| As an important structure of material storage in the world,spiral steel silo has the characteristics of fast construction,light weight,recyclable materials and perfect supporting facilities.Steel silo has been widely used in the storage industry,which has produced significant economic benefits.Compared with reinforced concrete silo,it has its unique advantages.In view of the important role of steel silo in national production and management,its mechanical performance has been widely studied by scholars in various countries.The research mainly focuses on dynamic loading and unloading,storage flow pattern,fluid design,stability performance,seismic performance,temperature effect and wind load on the performance of steel silo.In this paper,an actual spiral steel silo inclining accident is taken as the object,and the accident steel silo is detected and identified.ABAQUS software is used to carry out static analysis and local stiffener analysis of the steel silo under five working conditions.Finally,the seismic reinforcement analysis of the damaged silo is carried out.The main work and conclusions are as follows:(1)First,according to the engineering design,construction and use,based on the factory requirements and the preliminary investigation on the accident site,the foundation,foundation and superstructure of the spiral steel silo are tested and identified in detail.The results show that the 1# cement spiral steel silo accident is the local inclination caused by the failure and instability of the main structural components of the upper part of the spiral silo,rather than the overall inclination.The main causes of the accident are as follows: in the design aspect,the design sketch of the silo body is simple,and most of the structural details and details of the joints,such as the details of the connection joints of the stiffeners and the layout details,are the basic reasons for the structural safety hazards.In terms of structure,the weak axis of the stiffener is arranged in the direction of the maximum horizontal pressure on the silo wall,which greatly weakens the actual mechanical performance of the channel steel,reduces the overall and local stiffness of the cylinder structure,thus increasing the displacement of the silo wall and the stiffener composite structure in the stress direction,which is easy to form the local instability phenomenon.In terms of construction,the eccentricity of the connection of the stiffener is large,and the vertical stress is uneven,which is very easy to cause the local instability of the stiffener;the welding seam between the stiffener and the steel plate of the silo wall is not uniform in shape and appearance;the adjacent connection nodes of the vertical stiffener of the silo are in the same horizontal height,which will form the weak link of the silo under the horizontal pressure,and results in the brittle failure of the silo at the above joints.(2)Using ABAQUS software,the static analysis and localstiffener analysis(including loading 28 m and full bin)under five working conditions(loading 1 /3 bin,loading 1 / 2 bin,loading 2 / 3 bin,full bin and cement loading height 28 m in case of accident)were carried out.In the analysis of local joint stiffeners,according to the joint connection,it can be divided into three working conditions(complete connection,partial connection of a node and partial connection of B node).The overall analysis shows that the stress and displacement level of the whole silo structure increases with the increase of cement loading height.The maximum value of stress and displacement of silo mainly appears at the bottom of silo,the stress value of concrete beam and internal reinforcement is lower than the strength value of material,the concrete stress value of column is less than its strength value.The results show that the stress at the bottom of the silo exceeds the yield strength of the silo steel plate under the full bin condition and at 28 m loading,and the excess ratio is 0.16% and 0.01% respectively.Under full bin condition and 28 m loading,the column head reinforcement of KZ1 has just reached the yield value.At 28 m,the displacement in the middle of the silo is relatively large,reaching 21.07mm-22.87 mm.When the silo is full,the displacement in the middle of the silo reaches 22.79mm-25.17 mm.Comprehensive analysis,silo stiffener analysis and stiffener node analysis show that the damage of the actual silo structure does not appear in the position of the maximum stress and displacement of the silo,when the loading is 28 m,the stress and displacement of the actual damage part are large,when the connection failure occurs,the stress concentration of the silo wall will be different degrees.When the stress value exceeds the yield strength of the steel plate,the displacement increases to form local buckling.At the same time,the stiffener will penetrate through the silo wall and cause further damage,which is consistent with the actual failure mode.Using yingjianke software to rectify the inclination of the upper silo and analyze the seismic strengthening of the damaged silo.(3)Using YJK software to rectify the inclination of the upper silo and analyze the seismic strengthening of the damaged silo.The whole spiral steel silo is calculated and rechecked according to the upper and lower structures.Since the lower part is a concrete frame structure,and the upper part is mainly a steel structure,considering the incompatible deformation of the two materials,the upper and lower structures are calculated separately,and the overall calculation is selected for the load calculation according to the actual situation,The whole spiral steel warehouse is calculated and rechecked according to the upper and lower structures respectively.Since the lower part is a concrete frame structure,and the upper part is mainly a steel structure,considering that the deformation of the two materials is incompatible,the upper and lower structures are calculated separately.According to the actual situation,the overall calculation is selected for the load calculation.The results show that the bearing capacity,structure,deformation,axial compression ratio,shear span ratio and other main technical indicators of the reinforced supporting structure meet the requirements of technical code for steel silos(GB 50884-2013)and code for design of concrete structures(GB 500010-2010).The calculation of structural members,connection strength and stability of the upper silo body meet the technical specification for steel silos(GB50884-2013).The overall anti overturning calculation and stability calculation of steel silos are also in accordance with the technical specification for steel silos(GB50884-2013).Through the above calculation and review,the feasibility of the reinforcement scheme of the spiral steel silo is verified theoretically,which lays a theoretical basis for the subsequent accident treatment of the spiral steel silo. |
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