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The practice of externally bonded (EB) carbon fiber-reinforced polymer (CFRP) fabrics for structural strengthening increasingly shows evidence of effectiveness for the rehabilitation of existing structures. However, debonding of fiber- reinforced polymer (FRP), particularly in shear, is still a major premature failure mode when using FRP sheets to strengthen concrete structures. This paper presents the results of an experimental investigation of the performance of full-scale reinforced concrete (RC) beams strengthened in shear using EB-FRP U-wrapping (UW) and full wrapping (FW) with different fabric thicknesses. Full wrapping is used mostly on columns with all sides accessible and does not generally apply to beams. The main objectives of this study are to optimize FRP capacity and to evaluate the effect of confinement and the effectiveness of FRP using different strengthening configurations for RC beams, such as FW and UW. The results obtained in this study reveal that fully wrapped beams exhibit enhanced CFRP contribution to shear resistance compared to U-wrapped beams. In addition, the FW configuration eliminated the CFRP debonding failure mode and resulted in an increase in concrete strain. Key words: reinforced concrete (RC) beams, shear strengthening, CFRP fabrics, U-wrapping (UW), full wrapping (FW), codes and guidelines La pratique d'utilisation de materiel en polymere renforce de fibres de carbone (PRFC) pour le renforcement structurel montre de plus en plus l'efficacite de la remise en valeur des structures existantes. Cependant, le decollement de polymere renforce de fibres (PRF), en particulier en cisaillement, demeure un mode de defaillance premature majeur lorsqu'on utilise des feuilles de PRF pour renforcer les structures en beton. Cet article presente les resultats d'une etude experimentale sur la performance des poutres en beton arme (BA) renforcees en cisaillement a l'aide de PRF enveloppe en U (EU) et d'une enveloppe tout le tour (ETT) collees a l'exterieur (CE) avec differentes epaisseurs de materiel. L'ETT est utilisee principalement sur les colonnes avec tous les cotes accessibles et ne s'applique generalement pas aux poutres. Les principaux objectifs de cette etude sont d'optimiser la capacite des PRF et d'evaluer l'effet du confinement et l'efficacite des PRF en utilisant differentes configurations de renforcement pour les poutres de BA, comme l'ETT et l'EU. Les resultats obtenus dans le cadre de cette etude revelent que les poutres ETT presentent une contribution accrue du PRFC a la resistance au cisaillement comparativement aux poutres EU. De plus, la configuration ETT a elimine le mode de decollement du PRFC et a entraine une augmentation de la deformation du beton. [Traduit par la Redaction] Mots-cles : poutres en beton arme (BA), renforcement du cisaillement, materiel en polymere renforce de fibres de carbone (PRFC), enveloppe en U (EU), enveloppe tout le tour (ETT), codes et lignes directrices, Introduction U-wrapping fiber-reinforced polymer (FRP) configurations are a major shear-strengthening scheme in externally bonded (EB) FRP composites for restoring or upgrading the shear resistance of deteriorated reinforced concrete beams. However, [...]

Le present article traite du renforcement en cisaillement des poutres en beton arme (BA) a l'aide de materiaux composites a base de polymere renforce de fibres (PRF) colle en surface. La premiere partie de l'article fait le point sur l'evolution des codes et des normes nord-americains quant a la resistance a l'effort tranchant des poutres en BA renforcees a l'aide de composite en PRF colle en surface. La seconde partie presente une analyse exhaustive des parametres majeurs influencant la contribution du PRF a la resistance a l'effort tranchant. Elle presente egalement une comparaison des predictions des normes de conception en vigueur (ACI 440.2R 2017; CSA/S6 2019; CSA/S806 2012;fib-TG9.3 2001) avec les resultats des essais experimentaux rapportes dans la litterature. Il ressort de l'etude que des parametres majeurs influencant le comportement a l'effort tranchant n'ont fait l'objet, a ce jour, que de peu d'investigations. Parmi ces parametres, on peut citer en particulier : (i) la presence et le taux de l'acier transversal interne et (ii) le nombre de plis (couches) des PRF colles en surface. Cela peut expliquer les ecarts observes entre les resistances predites par les regles de calcul et celles obtenues a partir de tests. A la suite de ces observations, une base de donnees extraite a partir des etudes experimentales a ete elaboree dans le cadre de cette etude. Les resultats obtenus mettent en evidence et confirment l'existence d'une interaction entre le composite en PRF colle en surface et l'acier transversal interne quant a la reprise des efforts tranchants. Ils mettent egalement en evidence l'existence d'une rigidite optimale du PRF au-dela de laquelle le gain en resistance attribue au PRF colle en surface est plafonne. Mots-cles : beton arme (BA), cisaillement, materiaux composites, polymere renforce de fibres (PRF), renforcement, base de donnees, nombre de couches, acier transversal interne, normes de conception. This paper deals with the shear strengthening of reinforced concrete (RC) beams using externally bonded fiber- reinforced polymer (EB FRP) composite materials. The first part of the paper reviews the evolution of North American codes and standards for the shear resistance of RC beams strengthened with EB FRP composites, whereas the second part provides a comprehensive analysis of the major parameters influencing the contribution of FRP to shear resistance. It also presents a comparison of the predictions of current design standards (ACI 440.2R 2017; CSA/S6 2019; CSA/S806 2012;fib-TG9.3 2001) with the results 0f experimental tests reported in the literature. The study shows that major parameters influencing the shear behaviour have received little attention. These parameters include in particular: (i) the presence and ratio of internal transverse steel reinforcement and (ii) the number of EB FRP plies (layers). This may explain the observed discrepancies between the prediction models of existing equations for shear resistance and the results obtained from tests. Consequently, a database extracted from the experimental studies was developed as part of this study. The results obtained highlight and confirm the existence of an interaction between the EB FRP composites and the internal transverse steel reinforcement with regard to shear resistance of RC beams. They also show the existence of an optimal FRP stiffness beyond which there is no substantial gain in resistance attributed to the EB FRP. Key words: reinforced concrete (RC), shear, composite materials, fiber-reinforced polymer (FRP), strengthening, database, number of layers, internal transverse steel, design standards., 1. Introduction Les ouvrages en beton arme (BA) concus selon les regles en vigueur peuvent neanmoins presenter des deficiences durant leur duree de service. Ces deficiences peuvent etre dues a [...]

Masonry blocks are usually made of Portland cement and cured by steam. This study explores the possibility of making masonry blocks using steel slag as binder and carbon dioxide as curing activator. By carbonation activation of steel slag blocks, carbon dioxide can be permanently sequestered in steel slag as calcium carbonates, leading to stronger and more durable construction blocks. In this paper, carbonated steel slag paste was first evaluated by thermogravimetry, derivative thermogravimetry, X-ray diffraction, carbon uptake, strength development, and leaching tests. Based on the preliminary results, the full-size masonry blocks were fabricated using steel slag as the binder and granite as the aggregates. The physical properties and durability of full-size steel slag masonry blocks were then examined through their density, water absorption, moisture content, compressive strength, and fire resistance. An economic analysis was performed and a carbon dioxide utilization capacity was estimated. This study demonstrates that production of steel slag masonry blocks by carbonation is an economically feasible way to utilize carbon dioxide. Key words: C[O.sub.2] utilization, steel slag masonry blocks, carbonation, pilot study, sustainability, construction. Habituellement, les blocs de maconnerie sont faits de ciment Portland et durcis a la vapeur. Cette etude explore la possibility de fabriquer des blocs de maconnerie utilisant le laitier d'acier comme liant et le dioxyde de carbone comme activateur de durcissement. Grace a l'activation de la carbonatation de blocs de laitier d'acier, on peut sequestrer de maniere permanente le dioxyde de carbone dans le laitier d'acier comme carbonates de calcium, donnant lieu a des blocs de construction plus forts et plus durables. Dans cette etude, la pate de laitier d'acier carbonatee a d'abord ete evaluee au moyen de la thermogravimetrie, de la thermogravimetrie en derivation, de la diffraction des rayons X, d'essais d'absorption carbonique, de developpement de resistance et de lixiviation. Selon les resultats preliminaries, des blocs de maconnerie pleine grandeur ont ete fabriques utilisant du laitier d'acier comme liant et du granit comme granulat. Les proprietes physiques et la durabilite des blocs de maconnerie de laitier d'acier pleine grandeur ont alors ete examinees en fonction de leur densite, de leur absorption d'eau, de leur teneur en eau, de leur resistance a la compression et de leur resistance au feu. Une analyse economique a ete effectuee et la capacite d'utilisation de dioxyde de carbone a ete estimee. Cette etude demontre que la production de blocs de maconnerie de laitier d'acier par la carbonatation est une facon economiquement realisable d'utiliser le dioxyde de carbone. [Traduit par la Redaction] Mots-cles: utilisation du C[O.sub.2], blocs de macnnerie de laitier d'acier, carbonatation, etude pilote, durabilite, construction., Introduction Concrete masonry blocks are commonly used in construction for load-bearing walls and partition walls. Traditionally, concrete masonry blocks are made with Portland cement as the binder. In the United [...]

The embedded through-section (ETS) technique was recently developed to avoid the debonding failure that occurs with other fiber-reinforced polymer (FRP) strengthening techniques such as the externally bonded (EB) and near- surface-mounted (NSM) methods. The method offers greater confinement and leads therefore to a substantial improvement in bond performance. In addition, it requires less concrete preparation than the other strengthening techniques. In this study, experimental results from 13 direct-shear test specimens are reported. The influence of the following major parameters on the bond behaviour of FRP-strengthened reinforced concrete beams is examined: concrete strength, hole diameter, bar diameter, bar surface area, and bar bond length. The experimental results show that debonding can be avoided by providing a sufficient bar length and high concrete strength. Among the analytical models suggested in the literature for the bond behaviour of FRP reinforced concrete, the BPE modified model and the CMR model are compared with the experimental results obtained here. The CMR model with new fitting parameters is found to be an accurate way of simulating the experimental results. Key words: ETS method, FRP strengthening, direct shear, experimental test, parametric study, bond force-slip relations, analytical models. La technique de renforcement en cisaillement par insertion de barre en polymeres renforces de fibres (PRF) a travers la section (<< embedded through-section >> (ETS)) a ete recemment developpee pour palier aux ruptures prematurees dues a la delamination et au decollement du composite exhibees par les techniques classiques de renforcement externe en PRF (<< externally bonded >> (EB) et << near surface mounted >> (NSM)). La methode ETS offre un meilleur confinement et conduit a une amelioration substantielle du rendement de la matrice. De plus, la technique est facile a installer par rapport aux autres methodes de renforcement. Cette etude presente les resultats d'une etude experimentale impliquant des essais sur 13 specimens soumis a un cisaillement direct simulant la technique ETS. Elle compare egalement les resultats aux predictions des modeles existants. Les parametres suivants sont evalues : la resistance du beton, la section de la barre, le diametre du trou, le diametre de la barre et sa longueur de scellement sur le comportement de la matrice a l'interface PRF-beton. Les resultats experimentaux montrent que le decollement peut etre evite moyennant une longueur de scellement suffisante et une bonne resistance du beton. Parmi les modeles analytiques proposes dans la litterature pour le comportement des contraintes d'adherence PRF- beton, le modele (BPE) modifie et le modele (CMR) sont compares aux resultats experimentaux obtenus. Le modele CMR avec ses nouveaux parametres d'ajustement s'est avere un outil plus precis pour simuler le comportement des barres en PRF ancrees. Mots-cles : methode ETS, renforcement en PRF, cisaillement direct, essai experimental, etude parametrique, relation contrainte d'adherence-glissement, modeles analytiques d'adherence., Introduction Le renforcement des structures en beton au moyen de composites a base de polymeres renforces de fibres (PRF) colles en surface (EB) est considere comme une methode efficace pour [...]

The National Building Code of Canada (NBCC) takes into account the effect caused by the higher order vibration modes using the dynamic amplification factor [M.sub.v]. This factor depends on the types of systems used to resist seismic forces. However, for load-bearing partitions, the NBCC recommends using the [M.sub.v] that pertains to moment-resisting structures when the level of coupling, DC [greater than or equal to] 2/3 (coupled load-bearing partition system) or the [M.sub.v] pertaining to walls and structure-wall systems when DC < 2/3 (partially coupled load-bearing wall system). Consequently, the NBCC connotes a fundamentally different dynamic behaviour than these two load-bearing wall systems, even when the deviation of the respective DC on either side of the DC = 2/3 value is low. This deviation was the basis behind the present study to assess the effect caused by the higher order vibration modes in coupled and partially coupled load-bearing walls, and to propose an [M.sub.v] factor specific to these important structural systems. The numerical investigations of this study analyse a large array of load-bearing wall systems and take into account the following parameters: (i) three building heights (10, 20, and 30 storeys), (ii) two levels of coupling (DC = 0.6 and DC = 0.7), (iii) five soil classes (A to E), and (iv) two cities, Montreal and Vancouver, representative of the seismic risk zones for Eastern and Western Canada. [Journal translation] Key words: higher order vibration modes, dynamic amplification, level of coupling, elastic spectrum, coupled load-bearing partitions. Le Code national du batiment du Canada (CNBC) tient compte explicitement de l'effet du aux modes superieurs de vibration (EMSV) a l'aide du facteur d'amplification dynamique [M.sub.V]. Ce facteur depend, entre autres, du type de systemes de resistance aux forces sismiques (SRFS) adopte. Cependant, dans le cas des systemes de murs de refend (MR), le CNBC recommande de prendre le [M.sub.V] relatif aux ossatures resistant aux moments lorsque le degre de couplage (DC) est plus grand ou egal a 2/3 (systeme de MR couples) ou le [M.sub.V] relatif aux murs et aux systemes mur-ossature lorsque le DC < 2/3 (systeme de MR partiellement couples). Le CNBC sous-entend, par consequent, un comportement dynamique fondamentalement different de ces deux types de systemes de MR meme lorsque l'ecart de leurs DC respectifs, de part et d'autre de la valeur charniere DC = 2/3, est faible. C'est precisement cette incongruite qui a motive la presente etude qui a pour objectif d'evaluer l'EMSV dans les systemes de MR couples et partiellement couples, et de proposer un facteur [M.sub.V] specifique a ces systemes structuraux importants. Les investigations numeriques menees dans le cadre de cette etude portent sur une large gamme de systemes de MR couvrant les parametres suivants: (i) trois hauteurs de batiments (10, 20 et 30 etages); (ii) deux DC (DC = 0,6 et DC = 0,7); (iii) cinq classes de sol (A a E); et (iv) deux villes, Montreal et Vancouver, respectivement representatives du risque en zones sismiques de l'Est et de l'Ouest du Canada. Mots-cles: modes superieurs de vibration, amplification dynamique, degre de couplage, spectre elastique, murs de refend couples., Introduction Des etudes (D'Aronco 1993; Filiatrault et col. 1994) ont revele que durant les evenements sismiques majeurs, la demande en cisaillement dans les sections critiques des MR continue de croitre [...]

This article deals with the shear strengthening of reinforced concrete (RC) beams using externally bonded fibre-reinforced polymers (FRP). The requirements for shear strengthening of RC beams in CSA (Canadian Standards Association) S806-02 code are summarized and compared to other existing international codes. Moreover, a comprehensive analysis on major parameters influencing on shear contribution of FRP in relation with the current equations of the Canadian codes and other standards is represented in this article. Based on the mentioned analysis and recent achievements a new, rational and evolutionary predicting model to calculate the effective strain and the shear contribution of FRP is proposed. The new model takes into account the major parameters such as, the effect of transverse steel reinforcement. This model will ultimately be used in CSA S806-02. Key words: FRP composites, shear reinforcement, reinforced concrete, beams, parameters, standard, model. Cet article a trait au renforcement a l'effort tranchant des poutres en beton arme a l'aide de materiaux composites colles en surface. Il presente une synthese des prescriptions de la norme ACNOR (Association canadienne de normalisation) S806-02 relatives au renforcement a l'effort tranchant, en comparaison aux autres guides internationaux existants. Il presente egalement une analyse exhaustive des parametres majeurs influencant la contribution du composite a la resistance a l'effort tranchant en relation avec les equations actuelles de la norme canadienne et des autres guides. Sur la base de cette analyse et des recentes avancees en recherche, des perspectives pour l'elaboration d'un nouveau modele de calcul normatif et evolutif permettant de predire la deformation effective et donc la contribution du composite a base de polymere renforce de fibres (PRF) tenant compte des parametres majeurs, dont l'armature transversale en acier, sont enoncees. Ce modele sera ultimement integre a la norme ACNOR S806. Mots-cles : composites a base de polymere renforce de fibres (PRF), renforcement a l'effort tranchant, beton arme, poutres, parametres, norme, modele. [Journal translation], Introduction Les ouvrages en beton arme (BA) representent une partie importante du patrimoine bati au Canada et dans le monde. Beaucoup de ces ouvrages souffrent de degradation serieuse des materiaux. [...]

This paper presents results from an experimental investigation of the bond-slip performance of moderately confined concrete under monotonic and cyclic loading. The effects of six factors on the bond-slip response and on the bond mechanisms are investigated. These factors are grouped into two categories: the first category of four factors is related to the confining conditions, the second category to the loading conditions. A total of 43 pullout tests under monotonic and cyclic loadings were performed. Results show that the quantity of confining steel and the distance between the tested bar and the confining steel are the most important factors affecting the overall bond response. Bar spacing and height of concrete cast below the bar have less significant effects on the overall response, affecting mainly the initial response phase. The height of concrete cast below the tested bar is found to affect the maximum bond resistance to the same extent as in well-confined concrete. Cyclic bond behaviour of moderately confined concrete is found to be similar in shape and in cyclic degradation to that of well-confined concrete. It was also found that most of the bond response parameters, such as maximum bond resistance and the post-peak (softening) phase, can be predicted with excellent accuracy in terms of the factors investigated. Key words: experimental tests, reinforced concrete, bond performance, bond-slip response, moderate confinement, static loading, cyclic loading. Cet article presente les resultats d'une etude expeerimentale du comportement adherence-glissement du beton moderement confine sous chargement monotone et cyclique. Six facteurs influencant la response adherence-glissement et sur les meecanismes d'adherence sont etudiees. Ces facteurs sont regroupesen deux categories : la premiere categorie comporte quatre facteurs et est reliee aux conditions de confinement et la deuxieme categorie, aux conditions de chargement. Au total, 43 essais d'arrachement ont ete realises sous chargement monotone et cyclique. Les resultats montrent que le comportement de l'adherence est essentiellement affecte par la quantite de l'acier de confinement et la distance entre la barre mise a l'essai et l'acier de confinement. Les effets de l'espacement des barres d'armature et de la segregation du beton sur le comportement de l'adherence sont de moindre importance et affectent principalement la phase initiale dela reponse adheerence-glissement. L'effet de la segregation du beton affecte la resistance maximale de l'adherence au mieme titre que dans le beton bien confine;. Le comportement cyclique de l'adherence d'un beton moderement confine; est similaire en forme et en degradation cyclique a celui d'un beton bien confine;. Par ailleurs, la plupart des parametres de la reponse adherence-glissement, tels que la resistance maximale d'adherence et la phase post-pic (ecrouissage), peuvent eetre predits avec une excellente precision en termes des facteurs eetudiees. Mots-cles: essais expeerimentaux, beton arme, comportement de l'adherence, reponse adherence-glissement, confinement modere, chargement statique, chargement cyclique., Introduction Reinforcement slip is a fundamental and important aspect of the response of reinforced concrete (RC) structures. Under certain conditions, deformations arising from reinforcement slip within joints of structural members [...]

New technologies based on seismic isolation are gaining popularity among engineers given the savings on construction costs. The long-term advantage of these technologies preserve the serviceability of the structure after an earthquake and eliminate the cost of reconstruction. This advantage is critical for 'emergency' bridges, required to remain operational after an earthquake. The present article examines a method of isolating the foundation of existing bridges as part of a seismic retrofitting effort. This approach is supported by the increasing interest in this method, especially since its adoption by the Canadian standards and due to the fact that engineers are not too familiar with non-linear dynamic design methods. Another source of motivation is the opportunity to apply this technique to the refection of a few Quebec bridges. The steps of the antiseismic calculations as well as the results of non-linear analyses pertaining to the Madrid Bridge are presented and discussed. This paper may become a useful tool for engineers and their projects of retrofitting existing bridges. Key words: bridge, seismic retrofitting, standard, foundation isolation, Madrid Bridge, Quebec. Les nouvelles technologies basees sur l'isolation sismique connaissent un interet grandissant parmi les ingenieurs, compte tenu de l'economie sur le cout de la construction de l'ouvrage qu'elles offrent. Elles presentent egalement un avantage indeniable a long terme etant donne qu'elles preservent la fonctionnalite de l'ouvrage apres seisme et eliminent le cout de reconstruction. Cet avantage revet une importance capitale pour les ponts dits de secours qui doivent demeurer en service apres le seisme. Cet article presente une methodologie relative a l'isolation de la base des ponts existants dans un contexte de mise en conformite sismique. Cette demarche est motivee par l'interet grandissant de cette methode, notamment depuis son adoption par la norme canadienne d'une part et d'autre part par le fait que les ingenieurs praticiens sont moins familiers avec les methodes dynamiques non lineaires de conception. L'opportunite offerte aux auteurs de mettre en application cette technique pour la refection de quelques ponts au Quebec est une autre source de motivation. Les etapes de calcul parasismiques sont pourvues, et les resultats des analyses non lineaires relatives au pont Madrid sont presentes et discutes. L'article est destine aux ingenieurs praticiens qui y trouveront un outil utile pour leurs projets en rehabilitation de ponts existants. Mots-cles : pont, mise en conformite sismique, norme, isolation de la base, pont Madrid, Quebec., Introduction Les ponts sont des structures importantes dans la vie economique et sociale des nations. Dans les regions sismiques, de nombreux ponts, de part leur importance strategique, sont concus pour [...]

This paper presents a comprehensive review of the new provisions for the design of coupled shear walls in Canadian seismic zones. It follows major revisions that were incorporated in the National Building Code of Canada 2005 (NBCC 2005) and in the Canadian standard Design of concrete structures (CSA A23.3-04), which were due, in particular, to the adoption of a new Canadian map of seismic risk. The present study is intended to address recurring confusions in current practice and the difficulties expressed in the application and interpretation of the new NBCC 2005 and CSA A23.3-04 provisions. A design flowchart is thus proposed as a practical guide, describing, step by step, the required verifications at each stage of coupled shear walls calculation. Finally, to demonstrate the applicability of these new provisions, a numerical example is detailed, following the presented design flowchart. Key words: coupled shear walls, coupling degree, reinforced concrete, seismic design, NBCC 2005, CSA A23.3-04, ductility, dynamic amplification. Cet article presente une vue d'ensemble des dispositions nouvelles concemant la conception des murs de refend couples en zones sismiques canadiennes. Il fait suite aux revisions majeures incorporees dans le Code national du batiment--Canada 2005 (CNBC 2005) et la norme canadienne Calcul des ouvrages en beton (CAN/CSA-A23.3-F04), lesquelles etaient dues, en particulier, a l'adoption de la nouvelle carte canadienne du risque sismique. Cette etude a ete motivee par les confusions recurrentes observees dans la pratique courante et par les difficultes exprimees dans l'application et l'interpretation des nouvelles prescriptions du CNBC 2005 et de la norme CAN/CSA-A23.3-F04. A cet effet, un organigramme de conception est propose comme guide pratique, decrivant pas a pas les verifications requises a chaque etape du dimensionnement des murs de refend couples. Finalement, pour demontrer l'applicabilite des nouvelles prescriptions, un exemple numerique est traite dans le detail, conformement an dit organigramme de conception. Mots-cles : murs de refend couples, degre de couplage, beton arme, conception sismique, CNBC 2005, CAN/CSA-A23.3F04, ductilite, amplification dynamique., Introduction L'efficacite des systemes de murs de refend couples (MRC) comme systemes de resistance aux forces sismiques (SRFS) est desormais etablie. Elle resulte de la conjonction des proprietes mecaniques de [...]

Abstract: This paper presents results of an experimental investigation on the fatigue performance of the welded multiple support bar modular bridge expansion joint (MBEJ) used for the recent Jacques Cartier [...]

This paper describes the procedure and results of the field tests on high-density polyethylene (HDPE), PVC, and metal large diameter pipes subjected to a highway design truck loading. Numerical simulations using finite element method are performed to determine pipe-soil system response under live load application. Comparisons of field test data with the predicted responses are made for soil pressures around and above the pipes, deformed cross-sectional pipe profiles, and pipe deflections. The field test results indicated that the buried flexible pipes, embedded with highly compacted graded sand with silt, demonstrated good performance without exhibiting any visible joint opening or structural distress. Under shallow burial conditions, the AASHTO specified deflection limit of 5% is found to be adequate for installation of the flexible pipes during the construction phase, and a vertical deflection limit of 2% is suggested for HDPE pipes based on the truck load response and repeated loading effect. DOI: 10.1061/(ASCE)0887-3828(2006)20:1(21) CE Database subject headings: Soil-structure interaction; Soil pressure; Flexible pipes; Culverts; Storm sewers; Live loads; Load distribution; Highways; Trucks.

A fatigue study was performed on two commercial high-strength concretes of 70 MPa and 95 MPa with water/cementitious material ratios of 0.28 and 0.23, respectively. Specimens were cast at the construction site and cured in the laboratory. Tests were performed under constant amplitude, and strains were measured continuously using strain gauges. The McCall model for fatigue life prediction was found to be satisfactory, and safer than the usual Wohler curves. Strain evolution and stiffness degradation with the number of cycles in high-strength concrete were found to be similar to those of normal concrete. Strain at failure under cyclic loading was found to be of the same order as the strain at peak load under static loading. Interesting correlations between strain rate and number of cycles to failure and between stiffness decrease rate and number of cycles to failure were found. Evolution of the hysteresis loop was studied. Energy dissipated was found to decrease after the first cycles, and increased steadily thereafter up to failure. Finally, the differences in deformation characteristics between the two high-strength concretes studied in this investigation were analyzed.