This article presents the numerical analysis results of the stress-strain state of precast reinforced concrete frame elements connected using steel plates and bolts. Such connections are quickly constructed and, if necessary, can be disassembled without destroying the connected elements. As an example, it was considered the option of connecting a prefabricated reinforced concrete column and a crossbar. The column has a cantilever section of T-section with a shelf at the bottom. The cantilever section lower part has a protrusion designed to the beam support. The beam also has a T-section with a flange at the bottom, which is designed to support precast concrete slabs. For connections, steel plates with studs and vertical steel rods are used. The proposed connection, if necessary, can be made demountable. A comparison was made of the stress-strain state of prefabricated and monolithic beams with the same reinforcement and operating loads. The comparison showed that the prefabricated beam has almost the same rigidity and strength as the monolithic one.