PURPOSE: To make welding work unneccesary in installations where beams are installed to girders, and binders are installed to the beams.

CONSTITUTION: Bolt holes are drilled to connecting parts where beams 3 are installed to a girder 2, and gusset plates 7, 9 in large and small L shapes and in T shape with bolt holes drilled, with allowances given for slight movements in the upward, the downward, the rightward and the leftward directions, on positions corresponding to the connecting parts on opposite plate parts are prepared. Then, the beams are installed to the connecting parts with the gusset plates fastened with bolts.