Hanshin Expressway Large-scale Renewal Project
No.14 Matsubara Line, vicinity of Kireuriwari
~opened in 1980~
Subsidence Unforeseen in the Rational Design Concept
Major causes and damage
Hinge-type joints located near the center of the bridge girder sagged more than expected in the original design, which resulted in subsidence of the road surface.
Causes and Condition of Damage
Although the method regarded rational in those days was employed to match the locational conditions of this section, the hinge part near the center of the bridge girder gradually sagged, and the road level then greatly settled.
As an emergency measure, the sagging bridge girder was pulled up with cables.
This solution, however, showed no sufficient recovery, and subsidence is likely to start aggravation again.
Back in the Days of Construction
The structure in this section had to be a long bridge to cross over a major intersection.
The method that uses hinge type joints near the center of the bridge girder was a standard technique in the construction projects in those days as it was considered highly rational in terms of structural dynamics when a bridge structure with a long span and shorter bridge girders was constructed.
However, because of aging, the central part greatly sagged more than expected in the original design.
It is necessary to take measures to control sagging and make radical improvement of the structure by large-scale renewal.