مقاله بادبند
Brace
What is a Brace?
A roof truss is made of several pieces of wood that are joined together. Each piece of the truss is referred to as a "member". A brace is a member that prevents a structural element from buckling or racking. Members are generally subjected to tensile or compressive forces. As shown in figure 1, tension forces tend to pull a member apart while compressive forces tend to push a member together.
When a compressive force becomes great enough, it will tend to buckle or bow a member as shown in the left side of figure 2. This can be demonstrated by placing a yardstick on end on the floor while holding the upper end. When you push down on the upper end, the yardstick buckles in its narrow direction. The right side of figure 2 demonstrates the use of a brace at the middle of the structural member. Under the same compressive force, the brace prevents the member from buckling. This can be demonstrated by applying the same downward pressure on the yardstick with one hand, while restraining it at the middle with your other hand. The yardstick will not buckle under the same pressure.