Study On The Mechanical Properties Of The Transverse Tension Technology In The Simply-supported Continuous Bridge Structure System

With the growing traffic demand and varied unfavorable environmental factors, bridge structures, having been employed for decades, even centuries, inescapably suffered various diseases, breeding decreases in bearing capacity and durability. To ensure the safe run, and, avoid wasting money resulted from unnecessary demolition and reconstruction, the diseased bridge structures should be reinforced so as to improve the stress condition, enhance the bearing capacity and extend the service life.For the prefabricated multiple-span simply supported beam bridges with medium or small span, bridge transformation from simply supported system to continuous system is normally used as an effective, economical and thus competitive reinforcing method to improve the bearing capacity and stress state. The critical technology of this transformation is the connection design of the cast-in-place section on pier-top, which in practice is usually realized by setting prestressed tendons. Based on the pros and cons of the present prestressed technology, this paper puts forward a method, through which transverse tension technology, the structure of the anchorage of which is simple and the construction of which is convenient, is employed to realize the prestressed force of the cast-in-place segment, and studies on the behavior of the reinforcing system in overall process from construction to failure. Some good reinforcing results are eventually achieved. Meanwhile, some referential opinions for actual bridge design are provided.Initially, the key technology of transversely stretching prestressed tendons is studied. Given the differences of different stretching bars and the change of construction process, this paper, considering the properties of the selected steel bars, gives the range of the stress of tension control of the transverse tension prestressed system, and, aiming at the structure, deduces the formulas of the stretching loss of the transverse tension technology, which are different from ones of other prestressed technologies.Next, this paper, referring to the standard drawings of the 20-meter T-beam, analyzes the mid-span’s internal forces of a continuous beam bridge with different spans through Midas/civil, and, taking a continuous bridge with three spans as the reinforcing structure, presents the actual bridge reinforcing design of transforming from simple-supported system to continuous system. The spatial entities finite model of the strengthening bridge is established by Midas/FEA. Through the simulation of the construction phases and the comparison of the static and dynamic behaviors of the structure before and after reinforcement, the strengthened model is proved to be feasible and markedly effective.Finally, through the simplification of lateral distribution, this paper computes and analyzes the ultimate bearing capacity of single beam model before and after reinforcement through Midas/FEA, and the failure patterns and the laws of development of crack of this two systems under different loading conditions are obtained. Besides, the overloading potentials of the transverse tension prestressed structure are studied, providing a certain theoretical reference for engineering design.