لخّصلي

1.The conducted studies in the field of structural damage in past earthquakes show that adjacent buildings with partial discontinuity or with a common wall between two structures may suffer serious damage during an earthquake and even go to the point of collapse [3, 4].Introduction Today, in cities with high population density, the minimum gap among adjacent structures is an important issue due to the fluctuation of buildings during seismic excitations, and various codes in this field have specified the minimum distance to prevent buildings from colliding [1, 2].

1. Introduction
   Today, in cities with high population density, the minimum gap among adjacent structures
   is an important issue due to the fluctuation of buildings during seismic excitations, and
   various codes in this field have specified the minimum distance to prevent buildings from
   colliding [1, 2]. The conducted studies in the field of structural damage in past earthquakes
   show that adjacent buildings with partial discontinuity or with a common wall between
   two structures may suffer serious damage during an earthquake and even go to the point
   of collapse [3, 4]. Kamal and Inel showed that pounding phenomenon may alter the
   dynamic features of two adjacent buildings significantly [5]. The pounding problem was
   first numerically modeled for single-degree-of-freedom (SDOF) structures [6-8], and then
   for multi-degree-of-freedom (MDOF) structures, these analyses were performed
   numerically with concentrated mass [9, 10], and then for three adjacent buildings,
   numerical analyses related to pounding were also performed [11, 12]. Past earthquakes
   have shown that the pounding issue is a serious topic for tall buildings in the vicinity whose
   floors are not on the same level [13-17]. Another important reason for the pounding issue