An earthquake is a rapid highly nonlinear process. In effective normative documents there is a coefficient K1, which takes into account limit damage of building structures, i.e. non-linear work of building materials and structures during seismic load. Its value depends on the building constructive layout. However, because of the development of construction and new constructive solutions this coefficient should be defined according to design-basis justification. The article considers the five-storey building calculation on seismic impact by linear-spectral and direct dynamic methods. Our research shows that the coefficient K1 for this building is 0.4, which was calculated using nonlinear dynamic method. According to effective normative documents K1 is 0.25…0.3 for buildings of this type. Thus we get a lack of seismic stability of bearing structures by 1.5…2 times. In order to ensure the seismic safety of buildings and facilities, especially of unique objects, the coefficient K1 should be determined by calculations with sufficient scientific justification, particularly with the use of non-linear dynamic methods.