FCM공법으로 시공되는 교량의 경간비 결정

Abstract

This paper introduces a relation to determine the span ratio between exterior and interior spans, which is strongly required in the preliminary design stage of bridges constructe by Free Cantilever Method (FCM). A relation for the initial tendon force is derived on the basis of an assumption that no verical deflection occurs at the far end of a cantilever beam due to the balanced condition between the self-weight and the cantilever tendons. In advance, the span ratio can be determined by using an assumption that the negative maximum moment must be the same with the positive maximum moment along the entire spans to be a rational bridge design. Finally, many rigorous time-dependent analyses are conducted to establish the validity of the introduced relations. The obtained numerical results show that the rational design of FCM bridges may be achieved when the span length ratio of the exterior spant to the interior span ranges about 0.75 to 0.8.