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From:
http://www.fujita.com/news_release/36
News release dated 22 December, 2014
Fujita Corporation (Headquarter: Tokyo Shibuya-ku, President: Takuji Ueda) has developed an easily–manufactured, highly seismic resistant Fujita-style buckling restrained brace “FIRST Brace” (FIRST stands for ‘Fujita Improved and Reinforced Steel Brace’), which we are committed to using widely on our construction sites. The brace has been installed in five distribution warehouses, one production plant, and one office building. It is also in use in the seismic retrofitting of schools and hospitals. We would strongly suggest the use of this brace to improve earthquake performance for both new buildings and renovations.
Conventional steel braces lose compressive and tensile strength when they buckle. The “FIRST Brace” is designed in a way so it will not buckle. It was certified as a seismic member by the General Building Research Corporation of Japan in 2013 (GBRC performance verification No. 12-34).
The central part of the “First Brace”, where it conveys the axial force, is covered with buckling restrained material to prevent loss of compressive strength. It retains equal yield strength and deformation capacity through both compression and tension.
The “FIRST Brace” is composed of a steel tube (as buckling restrained member), a H-steel located in the center of the steel tube and cement mortar filled in the steel tube. Both sides of the H-steel are strengthened with steel cover plates. Either a circular or a square steel tube is used as the buckling restrained material. Steel mold is utilized in order to create cavity space, so it can reduce the amount of mortar used. The presence of the cavity restricts interference between the strengthened side parts and mortared part during compression. In addition, un-bond materials (sheet rubber material to eliminate friction) is used on the contact surface of the central steel, mortared part and steel mold so the axial force and compression on the center won’t be transmitted to the surrounding parts. The steel parts are manufactured as a part of the general steel frame member at steel fabrication works, and the mortar filling is executed either at the precast manufacturing plant or at the construction site. Since it is easily constructed without the need for any specialized procedure or technique, we are able to provide it with lower cost.
We can apply “FIRST Brace” to make structures more reliable and safe by preventing earthquake damage.
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