Performance Research Of Progressive Collapse On Steel-Concrete Composite Frame Structure

The main purpose of structural design is meeting people’s requirements on safety. But with the economy’s rapid development terrorist activities’increasing and the natural disasters’ frequently occurring, the probability of accidents will increase sharply, which will make the probability of the structure suffering from abnormal load greatly increase. The huge accidents caused by the lack of capacity to resist unexpected accidents show us:The Progressive Collapse Resistance of building still need to lucubrate under the effect of unexpected accidents and loads.As the fifth-largest structure type, steel-concrete composite structure is more and more widely used in tall buildings and super-tall buildings, because it not only has the excellent performance which both reinforced concrete structure and steel structure have, but also can save time and reduce cost. So it’s of practical significance to study progressive collapse resistance of steel-concrete composite structures, as there is less research on this problem currently.This article selects a four-layer concrete filled steel tubular column-section steel beam composite frame as the researching object. Then, the paper evaluates the resistance of the remaining structure that has been removed the special location’s columns by using alternate load path method in ANSYS. The main research contains three aspects as shown below:1)The author reviewed and organized literature on structural progressive collapse at home and abroad, summarized the most used methods of design and analysis about structural progressive collapse from existing standards, then also respectively stated their advantages、 disadvantages and the range of application. Finally, this paper adopts alternate load path method and nonlinear static analysis to analyze structural progressive collapse resistance.2) Based on the existing research results, the paper uses the appropriate constitutive relation model of materials, and correctly handles the connections between the steel tube and core concrete、between I-section steel beams and columns. Then, the article puts forward suitable methods to settle the misconvergence of nonlinear computation. The essay states ANSYS own "element birth and death" technology, which is used to simulate the failure of columns.3) For the purpose of modeling convenience, the paper adopts unified theory, which treats concrete-filled steel tube as a member that is made up of a unified material. And then, the essay provides its combinational parameters which the finite element model bases on. This article uses alternate load path method to analyze the remaining structure’s progressive collapse resistance by removing columns, which respectively are located in the corner、the middle of long side、the middle of short side and internal of the structure.