Initial evaluation of reinforced concrete bending frames with performance-based design goals

Performance design based on performance is a new method in which structural damage against different levels of risk (earthquake) is clearly assessed and structural and non-structural performance of structures by limiting strength, stiffness and ductility. Members are controlled. To achieve these goals, a nonlinear analysis of the structural model is essential. To perform this analysis, the basic characteristics of the structure (initial strength and stiffness) are required. The closer the initial values ​​are to the final values, the easier and faster the process of analyzing and designing the structure will be. The main purpose of this paper is to provide a method that can be used to easily and quickly obtain the initial strength and stiffness of the structure for nonlinear analysis. For this purpose, coefficients are proposed that can be used to make the required strength and stiffness of reinforced concrete bending frames for each of the functional modes; Intermediate use (IO), life safety (LS) and structural destruction limit (CP) were determined. These coefficients are the coefficient of behavior (Rw) and the coefficient of magnification of the displacement (Cd), which are used to calculate the strength and stiffness required by the structure, respectively. The recommended values ​​for behavioral coefficients in different functional states of IO, LS, and CP are 2.28, 4.43, and 5.3, respectively. The values ​​of 2.29, 4.73 and 5.83 have also been suggested for displacement magnification coefficients in different functional modes. Studies show that the use of the above coefficients in calculating the required strength (base shear) and initial stiffness (by controlling lateral displacement) of structures, will make the next steps of work and nonlinear analysis of structures easier and faster.