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Support replacement method

1. Overview

The support replacement method involves replacing supports which do not conform to current standards, which are deteriorated/damaged and steel supports with rubber supports which conform to current standards in order to ensure seismic performance of bridges.


Because the work involves manipulation of heavy objects in narrow locations and performing the work while the structure is in service, consideration must be given during the planning phase to the materials, machinery and methods that will be used. The photos below show application of the flat jack method in jacking up main girders.


2. Key Features

The flat jack method involves injecting a liquid (water, grout material, etc.) into the injection port of a light, ultra-thin (25mm) jack (flat jack) for an existing bridge, using the pressure of the liquid to generate lift. It is easy to utilize in narrow locations and can generate 100kN to more than 5,000kN of lift, depending upon the effective area. When used to install a new support, the interior of the flat jack is filled with a non-bleeding type of grout material which is then embedded inside the shoe base mortar. When replacing an existing support, the load on the existing support is temporarily borne by the flat jack while the support is replaced.


3. Our Construction

  • Osako Bridge

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