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Omikrine Metalssi O.,IFSTTAR | Ait-Mokhtar A.,University of La Rochelle | Turcry P.,University of La Rochelle | Ruot B.,CSTB
Construction and Building Materials | Year: 2012

This paper presents the consequences of the carbonation phenomenon in the case of a mortar with cellulose ether as admixture on its mechanical properties, microstructure and length variations. Carbonation was found to improve mechanical strengths and decrease the global porosity with modifying the pore size distribution. The latter is beneficial regarding durability. However, carbonation also led to an increase of shrinkage, and thus to a probable increase of cracking. Carbonation and shrinkage kinetics could be slowed down by sheltering the material from carbonation during hardening. © 2012 Elsevier Ltd. All rights reserved. Source

Gavan V.,CSTB | Gavan V.,INSA Lyon | Woloszyn M.,INSA Lyon | Kuznik F.,INSA Lyon | Roux J.-J.,INSA Lyon
Solar Energy | Year: 2010

The aim of this article is to present results of an experimental campaign performed on a full-scale facility provided with a double-skin façade. The behaviour of this architectural concept is tested under controlled climatic conditions. A summer case is scrutinised under different configurations: variation of the airflow through the double-skin façade and different angle of the solar shading device. This paper describes the experimental conditions, as well the test facility and the tested façade element. The results show the temperatures of the test cell and the façade and how they depend on the climatic conditions and the sun-shading device blade angles. One objective of this research was to measure and provide extensive data set detailing air and surface temperatures on the double-skin façade, together with airflow rates and air velocities. The experiments are fully described so that the results can be used for the validation of numerical models dealing with ventilated double-skin façades with venetian sun-shading device. © 2009 Elsevier Ltd. All rights reserved. Source

Racher P.,University Blaise Pascal | Laplanche K.,University Blaise Pascal | Dhima D.,CSTB | Bouchair A.,University Blaise Pascal
Engineering Structures | Year: 2010

As timber is a combustible material, fire safety is a significant obstacle for the development of timber usage in buildings. Among the various structural components, the connections are often the weakest elements in a timber construction. In fire as well as in normal conditions, they govern the load-bearing capacity of the structure. However, a lack of knowledge is pointed out for the design of connections in normal conditions and even more in fire conditions. In this paper, a three-dimensional finite element approach is developed to investigate the performance of dowelled timber connections in fire. The 3D mechanical model and the thermo-physical model for each connection component are described. For the mechanical model, the plastic behaviour of the materials is considered using the Von Mises criterion for steel and the Hill criterion for timber. Then a thermal and mechanical validation of the proposed model is achieved by comparison with the experimental results in normal and fire situations. The analysis is then focused on the behaviour of dowelled timber connections in a fire situation. Thus, timber-to-timber and steel-to-timber connections with fasteners of 12 to 20 mm in diameter are studied considering a load in direct tension parallel to the grain. A parametric analysis, based on the numerical model, is done to evaluate the influence of the timber thickness on the reduction of the load-bearing capacity of the connections. This influence is evaluated considering the time of fire resistance to deduct simple design methods. © 2009 Elsevier Ltd. All rights reserved. Source

Lefort A.,Supelec | Bourdais R.,Supelec | Ansanay-Alex G.,CSTB | Gueguen H.,Supelec
Energy and Buildings | Year: 2013

In this paper, a hierarchical control structure based on model predictive control (MPC) is proposed for managing energy in residential houses. The control objective is to minimize the building energy cost while fulfilling various constraints. The optimization problem takes into account the fluctuations of the energy tariff and the available power that can be supplied by the grid market. The structure is composed of two anticipative layers: a scheduling MPC (S-MPC) with a long time horizon, and a piloting MPC (P-MPC) dealing with short time horizon. This two-level MPC structure is explained in details and compared to a centralized control approach. The methodology is assessed on a case study, developed in SIMBAD, a MATLAB toolbox dedicated to building modeling and simulation. This representative case study is used to compare this hierarchical approach with a classical control structure. © 2013 Elsevier B.V. Source

Jouanneau S.,University of Nantes | Recoules L.,CNRS Laboratory for Analysis and Architecture of Systems | Durand M.J.,University of Nantes | Boukabache A.,CNRS Laboratory for Analysis and Architecture of Systems | And 6 more authors.
Water Research | Year: 2013

The Biochemical Oxygen Demand (BOD) is one of the most widely used criteria for water quality assessment. It provides information about the ready biodegradable fraction of the organic load in water. However, this analytical method is time-consuming (generally 5 days, BOD5), and the results may vary according to the laboratory (20%), primarily due to fluctuations in the microbial diversity of the inoculum used.Work performed during the two last decades has resulted in several technologies that are less time-consuming and more reliable. This review is devoted to the analysis of the technical features of the principal methods described in the literature in order to compare their performances (measuring window, reliability, robustness) and to identify the pros and the cons of each method. © 2013 Elsevier Ltd. Source

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