【正文】 fined in discrete systems are adapted to continuum models through an analytical expression that considers the heightwise variation of boundary conditions in discrete systems. The HS73 model is used as the base continuum model since it is capable of representing the structural response between pure flexure and shear behavior. The proposed analytical expression is evaluated by paring the deformation patterns of continuum model and actual discrete systems under the firstmode patible loading pattern. The improvements on the determination of EI and GA are bined with a second procedure that is based on limit state analysis to describe the global capacity of structures responding beyond their elastic limits. Illustrative case studies indicate that the continuum model, when used together with the proposed methodologies, can be a useful tool for linear and nonlinear static analysis. 2 Continuum model characteristics The HS73 model is posed of a flexural and shear beam to define the flexural (EI) and shear (GA) stiffness contributions to the overall lateral stiffness. Themajor model parameters EI and GA are related to each other through the coefficient α (). As α goes to infinity the model would exhibit pure shear deformation whereas α = 0 indicates pure flexural deformation. Note that it is essential to identify the structural members of discrete buildings for their flexural and shear beam contributions because the overall behavior of continuum model is governed by the changes in EI and GA. Equation 2 shows the putation of GA for a single column member in HS73. The variables Ic and h denote the column moment of inertia and story height, respectively. The inertia terms Ib1 and Ib2 that are divided by the total lengths l1 and l2, respectively, define the relative rigidities of beams adjoining to the column from top (see Fig. 3 in the referred paper). Equation 2 indicates that GA (shear ponent of total lateral stiffness) is puted as a fraction of flexural stiffness of frames oriented in the lateral loading direction. Accordingly, the flexural part (EI) of total stiffness is puted either by considering the shearwall members in the loading direction and/or other columns that do not span into a frame in the direction of loading. This assumption works fairly well for dual systems. However, it may fail in MRFs because it will discard the flexural contributions of columns along the loading direction and will lump total lateral stiffness into GA. Essentially, this approximation will reduce the entire MRF to a shear beam that would be an inaccurate way of describing MRF behavior unless all beams are assumed to be rigid. To the best of authors’ knowledge, studies that useHS73model do not describe the putation of α in depthwhile representing discrete building systems as continuum models. In most cases these studies assign generic α values for describing different structural behavior spanning from pure flexure to pure shear1. This approach is deemed to be rational to represent theoretical behavior of different structures. However, the above highlighted facts about the putation of lateral stiffness require further investigation to improve the performance of HS73 model while simplifying an actual MRF as a continuum model. In that sen