Experimental Research On Mechanical Behavior Of Concrete-filled Thin-walled Steel Tube Beams And Columns

The development of the concrete-filled steel tube (CFST) structures has a broad prospect. It can adapt to modern structure engineering developing to larger cross, taller, heavier bearing load and satisfy the need to withstand harsh conditions. It also can meet the requirements of modern construction technology industrialization. It is being increasingly widely used in industrial plants, high and ultra-high-rise buildings, bridges and underground structures and achieved good economic and architectural effect. The CFST structures have being an important direction of development of structural engineering sciences.Concrete-filled steel tube structures are mostly used for high-rise and super high-rise building. As load-bearing columns, they are mainly to bear axial force. In order to prevent lamellar tearing occurs of welded steel pipes, it's needed to consider using high-strength thin-walled steel pipe. For thin-walled steel pipe, it usually needs to consider the local buckling of the mechanical properties of components. This paper tests used in thin-walled steel pipe thickness has two kinds of 2mm and 3mm.The Concrete used in CFST is self-compacting concrete. Self-compacting concrete in cast is not required to be vibrated. It can be self-compacting the forming of the tube to facilitate the construction of concrete on its own gravity, and can reduce noise pollution, ensure project of great significance. Pour the self-compacting high performance concrete into the tube to form a tube of self-compacting high performance concrete, it can better bring into full play the advantages of the two materials.This article first take a theoretical analysis on concrete-filled steel tube of axial compression and pure bending under the action of the material constitutive relation , and then test to determine through the material of steel and self-compacting concrete material properties, through the material constitutive relation and material test research for the subsequent chapters provide the basis for performance analysis of component data. Axial compression force is a basic form of force means of structural components. This chapter takes test on 3 circular concrete filled steel tubular structures and 7 square and rectangular steel concrete structures for axial compression experiments. Then we observe the failure mode, analysis of the mechanism, give the load testing process - strain curves and load - displacement curves. For the mechanical properties of component factors, such as the radius-thickness ratio/width-thickness ratio, constraint effect coefficient, aspect ratio and so, we take them to a certain degree of comparison.There are no outstanding advantages of concrete-filled steel tubes used as flexural members. However, in practical engineering, the role of concrete-filled steel tubes used as the bending moment is not uncommon. For example, beam-columns and pull bending members, in addition to axial force, there are moments effect also. Therefore, the study bending properties are still necessary in order to deepen their understanding of concrete filled steel tubular eccentric force elements operating performance awareness. This chapter takes test on 8 concrete-filled steel tubular structures of pure bending, gives the corresponding load curve, and take a few analysis.Finally through the experiment by axial compression and pure bending on components, we get the values of bearing capacity of all components, comparing them with some national specifications. At last, we give an appropriate evaluation.