| Case Name |
A collapse of the mould timber support |
| Pictograph |
|
| Date |
August 12, 1995 |
| Place |
Kaminoyama City, Yamagata Prefecture |
| Location |
The construction work field of five-storied building of reinforced concrete |
| Overview |
When workers were constructing five-storied building of reinforced concrete, the mould timber support collapsed. And all 6 workers who were engaged in the installation work on slab of this position fell with the mould member to fourth floor and car road slope division downstairs and they were injured.Because they used the mould timber support whose height could not correspond to the standard assembly diagram prepared beforehand, it buckled. |
| Incident |
At the construction work field of five-storied building of reinforced concrete, concrete casting work of the fifth floor was carried out. At the casting point, the floor height was various. The boundary was a binding beam. The height of one side of the binding beam was equal to that of part which had been constructed beforehand. In the opposite side of the binding beam, the bottom floor (the fourth floor) was the car road slope and the height was higher than that of other parts.After the concrete installation was carried out in the place where floor height was low and the boundary was the binding beam, in the remainder place where floor height was high, the concrete casting was also carried out. Suddenly, a part of the binding beam sank and the slab of the casted part came out. As the result, all the workers who were engaged in the casting work on the slab fell with the mould member to the fourth floor and the car road division downstairs and were injured. |
| Sequence |
In this field, the standard assembly diagram prepared beforehand was made. All the places except the place where collapse was occurred were in the application range of this standard assembly diagram and major construction had already finished. However, in the collapsed position, the height of concrete casting point (the height of the mould timber support) was higher than that of assumption of the standard assembly diagram prepared beforehand and it was out of the application range. It was constructed according to the standard assembly diagram without examining the safety of the mould timber support sufficiently. |
| Cause |
It was constructed according to the assembly diagram without examining the safety of the mould timber support in spite of being out of the application range. And, as the result, the mould timber support buckled since the concrete load exceeded the load bearing capacity of it. |
| Response |
The mould timber support was reinforced so as not to collapse, from examining the safety of it. |
| Countermeasures |
When the standard assembly diagram was made, it was necessary to clarify the structure which could apply to it. If it was not applied, it was necessary to examine the safety sufficiently. |
| Knowledge Comment |
The standardization of construction methods is carried out in order to promote work efficiency. If the standard cannot be applied, other safe methods were examined beforehand and adopted without appropriating it.Similarly, when the structure of buildings is changed by design change etc, the safety is examined without carrying out the construction as originally assumed. |
| Background |
* Though most parts were in the application range of the standard assembly diagram, only the concerned position was out of the application range.
* There was no examination of the strength.
* The imperfection of the safety management system
* The inspection after the mould timber support assembly was a formality. |
| Reason for Adding to DB |
There are many collapse disasters in the situation of which the safety of the temporary structures is not confirmed. |
| Scenario |
| Primary Scenario
|
Insufficient Analysis or Research, Insufficient Environment Study, Production, Hardware Production, Failure, Fracture/Damage, Failure, Large-Scale Damage, Bodily Harm, Harm to Physical Well-being, Bodily Harm, Injury
|
|
| Sources |
http://www.jaish.gr.jp ( Japan Advanced Information Center of Safety and Health )
|
| Number of Deaths |
0 |
| Number of Injuries |
6 |
| Physical Damage |
mould timber support |
| Multimedia Files |
Fig2.Tamotsu Cou collapse accident
|
| Field |
Civil Engineering
|
| Author |
OHDO, Katsutoshi (National Institute of Industrial Safety)
KUNISHIMA, Masahiko (The University of Tokyo)
|
