Nonlinear Performance Evaluation of Diagonally and X-Braced Moment Resisting Frame Systems: Buckling and Post–Buckling Responses

Abstract

The inelastic post-buckling performance of braced moment resisting frame (BMRF) systems is notably affected by their strength, ductility, and stiffness which have been paid a great deal of attention in recent years. The concept of performance-based design requires a thorough appraisal of the system responses, and their improvements in conjunction with the design parameters in details. In this paper, we aim to provide insight into the above issues with an accurate evaluation of nonlinear post buckling response of BMRFs, and through a comprehensive comparison of such systems for different gusset-brace configurations, namely, diagonally braced moment resisting frames (DBMRFs) and X-braced moment resisting frames (X-BMRFs). The effect of different gusset plate connection sizes/types with linear and elliptical clearance offsets are fully considered, using high fidelity three-dimensional finite element models of the proposed system that are validated and verified globally/locally against available experimental results and numerical simulations. A number of BMRF models are developed, and the sensitivities of buckling and post–buckling states to changes in system parameters and geometric imperfections are discussed. The results of this study can be further extended to ascertain the effects of different types of beam-to-column connections. Additionally, brace-to-frame rigidities and material properties of BMRFs can be considered to determine optimum design parameters and to control interaction characteristics between different subsystems of BMRFs.