Modular buildings are currently a topical area of research. Erection of modular buildings in hard-to-reach areas needs special attention to the consideration of seismic loads. There are not many studies on the work of modular buildings on dynamic impacts in the Russian Federation.

The paper studies the influence of the parameters of modular buildings to the coefficients of dynamic during seismic action. Study of the influence of the elements flexibility on the coefficient of dynamic, an analytical formula for determining the period of natural oscillations was used. This formula was obtained for modular buildings with corner supported columns, rigid intramodular and pin intermodular connections. Based on the boundary values of the moments of inertia of the columns, at which the dynamic coefficient decreases, an assessment of real design solutions was made for various ratios of the moments of inertia of crossbars and columns of one-, two- and three-story modular buildings. The dimensions of the modules are set to be 3×6×3(h) m, the dead load on a floor is 100 kg/m² and 150 kg/m².

It was found almost all considered design solutions for modular buildings have a dynamic coefficient is 2,5 even for three-story buildings if there is ground categories III and IV. Dynamic coefficient decreases for some two-story buildings if there is ground categories I and II. Dynamic coefficient of one-story buildings is 2,5 for any ground categories. The ratio less than 1 of the moments of inertia of the crossbar and the column is the worst case of design in terms of seismic load.