| Research Abstract |
Toward 21 century, it is predicted that the labor power will decrease and that the budget for the construction of public facilities will be reduced. In this circumstances, in the field of bridge engineering, the development of new bridge systems with economy and higher durablility becomes an important and urgent issues.
In this research, the global and local structural behaviors of the bridges with a simple stiffening system is made clear by a three-dimensional FEM analysis with large degrees of freedom, then the possibility of this system as a new system is investigated.
First, the stiffening members (lateral bracing, cross beam for load distribution and sway bracing) in the conventional bridge are removed succesively, then the the global and local behaviors are investigated. As a result, it is known, if the conventional cross beams for load distribution is used, that the stress concentration can not be avoided. Secondly, the structural characteristics of 2-and multi-I girder bridges with small-sized cross beams is investigated. It is found, if the cross beam is installed at middle or lower parts in the heigth of the girder web, that the large stress concentration is observed at the upper part in the vertical stiffener. However, except the above part, the large stress is not observed. The stress concentration can be reduced increasing the thickness of the stiffener or attaching the flange to the stiffener. By employing these countermeasures, in steel bridge system with only small-sized cross beams at a distance of 5 to 10 meters, the large stress concentration is not observed. Hence this bridge system is expected to be economical and highly durable one.
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