The Modelling And Analysis Of Fan-shaped Tube In Tube Structural System Of Super Tall Buildings

The fan-shaped tube-in-tube structure is one of new-type structural systems for super-tall buildings. In order to analyze the structural system, both the modelling and analytical methods are investigated in the thesis. The principal works are as follows:Modelling: A fan-shaped tube-in-tube structural system is simplified as a thin-walled fan-shaped tube-in-tube shell of variable cross sections supported on a semi-infinite elastic body, based on the principle and method of equivalent stiffness and mass. Some proper nodal lines are utilized to discretize the in-tube and ex-tube so as to describe the displacement field or dynamic behaviors of the structural system by means of the one-variable functions defined on the nodal lines. The governing equations and corresponding boundary conditions of a desired problem are then developed by using the principle of minimum potential energy or Hamiltonian principle. The equations are ordinary differential equations which can be solved by means of computer software—ODE Solver.Analysis: The interactions between the soil and foundation and superstructures as well as the free vibration analysis of a fan-shaped tube-in-tube structural system of a super tall building are performed by numerical examples, respectively. Some conclusions are obtained, such as a fan-shaped tube-in-tube structure has a very good structural integrity and great stability, and it has very little sidesway under horizontal loads; The natural periods in the directions of x, y, z are different, therefore the long periodic coupling vibration is less easily happened under a ground tremor. But a fan-shaped tube in tube structure has relative weak torsional stiffness and is sensible to torsional vibration effect. Therefore, we should pay attention to the torsional aseismic design.