Seismic Evaluation of Reinforced Concrete Moment Frames Retrofitted with Steel Braces Using IDA and Pushover Methods in the Near-Fault Field

Document Type : Regular Paper


1 Professor, Faculty of Civil Engineering, Semnan University, Semnan, Iran

2 Associate Professor, Faculty of Civil Engineering, Semnan University, Semnan, Iran

3 Ph.D. Candidate, Faculty of Civil Engineering, Semnan University, Semnan, Iran


One of the methods for seismic retrofitting in reinforced concrete structures is the application of steel braces. In this paper, the effect of concentric and eccentric bracing systems on the seismic performance of dual reinforced concrete building systems was inspected through seven near-fault earthquake records. Pursuant to that, two reinforced concrete frames with 10-story and 5 spans were designed and analyzed by means of the incremental dynamical analysis (IDA) method where the braces were placed in the 1st and 5th spans. The results revealed that the bearing capacity of the reinforced concrete frame by applying CBF and EBF braces increases up to 2.3 and 2 times, respectively. The use of EBF brace in a reinforced concrete frame reduces the amount of the base shear applied to the structure up to 7 times compared with the CBF frame. Approximately, the displacement of the roof in the EBF frame is less than the CBF frame. Moreover, the ductility of the EBF frame against earthquake records causes an increase in the performance level of structure to the immediate occupancy (IO).


Main Subjects

[1] Goel, S.C., Lee, H.S. (1992). “Seismic Strengthening of Structures By Ductil Steel Bracing System“, Proceeding of Fourth U.S. National Conference on Earthquake Engineering, Vol.3, Canada.
[2] Nateghi, A. (1995). "Seismic Strengthening of Eight – Story R.C. Apartment Building Using Steel Brace", Engineering Structures; Vol. 17, No. 6, PP. 455- 461.
[3] Maheri, M.R., Sahebi, A. (1995). "Experimental Investigations of Steel Braced Reinforced Concrete Frames" Proceeding of the Second International Conference on Seismology and Earthquake Engineering; Vol. 1, Tehran Islamic Republic of IRAN: May 15-17, PP. 775- 784.
[4] Youssef, M.A., Ghaffarzadeh, H., Nehdi, M.  (2006). "Seismic Performance of RC Frames with Concentric Internal Steel Bracing", Engineering Structures, Volume 28, Issue 13.
[5] Haji Ghaffari, H. (1997). "Interaction of steel frames and braces in reinforced concrete structures to withstand lateral forces". 5th Civil Engineering Conference of the Sharif University of Technology, Tehran, p. 228-238.
[6] Kheyroddin, A., Shamkhali Moghaddam, A. (2001). "Investigation of eccentric bracing behavior in existing reinforced concrete frames" Second International Conference on Tall Buildings, Iran University of Science and Technology, 143-152. (In Persian).
[7] Maheri, M.R., Hadijpour, A. (2003). “ Experimental investigation and design of steel brace connection to RC frame”, Engineering Structures.
[8] Massumi, A., Tasnimi, A.A. (2008). “strengthening of low ductile reinforced concrete frames using steel X-bracings with different details” The 14th world conference on earthquake engineering, 12-17, China.
[9] Godinez-Dominguez, E.A., Tena-Colunga, A. (2010). "Nonlinear behavior of code-designed reinforced concrete concentric braced frames under lateral loading". Engineering Structures, Vol. 32(4): pp. 944-963.
[10] Massumi, A., Absalan, M. (2013). "Interaction between the bracing system and moment resisting frame in braced RC frames". Archives of Civil and Mechanical Engineering, Vol. 13(2): pp. 260-268.
[11] Kheyroddin, A., Sepahrad, R., Kafi, M.A. (2016). “Investigation of laboratory behavior of reinforced concrete frames with cross-linked braces Steel”. 4th International Congress on Civil Engineering, Architecture and Urban Development. Shahid Beheshti University, Tehran, Iran. (In Persian).
[12] Mazzoni, S. (2007). "OpenSees Command Language Manual". College of Engineering, University of California, Berkeley.
[13] Mander, J., Priestley, M., Park, R. (1988). "Theoretical Stressā€Strain Model for Confined Concrete". Journal of Structural Engineering, Vol. 114(8): pp. 1804-1826.
[14] Rahayi, A. Nemati, S. (2004). “Performance Evaluation and Reinforcement Methods for Concrete Structures”. Fadak Isatiz Printing. Tehran. Page 96.