The paper considers infl uence of sudden transformations, linked with foundation, to reliability of reinforced concrete structural systems at buckling one of load bearing elements. Authors investigated infl uence of deformation value to bifurcation type for each leg of building frame. It was determined subsidence value that leads to changing of bifurcation type for rod elements of the system.Authors shown a suggested criterion for stability assessment of compressed rod elements of structural systems operated in dangerous geotechnical conditions. Such criterion can be used for assessment residual resource of a building at special impacts linked with foundation subsidence under one support.