STUDY OF THE HYBRID STRUCTURES CHANGED FROM THE STEEL BRIDGES FOR RAILROAD WHICH CONSIDERED CONSTRUCTION

There has recently been a requirement for constructive structures to be efficiently maintained and managed. As another big issue for steel bridges in railways, on the other hand, there is a subject on how to suppress acoustic noises as well as the life prolongation. As a countermeasure for life-extension and noisereduction of such structures, revamping of existing steel bridges into composite structures is now under investigation. A shift to a composite structure is to proceed with an action to place a complementary member such as a concrete panel onto the existing steel girder for the purpose of preventing it from having corrosion, improving the beam stiffness, reducing the stress-amplitudes at the time of a response to active forces, and consequently prolonging the fatigue life. Furthermore, consolidating the steel and concrete, on the other hand, acoustic noises caused by the steel member can also be reduced at the same time. Therefore, this research offers a new composite-revamping method for railway bridges by assuming composite remodeling process of existing steel bridges having no specific fissure damages or serious corrosions and effectively making use of relatively new materials to it. Effects of noise reduction and improved stiffness were further confirmed through hammer-impact tests (vibration-measurement tests) and loading tests in order to prove the efficacy of the composite remodeling.