Seismic And Wind-driven Dynamic Characteristics Analysis And Safety Evaluation Of Long-span Coal Transport Trestle

With the development of our industry and the increasing demand of coal energy,there are a growing number of the long-span coal transport trestle in coal mines,coal preparation plants and thermal power plants and other energy projects.The high flexibility,high support,mass and stiffness along the vertical distribution are not uniform.The weak parts are many,the seismic resistance line is less,and the safety reserve is low,which causes the earthquake and the wind load is extremely sensitive to the long-span coal transport trestle.More than 80 percent of our country's mines are located in the earthquake zone.Earthquakes are often accompanied by various secondary disasters,such as disasters,and the frequency of disasters is high and duration.Therefore,it is urgent to solve the problems of earthquake and wind vibration characteristics analysis and safety evaluation of the long-span coal transport trestle.This article should be entrusted by the headquarters of Liaoning Fuxin Mining(Group)Co.,Ltd.,and Hengda coal industry company.Based on earthquake engineering,structural wind engineering,computational fluid dynamics,computational solid mechanics,elastic-plastic mechanics and structural dynamics,The theoretical analysis,field measurement and numerical simulation are used to study the seismic and wind-induced dynamic characteristics and safety evaluation of the long-span coal transport trestle in the coal preparation plant of Hengda coal industry company.The main research work and results are as follows:(1)The structure of the long-span coal transport trestle is measured,the wind speed is measured,and the structure response is measured in the case of strong wind.Based on the instrument and data acquisition system used in the field measurement of the long-span coal transport trestle,the natural frequency of the coal transport trestle,the measured wind speed and its wind-induced response data are obtained.Based on the analysis of the data,the results show that the measured wind speed spectrum is consistent with the Karman spectrum,indicating that the measured data is in line with the actual practice.(2)The establishment of the numerical model of the seismic and wind dynamic characteristics and safety evaluation of the long-span coal transport trestle.Considering the FSI(fluid-structure interaction),the ABAQUS finite element was used to establish the whole bridge model and the wind field model of "bridge truss-frame column".The numerical model was corrected by the measured data.The results of the field measurement and numerical simulation were compared.It proves that the numerical simulation of credibility and efficiency.(3)The dynamic characteristics of the long-span coal transport trestle under strong earthquake.The high stress concentration zone is formed in the coal transport trestle and the frame post and the beam column of the frame column.And there's a big dynamic response.It indicates that the joints and nodes are the weak points of the structural system.Frame columns are the main seismic line,as a component to resist lateral force,the elastoplastic displacement of horizontal vibration is opposite bigger,the seismic energy dissipation of a large number of trestle bridge truss,lead to the trestle near the frame columns truss vibration frequency are decreased obviously,showing good displacement ductility and energy dissipation capacity.The coal transport trestle truss has high seismic bearing capacity,in 7 degrees rarely met earthquake under the action of deformation is still has a large surplus,and inhibits the lateral horizontal displacement of frame column,has obvious reset function at the same time,to be able to play the role of "the second seismic line".(4)The dynamic characteristics of the long-span coal transport trestle in turbulent wind field.The coal transport trestle joints and nodes are formed due to the narrow channel effects of wind pressure concentrated area.There is a greater dynamic response.It indicates that the joints and nodes are the weak points of the structural system.There is obvious compression,pressure and velocity concentration in the FSI of the coal transport trestle.The VIV(vortex-induced vibration)is easy to be cause due to structural instability caused by aerodynamic flutter substantial coal transport trestle.And the coal transport trestle vibration is at about 1.0Hz-2.0Hz.Similar to the frequency of the wind field,it is easy to cause VIV.It is suggested that the FSI of wind field should not be ignored.(5)The dynamic characteristics of the long-span coal transport trestle under the combined effect of wind and earthquake.The connection between the coal transport trestle and the frame column and the beam column joints of the frame column formed a high stress concentration area due to the seismic action,which produced a large response.The coal transport trestle truss joints due to turbulent wind field narrow channel effect formation pressure zone,producing substantial flutter.The above areas are weak in the structural system and should be inspected regularly,especially the connection areas,ensuring the safe use of the coal transport trestle.(6)"The theory of three-dimensional effect of wind field affecting regional space" of the long-span coal transport trestle.The study of the characteristics of dimensionless displacement spectrum in different locations of coal transport trestle in turbulent wind field is obtained: Themiddle of the coal transport trestle is the turbulent colliding area,the bridge at both ends of the coal transport trestle is the gas separation area,the upper part of the frame column is the vortex shedding area,the lower part of the frame is the vortex area.(7)It is more conservative to ignore the seismic design of the long-span coal transport trestle with the effect of wind field FSI.The dynamic response value under the combined effect of wind and earthquake effect of FSI is 11.18% lower than that under earthquake action,It shows that the aerodynamic damping value of the wind and the structure is positive under the condition of pneumatic elastic stability.The function of FSI is to inhibit the structure of the coal rack and cause the structural energy dissipation.(8)The seismic and wind vibration safety evaluation of the long-span coal transport trestle.Based on the deep research on the seismic performance and dynamic characteristics of the same long-span coal transport trestle structure under earthquake,wind resistance and the combined effect of wind and earthquake,structural deformation is far less than the provisions of the relevant norms.It shows that Liaoning Fuxin Mining(Group)Co.,Ltd.group Hengda company open coal preparation plant coal transport trestle structure has good seismic and wind resistance,without reinforcement.