| A novel tunnel lining and segment consisting of fiber reinforced polymer(FRP),steel and concrete was proposed.The multi-cell steel tube-sandwich concrete-FRP tube-core concrete(MCSCFC)segment comprised the following four parts: multi-cell square steel tube,curved FRP tubes placed in cells,concrete between FRP tubes and square steel tube walls,core concrete confined by FRP tubes.The mechanical behavior of MCSCFC segments were studied by experiment,theoretical and numerical simulation.(1)Ten segment specimens were experimented with different FRP tube thicknesses,FRP tube layouts in cells,segment types,square steel tube types under the uniform lateral compression.The failure modes,load-displacement curves and stress-strain responses of MCSCFC segments were described.The MCSCFC segments have distinctive hardening behavior after yielding,and the loaddisplacement curves exhibit trilinear behaviour.The experimental result shows that:compared to that of the reinforced concrete(RC)segments,the load bearing capacity of MCSCFC segments was higher and the thickness was thinner.(2)The load-strain relationship expression of MCSCFC segment cross section and the constitutive model suitable for four components were proposed.Interaction between multi-cell square steel tube,curved FRP tubes,sandwich concrete and core concrete was considered on the constitutive model.(3)The mechanical behavior of MCSCFC segment under uniform compression was studied by numerical simulation through the ABAQUS.According to the loaddisplacement and load-strain curves of MCSCFC segment by the experiment,the parameters of finite element model were optimized.A numerical simulation scheme for MCSCFC segments under uniform compression was obtained.Compared to that of the concrete filled steel tube(CFST)and RC segments,the MCSCFC segment exhibit superior behavior proved by experiment.A simplify design method for MCSCFC segments was proposed. |
