On the design of new ductile knee bracing

An approximate method is presented that can be used to determine the nonlinear behavior of a new structural bracing system called the ‘Chevron Knee Bracing’ (CKB). In this framing system, an especial form of diagonal brace connected to a knee element instead of a beam-column joint is investigated. The diagonal element provides lateral stiffness during a moderate earthquake. However, the knee element is designed to have three plastic joints or two yielded specimens in flexural and shear yielding mode, respectively, for dissipation of the energy caused by a strong earthquake. This article demonstrates the transformation of a complex problem into a new, practical set of design charts and graphs. To severe purpose, first, an optimal shape and angle for the diagonal-knee element is considered based on the studying of the elastic and inelastic behavior of the system. Then, by use of the main graphs and charts designed accordingly, the dynamic response of this model is properly investigated. Finally, the correctness of the results is ascertained, using example problems. The comparison of the results between the technique presented in this paper and the exact finite element methods and/or experimental results shows very good agreement and very suitable conformity.