抄録
The loading position where the absolute value of bending moment or shearing force is maximum can be obtained by using the influence-line. But the composite stress can't be obtained by using the method because it always has positive value.'Therefore, Japan Specification for Highway Bridges (J.S.H.B) allows to use the simple method. However, it is certain that the result is smaller than quasi-maximum value. It is very important for designers to find the magnitude of difference between design value and quasi-maximum value obtained by using GA. This paper firstly explains about issues of running design method, theoretical background of this calculation method and its concrete procedure. Next, it shows existence of the intermediate loading situation which is larger than the composite stress specified in J.S.H.B by solving a typical problem which expresses a part of rahmen type bridge. Finally, a simple calculation method to obtain the composite stress which is comprised by bending moment and shearing force is presented.
