Search

This paper describes the development of a unique rolling load simulator (ROLLS) for testing bridge superstructure with a footprint up to 4 m ×17 m, and its first application to test a full-scale 1220 mm ×900 mm ×16000 mm B900 prestressed concrete box girder. This facility at Queen's University in Kingston, Ontario, is the first of its kind in Canada. ROLLS can apply cyclic loading in a controlled laboratory environment, under realistic highway scale 'rolling wheel loads', in lieu of the conventional 'pulsating stationary loads'. It has two half-axles of a large tandem, each comprising a dual 1140 mm diameter air-inflated tires spaced at either 1.2 or 2.4 m. Each half-axle can apply up to 125 kN, representing the heaviest half-axle load of the CL-625 design truck of the Canadian Highway Bridge Design Code (CHBDC). The maximum travel range and speed are 14.9 m and 6 m/s, respectively. A case study involving analysis of a bridge with eight adjacent B900 box girders of 27.6 m span was carried out prior to experimentally testing one of the girders using ROLLS. Load distribution analyses were conducted using both (i) a finite element model of the full bridge under various CL-625 truck loading configurations and (ii) the CHBDC load distribution method, and both agreed well. Scaling analysis of the girder load share was then conducted to account for shortening it to 16 m to fit in the laboratory, resulting in two-115 kN ROLLS design loads, 1.2 m apart. Multiple passes were conducted at various loads of 40%–100% of the design load, at speeds of 1–5 m/s to examine the machine and girder behaviours. It was found that the applied load fluctuates by less than 10% of full capacity and a 0.13 s/cycle time lag occurs. The measured girder deflection and elastic strains were 11%–20% lower than predicted theoretically. With the two half-axles assembly spaced at 1.2 m, the apparatus has the ability to complete three million cycles in approximately 4.5 months if ran continuously at 5 m/s. [ABSTRACT FROM AUTHOR]

The Canadian highway bridge design code (CHBDC) contains provisions for designing concrete members with fiber-reinforced polymer (FRP) reinforcement. In the second edition of the code, new shear design procedures for FRP-reinforced sections are provided. These procedures are consistent with those for steel-reinforced members in the code, in consideration of some modifications that account for the substantial differences between FRP and steel reinforcement. The shear approach adopted in the CHBDC follows the traditional approach of Vc + Vs for shear design. This paper presents an evaluation of this approach by comparing it with experimental shear strengths of available test data on beams longitudinally reinforced with FRP bars and with or without FRP stirrups. In addition, the CHBDC approach was compared with the FRP shear design provisions currently in effect in North America using the available test results. The comparison shows that the CHBDC method significantly underestimates the shear strength of FRP-reinforced concrete beams. A proposed modification to this method is presented and verified against available test results. Le Code canadien sur le calcul des ponts routiers (CCCPR) contient des dispositions pour la conception de membres de béton avec armature en polymères renforcés de fibres (PRF). Dans la 2e édition du code, de nouvelles procédures pour la conception de cisaillement pour les sections armées de PRF sont fournies. Ces procédures sont compatibles dans le code avec celles des membres armés d'acier en considérant certaines modifications pour tenir compte des différences substantielles entre les armatures en PRF et en acier. L'approche du cisaillement adoptée dans le CCCPR suit l'approche traditionnelle de Vc + Vs pour la conception du cisaillement. Cet article présente une évaluation de cette approche en la comparant à des forces de cisaillement expérimentales dans des données de test disponibles sur des poutres armées longitudinalement de barres de PRF, et sans ou avec étriers de PRF. En outre, l'approche du CCCPR a été comparée aux dispositions de conception de cisaillement PRF actuellement en vigueur en Amérique du Nord en utilisant les résultats de tests disponibles. La comparaison montre que la méthode du CCCPR sous-estime significativement la résistance au cisaillement des poutres armées en PRF. Une proposition de modification de cette méthode est présentée et vérifiée par rapport aux résultats des essais disponibles. [ABSTRACT FROM AUTHOR]