Experimental study of nonlinear stress mechanism ofsteel-asphalt composite isolation layer

Low frequency cyclic loading test was conducted against steel-asphalt composite isolation layers (SACIL) with different steel contents. The vertical/horizontal force-displacement relationships of SACIL were studied and the vertical/horizontal internal force redistribution was investigated. The results show that the stress and the horizontal displacement of the steel and brick piers of SACIL form a nonlinear relationship. In the vertical direction, failure process of the isolation layers contains three relatively significant stages: the early stage (the vertical steel is compressed), the intermediate stage (the vertical steel is tensioned and the brick piers are compressed), and the ultimate stage (the brick piers are damaged by compression). In the horizontal direction, the loading process of the isolation layers also contains three relatively significant stages, the early stage (steel stress increases slowly from zero), the intermediate stage (steel stress increases rapidly), and the ultimate stage (steel stress drops). Based on the test results, the vertical/horizontal force-displacement curves and the vertical/horizontal internal force redistribution curves were analyzed. The results show that the loads redistribution between steel and brick piers have a decisive impact to the force-displacement curves of SACIL.