Torsion and ductility demands on buildings under seismic action

Summary

It is repeatedly observed that unexpected and strong torsional effects are produced in buildings subjected to earthquakes. These torsional effects often have a decisive influence for their collapse.

These experiences have led engineers to include torsional effects in existing codes through simple building rules and magnified static lateral forces. The goal has been to reduce the inelastic translatory deformations of critical elements by storey twist. These rules, expressed only in terms of the properties of elastic structures, are irrelevant and describe the real dynamic nonlinear torsional behavior only approximately. Using Finite Elements, complicated torsional effects in structures can be now determined quite precisely, especially in the nonlinear material domain.

The project investigates the numerical ductile system behavior of buildings. Starting with a linear material model, the interactions between plan asymmetry and torsional response will be examined, and the interrelationship between bending and torsional response compared. The influence of nonlinear material behavior will then be studied in depth in order to determine the local ductility demands induced by the twist effects. Simple rules should be derived from this study for the design of asymmetric structures.

Staff

Prof. Dr. Hugo Bachmann (Guideance)
Dr. Alois Sommer
Dr. Thomas Wenk
Prof. Dr. Dr. h.c. Thomas Paulay