Empirical design of floor and roof framing systems

The principles of empirical design can be applied to the design and construction of floor and roof systems for buildings. In this chapter, we will define such systems as combinations of columns and beams, which have been previously described individually in Chapters 4 and 5, respectively, into a system that resists gravity and lateral forces and that has inherent stability. The issues of design of lateral force resisting systems will be noted in this chapter, but a fuller treatment of this topic is reserved for Chapter 10.

The remainder of this discussion concerns the sizing of building frames for gravity loads (dead load and live load). In most cases, the design of beams and columns in gravity-loaded frames follows the rules used earlier in Chapter 4 (columns) and Chapter 5 (beams). However, additional rules on the size of the bays in conventional frames, and the influence of continuity are presented here. The effects of lateral forces (discussed in Chapter 10) may increase the size of the individual elements of the load-resisting system, but the bay sizes and proportions do not change greatly from those dictated by resistance to gravity loads.