Vol.:(0123456789) 1 3 Asian Journal of Civil Engineering https://doi.org/10.1007/s42107-018-0092-6 ORIGINAL PAPER Investigation of retroftting RC moment resisting frames with ADAS yielding dampers M. TahamouliRoudsari 1  · K. Cheraghi 2  · M. R. Habibi 1 Received: 22 May 2018 / Accepted: 9 October 2018 © Springer Nature Switzerland AG 2018 Abstract Many buildings require reinforcement for various reasons including earthquake damage, change in design regulations and occupancy, adding stories, and lack of proper construction. One of the retroftting systems that, in addition to increasing the lateral strength, provide the structure with signifcant ductility is the ADAS yielding damper and is of great interest today. The main objective of this research is to numerically investigate the efects of ADAS plates and columns’ axial loads on the seismic parameters of reinforced concrete (RC) moment resisting frames. Therefore, based on 48 calibrated numerical models, the Pushover analysis was performed and the efects of axial force and number of ADAS plates on the seismic parameters of the frame such as efective stifness, ultimate strength, energy dissipation, and ductility were investigated. In addition, analytical relationships were presented to determine the ultimate strength and stifness of the reinforced frame. The results show that the number of ADAS plates should be determined in such a way so that the shear strength of the RC frame is at most about 3 times greater than that of the original concrete frame. Keywords RC moment resisting frame · Rehabilitation · ADAS yielding damper · Pushover analysis Introduction Some of the existing concrete structures require retroftting due to earthquake damage. Other reasons for retroftting are changes in design regulations, change in the occupancy and the number of stories to the building, and low-quality construction. There are two options for the seismic retro- ftting of concrete structures: Strengthening the existing seismically resistant elements or adding new ones. In some structures, the addition of new seismic elements is inevitable due to the signifcant lack of strength and lateral stifness. Of course, adding these elements causes a change in many seismic parameters such as the strength reduction factor, ductility, period, etc., and consequently, the base shear of the earthquake. Seismic properties of the new hybrid system should be specifed for structural rehabilitation. In various design standards such as ASCE 7-10 (2010), the seismic properties of conventional systems such as diferent types of moment resisting frames or bracings are provided. However, there is very limited information on the seismic properties of such composite frames in these standards. Generally, evaluating the performance of retroftted structures is based on engi- neering judgment and nonlinear analyses. Of course, due to the relatively complex behavior of concrete, and especially the contact elements between steel and concrete, it is not economically sound to conduct complex Finite Element analyses for designing and retroftting a structure. Many studies have been conducted on the use of Added Damping and Stifness (ADAS) in structures. The frst stud- ies carried out in this area relate to the work of Kelly et al. (1972), which introduced the idea of using a metal damper for the loss of seismic energy in a structural system. By expanding the analytical relationships for these dampers and simultaneously using them in various bracing systems such as CHEVRON, CBF, and EBF, researchers have found that their use enhances ductility and energy dissipation. (Skinner et al. 1980; Tsai et al. 1993; Jurukovski et al. 1995; Juruko- vski and Simenov, 1988). * M. TahamouliRoudsari tahamouli@iauksh.ac.ir 1 Department of Civil Engineering, College of Engineering, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran 2 Department of Civil Engineering, Razi University, Kermanshah, Iran