Research On Several Problems In Design Theory Of Concrete-Filled Steel Tube Arch Bridge

Due to its outstanding mechanical behavior, excellent erection performance as well as beautiful bridge style, concrete-filled steel tubular arch bridge was strongly competitive in the span between 50m to 500m. As the end of 2008, there were more than 300 bridges of this type in China. However, because of the lack of indepth study and specialized design, construction, maintenance standards, the further development of arch bridge has been seriously hampered.Relying on the scientific research task "Key technologies in design, construction and maintenance for concrete-filled Steel tubular (CFST) arch bridge" supported by Ministry of Transport for western region, the ultimate bearing capacity, the serviceability limit state calculations and creep of concrete-filled steel tube arch bridge were studied as follows.Firstly, based on the experimental research on axial compression components, bias components and flexural members of umbbell-shaped concrete filled steel tube and the bias components and bearing capacity of concrete filled steel tubular truss structures, the simple method to estimate the ultimate capacity of these structures were proposed. It is shown that the ultimate flexural capacity calculated by the method agrees well with, more precisely is about 10% less than, the experimental results. It is concluded that the method can be conservatively applied in pratice.Secondly, with field tests of three CFST arch bridges, the investigations of design stiffness and deform limitation were carried out with the FE model which were created by the certification of test dates. And then the design suggestions for stiffness and deform limitation of CFST arch were proposed. Different formulae of calucating the rigidity of the arch should be applied for design check of capacity and design check of deformation, respectively. The different rigidity formulations have minor effects on modal parameters of arch bridges. It is further suggested that, instead of deformation limit, modal frequencies and RMS value of vibration reponse should be used for user comfort assessment.Finally, a long-period and large sized shrinkage and creep experiment of CFST structure was carried out. Based on the test, the formula of shrinkage and creep of CFST structure were obtained and a program for creep analysis of CFST arch bridge is compiled.The program results are compared with the experimental data, which proved the programming procedure is correct and finding some creep law of CFST. Comarpive study shows that is more accuate in predicting creep coefficients of arch bridges.