Monorail transportation systems are widely built in medium and small cities, as well as hilly cities, because of their excellent performance. A prestressed concrete track beam is a key load-carrying structural component and guideway subjected to repeated traffic load. The fatigue behavior of the prestressed concrete beam is critical for the safety of the transportation system. This paper presents the results of an experimental study on the fatigue behavior of a prestressed concrete beam in terms of stiffness degradation and strain change. The displacement and rotation of the beam of concrete and reinforcement were examined, respectively. A three-dimensional finite element model was established to help understand the development of the mechanical behavior. No crack was observed throughout the test. Both concrete and bars behaved in their linear-elastic stage throughout the test, and the bond between them performed well.During the last decade, a large amount of theoretical and experimental research has been proposed to investigate the fatigue behavior and mechanism of the PC beam in detail [10][11][12]. Harajli and Naaman [13] found that the fatigue life of PC beams is related to the degree of prestressing, the longitudinal reinforcement ratio, and the strength of concrete. Feng et al. [14] found that cracking and deflection changed rapidly in the initial stage of fatigue, and changed stably afterwards until failure. Wollmann [15] carried out an experimental investigation of the fatigue strength of post-tensioned concrete girders, finding that fatigue failure occurred in the vicinity of cracks. Li et al. [16] analyzed the evolution of the fatigue failure pattern of PC beams and regularities of midspan deflection and strain of concrete of PC beams. However, most of the studies focused on the fatigue behavior of partially-prestressed concrete beams [17] and beams strengthened with carbon fiber-reinforced plastics sheets [18][19][20][21]. However, there is no research on fatigue behavior of fully prestressed concrete beams. The primary reason is that fully prestressed concrete beams are considered not susceptible to fatigue damage due to the applied full prestressing force. However, fully prestressed concrete beams can be turned into partially prestressed concrete beams under the effects of overloading or other extreme events. Moreover, cracks are not allowed in fully prestressed concrete beams under service loads, which is different from partially prestressed concrete beams.Model tests and in situ tests have been considered as effective approaches to investigate mechanical performances of structures [22][23][24][25][26][27][28][29][30]. In this study, a full-scale fatigue test of a prestressed concrete beam was carried out. Displacement, rotation, strain of concrete, and reinforcement were examined under post-fatigue static loading condition. A three-dimensional finite element model was established to understand stress distributions.
Experimental Program
MaterialsA PC beam was fabricated to represent the typical PC t...