Analysis Of Tall Hybrid-structures With Construction Process, Creep And Shrinkage Effects

In China, tall building hybrid structures, which are composed with steel frames and concrete core-tubes or with composite steel frames and concrete core-tubes, have been widely applied recently. A noticeable problem of this structure system is that concrete has the characteristics of creep and shrinkage while steel hasn't. Along with the time, obvious different vertical different displacements will produce between neighbor vertical members, which should result in great additional internal forces and have big effects on the structural security and applicability. In this thesis, combined with the research project"Research on the behavior of the tall building hybrid structures"financed by the Natural Science Foundation of China (NSFC), methods to calculate different displacements of hybrid structure and corresponding engineering measures are studied. Productions obtained are as follows.1. According to the creep behaviors of statically determinate structure under constant load and changing load, respectively, the internal analysis method of statically indeterminate structure considering the effects of construction and creep is put forward first. This method is based on the ideas of force method and age-adjusted effective module method. By removing redundant restraints, the initial structure is equivalent to a statically determinate structure, named released structure, which subjected to loads, redundant forces obtained in elastic analysis and creep-redundant force changing with time due to the creep of structure. Displacements on the directions of redundant forces can be obtained by creep analysis of released structure under every force mentioned above. According to conformability of deformation, creep-redundant forces can be attained by resolving equilibrium equations. Effects of relevant factors on the statically indeterminate structure are presented here through a numerical example.2. The displacement method to analyze creep effects of structures is established first. The key problem of displacement method in creep effect analysis of statically indeterminate structures is to determinate fixed-end forces of the element. Based on the ideas of force method and virtual-work principle, calculation formulas of the fixed-end forces in element-system structures are deduced. It is found that the fixed-end forces of element are function of creep coefficient and elastic fixed-end forces of the element. According to the formulas, a computer program of displacement...