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Cremona C.,Bouygues Travaux Publics | Cremona C.,Technical Center for Bridge Engineering | Poulin B.,West Territorial Direction
Structure and Infrastructure Engineering | Year: 2016

In recent years, the condition of deficient bridges has reached such a level that the volume of required repair actions becomes significant for many countries. As budgets for maintenance, repair and rehabilitation are always limited and demands are constantly increasing, to find an optimal balance between cost and safety is today a new trend in bridge maintenance. Optimising bridge maintenance and management is a strong expectation for owners and stakeholders facing ageing bridge stocks and increasing aggressive traffic. In this context, the assessment of the structural performance may be necessary for various reasons thorough its lifetime. In France, there are no standards or regulations for structural assessment of existing structures. The studies on a new Eurocode standard for the ‘Evaluation and rehabilitation of existing structures’ are just starting and it will be published in several years. For this reason, the French Ministry of Transport has decided to develop recommendations for the assessment of the structural performance of existing bridges. In a first part, the paper summarises today’s practice in France, but it also details the ongoing calibration process for setting appropriate partial factors for existing bridges. Implementation is given as example for the assessment of reinforced concrete slabs. © 2016 Informa UK Limited, trading as Taylor & Francis Group Source

Storry R.B.,Bouygues Travaux Publics | Pina R.M.,Langan Engineering and Environmental Services | Hight D.W.,Geotechnical Consulting Group
Proceedings - Rapid Excavation and Tunneling Conference | Year: 2013

The Port of Miami Tunnel will connect PortMiami directly to the surrounding highways, alleviating traffic congestion. The project comprises two 11.3-m-internal-diameter, 1.27-km-long tunnels bored under the main shipping channel in Biscayne Bay. These are the first large-diameter tunnels constructed through Florida's challenging carbonate geology, and because of the heterogeneous ground conditions, the baseline investigation left many geotechnical uncertainties. To reduce these uncertainties, a phased complementary ground investigation was performed, adopting numerous techniques, the integrated interpretation of which allowed development of a realistic ground model. The ground investigation, which proved to be one of Florida's most comprehensive, had a major impact on the tunneling methods that were adopted. Source

Tailhan J.-L.,Laboratoire Central des Ponts et Chaussees | D'Aloia L.,Center dEtudes des Tunnels | Autuori P.,Bouygues Travaux Publics
Bulletin des Laboratoires des Ponts et Chaussees | Year: 2010

An effective control over early-age behavior in concrete serves to guarantee successful applications on civil engineering project sites. Numerical tools designed to assist decision-making during the critical phases of concrete structure design and execution are indeed available. This document provides a summary presentation of a simple numerical simulation model of the thermomechanical behavior of early-age concrete; it offers insight into both the temperature and stress fields that develop as of the first few hours of concreting within structures and moreover enables conducting a cracking risk analysis. An industrial application example using this tool is also proposed herein. Source

Cremona C.,Bouygues Travaux Publics | Calado L.,University of Lisbon | Orcesi A.D.,University Paris Est Creteil
Structural Control and Health Monitoring | Year: 2016

Structural health monitoring (SHM) strategies should ideally consist of continuous on-line damage detection processes, which do not need to rely on the comparison of newly acquired data with baseline references, previously defined assuming that structural systems are undamaged and unchanged during a given period of time. The present paper addresses the topic of SHM and describes an original strategy for detecting damage in an early stage without relying on the definition of data references. This strategy resorts to the combination of two statistical learning methods. Neural networks were used to estimate the structural response, and clustering methods were adopted for automatically classifying the neural networks' estimation errors. To ensure an on-line continuous process, these methods were sequentially applied in a moving windows process. The proposed original strategy was tested and validated on numerical and experimental data obtained from a cable-stayed bridge. It proved highly robust to false detections and sensitive to early damage by detecting small stiffness reductions in single stay cables as well as the detachment of neoprene pads in anchoring devices, resorting only to a small amount of inexpensive sensors. © 2015 John Wiley & Sons, Ltd. Source

Saillio M.,University Paris Est Creteil | Baroghel-Bouny V.,University Paris Est Creteil | Barberon F.,Bouygues Travaux Publics
Construction and Building Materials | Year: 2014

Carbonation and chloride ingress are the main causes of reinforced concrete structures degradation. Usually, these two phenomena are studied individually. Here, chloride ingress has been investigated on sound and carbonated cementitious materials (cement pastes and concrete). The supplementary cementitious materials (SCM) are fly ash, slag and métakaolin. The materials were carbonated by exposure to accelerated conditions (1.5% CO 2 and 65% RH) in laboratory. Chloride binding isotherms of sound and carbonated samples were assessed by the equilibrium method (exposure to various alkaline NaCl solutions). The microstructure was characterized not only by usual techniques such as XRD and TGA-DTA, but also by 29Si and 27Al NMR spectroscopy. The results show that carbonated samples bind less chlorides than sound ones. The use of a combination of various techniques of microstructural characterization reduces the number of the possible explanations of these findings. In carbonated materials, both the quantity of Friedel's salts and of chlorides bound by C-S-H decrease. The first decrease can be explained by a lack of portlandite and modification of aluminate phases equilibrium. The second decrease seems to be due to a modification of the C-S-H (change of surface charge) during the carbonation process. Moreover, differences according to the nature and the amount of supplementary cementitious materials (SCM) were observed. © 2014 Elsevier Ltd. All rights reserved. Source

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