Research On Interaction Between Superstructure And Base Of Ultrahigh-rise Tube-in Tube Structure

As the number of the tall-building and computer technology were developed rapidly and emerged, interaction between superstructure and foundation becomes a jumped-up research subject. At present, the question of interaction between superstructure and foundation is paid attention to more and more by project circle. In the structural design of the building at present, regard the superstructure as the top of column be root the base of independent structure, which does not consider interaction between superstructure and foundation. It caused a big discrepancy in the result of calculation and reality. The unreasonable phenomenon is more obvious, especially in tall-building. Superstructure in tall-building, base and foundation are an organic whole. The three connecting each other and influencing each other .In the structural design of the building, influence of interaction can not be ignored.This paper looked at the practical project - the building of post and telecommunication and administration of networks in Shanxi as the research example. The paper used large-scale finite element program (ANSYS), looked grouped piles foundation as the composite material, established reasonable and efficient analysis model, and made research on interaction structure static and dynamic behavior. The contents and results of this paper were as follows: (l)The base model was established, some pile tensile phenomenon for which the throwequivalent thermal load simulated stopped dewatering, and the phenomenon was explained in quality and in quantity.(2)The single pile finite element model was simplified, and the pile-soil system in grouped piles foundation was looked as one kind of composite material in terms of the equivalent continuum method ,on this base, the pile-soil composite material's constitutive relation and equivalent complex model were established. The result showed the equivalent complex model reflected the grouped piles foundation's load transfer mechanism well, which reduced the finite analysis difficulty and explored efficient solution for the interaction between superstructure and foundation of ultrahigh-rise building's analysis in order to take advantage of finite element software.(3)The superstructure internal force and the foundation settlement law, the raft thickness and the foundation elastic modulus' effect were received by analyzing the superstructure-soil interaction model and comparing the model established on the rigid foundation. (4)The superstructure in regard of mutual interaction was analyzed in the way of dynamic behavior ,and the conclusion that the superstructure-soil interaction(compared with the rigid foundation's structure) changed the structure dynamic behavior-the natural period was prolonged and the modes of vibration was changed was made in this paper.