CHAPTER II. 

 STEEL OFFICE BUILDINGS. 



Skeleton Construction. Skeleton construction is a building where all external and internal 

 loads and stresses are transferred from the top of the building to the foundations by a skeleton or 

 framework of steel or reinforced concrete. In steel skeleton construction the framework con- 

 sists of columns, floorbeams, girders, trusses, and diagonal and transverse bracing. The steel 

 trusses have riveted connections and all connections in the steel framework should be riveted. 



Fire Resisting Construction. To protect the structural steel from fire the framework is 

 covered with materials that are slow heat conducting or "fireproof material." The steel frame- 

 work may be fireproofed with reinforced concrete, brick, tiles of burnt clay, or terra cotta. The 

 windows on exposed sides and elevator enclosures are glazed with wire glass set in metal frames or 

 are protected with fire shutters. Doors and other exposed openings are protected with fire doors 

 or shutters. The interior finish, doors, etc. should be of metal and every precaution should be 

 taken to prevent the spread of fire. Reinforced concrete fireproofing is usually made of the 

 following thickness: For columns, trusses, girders or other very important members at least 2 

 inches of concrete outside of the metal reinforcement ; for ordinary beams or long span floor slabs 

 or arches, I \ inches of concrete outside of the reinforcement, and for short span floor arches and 

 slabs, partitions and walls at least I inch outside the metal reinforcement. Fireproofing of brick, 

 tile or terra cotta is usually made with a thickness of not less than 4 inches for columns and the 

 main framework. Metal flanges should be protected with not less than 2 inches of fireproofing 

 at any point. 



TABLE I. 



WEIGHTS OF BUILDING MATERIALS, ETC. 

 POUNDS PER CUBIC FOOT. 



