ABSTRACT
This chapter integrates material to create three distinct approaches for design and assessment: a straightforward code comparable approach and two more sophisticated approaches that require nonlinear response history analyses for design validation and determination of forces in force-controlled members. Having established a preliminary design, a linear elastic model of the structure is prepared and its first-mode properties are determined in a modal analysis. Threshold limits represent capacities that are grounded in physical reality. Some, like plastic hinge rotation capacities or shear strengths, may be directly related to physically observable phenomena. In some cases, the failure to meet a performance objective is based on a comparison of deformation demands and capacities; in others, it is based on a comparison of strength demands and capacities. The failure of some components may jeopardize both lateral resistance and gravity load support, and thus should be assigned the higher applicable confidence level.
