- Background and Purpose of Development
- A connection method called the Through Diaphragm Type Connection is used for the joints of steel constructions made of traditionally used square steel tube columns and H-shape steel beams. This Through Diaphragm Type Connection is a method of cutting off the column once and re-welding the cutting parts together with a diaphragm in between. Although joints of steel construction are the most important part structurally, they had a weak side of being problems such as poor welding. The DSQ Frame System is the construction system developed for the purpose of structural safety and quality assurance of buildings by eliminating such structural weaknesses by using thickened square steel tubes.
- Contents of Development and Results
- The DSQ Frame System is a system of steel moment frame, which applies thickened square steel pipes for columns and H-shaped steel for beams. To thicken is a process of increasing the thickness of steel pipes by compressing the steel pipe axially, while linearly heating it circumferentially by high-frequency induction heating. It can add specified thickness to steel pipes at specified position and length. Through the process of thickened, the mechanical properties of the thickened area significantly improves compared to the original steel pipe, improving the tenacity of the material dramatically (This technique of thickened was developed jointly by Daiwa House Industry and Daiichi High Frequency Co., Ltd.)
The DSQ Frame System almost doubles the thickness of the column and beam joint. By improving the strength and resistance of the joint, the diaphragm that was required in traditional welding method can be eliminated. Since the DSQ Frame System uses no diaphragm, the difference and unevenness of the beam height attached to the joint can be addressed easily, creating a clean joint.
There are two methods of connecting beams: High strength bolted connection using one-sided bolts and welding connection. With high strength bolted connection, torshear type high strength one-sided bolts are used for welding by attaching an endplate to the end of the H-shaped beam. With welding connection, H-shaped beam is welded to the thickened part.
DSQ Frame that uses thickened steel pipes can ensure outstanding structural safety, since it reinforces the thickness of the joints of column and beam, and dramatically improves the tenacity of the thickened part by modifying its mechanical properties.Illustration above is the high strength bolted connection, and below is the welding connection.
- High frequency induction heating thickening method
- This technique can ensure outstanding structural safety, since it doubles the thickness of the joint with a beam by heating the part of a column that connects with a beam. High frequency heating treatment increases the reserve capacity of the thickened part of a column that goes under considerable stress during an earthquake after it yields, and exhibits further tenacity.
- One sided bolt
- One sided bolt is a high strength bolt developed for welding. It has a blind side like a joint of the box column and H-shaped steel beams. Since the bolt-head can be formed by just screwing it into the hole of the steel pipe, the bolt can be tightened from one side when connecting a beam to a column. It does not require special techniques, and construction is made easy and steady.
- One sided bolt (video)
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- Narrowband (low definition)
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- Joint Development Organizations
- Daiichi High Frequency Industry Co., Ltd. (development of thickening technique)
- Daiwa House Industry Co., Ltd.
- Major awards and patents
- *The following patents have been obtained or approved for this development.
- ･Patent related to DSQ Frame (In Japan and in eight countries outside Japan)
- ･Approved by the Mister of Construction (former building codes section 38 approved)
- ･2nd Construction Technology Development Award (July, 2000)
- ･Achievement Award, Japan Society of Steel Construction (June, 2001)