Ground and structure
Bracing
timber housing warehouse techo steel building
It is a diagonal member that connects beams and columns so the frame does not deform.
What it solves
It turns an unstable rectangle into rigid triangles. This way the structure resists the lateral push of wind and earthquakes.
Today
Place bracing in both directions and distribute it symmetrically. The connections must be as strong as the diagonal.
Common mistake
Removing diagonals to open a window or a door without restoring the stiffness elsewhere.
Tomorrow
Braces with dampers work like fuses that absorb the earthquake and are replaced after a strong event. Repairing one piece is better than replacing the whole structure.
Fact A triangle is the simplest figure that does not change shape as long as its sides do not change length. That is why one diagonal is enough to stiffen a frame.
Where it comes from
- 1Quincha coast of Peru, ancient use, widespread after the 1759 earthquake
A framework of timber and cane covered with mud that was used to rebuild Trujillo and moves with the earthquake without breaking. - 2Pombaline cage (gaiola) Lisbon, Portugal, 1755 to 1880
After the 1755 earthquake an inner timber frame with double diagonals inside the walls was required. - 3Braced steel frames Chicago, United States, industrial era
They were created to resist wind in tall buildings and were later adapted to earthquakes.
Masters
- Fazlur Rahman Khan John Hancock Center, Chicago, United States, 1969
He designs the tower with large X diagonals on the facade that work as a rigid tube. The bracing resists wind and earthquakes and leaves the interior floors free.
Appears in the routes
See also
Also in Ground and structure
Diagrams and texts by LDB Arquitectura. They are shared under the CC BY 4.0 license, which allows them to be used and adapted with credit to the source.