Study On Overall Stability And Bearing Capacity Of L-shaped Steel Columns In Prefabricated Steel Structure Residences

In the prefabricated house,the use of L-shaped,T-shaped,cross-shaped cross-section columns can not only solve the problem of indoor exposed pillars in steel structure residential buildings,but also has the advantages of large delivery area,quick construction and time saving.Concrete special-shaped column system has been widely used in residential buildings in China,and has been followed by specifications.However,the application specifications of steel special-shaped columns have not yet been comprehensive,so it is not widely used in fabricated steel structure houses.Because there is no axis of symmetry in the section of the special-shaped column,the bending and torsion buckling is easy to occur under the biaxial compression load.It is necessary to study the theory and calculation method of the ultimate bearing capacity of the steel special-shaped column and its influencing factors.Inspired by domestic and foreign scholars on the research methods and research ideas of other cross-section shaped columns,this paper has done the following research work on the above issues:1.This paper has a large number of literatures,and compares and summarizes the cross-section forms of common shaped cross-section columns in prefabricated houses.The results show that the static performance of different cross-section columns is very different.By reading the relevant literatures on the research of steel special-shaped columns at home and abroad,the influencing factors of the overall stability formula and ultimate bearing capacity of L-shaped steel columns are proposed.2.The derivation process of the calculation formula for the stable bearing capacity of T-shaped and cross-shaped sections with symmetry axes in the current steel gauge is explored.The general stability formula derivation of the L-shaped steel column under biaxial compression and axial compression is briefly introduced.The design of the bearing capacity of the steel column is complicated by the calculation of the section characteristics,and the corresponding program is programmed to simplify the calculation process.3.The finite element model of the L-shaped steel column is established with reference tothe existing experimental conditions.The characteristic buckling value is obtained and compared with the derived bearing capacity formula.Considering the initial defect,the nonlinear buckling analysis is carried out to obtain the ultimate bearing capacity value and test results.Control,prove the validity of the model.4.Six groups of L-shaped steel column finite element models were established to analyze the relevant parameters,and the influence of panel width-to-thickness ratio,eccentricity,member length,non-equal bending moment and the constraint of both ends on the ultimate bearing capacity of L-shaped steel special-shaped columns were investigated..It is found that each member undergoes bending-torsional buckling under biaxial compression and bending.The load-displacement curve can be divided into linear phase,nonlinear phase and descending phase.The analysis of each influencing parameter leads to the following conclusion: the eccentricity is too large to make the L-shaped section steel The ultimate bearing capacity of the column is greatly reduced due to excessive torsional deformation.Asλf increases,the deformation increases and the bearing capacity decreases rapidly.This phenomenon is more obvious when the eccentricity is large.A suitable flange width to thickness ratio and a web height to thickness ratio can ensure the bearing capacity of the member,resulting in less deformation.The larger column length makes the load-displacement curve of the L-section steel special-shaped column decrease rapidly after reaching the ultimate bearing capacity.In the case of failure,the maximum deformation is generally located in the middle of the column.When the constraints are different at both ends,the maximum displacement will move along the longer direction of the member to the more free end.5.The seismic behavior of L-section steel columns under cyclic loading is analyzed.Twenty-two finite element calculation models were established,and the load-displacement hysteresis curve of a large number of L-shaped steel columns under cyclic loading was obtained.According to its deformation characteristics,bearing capacity value and ductility performance,the flange width-thickness ratio and web height-thickness ratio were explored.The influence law of the axial compression ratio on the hysteresis curve of the eccentric compression member.It is proposed that the L-shaped steel column maintains local stability under cyclic loading,and satisfies the requirements of ductility,flange width-to-thickness ratio,web height-thickness ratio and axial pressure ratio limit formula with higher post-buckling strength.Steel special-shaped column structure is more in line with the national sustainable development strategy compared with H-shaped column and concrete special-shaped column.The theory and analysis method of steel column stability analysis plays an important role in the promotion of residential industrialization.The research result is steel profile.The formulation of column-related specifications laid the theoretical foundation.