Complementary evaluation of diagonal tension field inclination angle in steel plate shear walls

Complementarily to previous studies, research was conducted to investigate whether the equivalent constant angle of diagonal tension field action should be taken as either 40° or 45° for ductile steel plate shear walls (SPSW) designed per current codes. A two-dimensional finite element (FE) model was first calibrated against results from a prior study of “limited-ductility SPSW” by comparing effective stress contours and average angle of diagonal tension field action at different locations across the web plate. Then, this SPSW was redesigned as a ductile SPSW in compliance with the 2016 AISC Seismic Provisions (AISC, 2016a) to have fully restrained beam-to-column connections and analyzed using strip models and finite element models, respectively. The AISC moment-axial force interaction equation was used to compare demands in the SPSW boundary elements obtained from the strip and finite element models. With respect to the use of a single angle in design, it is shown that using an inclination angle of 45° is slightly (but not significantly) more conservative than using 40° as far as boundary element design is concerned. On the basis of these observations, along with findings from previous research on the diagonal tension field inclination angle, it is recommended that a single constant angle of either 40°or 45° be used for the design of SPSW.