Halls made of light steel elements have been known for years. The main reason for using steel in hall structures is easy and quick assembly, largely independent of the prevailing weather conditions and the possibility of full prefabrication. Using steel also ensures a relatively low object weight and a small cross halls made of light steel elements have been known for years. The main reason for using steel in hall structures is easy and quick assembly, largely independent of the prevailing weather conditions and the possibility of full prefabrication. Using steel also ensures a relatively low structure weight and a small cross-section of the structural elements. Steel is also a material that is easily recycled, which leads to the protection of natural resources by the principle of sustainable development. With the passage of time and the development of technology, the structure is required to use the load-bearing cross-section to the maximum. The problem occurs when we have halls with a significant span, and the deflections of the beams become significant. An alternative may be, for example, roofs in the form of trusses or replacing prismatic cross-sections with cross-sections with belts-tapered or web-tapered. However, the question arises about how tapered cross-sections in the hall structure will affect steel consumption if the hall is located in a seismic area. This is an interesting aspect from the contractor and investor's point of view. Thus, the major aim of this paper was a numerical analysis of a steel hall with prismatic and tapered cross-section elements. The analysis was performed in the Dlubal RFEM program using the finite element method. The halls were located in a seismic area. Seven seismic recordings with different durations and recording frequencies were used for the analysis. The paper included an analysis of displacements, velocities, and accelerations for the numerical models tested. It was found that using cross-sections makes sense, but it depends on several factors the designer should consider when analyzing the steel structure. It should be added that the results from this analysis show how it is possible to lower the use of steel to build lightweight structures.