| According to the strengthening of existing reinforced concrete column and the retrofitting requirement of engineering practice,a noval RC column retrofitting pattern of post-wrapped steel tube retrofitted RC(PSTRRC)column was proposed.Based on the maintained architectural aesthetics and space of original building as well as cross-sectional dimension of component,the bearing capacity and ductility of PSTRRC column had a significant improvement.Previous studies focused on strengthening method in specification and post-wrapped steel tube confined concrete.The researches on analysis of the novel PSTRRC column were bare.To promote the application of the novel strengthening method in practical engineering,this paper developed experimental and finite element(FE)analysis on the axial compressive performance of stub and slender PSTRRC column.The specific research was summarized as follows:(1)Performed axial compressive tests of nine stub rectangular PSTRRC column and one stub column retrofitted with grout.Four parameters contained the cross-sectional area ratio of core column,steel strength,aspect ratio and concrete strength were considered in tests.According to the experimental results,the failure modes,the bonding of interface,ductility factor,the contribution of concrete and so on were discussed.(2)The innovative confined constitutive relationship of grout was presented in this paper.The FE model of stub PSTRRC column was established by ABAQUS software and verified well with the experimental results.Furthermore,the structural behaviour of stub PSTRRC column was explored in terms of material,geometric and load parameters.(3)The tests of eight slender rectangular PSTRRC column subjected to axial load were developed.And the change regulations of failure modes,the relationship of axial load(N)-vertical displacement(Δ),the curve of axial load(N)-lateral displacement(u_m),the half-wave sine curve and axial load-strain curve were analyzed.(4)The FE model of slender PSTRRC column was established and verified well with the experimental data.The results of parameter analysis on slender PSTRRC column was put emphasis on the distribution rules of the axial load(N)-lateral displacement(u_m)curve,stability coefficient and ductility factor.(5)The simiplied design formulas for axial bearing capacity of PSTRRC column were proposed.In addition,the applicability of design formulas was verified compared to the results of experiment and FE analysis.It could be concluded that the design formulas can be applied to stub and slender PSTRRC column. |
