| As a new type of structure,the double-layered concrete-filled steel tube shoulder beam has been used in actual projects.The mechanical properties and failure modes of this structure lack corresponding research.Designers still use the design method of singlelayer shoulder beams to give design belts There is a big security risk.The thesis takes the double-column shoulder beam as the research object,through theoretical analysis,experimental research and finite element simulation to determine the bearing capacity,failure mode,internal force distribution and stress distribution of this structure under the high-level crane vertical load.Provide a basis for the design of the double-layer shoulder beam of the side column.The main research contents and conclusions are as follows.In the experiment,the main variable of the position of the inner limb of the center column on the lower shoulder beam was designed,and three types of nine members were designed,namely the double shoulder beam of the double limb side column,the double shoulder beam of the three limb side column and the double shoulder of the four limb side column Beam.In order to simulate the vertical load of the high-level crane,a monotonic loading test was carried out on the test piece,and the yield mechanism and failure mode of the test piece,the bearing capacity and the stress on the main parts were analyzed in depth.The results show that the elastic bearing capacity of the double shoulder beam specimen with multiple limbs is controlled by the shear yield of the inner web of the lower shoulder beam,and the failure is caused by the larger convex deformation of the inner web of the lower shoulder beam.;In the process of the lateral displacement of the inner limb of the center column,the shear force of the inner limb of the lower shoulder beam is reduced,and the bearing capacity of the double-layer shoulder beam specimen is improved;from the comparison of the bearing capacity of the single and double web specimens,the double The elastic bearing capacity of the web is about twice that of the single web,indicating that with the increase of the cross-sectional area of the web of the lower shoulder beam,the bearing capacity of the double-layer shoulder beam increases in proportion to the elasticity of the three-limb and four-limb members that are also double webs The bearing capacity is basically the same;due to the impact of the squeezing stress,the upper flange plate under compression of the lower shoulder beam is more stressed than the lower flange plate under compression.It is recommended to strengthen the upper flange plate in the design;Due to the influence of the bending moment on the side flange,the stress on the inner flange plate is relatively large,which should be considered in the design.Through the finite element software,the bearing capacity of the double-layer shoulder beam of the side column is analyzed,and the effect of the yielding order of the full-section webs on the inner and outer sides of the lower shoulder beam on the elastic bearing capacity of the double-layer shoulder beam member is mainly studied.The results show that the elastic bearing capacity of the member corresponds to the full-section yield of the inner-limb web when the inner-limb web yields first;when the outer-limb web yields,the elastic-bearing capacity of the member is between Between the full-section yield of the inner and outer webs of the shoulder beam,at this time,the elastic bearing capacity of the double-layer shoulder beam member can be conservatively removed when the shear strength of the inner and outer sides of the shoulder beam is equal.At the same time,the finite element software was used to analyze the shear force distribution under the load of the high crane,and it was concluded that the shear force calculation of the inner limb side of the lower shoulder beam was the same as the single-layer shoulder beam.In order to understand the distribution of upper and lower shear forces on the lateral side of the extremity,the parameters of the upper shoulder beam height,center column inner limb center distance,lower shoulder beam height-span ratio,middle column inner limb height,and middle column inner limb section height were studied.,Taking the height of the inner limb section of the center column as the variable that has the most significant influence on the distribution ratio,the shear distribution coefficient of the upper and lower shoulder beams on the outer limb side is determined by formula fitting,and the main section of the shoulder beam under different conditions is given.Shear force calculation formula,and use this to derive the critical value of the equal shear force on the inner and outer sides of the lower shoulder beam,which is used to determine the yield order of the inner and outer sides of the lower shoulder beam.The stress of the web of the shoulder beam is further analyzed by finite element software.The results show that the distribution of shear stress along the height of the section is consistent with the equivalent stress,and the points of the section at the time of yield basically reach the shear yield strength,based on this,Combined with the above analysis,the design method of the double-layer shoulder beam with multiple limb side columns is given. |
