Static Finite Element Analysis And Optimal Design Of Large Prestressed Concrete Coal Silos

The silo structure has the advantages of small floor area,large storage capacity,simple operation,high degree of automation and green environmental protection.It is widely used in the fields of coal,electricity,agriculture and port in our country.with the continuous improvement of the finite element calculation and the prestressed structure design technology,the scale of the silo structure is gradually enlarged,the development of prestressed concrete silo structure has been in the direction of greater capacity.However,due to the complexity of the large prestressed concrete silo structure,The research on the calculation theory and design method of large prestressed concrete silo structure is inadequate in china.Commissioned by North China Power Engineering Co.Ltd.School of civil engineering Wuhan University undertook the subject of "finite element analysis and optimal design of Sanhe Power Plant large prestressed silo structure”,this is one of the subject of the research report.In this paper,combining with Sanhe power plant of large prestressed concrete silo project,under static load,stress performance,reinforcement design and structural optimization of silo structure was studied by ANSYS finite element software.The main conclusion of this text is as follows.(1)In all kinds of static load,the impact of silo structure's stress performance,coal storage pressure,silo wall temperature difference and sunshine temperature difference effect is the most significant,otherwise have decisive effect on silo wall reinforcement and crack control,process of live load?the floor live load?wind load have less influence on the stress performance of silo structure.(2)Under the pressure of coal storage,circumferential force of the middle and lower part of the silo wall is large,the top of silo wall is small,circumferential moment of the whole silo wall is relatively small;the silo wall vertical force and vertical moment is relatively small.The silo hopper wall mainly by circumferential force,and circumferential force is large,the force near the mouth of the hoop is maximal,circumferential force of the root of the hoop circumferential tension is decrease;Affected by the hoop wall tangential force,radial force of the hoop silo wall is relatively small in the hoop opening.In the hoop wall root is relatively large;the hoop wall circumferential and radial moment is relatively small.The cylinder wall is subjected to large vertical pressure and circumferential pressure,and the circumferential moment and vertical moment are relatively small.(3)Under the influence of sunshine temperature difference,the stress calculation of circular silo structure belongs to the non axisymmetric problem.The irradiation angle of sunlight has great influence on the internal force of silo structure.In the vertical plane of direct sunlight,silo wall and cylinder wall are mainly affected by the axial pressure and moment,at the top and bottom of the silo wall and the bottom of cylinder wall for respectively by top floor and ring beam and the bottom of the silo constraint,produce large axial pressure and moment;and the angle of direct sunlight for vertical plane 90 degrees,the wall of the chamber,and the lower end of the cylinder wall circumferential force is small,the vertical is mainly affected by the axial force effect,and the positions at the top of the silo wall and pulling force is small,middle and lower part of the cylinder wall,the force is relatively large,the silo wall and wall of the vertical moment and circumferential moment are small with the angle of sunlight;The vertical plane 180 degrees,in addition to the silo wall,vertical pressure slightly lower and the cylinder wall is too large,the circumferential axial force and moment and vertical moment are small.The soil wall is not directly exposed to sunlight,and its internal force is relatively small.(4)Under the joint action of coal storage pressure and circumferential prestress,the inner and outer side walls of the silo are both in compression state,and the stress difference between the inner and outer side concrete is not big;The top and lower part of the hoop wall's concrete is in the compression state,the central concrete is in the state of tension,but its tensile stress is less than the standard value of tensile strength of concrete ftk.So configuration of ring tendons in the silo wall and hoop wall is reasonable.Reducing the silo wall and the hoop wall concrete ring stress is ignificant and effectively control the silo structure tensile crack under load.(5)The floor structure under the condition of 0.000m is canceled,and the distribution law of stress and internal force before and after optimization of the silo structure is almost unchanged under each load condition.In the process of gravity,live load,floor live load,wind load,internal force of silo structure between before and after optimization is very small;Under the pressure of coal storage,before and after optimization of silo structure change of internal forces in the near wall 0.000m,the rest of the internal force influence can be ignored;Under the influence of silo wall temperature difference and sunshine temperature,the action of internal force changes before and after optimization of silo structure ring beam in the silo wall is larger,the remaining parts of silo change small.Therefore,in the design of silo structure,if remove floor structure at 0.000m,need to consider 0.000m vertical force under the pressure of coal storage,beam internal force change ring near the silo under silo wall temperature difference and sunshine temperature difference the effect on structure reinforcement.