Mechanical Property Of Composite Beams Of Concrete-filled Steel Tubular And T-beam And The Analysis Of Concrete Creep Effect

With the recent rapid development of China's economy, transport conditions have been improved, a large number of infrastructure facilities get constructed and renovated, and human get higher and higher requirements to the use of the bridge function and appearance requirements.There is an emergence of all kinds of pretty large number of large-span bridge,it is a great challenge to the traditional architectural structure. There is a restriction to the properties of the structrues which are made of single material,and the restrictions can no longer meet the requirements of the building. The composite beam which is made up of concrete-filled steel tube and t-beam is similar to the steel structure,but can change the performance of concrete under pressure effectively,and improve the stress state of concrete. The concrete-filled steel tube above is similar to the concrete-filled steel tube which is under pressure. And the steel beem tensiles or bends. If the prestressed reinforcement is layed out on the both sides of the web of steel beam symmetrically, the stuctures will become prestressed composite beams which can mprove the bearing capacity and stiffness. The combined structure is a new type of structure, there are no studies on it at home, but foreign countries have relevant aspects of research and application.In this paper, a series of analysis of the composite beam of concrete-filled steel tubular and t-beam are studied by the methods of theoretical research, the research contents are as follows:the paper carries out analysis of force of composite beam, derives the formulas for calculating the bearing capacity of flexible and calculating flexural capacity limit by different location of neutral axis; anylysis the process of the prestress of the composite structure and the various stages of the stress and deformation of the corresponding parts;derives the formulas for calculating the bearing capacity of flexible and calculating flexural capacity limit of the prestressed composite beam;analysis the varieties of influencing factors of the concrete creep of the composite beam and the influentions of the concrete creep to the bearing capacity of composite beam. The paper takes analysis of the creep effect of composite beams of concrete-filled steel tubular and t-beam through the establishment of models and the analysis of the use of programming methods. The results show that the impact of the tructure of the steel ratio and the initial moment to the concrete creep is obviouse, but the impact of concrete can be ignored. The paper takes analysis of the influence of the creep to the concrete axial stress,and comes to the conclusion that creep make it decrease and tend to a stable value. The paper analysises the influence of the concrete creep to the bearing capacity of composite beam:steel ratio is greater, the influence of creep to the bearing capacity is smaller; concrete grade is greater, the influence of creep to the bearing capacity is bigger.