framed, structures
A framed structure in any material is a structure that is made stable by a skeleton that can stand by itself as a rigid structure without depending on floors or walls to resist deformation. Materials, such as wood, steel and reinforced concrete, which are strong intension and compression, are the best members for framing. The heavy timber frame, in which large posts spaced far apart, support thick floor and roof-beams, was the most usual type of construction up to the middle of The 19-th century. Then a light wood frame was introduced which was composed of many small and closely spaced members that could be easily handled and quickly assembled. Construction is the same in these two systems. Posts must rest on a level water proof foundation, usually of masonry or concrete on which the sill (base member) is attached. Each upper storey is laid on cross beams supported on the exterior wall by horizontal members. Interior walls give additional beam support. In the heavy timber system, the beams are strong enough to allow the upper story and roof to project beyond the plane of the ground floor posts, increasing the space and weather protection. — Steel framing is based on the same principles but is much simplified by the greater strength of the material which provides more rigidity with fewer members. The load-bearing capacity of steel is suitable for buildings much higher than the buildings made of other materials. As the column and beam are fused by welding or riveting, stresses are distributed between them. As structural steel must be protected from corrosion, the skeleton is covered by curtain walls or surfaced in concrete.
