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Behaviour of a pre-stressed concrete pressure-vessel subjected to a high temperature gradient; Comportement d'un caisson en beton precontraint soumis a un gradient de temperature eleve

Abstract

After a review of the problems presented by pressure-vessels for atomic reactors (shape of the vessel, pressures, openings, foundations, etc.) the advantages of pre-stressed concrete vessels with respect to steel ones are given. The use of pre-stressed concrete vessels however presents many difficulties connected with the properties of concrete. Thus, because of the absence of an exact knowledge of the material, it is necessary to place a sealed layer of steel against the concrete, to have a thermal insulator or a cooling circuit for limiting the deformations and stresses, etc. It follows that the study of the behaviour of pre-stressed concrete and of the vessel subjected- to a high temperature gradient can yield useful information. A one-tenth scale model of a pre-stressed concrete cylindrical vessel without any side openings and without a base has been built. Before giving a description of the tests the authors consider some theoretical aspects concerning 'scale model-actual structure' similitude conditions and the calculation of the thermal and mechanical effects. The pre-stressed concrete model was heated internally by a 'pyrotenax' element and cooled externally by a very strong air current. The concrete was pre-stressed using horizontal and vertical cables held at 80 kg/cm{sup 2}; the thermal  More>>
Authors:
Dubois, F; [1]  Bonvalet, Ch; Dawance, G; Marechal, J C [2] 
  1. Commissariat a l'Energie Atomique, Saclay (France). Centre d'Etudes Nucleaires
  2. Centre Experimental de Recherches et d'Etudes du Batiment et des Travaux Publics (CEBTP), 76 - Harfleur (France)
Publication Date:
Jul 01, 1965
Product Type:
Technical Report
Report Number:
CEA-R-2829
Subject:
36 MATERIALS SCIENCE; ACOUSTIC TESTING; CABLES; CRACK PROPAGATION; CREEP; CYLINDRICAL CONFIGURATION; DEFORMATION; DILATANCY; HUMIDITY; MOCKUP; PRESSURE VESSELS; PRESTRESSED CONCRETE; STRESS ANALYSIS; STRESS RELAXATION; TEMPERATURE GRADIENTS; THERMAL CYCLING; YOUNG MODULUS
OSTI ID:
20680273
Research Organizations:
CEA Saclay, 91 - Gif-sur-Yvette (France)
Country of Origin:
France
Language:
French
Other Identifying Numbers:
TRN: FR05R2829115163
Availability:
Available from INIS in electronic form
Submitting Site:
FRN
Size:
99 pages
Announcement Date:
Jan 07, 2006

Citation Formats

Dubois, F, Bonvalet, Ch, Dawance, G, and Marechal, J C. Behaviour of a pre-stressed concrete pressure-vessel subjected to a high temperature gradient; Comportement d'un caisson en beton precontraint soumis a un gradient de temperature eleve. France: N. p., 1965. Web.
Dubois, F, Bonvalet, Ch, Dawance, G, & Marechal, J C. Behaviour of a pre-stressed concrete pressure-vessel subjected to a high temperature gradient; Comportement d'un caisson en beton precontraint soumis a un gradient de temperature eleve. France.
Dubois, F, Bonvalet, Ch, Dawance, G, and Marechal, J C. 1965. "Behaviour of a pre-stressed concrete pressure-vessel subjected to a high temperature gradient; Comportement d'un caisson en beton precontraint soumis a un gradient de temperature eleve." France.
@misc{etde_20680273,
title = {Behaviour of a pre-stressed concrete pressure-vessel subjected to a high temperature gradient; Comportement d'un caisson en beton precontraint soumis a un gradient de temperature eleve}
author = {Dubois, F, Bonvalet, Ch, Dawance, G, and Marechal, J C}
abstractNote = {After a review of the problems presented by pressure-vessels for atomic reactors (shape of the vessel, pressures, openings, foundations, etc.) the advantages of pre-stressed concrete vessels with respect to steel ones are given. The use of pre-stressed concrete vessels however presents many difficulties connected with the properties of concrete. Thus, because of the absence of an exact knowledge of the material, it is necessary to place a sealed layer of steel against the concrete, to have a thermal insulator or a cooling circuit for limiting the deformations and stresses, etc. It follows that the study of the behaviour of pre-stressed concrete and of the vessel subjected- to a high temperature gradient can yield useful information. A one-tenth scale model of a pre-stressed concrete cylindrical vessel without any side openings and without a base has been built. Before giving a description of the tests the authors consider some theoretical aspects concerning 'scale model-actual structure' similitude conditions and the calculation of the thermal and mechanical effects. The pre-stressed concrete model was heated internally by a 'pyrotenax' element and cooled externally by a very strong air current. The concrete was pre-stressed using horizontal and vertical cables held at 80 kg/cm{sup 2}; the thermal gradient was 160 deg. C. During the various tests, measurements were made of the overall and local deformations, the changes in water content, the elasticity modulus, the stress and creep of the cables and the depths of the cracks. The overall deformations observed are in line with thermal deformation theories and the creep of the cables attained 20 to 30 per cent according to their position relative to the internal surface. The dynamic elasticity modulus decreased by half but the concrete keeps its good mechanical properties. Finally, cracks 8 to 12 cm deep and 2 to 3 mms wide appeared in that part of the concrete which was not pre-stressed. The results obtained make it possible both to draw up a programme for future tests and to propose a calculation model for pre-stressed concrete pressure-vessels. (authors) [French] Apres avoir rappele les problemes poses par les caissons pour les reacteurs atomiques (formes des caissons, pressions, ouvertures, fondations, etc.), on expose l'interet presente par les caissons en beton precontraint, par rapport aux caissons en acier. Toutefois, l'utilisation des caissons en beton precontraint souleve de nombreuses difficultes liees aux proprietes des betons. Ainsi, faute de connaissances approfondies du materiau, il est necessaire de placer une peau d'etancheite en acier contre le beton, d'avoir un isolant thermique ou un circuit de refroidissement pour limiter les deformations et les contraintes, etc. Par suite, l'etude du comportement du beton precontraint et du caisson soumis a un gradient eleve de temperature peut apporter des informations utiles. Une maquette au l/10eme d'un caisson cylindrique en beton precontraint sans fond ni ouverture laterale, a ete realisee. Avant de decrire les essais effectues, quelques considerations theoriques sont developpees concernant les conditions de similitude 'modele reduit - ouvrage reel' et le calcul des sollicitations thermiques et mecaniques. La maquette de caisson en beton precontraint etait chauffee interieurement par un element de pyrotenax et refroidie exterieurement par un violent courant d'air. Le beton etait precontraint par des cables horizontaux et verticaux a 80 kg/cm{sup 2}; le gradient thermique atteignait 160 deg. C, Les deformations globales et locales, la variation de la teneur en eau, le module d'elasticite, la tension et le fluage des cables, la profondeur des fissures ont ete mesures au cours des differents essais. Les deformations globales observees sont compatibles avec les theories des deformations thermiques et le fluage des cables a atteint 20 a 30 pour cent suivant leur position par rapport a la surface interieure. Le module d'elasticite dynamique a diminue de moitie mais le beton conserve de bonnes caracteristiques mecaniques. Enfin, des fissures ayant 8 a 12 cm de profondeur et 2 a 3 mm de largeur sont apparues dans la zone ou le beton n'etait pas precontraint. Les resultats obtenus permettent d'une part, de definir un programme d'essais ulterieurs, d'autre part, de proposer une methode de calcul des caissons en beton precontraint. (auteurs)}
place = {France}
year = {1965}
month = {Jul}
}