Study On Static Reformancc Of The Concrete Filled Circular CFRP-stecl Tube Under Compression-torsion

The study on composite materials is a field with much attention recently, of which carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) are on the behalf. CFRP has high strength, light weight, tensile and other characteristics and is widely used in structural fortification and restoration works after fire. Multiplying the advantages of CFST with that of CFRP, we can stick CFRP to the outside of CFST which make the concrete filled steel tubular confined by CFRP, and that will to some degree increase the bearing capacity of CFST. Since the circular sectional member has good mechanical performance, it has been studied better. The rectangular sectional member will become primary in part of modern engineering for its sectional characteristics, so the research on it is gradually developed. Carbon fibre reinforced concrete circular steel tubes of the axial compression, bending, by hydraulic properties of research has had certain basis, but its torsion.it shear properties, and has not yet been fully extended, and of the concrete filled steel tube is turned, shear performance of concrete filled steel tube is an integral part of the performance, so this part of the study is very necessary.In this paper, further analyses on the torsional behavior of CFST confined by CFRP subjected to combined action of load-torsion on the basis of the study of torsion of CFST are performed. Through analysing the test data and with the help of finite element analysis software ABAQUS, we can obtain some important conclusions of CFST subjected to combined action of load-torsion.This paper has several parts as follows:1. State the advantages of CFST and CFRP systematically, analyse the necessaries of CFST confined by CFRP emerging and rising and summarize the researches of domestic and overseas simply.2. With eight circular concrete filled steel tubular CFRP enhanced torsional components studied. The main parameters considered:(1) axial compression ratio (n);(2) from the longitudinal layer of carbon fiber (mθ);(3) ring to the carbon fiber layers (m1);(4) concrete strength (fcu).3. Simulate the whole process of the experiment with the finite element analysis software ABAQUS, and we will get the load-displacement curve which is close to that of the experiment. Moreover, the fracture morphology of the simulation and the experiment are approximately the same, so we can come to a decision that the model we set up is correct. Analyse other behaviors of the members with this model, such as constraint force the steel tube to concrete, the changing patterns of stress-strain curve of core concrete and so on, through which reveal the mechanisms of CFST subjected to combined forces.