Structural Analysis and Design-General

The Code is based upon design in two stages, strength and serviceability. Design for strength (safety) (Section 9.1.1) involves use of load magnification factors to obtain the required strength (Section 9.2) and strength-reduction (O) factors (Section 9.3.1) to determine the design strength. Strength-reduction factors allow for various possible understrength effects and to reflect the required ductility, reliability, and relative importance of the member. The second stage of design, serviceability (Section 9.1.2), consists of controls on the computed deflection and crack widths under service loads (Sections 9.5 and 10.6). This design method is called “Strength Design.” The design philosophy is referred to as “Load Resistance and Factor Design” by building codes for other construction materials.