Reaction control device was developed for the hybrid foundation consisting of a mat foundation and a small number of complementary bearing piles. The device allows a pile to retain its acceptable maximum axial force through friction mechanism even if the building subsides due to consolidation of the subsoil. The device is configured by internal pipe, slit pipe and external pipe. The slit pipe is deformed and contacted with the external pipe to create friction force by pressurizing oil. The relationships among friction force, sliding displacement and oil pressure have been measured to evaluate the coefficient of friction.
