An alternative frame-shear wall model: continuum formulation

The basic assumption of the analysis of wall-frame structures is that two dissimilar structural systems, deforming in shear and flexural modes, are constrained to act together. The same set of boundary conditions is also assumed to be applicable to both types of components. An inconsistency arises when the rotation at the lower end of the combined beam is assumed to be zero because this boundary condition is applicable only to the flexural component of deformation. For the shear component that is related to the slope of the elastic curve to calculate the force, this assumption results in zero base shear force. In this study, a modified theory is developed on the premise that a frame-wall system can be separated into two substructures that lie above and below the point of counter-flexure in the base story columns. Except for a modification to include the effects of link beams, the generalized continuum approach is employed to derive the governing differential equation of the upper substructure. The bottom substructure is used to transmit the applied base boundary conditions to the continuum model, thus allowing a more accurate shear force calculation for each of the components. Comparisons of results calculated from this artifice with other formulations prove the superiority of the proposed improvement. Copyright (c) 2010 John Wiley & Sons, Ltd.