The Eccentric Compression Performance Of ECC Steel Composite Column

Currently,research on high toughness Cementitious Composites(hereinafter referred to as "ECC")by scholars at home and abroad is gradually increasing.Especially,the research on ECC materials by scholars in universities accounts for the vast majority.In order to make use of the advantages of ECC material,this new type of composite material was used to analyze the mechanical properties of biased components to study whether it can improve the bearing capacity and crack control ability of components.In the column design,the column component is mainly considered to bear the axial force,but in the actual project,the eccentric compression is mainly.When in the eccentric compression state,its stress state is more complex.Therefore,the mechanical properties of ECC steel composite column under eccentric compression are studied and analyzed in this paper.Six ECC composite steel columns were designed using eccentricity and PVA(Polyvinyl alcohol)fiber volume ratio as variable parameters to conduct eccentric compression tests.The effects of PVA fiber volume ratio and eccentricity on the mechanical properties of the components were analyzed.After the experimental analysis and the establishment of the finite element analysis,in the verification of the model and the test consistent,the H-beam composite column and the composite column without H-beam were compared and analyzed,obtained the H-beam composite column and the composite column without H-beam bearing capacity experimental data.The main conclusions are as follows:(1)The test results of ECC section steel composite column show that the ultimate bearing capacity is increased by 41.6% on average when the eccentricity is 32 mm compared with 96 mm.It can be concluded that the ultimate bearing capacity of the composite column decreases with the increase of eccentricity.(2)Under the action of bias pressure,with the increase of PVA volume ratio,the maximum compressive strain at the near-axial side increases,and the tensile strain at the far-axial side also increases.The results show that the fiber addition can provide the load-bearing capacity to the component stably.(3)When the eccentricity is 32 mm,the ultimate load of 5# member is 19.8k N higher than that of 1# member,with an increase of 2.6%;When the eccentricity is 96 mm,the ultimate load of 6# member is increased by 7.0k N and 1.5% compared with that of 2#member.It can be concluded that with the increase of PVA fiber content,the ultimate bearing capacity of ECC steel composite column increases but the increase is not large.(4)The larger the eccentricity is,the smaller the bearing capacity of the component is.At the same time,the larger the bending moment of the column end is and the less ECC is wrapped,so the component is easy to be damaged.When the ECC of the component is mixed with the steel bar,the crack can be effectively controlled and the bearing capacity can be improved.(5)When the eccentricity is 32 mm,the bearing capacity of the member containing section steel is increased by 11%～15% compared with that without section steel.It can be seen that the increase of section steel can effectively improve the bearing capacity.When the eccentricity is 96 mm,the bearing capacity of the member containing section steel is increased by about 5%～7% compared with that without section steel.The results show that the increase of section steel content can effectively improve the bearing capacity of the member,and the smaller the eccentricity,the greater the increase of the bearing capacity.(6)Based on the limit state design method of reinforced concrete,the bearing capacity calculation formula of ECC steel composite column is deduced.