Wikipedia
A Cross brace is the cross-beam connecting between arches that is meant to add rigidity to the construction of mining tunnels. It is often tubular, having a diameter (generally made of lengths of pipes), and modified on the ends with clips or apertures for screw fastening; it serves as a stiffening element for the stability of a design. This brace could also be an ordinary cross-section wooden cross-beam, or even a board.
Usage examples of "cross brace".
He can leave-this time-when that cross brace is welded and the brackets are set.
Jabitha was pushed forward from the back of the cabin, where she had hidden behind a thick cross brace.
Eight feet under the deck of the pier, an iron cross brace was attached to two of the thick concrete columns that disappeared into the water.
Hugging a cross brace with his left arm, he reached into his shirt and pulled out a pair of needle-nose pliers.