A piece of material used to transmit, or change the
   direction of, weight or pressure; any one of the pieces, in a frame or
   truss, which divide the structure into triangular parts. It may act as
   a tie, or as a strut, and serves to prevent distortion of the
   structure, and transverse strains in its members. A boiler brace is a
   diagonal stay, connecting the head with the shell.