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The Behavior of Recycled Concrete through the Application of an Isotropic Damage Model

Open Journal of civil engineering 2015年第3期5卷 339-351页

作者： Marcelo Pedreira da Silva Magno Teixeira Mota Anderson de Souza Matos Gadea Monica Batista Leite Koji de Jesus Nagahama Civil and Environmental Engineering Post-Graduate Program State University of Feira de SantanaFeira de SantanaBrazil

The main goal of this paper is to describe the mechanical behavior of the CDW recycled concrete in compression, using an isotropic damage model adapted to the variation of the replacement rate of natural aggregates by recycled ones. The isotropic model by Mazars was used as a constitutive equation for the CDW concrete and its adjustment parameters, A and B, were written as quadratic polynomials according to the aggregates replacement rate. The model was evaluated for conventional and recycled concretes. For the latter ones, the aggregates replacement ratios evaluated were 50% and 100%. The results show good approximation between the analytical and numerical values obtained with the adapted isotropic damage model and experimental concrete results for both compressive and flexural strength.

关键词： Recycled Concrete Construction and Demolition Waste Isotropic Damage Mazars Isotropic Model

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Effect of treatment of sisal fiber on morphology, mechanical properties and fiber-cement bond strength

Effect of treatment of sisal fiber on morphology, mechanical...

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作者： Santos, Rogério De Jesus Lima, Paulo Roberto Lopes Post-graduate Program of Civil and Environmental Engineering Department of Technology State University of Feira de Santana Av. Transnordestina S/N-Novo Horizonte Feira de Santana Bahia44036-900 Brazil

The dimensional instability of vegetable fibers due to hygroscopicity results in a gradual loss of adherence in cement based composites which, when in service, are submitted to a natural variation of humidity. Such an effect reduces the contribution of the fiber as a reinforcement and can cause the early rupture of the material. In this work, a treatment of the sisal fibers is performed with the applying of wetting-drying cycles in order to alter their crystalline structure and improve the dimensional stability of the fiber to withstand the variation of humidity: 6, 10, 20, 30 and 34 cycles were applied in order to evaluate the effect on the properties of fiber;a tensile test, the morphological characterization (MEV) and the evaluation of the chemical structure of fiber were carried out. The effect of the treatment on fiber-matrix behavior was evaluated using the pull-out test. Embedded lengths of 16, 20, 30, 40 and 44 mm were defined through a factorial design and used in the test. It is verified that the use of 10 wetting-drying cycles causes less damage to the tensile strength and the elastic modulus of the fiber and contributes to a better adherence with the matrix, with an increase of up to 23 % compared with the untreated fiber. The statistical analysis of the interaction effect between the studied factors, using 2K factorial design with central composite design, indicates that the number of cycles can be decreased when using a longer length of the embedded fiber. © (2015) Trans Tech Publications, Switzerland.

关键词： Tensile strength

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The role of traffic flow and the Floor Space Index (FSI) in predicting environmental noise 14

The role of traffic flow and the Floor Space Index (FSI) in ...

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14th International Conference on Computers in Urban Planning and Urban Management, CUPUM 2015

作者： Giunta, Mariene Benutti Suriano, Marcia Thais De Souza, Léa Cristina Lucas Viviani, Eliane Graduate Program in Urban Engineering Federal University of São Carlos São Carlos Brazil Post-Doctoral Program Federal University of São Carlos São Carlos Brazil Department of Civil Engineering Federal University of São Carlos São Carlos Brazil

ISBN: (纸本)9780692474341

Traffic flow and building parameters are analysed jointly to identify urban noise tendencies. For this purpose, the building parameter applied is the Floor Space Index (FSI). Acoustical and traffic flow data were collected and incorporated into a Geographical Information System (GIS). The fu-ture scenarios for this zone were created. For the FSI parameter, it was ver-ified that the higher the value of the average FSI, the higher the noise lev-els registered in urban canyons.

关键词： Floors

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Analysis of the possible failure modes in CSH bolted sleeve connections 15

Analysis of the possible failure modes in CSH bolted sleeve ...

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Proceedings of the 15th International Symposium on Tubular Structures, ISTS 2015

作者： Amparo, L.R. Sarmanho, A.M. De Araújo, A. Requena, J. Post-Graduate Program in Civil Engineering Federal University of Ouro Preto Ouro PretoMG Brazil V&M do Brasil S. A Belo HorizonteMG Brazil State University of Campinas CampinasSP Brazil

ISBN: (纸本)9781138028371

Steel circular hollowsections (CHS) have good resistance under tension, compression and torsion loads, considered isolated or combined. Recent researches have been carried out to evaluate the behavior and resistance of these structures. A current use of steel hollow sections is roof trusses, a kind of structure that demands standard procedures and fast assemblage. This work presents an experimental study of a new type of connection called sleeve, developed to attend the assembly process. The connection consists of two tubes internally connected through a third tube with a smaller diameter with passing bolts arranged in line and cross. This connection makes easier the structure assemblage and is aesthetically advantageous if compared to usual flanged connection used in hollow sections. An experimental program of the sleeve connection with bolts in line (along the tube) and crossed at 90◦ was developed. In this work were tested 3 prototypes with staggered bolts to complement previous research and 12 prototypes with crossed bolts. The parameters considered in investigation were tube diameter and thickness and number of bolts. Experimental results lead to identification of failure mode and the resistance of sleeve connection. The analysis of theoretical and experimental data revealed that the dominant failure mode was bending in the bolts, and indicated a reduction in connection resistance that needs to be quantified. For the prototypes with staggered bolts, the analysis also let the development of an expression for the determination of flexural failure in the bolts. The results have demonstrated the viability of this new type of connection, but indicated that all possible failure modes need to be carefully checked. © 2015 Taylor & Francis Group, London.

关键词： Failure modes

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Evaluation of the Performance of Different Damage Indicators in Railway Bridges

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Procedia engineering 2015年 114卷 746-753页

作者： Vinicius Alves Andreia Meixedo Diogo Ribeiro Rui Calçada Alexandre Cury Post-Graduate Program in Civil Engineering Federal University of Ouro Preto Ouro Preto Brazil Faculty of Engineering University of Porto Porto Portugal School of Engineering Polytechnic of Porto Porto Portugal Departament of Applied and Computational Mechanics Federal University of Juiz de Fora Juiz de Fora Brazil

This article describes a damage identification methodology based on a genetic algorithm and its application to the numerical model of a railway bridge. The identification method is based on an iterative process that in each iteration compares the values of the bridge's dynamic response for a test damage scenario with the response values for a reference damage scenario. The introduction of damage to the test numerical model is based on the modification of a preselected numerical parameter values. The genetic algorithm allows the identification of damage by minimizing the residue of an objective function constructed from the responses of the test and reference model, and based on the so-called damage indicators. In this study are defined and tested damage indicators based on modal parameters (frequencies and vibration modes) in parameters built from the modal parameters (modal curvatures and flexibility curvatures), and in dynamic responses under action of impulsive loads from frequency response functions (FRFs). The proposed methodology for identifying damage was tested based on a two-dimensional numerical finite element model of a railway bridge including the railway track. The results allowed evaluating the efficiency and reliability of the methodology and of the damage indicators which, in most situations, showed potential in the detection, location and quantification of the severity of the damage.

关键词： Damage identification iterative method genetic algorithm damage indicators railway bridges.

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Seawater Intrusion Modeling on Groundwater Confined Aquifer in Semarang

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Procedia Environmental Sciences 2015年 23卷 110-115页

作者： Edy Suhartono P. Purwanto S. Suripin Doctorate Program Of Environmental Studies Post Graduate Program Diponegoro University Jl. Imam Barjo SH No. 5 Semarang-Indonesia-50000 Polytechnic State Of Semarang Jl. Prof.Sudarto SH Semarang - Indonesia- 50000 Department Of Chemical Engineering Faculty Of Engineering Diponegoro University Jl. Prof.Sudarto SH Semarang – Indonesia- 50000 Department Of Civil Engineering Faculty Of Engineering Diponegoro University Jl. Prof.Sudarto SH Semarang – Indonesia- 50000

The focus of this study is to identify and describe of a seawater intrusion in confined aquifer modelling in Semarang with a descriptive quantitative analytical method. The results showed potentially experiencing seawater intrusion which increased of 0.575 km2/years. Seawater intrusion models divide to 3 models are the western route have a maximum error is 27.9%, then the middle route have the maximum error is 41.1% and the eastern route have the maximum error is 40%. In 2035, the seawater intrusion on western route is predicted about 3.0 km from the coastline, 4 km for middle route, and about 3.25 km for eastern route. This is one of the information that from right now, the management of a groundwater in the confined aquifer in Semarang is necessary to supervise and better and more optimal controlling

关键词： Coastal Areas Groundwater Chloride Seawater Intrusions

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Causes of blindness and vision impairment in 2020 and trends over 30 years, and prevalence of avoidable blindness in relation to VISION 2020: the Right to Sight: an analysis for the Global Burden of Disease Study (vol 2, pg 144, 2021)

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LANCET GLOBAL HEALTH 2021年第4期9卷 E408-E408页

作者： Steinmetz, Jaimie D. Vision and Eye Research Institute Anglia Ruskin University Cambridge United Kingdom Biomedical Informatics Seoul National University Hospital Seoul South Korea Institute for Health Metrics and Evaluation University of Washington Seattle WA United States Department of Health Metrics Sciences School of Medicine University of Washington Seattle WA United States Institute of Health Services Research Yonsei University Seoul South Korea Department of Ophthalmology University of Washington Seattle WA United States Department of Mathematics Imperial College London London United Kingdom WHO Collaborating Centre for Public Health Education and Training Imperial College London London United Kingdom Department of Primary Care and Public Health Imperial College London London United Kingdom School of Population and Global Health University of Melbourne Carlton VIC Australia School of Optometry and Vision Science UNSW Sydney NSW Australia Brien Holden Vision Institute Sydney Australia Department of Ophthalmology University of Adelaide Adelaide SA Australia Department of Parasitology and Mycology Jahrom University of Medical Sciences Jahrom Iran Department of Clinical Sciences University of Sharjah Sharjah United Arab Emirates Ophthalmic Research Center Shahid Beheshti University of Medical Sciences Tehran Iran Department of Ophthalmology Shahid Beheshti University of Medical Sciences Tehran Iran Research Institute for Endocrine Sciences Shahid Beheshti University of Medical Sciences Tehran Iran Ophthalmic Epidemiology Research Center Shahid Beheshti University of Medical Sciences Tehran Iran Health Services Management Department Qazvin University of Medical Sciences Qazvin Iran Department of Systems Populations and Leadership University of Michigan Ann Arbor MI United States Department of Medicine Sofia Ismail Memorial Medical Centre Bogura Bangladesh The Fred Hollows Foundation Sydney NSW Australia Berhan Public Health & Eye Care Consultancy Addis A

Hospital El Salvador: a novel paradigm of intensive care in response to COVID-19 in central America. Lancet Glob Health 2021;9: e241?42?In this Comment, the conflict of interest statement should have included the following: ?By virtue of their roles within a public hospital or the Ministry of Health, MB, LC, WH, and XS are government employees. The findings and conclusions in the Comment are only those of the authors.? This correction has been made as of Feb 26, 2021.

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Polymer concrete reinforced with luffa fibers: Effect of gamma radiation

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Revista Tecnica de la Facultad de Ingenieria Universidad del Zulia 2014年第3期37卷 22-29页

作者： Martínez-Barrera, Gonzalo Martínez-López, Miguel Vigueras-Santiago, Enrique Gencel, Osman Beycioglu, Ahmet Dos Reis, João Marciano Laredo Facultad de Química Universidad Autónoma del Estado de México Km.12 de la carretera Toluca-Atlacomulco San Cayetano Mexico Civil Engineering Department Faculty of Engineering Bartin University Bartin Turkey Civil Engineering Department Faculty of Technology Düzce University Düzce Turkey Theoretical and Applied Mechanics Laboratory - LMTA Mechanical Engineering Post Graduate Program - PGMEC Universidade Federal Fluminense - UFF RuaPasso da Pátria 156 Bl. E sala 216 Niterói RJ Brazil

The interest of many research groups regarding manufacture of composite materials by using natural fibers is increasing world-wide. The main objectives involve the improvement of mechanical properties, mainly those related to resistance and elasticity. In the present study in a first stage, polymer concrete specimens were elaborated by using an unsaturated polyester resin, silica sand and luffa fibers; after, they were gamma irradiated at different doses and their mechanical properties were evaluated. Two different silica particle sizes (0.15 mm and 0.6 mm), and four different luffa fiber concentrations (0.3, 0.6, 0.9 and 1.2 wt%) were used, as well as 50 and 100 kGy of radiation dose. The results show a gradually diminution of compressive strength and modulus of elasticity when adding luffa fiber concentration. Nevertheless, such mechanical features are increasing when polymer concrete is gamma irradiated.

关键词： Unsaturated polymers

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Organizational Trouble Shooting through Integration between the Theory of the Restrictions Thinking Process and Lean Tools

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Journal of civil engineering and Architecture 2014年第6期8卷 738-745页

作者： Tatiana Gondim do Amaral Vitor Hugo Martins Resende Department of Post Graduate Degree Program in Geotechnical Civil Construction and Structure (PPGECON) FederalUniversity of Goidts Goidnia 74886044 Brazil Department of Engineering Catholic University of Golds Goiania 74605-220 Brazil

The theory of constraints thinking process, created by Israeli physicist Eliyahu M. Goldratt, has emerged as a tool for achieving competitive advantage. Many researches also focused on the application of lean thinking developed by Toyota and proposed by Ohno. This philosophy has been proven to be effective in several production processes. This paper aims to propose a method of problem solving through the integration of theory of constraints thinking process and the principles of lean production. As a tool for problem identification, the method defends the use of current reality tree and, to solve problems, the lean thinking tools, proposed by Picchi. The developed method was implemented in a contractor. The research methodology was research-action. Among the results, there was a realistic diagnosis about the core problems in company. According to this, the core problem of the contractor is “the lack of commitment of manpower” that results in the main problem “the financial loss”. The principle of perfection was verbalized as a proposal to solve the problems and the tools to be implemented for solving problems were “commitment of senior management to employees” and “simplicity in communication”.

关键词： Commitment people culture change agreement theory.

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Finite Element Modelling of Steel Beams with Web Openings

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engineering（科研） 2014年第13期6卷 886-913页

作者： Flavio Rodrigues Pedro C. G. da S. Vellasco Luciano R. O. de Lima Sebastiã o A. L. de Andrade PGECIV—Post Graduate Program in Civil Engineering UERJ—State University of Rio de Janeiro Rio de Janeiro Brazil Structural Engineering Department UERJ—State University of Rio de Janeiro Rio de Janeiro Brazil

Height limitations are not uncommon in multi-storey buildings due to economic requirements and esthetical considerations. Substantial spaces are normally required to enable the passage of large pipes and ducts beneath steel beams leading to uneconomic floor heights. The most adopted solution for this issue is the use of steel beam web openings to provide the required space for services. These openings could lead to a significant decrease of the beam load carrying capacity depending on the adopted openings shape, size and location. These aspects motivated the present study based on FE simulations calibrated against numerical and test results. The results accuracy enabled a comprehensive parametric analysis of beams with web openings to be made focused on the profile size, web opening location, among others. The study also investigated the efficiency of longitudinal stiffeners welded at the opening region and benefits of using an adequate edge concordance radius in beams with rectangular and square openings. The obtained results showed the need of using welded longitudinal stiffeners in order to increase the beams ultimate load carrying capacity. This adoption can double or even triple the ultimate load of beams with rectangular and square opening heights equal to 0.75 H, respectively.

关键词： Non-Linear Analysis Steel Structures Web Openings Steel Design and Behavior Finite Element Method

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