磨牙

土木工程的key哀，速度，
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