Analysis Procedures and Seismic Design Principles for Building Structures

Seismic analysis procedures and design principles are developed for building structures in this Chapter. Dynamic degrees of freedom are defined at each story by using the rigid diaphragm assumption, leading to a diagonal mass matrix. Stiffness matrix is derived for 3D buildings with unsymmetrical stiffness distribution in plan, leading to a coupled stiffness matrix. The effect of unsymmetrical stiffness distribution on the mode shapes is discussed, with emphasis on torsional coupling. Modal response spectrum analysis and equivalent lateral load procedure are introduced in the general seismic code format. Basic design principles and performance requirements for buildings are reviewed. Structural irregularities given in seismic codes and their effect on analysis procedure selection are discussed. The concept of seismic deformation control associated with interstory drift limits, second order effects and pounding is explained.