PURPOSE: To reduce the weight of arch ribs by arranging a plurality of hydraulic jacks at the top of a construction tower, connecting a plurality of arch ribs to be installed with a plurality of steel cable and simultaneously adjusting tensions of all the steel cables.
CONSTITUTION: A plurality of hydraulic jacks 5 are arranged at the top of a construction tower 4. An arch rib 1 of an arch bridge to be built and the hydraulic jack 5 are connected to each other with a front steel cable 2 and a middle steel cable 3. The arch rib 1 of the arch bridge is then pulled up obliquely and held while adjusting the tensions of respective steel cables simultaneously by respective hydraulic jacks 5. At this time, the hydraulic pressures of the hydraulic jacks are detected to centrally control all of the jacks. This makes it possible to reduce the weight of the arch rib in comparison with conventional arch rib pulled up one by one with the steel cable.
TOMITA NOBORU
YOKOYAMA IWAO
KURIYAMA SHINGO
