Steel bar joist for the covering of industrial buildings with five-canted and square tubing

A set of five-canted and square tubes used in medium and highly corrosive enviroment is developed to replace familiar bar joists made of channel beams of a standard set of the Central Research and Design Institute of Construction Metal Structures, which are intensively corrosive in medium (up to 0.1 mm per year) and highly corrosive environments (more than 0.1 mm per year).