Document Type : Original Research Paper


Faculty of Civil Engineering, Tarbiat Dabir Shahid Rajaei University of Tehran, Iran


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. .


Main Subjects

[1] ATC, Seismic Evaluation and Retrofit of Concrete Buildings, Vol. 1, ATC 40, Applied Technology Council, Redwood, CA, 1996. [2] FEMA, NEHRP Guidelines for the Seismic Rehabilitation of Buildings, FEMA 273, 1997. [3] Fajfar, P., A Nonlinear Analysis Method for Performance Based Seismic Design, Earthquake Spectra, Vol. 16, No. 3, August, pp.573-592, 2000. [4] Fajfar, P., Extensions of the N2 Method Asymmetric Buildings, Infilled Frames and Incremental N2, International Workshop on Performance Based Seismic Design, Bled, Slovenia, 2004. [5] Miranda, E., Strength Reduction Factors in Performance-Based Design, Proceedings of the EERC-CUREe Symposium, Berkeley, California. 1997. ﻣﺤﻤﻮدی ﺻﺎﺣﺒﯽ، ﻣﻮﺳﯽ،  اﺛﺮ زﻣﺎن ﺗﻨﺎوب و ﻣﻘﺎوﻣﺖ [6] ﻏﯿﺮ ارﺗﺠﺎﻋﯽ ﻗﺎﺑﻬﺎی ﺧﻤﺸﯽ ﺑﺘﻦ –اﻓﺰون ﺑﺮ ﻧﯿﺎز ﻟﺮزه ای ﻣﺴﻠﺢ  ، رﺳﺎﻟﻪ دﮐﺘﺮی ، داﻧﺸﮕﺎه ﺗﺮﺑﯿﺖ ﻣﺪرس ﺗﻬﺮان،  1377  . [7] Uang C.; Maarouf A. , Deflection amplification factor for seismic design provision, Journal of Structural Engineering, Vol. 120(8), p.p. 2423-2436, 1994. [8] Riddell R, Hidalgo P, Cruz E. Response Modification Factors for Earthquake Resistant
Design of Short Period Buildings, Earthquake Spectra, 5(3):571-589, 1989. [9] Miranda E., Site-dependent Strength Reduction Factors, Structural Engineering; 119(12):        35033519, 1993. [10] Fischinger M., Fajfar P., Seismic Force Reduction Factors, Proceeding of Earthquake Engineering, Rutenberg, Balkema, Rotterdam, ISBN 90 541 391-4, 1994.  [11] Nassar A, Osteraas J, Krawinkler H. Seismic Design Based on Strength and Ductility Demands, Proceeding of the Earthquake Engineering Tenth World Conference, Balkema, Roterdam: 5861-5866, 1992. [12] Mahmoudi, M., Tasnimi, A.A., The Relationship Between Local and Global Ductility for R/C Flexural Frames, (Persian), Proceedings of the Third International on Earthquake Engineering and Seismology, Tehran, Iran, 1999. [13] Tasnimi, A.A.,
 Mahmoudi, M. , Prediction of Overstrength of Reinforced Concrete Moment Resisting Frames Using Nonlinear Inelastic Analysis, Proceeding of the XI ECEE, 1999. [14] Mahmoudi, M., The Relationship Between Overstrength and Members Ductility of R.C. Moment Resisting Frames, 7th Pacific Conference on Earthquake Engineering, University of Canterbury, Christchurch, New Zealand, 2003.