This paper presents an investigation for reducing traffic-induced vibration of a steel truss bridge by means of the no-joint method which renders bumps on expansion joints of bridges to be flat and, as a result, reduces the impulsive energy generated from vehicles. In this study, effectiveness of the no-joint method as a countermeasure against the vibration radiated from joints is confirmed through out dynamic response analyses under a moving vehicle. The successful reduction of the vibration between 10Hz and 20Hz observed from the analytical investigation encourages the use of the no-joint method to an actual steel truss bridge. The experimental investigation by comparing the responses before and after the no-joint method demonstrates effectiveness of the method even under usual traffic condition.
Shear-bending cyclic loading tests were performed to investigate structural behavior of shear-yield-precedence short-span beam. Main test parameters are the following: beam-end connection detail (only welded or both welded and bolted connection), design principle (designed only for bending or for bending and shear), and beam web detail (stiffened by web stiffeners or with reinforced web openings). Beam-end weld connections do not fracture in the all specimens, and the all test specimens showed good plastic deformation capacity because shear yielding of the web occurred prior to shear buckling; all the test results support feasibility of shear-yield-precedence design of short-span beam.
In the desert area of Libya, an incident involving the collapse of several telecommunication towers became a very serious problem. Such incidents can be prevented by taking adequate measures to strengthen the tower structures. However, most towers that needed to be reinforced are located in the middle of the desert with frequent harsh windy conditions and are difficult to reach. Any construction work at these locations faces great challenges in mobilization of heavy equipment as well as materials and personnel. Therefore, it was essential that any remedial measure should be simple and easy to undertake. In this paper, we present a new structural steel reinforcement methodology that is both simple and easy to implement, but yields effective and guaranteed results. It does not require any drilling or welding of the existing tower structures. Such new and innovative methodology have now been employed in the Libyan Desert, which were extensively tested and found to be very effective and resulted in significant savings to the clients.
Fatigue cracks were detected on welded joints between vertical stiffeners and orthotropic deck plate in 30 span of Hanshin Expressway bridges. This paper describes about study on retrofitting measures in weld of vertical stiffener cutting treating of the semicircle in orthotropic steel deck. At first, FEM analysis was conducted in order to evaluate the effect of stress reduction in this area by semicircle notching. Next, loading test using real size specimen was carried out. Finally, proposed retrofitting measures: semicircle notching was conducted on vertical stiffener of a bridge in the Hanshin Expressway and actual stress reduction effect was evaluated.
For evaluating seismic resistance of railway transfer overbridges constructed with reused aged rails, we investigate the deformation properties and M-φ relationships of axially loaded aged rail columns by conducting cyclic loading tests. Using four kinds of different aged rails of the product year (1888, 1895, 1922 and 1925) and different product countries, we perform forced deformation bending test around both of weak and strong axes for each aged rail columns. As the results of this experimental study, we obtain hysteresis curves and M-φ relationships which is available for practical use of evaluating seismic performance. In this manner, it is possible to evaluate the ductility of aged rail columns accurately.
This research is concerned with the seismic response of the 3-dimensional frames. Analyses were carried out by using bidirectional ground motion transformed into the directions of strong and weak axes. The maximum story drift angle caused in an arbitrary direction when bidirectional ground motion was inputted along all the directions can be almost approximated by the maximum value among the responses when only the strong-axis ground motion was inputted along the direction of the structural plane and the responses when only the strong-axis ground motion was inputted along the direction where the strength of the frame is the maximum.
In this study, for rationalization of high-strength friction grip bolted joints (hereinafter called H.S.F.G. bolted joints) in rationalized plate girder bridges, organic and inorganic zinc-rich paints with high slip factor were developed and their slip factor, relaxation characteristics and durability were examined through some kinds of performance tests. Furthermore as results of tentative calculations the number of high-strength bolts, painting area and weight of splices can be reduced compared with conventional design by using developed paint with high slip factor.