Quasi-Dynamic Implicit Finite Element Analysis of Steel-Clad, Wood-Framed Shear Walls

Abstract

HighlightsA new finite element modeling method was developed to predict performance of steel-clad, wood-framed diaphragms.The new method overcomes limitations of previous models and accurately predicts yielding and buckling behaviors.The new method will save time and money in developing design values for steel-clad, wood-frame diaphragms.Abstract. Various finite element codes and solution techniques have been developed for steel-clad, wood-framed (SCWF) shear walls over the past few decades. Most previous finite element models for SCWF shear walls under monotonic loading were based on a static implicit solution technique. Previous researchers stated that the static implicit technique showed promise for modeling SCWF diaphragms; however, the solution technique failed to converge to equilibrium as local instabilities in the form of snap-through buckling of steel cladding occurred or geometric nonlinearities were included in the model. In this study, a nonlinear quasi-dynamic implicit finite element analysis (FEA) of SCWF shear walls subjected to monotonic loading was developed to overcome the deficiencies of the static implicit approach. Three types of elements were used, including beam elements to model wood framing, shell elements to model steel cladding, and nonlinear spring elements to model connectors. Screw connector tests were conducted to obtain the load-displacement constitutive relationships needed for finite element models. Nine types of SCWF shear walls with and without lap seam stitching were tested to validate the finite element model. The ratios of predicted to test values for ultimate shear strength averaged 0.97 with a coefficient of variation (COV) of 8.1%, and the ratios for effective shear modulus averaged 1.13 with a COV of 30%. The quasi-dynamic implicit FEA is a significant improvement over previous static implicit techniques and should be a useful tool to predict the ultimate shear strength and effective shear modulus of SCWF shear walls under monotonic loading. Keywords: Diaphragm design, Post-frame building, Steel-clad wood-frame diaphragm.