# Accounting for Resilience in the Selection of R Factors for a RC Unsymmetrical Building
###### Abstract  
Several design codes consider the non-linear response of a building by using one of the most important seismic parameters, called the response reduction factor (R). The lack of a detailed description of the R factor selection creates the need for a deeper study. This paper emphasises a methodology for the selection of a proper R factor based on resilience aspects. Unsymmetrical/irregular buildings have become the most common in recent times due to aesthetic purposes. However, because of the complexity due to the torsional effect, the selection of the R factor is even more difficult for this type of building. Therefore, a high-rise G+10-storey L-shaped building is herein considered. The building has re-entrant corners based on the structural/plan arrangement. Different R factors were used in the building design, considering buildings subjected to both unidirectional and bidirectional seismic loading scenarios. The building response with respect to various R factors (R equal to 3, 4, 5 and 6) in terms of its performance level, functionality, damage ratio and resilience was assessed at two design levels, i.e., design basic earthquake (DBE) and maximum considered earthquake (MCE). The study concludes that, considering the above criteria along with the resilience aspect, a maximum R factor up to 4 can be recommended for unidirectional loading, whereas for bidirectional loading, the maximum recommended R factor is 3.  
seismic resilience; building functionality; ductility demand; response reduction factor; performance level +
Footnote †: journal: Applied Sciences  
system configuration may affect the R factor, finding that the latter increased by placing bracing/shear walls in different bays. [PERSON] et al. [8] focused on analysing the actual R values using pushover analysis and taking into account the influence of geometrical non-linearity, storey height, etc. ; they found that the R value suggested by the Indian code (IS: 1893-2016) was on the higher side. A non-linear pushover analysis was then performed by [PERSON] et al. [9] showing that the load path, the ductility factor and the beam-column strength ratios have an impact on the R factor. In addition, the effect of vertical connections in braced frames on R in accordance with the seismic demand and capacity of the frames was assessed by [PERSON] et al. [10]. [PERSON] and [PERSON] [11] used non-linear static pushover analysis to investigate how soil flexibility affects R, the time period and the overall structural performance. A non-linear time history analysis (NLTHA) for a three-storey medium seismicity healthcare facility was conducted by [PERSON] and [PERSON] [12] with varying significance/importance factor (I) values of 1.0, 1.2, 1.4 and 1.5, which are different from R. The result shows that the building receives less damage when a crucial constituent is higher. [PERSON] et al. [13] investigated the effect of non-uniformity on R with respect to span and height, and the results indicate that non-uniformity has a considerable negative impact on the R value with respect to height. [PERSON] and [PERSON] [14] looked at the impact of modifying the building boundary condition on the R factor. [PERSON] and [PERSON] [15] performed a study to evaluate the R factor for unbraced and steel-braced RC framed structures, and [PERSON] [16] conducted research to pinpoint several factors, including ductility and the overstrength factor, which affect the building response. [PERSON] and [PERSON] [17] investigated the characteristics required to define R for a framed RC structure, while the significance R factor for the structural behaviour of RC members was assessed by [PERSON] et al. [18]. According to [PERSON] et al. [19], the building non-linear behaviour for increasing ground motion levels is influenced by the R factor. [PERSON] and [PERSON] [20] utilised the cracking coefficient to take into consideration strength degradation in terms of stiffness.