Research: Shear - Moment Interaction in Damage Analysis

2007-01-13T16:23:00.000-03:00

It is still uncertain the interaction between flexural and shear responses. Most of the codes suggest that the flexural and shear design are independent of each other. That is very convenient for design purposes, but quite unreal, if cyclic loads are acting on the structural element. Our research at the university show that the flexural and shear responses are coupled. Various shear walls were tested both cyclic and monotonic load history. Results show that however flexural response should be developed, shear non linear displacements were observed. That prove that shear deformatons don't remain elastic for large flexural displacement. Although the flexural capacity was quite lower that shear strength. The shear response degrades under cyclic loading. So the response of the wall is affected if shear non linear behavior ocurrs. This undesirable effects of shear are energy dissipation capacity degradation, stiffness degradation and probably a degradation in ultimate resistance. It was defined the "fail ratio", wich is the ratio between shear strength and flexural capacity, that depends on the nominal moment of the seccion. If the fail ratio is less than 1, then a brittle shear failure ocurrs. In the other case (>1), a flexural failure is expected. Since under cyclic loading the shear strength is degraded, it can happen that for fail ratio values up to 1, but near 1, a ductile shear failure may develop for severe cyclic loading.

Francisco Wittwer

Research: Shear - Moment Interaction in Damage Analysis