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An extensive experimental program is conducted in the present study to investigate the cracking behavior of two normal strength concrete plates and thirteen high strength concrete plates. The results raise questions about the applicability of the present code approaches to predict the crack width of thick concrete plates used for offshore structures and containment structures for nuclear power plants. The main objective is to provide a simple equation for crack width prediction of a concrete plate to ensure the control of crack openings in designing thick high strength reinforced concrete structures. The model predictions are compared with the results of the tests of reinforced concrete panels subjected to in-plane tension forces along with the code approaches for predicting the crack width. Key words: crack width, crack spacing, thick high strength reinforced concrete plates, offshore structures, nuclear containments, in-plane loading. Un vaste programme experimental est realise dans la presente etude afin d'examiner le comportement en fissuration de deux plaques de beton a resistance normale et de treize plaques de beton a haute resistance. Les resultats soulevent des questions quant a l' applicabilite des approches du code actuel pour predire la largeur des fissures dans des plaques de beton epaisses utilisees dans les constructions en mer et les structures de confinement des centrales nucleaires. L'objectif principal est de fournir une equation simple pour predire la largeur des fissures d'une plaque de beton afin d'assurer le controle des ouvertures de fissures lors de la conception de structures epaisses en beton arme a haute resistance. Les previsions du modele sont comparees aux resultats des essais de panneaux en beton arme soumis a des forces de tension en plan selon les approches du code pour predire la largeur des fissures. Mots-cles : largeur de fissures, espacement des fissures, plaques epaisses de beton arme a haute resistance, constructions en mer, confinement nucleaire, charge en plan. [Traduit par la Redaction], 1. Introduction It is desirable to limit the crack width under serviceability limitations to avoid esthetical and durability concerns. Extensive investigations were carried out (Clark 1956; Frantz and Breen 1980; [...]

In this study, the equation for the punching shear strength prescribed in the Canadian code is evaluated based on a database of experimental results. This paper also includes a discussion of the effect of several parameters on the punching shear strength in the Canadian and European codes. The experimental work presented includes testing of ten full-scale two-way slabs with different reinforcement ratios to examine the effect of reinforcement ratio on punching shear capacity. A simplified practical punching shear equation is also proposed based on statistical analysis of experimental results from the database. Statistical regression analysis is conducted on 190 test data available in the literature to evaluate the influence of reinforcement ratio on punching shear strength. The proposed equation accounts for the effect of slab depth using fracture mechanics concepts. The analytical study showed that the reinforcement ratio has a strong influence on punching shear strength. The proposed equation could be an alternative to the current punching shear equation used by Canadian Standards Association CSA-A23.3-04 design code. Key words: concrete strength, reinforcement ratio, size effect, database, statistical analysis, regression, ductility, punching. Dans la presente etude, l'equation de la resistance au cisaillement par poinconnement dans le code canadien est evaluee en se basant sur une base de donnees de resultats experimentaux. Cet article comprend egalement une discussion de l'effet des parametres sur la resistance au cisaillement par poinconnement dans les codes canadien et europeen. Le travail experimental presente comprend des essais sur 10 dalles bidirectionnelles a pleine echelle presentant differents pourcentages d'armature afin d'etudier l'effet du pourcentage d'armature sur la resistance au cisaillement par poinconnement. Une equation pratique et simplifiee du cisaillement par poinconnement est egalement proposee, basee sur une analyse statistique des resultats experimentaux de la base de donnees. Une analyse statistique de regression est realisee sur 190 donnees d'essai disponibles dans la litterature afin d'evaluer l'influence du pourcentage d'armature sur la resistance au cisaillement par poinconnement. L'equation proposee tient compte de l'effet de l'epaisseur de la dalle en utilisant les concepts de mecanique des fractures. L'etude analytique indique que le pourcentage d'armature a une forte influence sur la resistance au cisaillement par poinconnement. L'equation proposee pourrait constituer un autre choix que l'equation actuelle de cisaillement par poinconnement utilisee dans le code de calcul CSA-A23,3-04. Mots-cles : resistance du beton, pourcentage d'armature, effet de dimensionnement, base de donnees, analyse statistique, regression, ductilite, poinconnement. [Traduit par la Redaction], Introduction The two-way slab system is a unique efficient structural system. It is economical and is widely used in different structural applications such as floors, roofs of buildings, and walls [...]

The strut-and-tie method is a rational approach to structural concrete design that results in a uniform and consistent design philosophy. A strut-and-tie model has been developed to model the punching-shear behaviour of thick concrete plates. This model provides a quick and simple approach to check the punching-shear behaviour. Thick concrete slabs (250-500 mm) without shear reinforcement can exhibit brittle shear failure under a central force and an unbalanced moment. Shear reinforcement has proven to be very effective in preventing such failures. The developed strut-and-tie model has also been used to evaluate the minimum shear reinforcement required to prevent brittle shear failure of two-way slabs in the vicinity of concentrated loads. The strut-and-tie model for symmetric punching consists of a 'bottle-shaped' compressive zone in the upper section of the slab depth, leading to a 'rectangular-stress' compressive zone in the lower section of the slab depth. Inclined shear cracking develops in the bottle-shaped zone prior to failure in the lower zone. Cracking in the bottle-shaped zone is related to the splitting tensile strength of concrete. Key words: thick plates, strut-and-tie model, shear reinforcement, size effect, splitting bond stress, punching, bottle-shaped strut. La methode de modele a treillis est une approche rationnelle au calcul du beton structural qui resulte en une philosophie de conception uniforme et constante. Un modele a treillis a ete developpe pour simuler le comportement en cisaillement par poinconnement de plaques de beton epaisses. Ce modele represente une approche rapide et simple de verifier le comportement en cisaillement par poinconnement. Les dalles de beton epaisses (250-500 mm) sans armature contre le cisaillement peuvent montrer une rupture fragile en cisaillement sous une force centrale et un moment non equilibre. L'armature contre le cisaillement s'est montree tres efficace pour prevenir de telles ruptures. Le modele a treillis developpe aegalement ete utilise; pour eevaluer l'armature minimale requise contre le cisaillement afin d'empeecher la rupture fragile en cisaillement dans les dalles bidirectionnelles pres des charges concentrees. Le modele a treillis pour determiner le poinconnement symeetrique consiste en une zone de compression en << forme de bouteille >> dans la section superieure de la dalle, engendrant une zone de compression de << contrainte rectangulaire >> dans la section inferieure. Une fissuration de cisaillement inclineeese developpe dans la zone en forme de bouteille avant la rupture dans la zone inferieure. La fissuration dans la zone en forme de bouteille est associeeea la resistance du beton a la traction par fendage. Mots-cles: plaques epaisses, modele a treillis, armature contre le cisaillement, effet de taille, contrainte d'adheerence en fendage, poinconnement, entretoise en forme de bouteille. [Traduit par la Redaction], Introduction Thick concrete slabs (250-500 mm) without shear reinforcement usually exhibit brittle shear failure under a central force and an unbalanced moment that is transferred between the column and the [...]

A simple method is used to predict damping and natural frequencies of a fixed offshore platform subjected to wind-generated random waves using its stationary response. The method also predicts the reaction forces and bending moment at the foundation of the platform. The method uses the random decrement signature as a tool to identify the parameters in the equation of motion. Excellent agreements were obtained between the estimated and actual values of the parameters as well as for the reaction and moment at the platform foundation. The method can be applied without any interruption to the operation of the offshore structure. The method is easy to apply and uses inexpensive motion measurement instruments. The estimated forces and bending moments can be used as a tool for an on-line foundation check. A study on the limitations of applying the random decrement technique is also presented. Key words: offshore platform, excitation force, random decrement, reaction force. Une methode simple est utilisee pour predire l'amortissement et les frequences naturelles d'une plate-forme de forage en mer soumise a de la houle aleatoire generee par le vent par l'emploi d'une reponse stationnaire. Cette methode predit egalement les forces de reaction et le moment de flexion a la base de la plate-forme. La methode utilise la methode du decrement aleatoire comme outil pour determiner les parametres dans l'eequation du mouvement. D'excellentes correlations ont ete obtenues entre les valeurs estimeees et reelles des parametres et de la reaction et du moment a la base de la plate-forme. La methode peut etre appliqueee sans interrompre les operations de la structure de forage en mer. La methode est facile a appliquer et utilise des instruments peu dispendieux de mesure du mouvement. Les forces et les moments de flexion estimees peuvent etre utilises comme outil de verification de la base en ligne. Une etude des limites d'application de la technique de decrement aleatoire est egalement presentee. Mots-cles: plate-forme de forage en mer, force d'excitation, decrement aleatoire, force de reaction. [Traduit par la Redaction], Introduction An early detection of fatigue cracks occurring in offshore platform members is critical to the safe, efficient, and economic operation of the platform. Several approaches have been suggested to [...]

The main focus of this investigation is directed toward the examination of crack-spacing expressions suitable for offshore concrete structure applications. Offshore structures are unique structures that are constantly exposed to harsh environmental conditions, including exposure to seawater and sea spray. The splash zone of an offshore structure is the section of the platform that is the most exposed to both a harsh marine environment and seawater. The design of offshore structures is controlled by mandatory design codes to ensure structural safety and integrity. Most of the available expressions for crack spacing were developed for building structures using normal-strength concrete and normal concrete cover. However, offshore structures are built using high-strength concrete with a thick concrete cover. Very little information is published on the crack analysis of high-strength concrete with a thick concrete cover for offshore applications. An experimental testing program was designed to examine the effects of concrete cover and the bar spacing of normal- and highstrength concrete on crack spacing. The different code expressions are evaluated with respect to the experimental results. Key words: crack spacing, crack width, bar spacing, concrete cover, high-strength concrete, normal-strength concrete, concrete slabs. Cette etude porte principalement sur l'examen des equations de l'espacement des fissures pour les structures en beton en mer. Les constructions en mer sont des structures uniques qui sont constamment exposees a des conditions environnementales agressives, incluant l'exposition a l'eau de mer et aux embruns salins. La zone d'action des vagues sur une construction en mer est la section de la plate-forme qui est la plus exposee a l'environnement marin agressif et a l'eau de mer. La conception des structures en mer est regie par des codes de conception obligatoires afin d'assurer la securite et l'integrite des structures. La plupart des equations disponibles pour l'espacement des fissures ont ete developpees pour des structures de batiments utilisant des resistances normales du beton et un enrobage normal de beton. Toutefois, les structures en mer sont construites en utilisant du beton a haute resistance et un enrobage epais de beton. Tres peu d'information est publiee sur l'analyse des fissures dans du beton a haute resistance et un enrobage epais de beton pour les utilisations en mer. Un programme d'essai experimental a ete concu pour examiner les effets de l'enrobage de beton et de l'espacement des barres d'armature dans du beton normal et a haute resistance sur l'espacement des fissures. Les differentes equations contenues dans les codes sont evaluees par rapport aux resultats experimentaux. Mots-cles : espacement des fissures, largeur des fissures, espacement des barres d'armature, enrobage de beton, beton a haute performance, beton a resistance normale, dalles de beton. [Traduit par la Redaction], Introduction The low tensile strength of concrete directly contributes to cracking of concrete in offshore structures. The design of offshore structures is controlled by mandatory design codes to ensure structural [...]

This research's primary objectives were first to verify a reliable structural health monitoring (SHM) experimental technique for reinforced concrete slab plates, and secondly, to introduce a special fiber Bragg grating (FBG) sensors cable system for continuous field monitoring of concrete. The particular focus was on the damage assessment, using an effective ambient vibration-based damage diagnostic technique of random decrement (RD). An investigation examined the extent of damage induced by progressive static loading through a numerical RD algorithm for four concrete plate specimens: three reinforced high-strength concrete (HSC) plates with different reinforcement ratios, and one ultra-high-performance fiber-reinforced concrete (UHP-FRC) plate. The extent of damage was measured through relative changes in the natural frequency and damping ratio as dynamic parameter damage indexes, which were obtained from RD signatures at cracking, yield, and ultimate loadings. Concurrently, the behavior of the concrete slabs was examined regarding the load-deflection relationship at service and ultimate load, crack pattern, and failure modes. [ABSTRACT FROM AUTHOR]