Comperssive Performance Study Of Square Concrete Columns Confined By CFRP With Corner Reforced

CFRP confined concrete structure is a new and high-profile reinforcement form.It has been widely used for its characteristics like light weight, high strength,durable, simple and convenient. At present, the research and application of CFRP constraint columns has been relatively mature. But for CFRP constraint square column, the problem of stress concentration at angle leads to the non-uniform lateral restraint stress of CFRP, which has influenced the effect of restraint greatly, and has been the difficulty of the research and application. Many studies have shown that this kind of problem can not be solved by increasing CFRP constraint layers simply.For this problem, in order to reduce the effects brought by corner stress concentration, this article takes special measures through the specific local constraints.Thus increases the bearing capacity of the constraint column greatly through the increase of a small amount of constraints material. On the basis of the ordinary CFRP confined concrete square column, a particular way is used by pasting local enhancement CFRP layer in the corner. Local enhancement layers are bonded together through epoxy resin as a whole. In this way, it can effectively improve the constraint effect of confined columns, and have a good application prospect.Four variables were involved in this article. They are the number, location, Paste way and overlap length of the local reinforcement layer respectively. Hoping to find the best form of constrains through the study of these variables. The specific work and research results are as follows.1) This paper designs eight groups of square column with three specimens in each group. The size of each specimen is 300 ? 300 ? 600 mm with a 30 mm prefabricated chamferingin at each corner. And the strength grade of concrete is C30.Each set of specimens with different forms of constraint, and carries on the static axial compression test. The test measured axial compressive strength, the axial strain and the hoop strain in each group. Through the study it is found that the local enhancement layers can obviously improve the bearing capacity of the constraint column. The failure mode, the CFRP hoop strain distribution and the ductility are also improved indeed.2) The local enhancement number had significant effect on the restraint effect of the constraint column. The compressive strength of constraint column increase as theincrease number of local enhancement layer, damage point change from the Angle to the face, the CFRP hoop strain obviously changes at the same time, and the column ductility increases as well.3) The paste way of local enhancement layer had significant effect on the restraint effect of the constraint column as well. In general, the constraint effect of "W+ 1 + W" is superior to the form of "1 + W". But local enhancement layer thick Ness and overlap length had insignificant effect on constraint effect of constraint column.Double the thick Ness of local enhancement layer, the compressive strength is only increased by 3%. When the overlap length reaches more than 40 mm, constraint effect basically remain unchanged. Through analysis and comparison, this paper concluded that the most effective form of constraints, the form of "W + 1 + 1 + W + W … ".Enhance in this form is both economic and efficient.4) Experimental datas are simulated in this paper, using the finite element model.The reliability of the model was validated, and the other parameters are simulated.Based on this, combining with the above test results, a design formula of the compressive strength is obtained. The formula calculation results are in good agreement with the test results and be safe.