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Draft of Spanish Standard for the Use of Recycled Aggregate in the Production of Structural concrete

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Draft of Spanish Standard for the Use of Recycled Aggregate ...

The 6th International Symposium on Cement & concrete and Canmet/Aci International Symposium on concrete Technology for Sustainable Development

作者： Pilar Alaejos Marta Sánchez de Juan Marilda Barra Manuel Burón Enrique Dapena Miren Etxebarría Gilbert Francisco Belén González Fonteboa Fernando Martínez Abella Isabel Martínez Lage José Luis Parray Alfaro Juan Antonio Polanco Mariano Sanabria Enric Vázquez Task Force of Standing Committee of concrete

In November 2002, the Spanish Standing committee of concrete created a task force commissioned to draft a document to complement current regulations on structural concrete and to set out specific reco

关键词： Recycled concrete aggregate, Standardization, structural concrete.

Strength analysis of reinforced concrete columns with arbitrary cross-section under bieccentric loading

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Progress in Natural Science:Materials International 2001年第4期11卷 71-77页

作者：刁波,L.SPAROWITZ,叶英华 Department of Civil Engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China Institute of concrete Structures Graz Technical University Graz Austria Department of Civil Engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

A numerical method to analyze the failure load of reinforced concrete columns under bieccentric loading is presented. This method takes into account both material nonlinearity and geometric nonlinearity. The nonlinear constitutive relationships of concrete and steel bars are simulated by some cubic-splines. The derived element stiffness matrices are simple addition of the small-displacement stiffness matrix, geometric stiffness matrix and interaction component matrix. The element model may be used to analyze the ultimate load according to the material strength or stable limits . The formulations of reinforced concrete column elements derived here may also be used for beams or columns with arbitrary cross-section. The standard finite element approach presented in this paper is compatible with other finite element models. The theoretical results agree well with the experimental data.

关键词： arbitrary cross-section ultimate load reinforced concrete column nonlinearity.

Consideration of Viscoelasticity in Time Step FEM-Based Restraint Analyses of Hardening concrete

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Journal of Modern Physics 2013年第10期4卷 9-14页

作者： Dirk Schlicke Nguyen Viet Tue Institute of Structural concrete Graz University of Technology Graz Austria

concrete structures may suffer considerable restraint stresses during their hardening period. This is caused by several deformation impacts, especially temperature field changings due to hydration heat and volume changes due to autogenous shrinkage. Mainly affected are massive concrete members, but also the application of new concrete types or the erection of outstanding constructions requires further investigations in this context. 3D-FEM analyses of hydration heat induced temperature development in combination with the well known shrinkage give sufficient results for the deformation impact. The according elastic restraint stresses can be determined with consideration of the concrete’s rising elastic modulus and the restraint degree of the system. But due to duration of the heat flow process, the height of restraint stresses is strongly dependent from the viscoelasticity of the concrete. The viscoelastic effects consist of many components constituted by changing material properties influencing themselves. In practice, different simplified approaches are available for considering this in calculations. Their implementation in time step analyses is not generally admitted and requires expertise. In contrast, present research develops material models needing specific input parameters for every use case. This contribution focuses on a practicable approach considering the superposition of the viscoelastic behaviour of every stress increment in time step FEM analysis. The differentiation between the pure viscoelastic material behaviour (as it is given in the codes for idealistic conditions like creep or relaxation) and the according viscoelastic system response (addicted to the systems variable restraint degree) allows the transfer of this model into practice. As one application example of this approach, the compatibility check and the FEM-based recalculation of the monitoring program of a massive power plant slab will be presented.

关键词： Viscoelasticity Hardening Mass concrete FEM Restraint Analysis Time Dependant Material Properties Hydration Heat Evolution of Stiffness Quantification of Restraint Stresses In-Situ Measurements Recalculation of Measurement Data

Structural Glass Fiber Reinforced concrete for Slabs on Ground

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World Journal of Engineering and Technology 2014年第3期2卷 48-54页

作者： Philipp Lober Klaus Holschemacher University of Applied Sciences Institute of Concrete ConstructionLeipzigGermany

This paper aims to contribute to the classification and specification of glass fiber reinforced concrete (GFRC) and to deal with the question if structural glass fiber reinforced concrete as a special kind of glass fiber reinforced concrete is suited for use in load-bearing members. Despite excellent material properties, the use of glass fibers in a concrete matrix is carried out so far only in non- structural elements or as a modification for the prevention of shrinkage cracks. The aim of re- search at the University of Applied Sciences in Leipzig is the use of alkali-resistant macro glass fibers as concrete reinforcement in structural elements as an alternative to steel fiber reinforcement. Slabs on ground, as an example for structural members, provide a sensible application for the new material because they can be casted as load bearing and non-load bearing and are mostly made of steel fiber reinforced concrete. In the future, structural glass fiber reinforced concrete shall provide a simple and visually appealing alternative to conventional steel bar or steel fiber reinforced concrete. The glass fibers can also be used in combination with conventional reinforcing bars or mat reinforcements. Initial investigations have announced some potential.

关键词： Glass Fiber Reinforced concrete GFRC Slab on Ground Structural concrete Bending Test

ANALYSIS OF concrete DAMS UNDER SWELLING PROCESSES

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ANALYSIS OF CONCRETE DAMS UNDER SWELLING PROCESSES

第十二届国际混凝土碱集料反应会议

作者： Jose Piteira Gomes António Lopes Batista Sérgio Oliveira concrete Dams Department National Laboratory for Civil Engineering （LNEC） Lisbon Portugal concrete Dams Department National Laboratory for Civil Engineering （LNEC） Lisbon Portugal concrete Dams Department National Laboratory for Civil Engineering （LNEC） Lisbon Portugal

＜正＞ This paper presents a chemo-visco-elastic model to simulate the behaviour of mass concrete structures subjected to swelling resulting from internal alkali-silica reactions （ASR）. The evolution of the swelling process is quantified taking into account the concrete properties, environmental conditions （temperature and moisture） and structural effects induced by other external actions. As a case study, it is presented the analysis and interpretation of the structural behaviour of Santa Luzia dam （which concrete has been subject to swelling due to ASR）, since the first filling of the reservoir, occurred in October 1942, until the end of 2003. This is achieved by comparing the mathematical results with the results of the continuous observation of the works.

关键词： Alkali-silica reaction (ASR) Chemo-visco-elasticity Finite element analysis Structural effects Rheological model.

Recent studies on mechanical properties of recycled aggregate concrete in China-A review

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Science China(Technological Sciences) 2012年第6期55卷 1463-1480页

作者： XIAO JianZhuang LI WenGui POON ChiSun Department of Building Engineering Tongji UniversityShanghai 200092China Department of Civil and Structural Engineering Hong Kong Polytechnic UniversityHong KongChina Committee of Recycled Aggregate concrete Civil Engineering SocietyShanghai 200092China

Numerous experimental and theoretical studies on recycled aggregate concrete have been carried out in China in the past 10 *** paper provides a comprehensive review of the related findings of research on the mechanical properties of RAC in *** influences of the RCA on the strength and deformation characteristics of concrete,the statistical characteristics for the strength of RAC,fracture energy,stress-strain relationships under uniaxial compression,uniaxial tension as well as pure shear,and the residual strength of RAC after exposure to high temperatures,the bond between RAC and different kinds of steel rebar were also ***,some recent studies on the numerical simulation of the failure mechanism for RAC at the meso-structure level were discussed.

关键词： construction and demolition (C&D) wastes recycled coarse aggregate (RCA) recycled aggregate concrete (RAC) me-chanical property test numerical simulation

Current State of High 120 m concrete Dam Bratsk Hydroelectric Power Plant

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Journal of Civil Engineering and Architecture 2017年第3期11卷 222-231页

作者： Mark A. Sadovich Tatyana F. Shlyakhtina Sofia M. Ginzburg Alexander M. Yudelevich Department of Civil Engineering Bratsk State University Bratsk 665709 Russia Department of concrete and Reinforced concrete Structure Vedeneev VNIIG St.Petersburg 195220 Russia

The research object was high 120 m concrete gravity dam of the Angara Bratsk hydroelectric power plant. The state of the concrete dam is estimated based on the results of continuous supervision performed by site personnel as well as periodic monitoring. According to the classification of the interrelations in the system ＂concrete-environment＂, there were selected some important parts of dams and a comprehensive analysis of concrete was executed on these parts. Concerning the complex research of concrete, a combination of full-scale tests with core-sampling has been proposed. Core samples tests had an object to study the deep concrete layers and to determine the specific indicators such as strength, density, porosity, comparative diameter of capillary pores, CaO content in cement stone and others. Obtained findings and recommended criteria can be applied when selecting technologies for constructing dams that guarantee their durability in the north.

关键词： concrete gravity dam hydroelectric power plant monitoring.

Encased Composite Beams Made of High Strength Steel and High Strength concrete in Hogging Bending Zone

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Encased Composite Beams Made of High Strength Steel and High...

国际桥梁2004年大会

作者： Josef HEGGER Claus GORALSKI Sabine RAUSCHER Professor Institute of Structural concrete （IMB）RWTH Aachen University Aachen Germany Research Engineer Institute of Structural concrete （IMB）RWTH Aachen University Aachen Germany Research Engineer Institute of Structural concrete （IMB）RWTH Aachen University Aachen Germany

＜正＞ The design of the load carrying behavior of composite beams is carried out by means of the yield-line theory, assuming lull plastic stress distribution. In the hogging bending zone the steel profile is under compression. Applying concrete encasement takes advantage of concrete carrying high compression forces, thus, not only the load carrying capacity but also the rotation behavior can be increased. To activate the concrete the degree of shear connection between the encasement and the steel profile is important. Due to the constriction through the steel flanges the bearable compression strain of the concrete is higher. Also buckling of the steel profile in the compression zone is almost diminished. Eurocode 4 gives design rules for steel profiles up to S460 and concrete grades not higher than C60/67. This paper describes the influence of the degree of shear connection on the load carrying behavior of composite beams made of high strength materials under negative bending.

关键词： web encasement composite beam high strength concrete high strength steel hogging bending zone.

Research Progress of Eco-Friendly Portland Cement Porous concrete:A Review

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Journal of Renewable Materials 2023年第1期11卷 103-130页

作者： Xin Cai Fan Li Xingwen Guo Ren Li Yanan Zhang Qinghui Liu Minmin Jiang College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing210000China College of Mechanics and Materials Hohai UniversityNanjing210000China Jiangsu Jiuding Green concrete Corporation Yangzhou225000China China Three Gorges Corporation Beijing100000China

With the great impetus of energy conservation and emission reduction policies in various countries,the proposal of concepts such as“Sponge City”and“Eco-City”,and the emphasis on restoration and governance of ecological environment day by day,portland cement porous concrete(PCPC),as a novel building material,has attracted more and more attention from scientific researchers and *** possesses the peculiar pore structure,which owns numerous functions like river embankment protection,vegetation greening as well as air-cleaning,and has been of wide application in different engineering *** paper reviews the salient properties of PCPC,detailedly expounds the research progress of domestic and foreign literature about this subject in the past ten years(2010–2020),conducts the statistical analysis of the distribution rule of its major properties around the world,combines with the engineering application to summarize the excellent properties of PCPC,and makes a forecast of future research direction.

关键词： Portland cement porous concrete(PCPC) penetrating quality mechanical properties durability photocatalysis endothermic function slope protection with vegetation