More Efficient Seismic Loading for Multidegrees of Freedom Structures

In the equivalent-static-force procedure, the heightwise distribution of seismic load is implicitly related to the linear dynamic response. However, this contradicts the fact that structures undergo large nonlinear deformation during severe earthquakes. Hence, the question arises, how should the lateral loading pattern in seismic design be modified to ensure that the ductility demands are the minimum? This technical note addresses this question in detail. The shear and frame building models of multistory structures have been studied. Employing a new assessment criterion, the adequacy of various distribution patterns is examined, and a more efficient pattern is introduced. It has been shown that for any given earthquake, there can be found a unique strength distribution pattern that leads to the most uniform distribution and the least amount of ductility demand.