STR-823: FLEXURAL BEHAVIOUR AND BOND-DEPENDENT COEFFICIENT OF BASALT FRP BARS IN CONCRETE BEAMS

This paper presents an experimental study aimed at determining the bond-dependent coefficient (kb) and investigating the flexural performance of concrete beams reinforced with ribbed basalt fiber-reinforced polymer (BFRP) bars. The performance of the BFRP-RC concrete beams is compared against that of GFRP-RC ones. A total of five concrete beams measured 200 mm wide × 300 mm deep × 3100 mm long were constructed and tested in four-point bending over a clear span of 2700 mm. The main variables were reinforcement type (BFRP, GFRP, and steel bars as reference) and reinforcement ratio. The test results showed that the average kb was 0.85 for the ribbed BFRP bars. The kb value of ribbed BFRP bars was lower than 1.0 recommended by the Canadian Highway Bridge Design Code, CHBDC (CSA S6-14)

STR-824: FATIGUE BEHAVIOR OF CONCRETE UNDERGROUND CHAMBERS REINFORCED WITH GFRP BARS

Precast underground concrete chambers reinforced with steel bars are used frequently in construction and electrical industry for housing power cables and transformers. In Quebec, more than 30,000 of these chambers have been installed by Hydro-Quebec during the last 30 years. However, like other conventionally reinforced concrete structures, corrosion of steel reinforcement constitutes the major cause of chambers deterioration, leading to costly repairs and rehabilitation as well as a significant reduction in service life. This paper presents experimental data on the fatigue and static behavior of full-scale underground concrete chamber reinforced totally with glass fiber-reinforced polymer (GFRP) bars. The chamber measure 2,300 mm in width by 3,800 mm in length and the walls are 2,800 mm high. The chamber was tested under fatigue loading up to one million cycles then test under static load to simulate the traffic load on the manhole. The experimental results were reported in terms of strain and deformation behavior

STR-828: BEHAVIOR OF CIRCULAR FRP-REINFORCED CONCRETE COLUMNS UNDER ECCENTRIC LOADING

This paper presents the results of an investigation of the eccentric compression behavior of three full-scale circular concrete columns reinforced with the glass-fiber-reinforced polymer (GFRP) bars and spirals. The column specimens measured 1500 mm height, 305 mm diameter and were tested under monotonic eccentric loading. The main variable was the eccentricity-to-dimeter ratio. Three values were considered in this study (8.20%, 16.39%, and 65.57%). The failure mechanism was changeable according to the level of the applied eccentricity. The failure mechanism of columns at small eccentric loading was defined as compression-controlled due to concrete crushing. At high eccentric loading, the failure of the column cannot simply be characterized by a compression failure, it was rather controlled by the properties of the GFRP bars. The test results were plotted to obtain the experimental P-M interaction diagram. Finally, the experimental results were analyzed and compared with predicted results

STR-864: PROPOSED STRUT-AND-TIE MODEL FOR CONCRETE DEEP BEAMS REINFORCED WITH FRP BARS

A compiled database of 53 tests of FRP-reinforced concrete deep beams with shear span–depth ratios of less than two was used to evaluate the strut-and-tie models (STM) provided in ACI 318 (2014), CSA S806 (2012), CEB-fib (1999), and JSCE (2007). All provisions were found to be inadequate in calculating the capacity of FRP-reinforced deep beams due to inherent shortcomings in each provision. Hence, a new STM-based procedure for FRP-reinforced deep beams was proposed. The new model incorporates the effect of shear span–depth ratio (a/d), concrete compressive strength (fc’), and tensile strain in the adjoining tie (ε1). The contribution of the web reinforcement on the strut efficiency factor was found to be insignificant. The new model was capable of predicting the ultimate capacity of the compiled FRP-reinforced concrete deep beams with satisfactory conservatism

STR-829: BEHAVIOR OF GFRP-REINFORCED CONCRETE SQUAT WALLS UNDER SIMULATED EARTHQUAKE LOADING

Steel-reinforced squat walls are used as the main component for earthquake resistance in low-rise structures. Deterioration due to corrosion of steel reinforcement is one of the major challenges facing the construction industry. Furthermore, given the low aspect ratio of squat walls, their behavior is dominated by inelastic shear deformations activated by the yielding of flexural reinforcement. These deformations degrade strength and stiffness with subsequent shear failure, preventing the wall from achieving its flexural capacity, which is a prerequisite for adequate seismic design. Using noncorrodible glass-fiber-reinforced-polymer (GFRP) bars represents an effective method for overcoming corrosion problems. In addition, the available experimental studies on mid-rise shear walls show that GFRP reinforcement can control shear deformation, which is a major problem with steel-reinforced squat walls. Our study was experimentally conducted to investigate the shear-deformation behavior of GFRP-reinforced squat walls. Two full-scale squat walls with an aspect ratio of 1.3 were constructed and tested to failure under quasi-static reversed cyclic lateral loading: one was reinforced with steel bars; the other with GFRP bars. The experimental results show that the GFRP-reinforced wall evidenced significantly enhanced behavior related to ultimate strength, drift ratio, control shear distortion, and mode of failure compared to the steel-reinforced wall

STR-827: SHEAR STRENGTH OF CIRCULAR CONCRETE BEAMS REINFORCED WITH GFRP BARS

This paper presents the results of an investigation of the shear strength and behavior of three circular concrete beams reinforced with glass-FRP (GFRP) bars and spirals. The beams, which measured 3,000 mm in length by 500 mm in diameter, were tested under four-point bending. The test parameters included the GFRP-spiral-reinforcement ratio (different spiral spacings [150 and 200 mm] and spiral diameters [13 and 15 mm]). As designed, the beams failed in shear due to GFRP-spiral rupture. The test results indicated that the higher the GFRP spiral reinforcement ratio, the higher the enhancement of the shear strength due to the confinement, which controls shear cracks and improves aggregate interlocking

Contribution à l'étude du comportement à l'arrachement et au fluage des ancrages actifs injectés dans la roche

Nous avons également étudié l'effet superplastifiant du PNS a partir, principalement, d'expériences calorimétriques et rhéologiques sur des suspensions concentrées de ciment. Nous avons de plus effectué quelques expériences de sédimentation et de calorimétrie sur des suspensions diluées. Le rôle du contre-ion du PNS (Na\sp+, K\sp+, Mg\sp{2+}, Ca\sp{2+}, Ba\sp{2+}, monoethanolammonium, diethanolammonium, triethanolammonium, tetramethylammonium) et l'effet de la masse molaire ont été étudies. Le Mg\sp{2+} est le seul contre-ion qui inhibe complètement l'effet dispersant et presque complètement l'effet fluidifiant du PNS. Les monomères, les oligomères et une fraction du PNS contenant des hautes masses molaires n'ont pas fluidise les suspensions concentrées de ciment. Lorsqu'un PNS est sépare en fractions de différentes masses molaires moyennes, les fractions qui fluidifient le plus les suspensions de ciment s'averent etre celles qui ont le moins retarde les réactions d'hydratation

Comparison between ASTM D7205 and CSA S806 tensile-testing methods for glass-fiber-reinforced-polymer bars

The American Society of the International Association for Testing and Materials (ASTM) D7205 / D7205M-06 and the Canadian Standards Association (CSA) S806 contain the commonly used test methods for characterizing the tensile properties of glass-fiber-reinforced-polymer (GFRP) bars for use as reinforcement in concrete structures. These two standards, however, use different anchor dimensions and loading rates, thereby possibly yielding different properties for the same type of FRP bars. This paper assessed the results of a four-laboratory testing program comparing the sample preparation methods and test results according to ASTM D7205 and CSA S806. Each laboratory tested at least 10 samples prepared according to the recommendations in Annex A of the ASTM standard, and Annex B of CSA S806. Each type of sample was prepared by a single laboratory in order to minimize variation among the test specimens. The results show a statistically significant difference between the tensile strength measured using the CSA and ASTM provisions. Regardless of specimen preparation, the modulus of elasticity of the GFRP bars was the same with both test standards, but the ASTM standard returned a wider variation than the CSA

Contribution à l'étude de la résistance et de la consolidation d'argiles remaniées

Ce présent mémoire présente une étude en laboratoire sur le comportement des argiles remaniées de type marin (mer de Tyrrell et de Champlain). Les principaux points qui ont été analysés sont: 1. variations de la résistance au cisaillement en fonction de l'indice de liquidité 2. consolidation et compressibilité 3. variations de la résistance au cisaillement en fonction de la pression effective de consolidation. Les travaux ont porté sur les sites suivants: . rivière Broadback (mer de Tyrrell) . Saint-Léon (mer de Champlain) . Saint-Marcel (mer de Champlain). Les résultats obtenus ont montré principalement que: 1. la résistance au cisaillement de l'argile remaniée est reliée par une relation unique à l'indice de liquidité 2. l'évolution de la résistance au cisaillement Cu en fonction de la pression effective de consolidation o’v se décompose en trois zones distinctes; a. une première zone où Cu croît fortement en fonction de o’v b. une deuxième zone dans laquelle Cu croît très peu en fonction de o’v c. une troisième zone dans laquelle Cu croît de façon proportionnelle à o’v. Ce comportement découlant des essais en laboratoire peut se rapprocher de celui observé en chantier dans les dépôts d'argile homogène. Le modèle de comportement mécanique proposé est particulièrement très important pour la prévision du comportement des digues et remblais construits avec de tels matériaux (argile). 3. une sensibilité St se développe durant la consolidation. 4. les gains de résistance résultant de la thixotropie sont fort appréciables