Earthquake Brace — Seismic Bracing Company

What’s a BRB?

Basically you take a solid steel core, typically rectangular in shape, then wrap it in special material, then place it through a steel tube and then fill the space between the core and the tube with grout. The special material prevents the steel core from bonding with the grout so the grout and tube will not take any load and only the steel core does. The grout and steel tube are only needed when the steel core is in compression and tries to buckle. The grout confines buckling of the steel core on a local level and the larger more stable steel tube surrounding the grout prevents the entire BRB from buckling. In tension the grout and steel tube do nothing and just go along for the ride.

BRB Config.PNG

Why they are so cost effective?

The cost effectiveness of BRBs comes from three main reasons. The first is their ductility/durability, which allows the engineer to reduce seismic loads more than ordinary braced frames. The second is that BRB frames are less stiff than ordinary braced frames, which reduces the overall structure’s accelerations. The third is the lower force that BRBs can possibly deliver to the structure than ordinary braces. Ordinary braces have a much lower compressive strength than their tension strength because they buckle in compression. With BRBs, we just need to provide enough cross sectional area for the steel core to handle the seismic force. With ordinary braces you have to size them so they won’t buckle and then you have all this extra steel that can deliver more force to the structure when in tension. In both BRB and ordinary braced frames, the entire braced frame structure must be capable of sustaining the maximum force the brace can deliver. All of this results in orders of magnitude less force in structures utilizing BRBs. Thus, with BRBs, the structure’s connections, columns, beams, and foundation sizes can be reduced by a considerable amount.

Occupancy:

BRBs are capable of sustaining deformation far greater than they will experience during big earthquake and their durability can sustain several big earthquakes. Thus, the chances of occupying and utilizing a BRB braced building after an earthquake is more likely. Ordinary braces will most likely buckle during a big earthquake and possibly fracture making it less likely to be able to occupy and use an ordinary braced building after an earthquake.