Maintenance business that protects bridges using technology and experience cultivated over many years
In our maintenance business, we utilize the technology and experience that the Yokogawa Group has cultivated over its long history.
Furthermore, by introducing new technologies and construction methods, we will work on extending life, large-scale renewal, seismic reinforcement, and disaster recovery.
We will protect bridges, which are important social capital, and pass them on to the next generation.
Solutions
Problem solving episode
Development of a floor slab that reduces concrete curing time to 1/3
Generally, long-term road closures are required to replace floor slabs. The Miyuki Bridge on the Nishi-Meihan Expressway, which underwent floor slab replacement over three periods starting in 21, has a high traffic volume and there are no alternative routes. will be huge. In order to reduce the impact of road closures, during the first phase of construction, a method was adopted that was the first of its kind on an expressway: the entire road was closed at night to replace the slab, and one lane was opened during the day.
In Phase III construction, we aimed for even faster construction, and in order to significantly shorten concrete curing time, which is a critical part of work time, we considered changing the filling material from super-fast-hardening concrete to super-fast-hardening mortar. I ran into the problem of a large heat of hydration.
However, under the guidance of Professor Emeritus Shigeyuki Matsui of Osaka University, the problem was solved by the development of a ``slit loop joint'' that suppresses the effects of hydration heat and saves labor in reinforcing and formwork work. We were able to shorten the time from 24 hours to XNUMX hour. (Miyuki Ohashi III stage completed in May XNUMX: Received the Branch Manager Award from the Kansai Branch of West Japan Expressway Co., Ltd.)
Slump flow measurement status of filler material
We were able to meet the above conditions by adding small gravel as coarse aggregate to ultra-fast hardening, non-shrinking mortar that develops strength in one hour.
- Developing strength that enables early introduction of prestressing
- Must have the same strength and elastic modulus as concrete in the precast part
Overview of slit loop joint structure
It is based on a loop joint structure, but has the following features.
- Shortening of curing time by changing the material of the filling part to "ultra-fast hardening non-shrinking mortar + small grain gravel"
- Reinforcement work time is shortened by changing the steel materials placed perpendicular to the bridge axis from reinforcing bars to prestressed steel materials.
- Reduced heat of hydration by creating a slit shape and reducing the pouring volume
| Orderer (Original order) | Kanto Regional Development Bureau Chiba National Highway Office |
|---|---|
| Construction site | Chiba |
| Construction scale | Steel deck plate reinforcement at 999 locations |
| Construction overview | As cracks appeared in the steel deck of Ichikawa Bridge, the pavement of the bridge surface was cut and the steel deck was reinforced with patch plates. |
| Construction year | 2014 |
| Orderer (Original order) | Hokuriku Regional Development Bureau Fushiki Toyama Port Office |
|---|---|
| Construction site | Toyama |
| Construction scale | 14 high damping rubber dampers |
| Construction overview | We installed high-damping rubber dampers and viscous dampers at the Shinminato Bridge (a 5-span continuous composite cable-stayed bridge). |
| Construction year | 2014 |
| Orderer (Original order) | Tohoku Regional Development Bureau Sendai River and National Highway Office |
|---|---|
| Construction site | Miyagi |
| Construction scale | 12 buffer chains |
| Construction overview | Earthquake reinforcement work for Tadagawa Bridge and four other bridges. |
| Construction year | 2013 |