Analysis For The Ultimate Bearing Capacity On Typical Base Plate Of UHV Transmission Tower

In order to meet the needs of residential and industrial electricity,UHV transmission lines are becoming more and more widely used.Although the wide application of UHV transmission lines can enhance the transmission capacity of the line and reduce the loss caused by the power transmission process,since this type of transmission tower has a tall tower body,the load it bears is large,so When designing it,you need to pay attention to its structure.For the transmission tower,the base of the tower is the bottommost component,and the load on the base of the tower is the largest.Therefore,it is necessary to make the tower base plate have certain reliability and safety.Compared with the traditional transmission tower,the UHV transmission tower has a larger load and a higher tower height.Therefore,if the conventional four-foot bolt mode is adopted,the load demand of the UHV transmission tower cannot be met,so in practical application.In the middle,the tower base plate of the UHV transmission tower uses eight anchor bolts.No matter whether it is domestic or foreign,there are few researchers studying the bearing capacity of the base plate of the eight-pin bolt tower.In practical engineering applications,few research results can provide design basis and theoretical guidance for engineering implementation.Therefore,this paper chooses to study the bearing capacity of the base plate of the eight-foot bolt tower.The main research contents are as follows:(1)Eight floor tower anchor bolt full scale tests have been carried out.Through the experimental study on the eight floor tower anchor bolt under the limit state of failure mechanism and failure phenomenon.Experimental results show that: 1)the rigid floor tower stiffener height had a greater influence on the tensile stiffness of the rigid plate,stiffener shoulds not be too short,otherwise easy to appear the bearing capacity of displacement control of circumstance,make material strength can not be full play;Floor with boots in the plate junction strain is bigger,is easy to yield failure takes place;Stiffening rib with boots in the plate junction strain is larger,prone to yield failure;With the increase of the thickness of the base plate,the bearing capacity of rigid plate has a increasing trend,plate bearing capacity and decreases as the area's width,as the thickness increases;When the bearing capacity is controlled by the strength,the thickness of the plate tower's contribution to the bearing capacity is particularly important;When the bearing capacity is controlled by deformation,stiffness of the stiffener have bigger influence on the bearing capacity;Rigid tower board screw hole radius will sharply reduce the bearing capacity,under the condition of the same radius,the screw hole as far as possible to the stiffener.2)flexible plate in order to ensure the flexible plate tower has enough tensile bearing capacity,screw hole radius should not be too big,under the condition of satisfy the use requirement,shortening the distance between screw hole with the plate center as far as possible,and keep the screw holes to boot plate;Floor with boots in the plate junction strain is larger,prone to yield failure,stiffener layout and effective to prevent the development of the plastic area,can significantly improve the tension bearing capacity of flexible plate tower;With the increase of the thickness of the base plate,the bottom bearing capacity had a tendency to increase,plate bearing capacity and decreases as the bottom width,as the thickness increases;When the bearing capacity is controlled by the strength,the thickness of the plate tower's contribution to the bearing capacity is particularly important;When the bearing capacity is controlled by deformation,boots plate stiffness influence on bearing capacity is bigger.(2)Based on the traditional plastic hinge method,the slip line field theory is introduced to replace the virtual work principle to solve the plastic limit problem of the bottom plate.through the slip line field theory,the relationship between the shear force and bending moment at the boundary of each plate is established.finally,the ultimate plastic ultimate bearing capacity of the floor is solved by the equilibrium equation.The theoretical derivation of the two kinds of constraint conditions is carried out,and the theoretical analysis model of the bearing capacity of the eight foundation bolt tower is established.The model considering the strength of rigid and flexible tower tower plate plate for control or displacement control and reach the ultimate load,and can be divided into the bolt strength control according to the breakdown point tensile yield failure,bottom tensile yield failure and bottom three screw hole extrusion deformation and destruction.Also examines the stiffener height,stiffener thickness and the thickness of the base plate,the bearing capacity of plate tower.(3)On the basis of experimental results and theoretical analysis,finite element model is established,and further investigates the failure mode of the eight floor tower anchor bolt,and the rigid floor tower and flexible floor tower are analyzed in finite element parameters.Parameters of the finite element analysis results show that: 1)the rigid plate tower stiffener height,bearing capacity of each case change tendency;Increased as the stiffener and improve the bearing capacity,but when > 200 mm,the bearing capacity growth is very small;Bearing capacity and decreases as the overall;The bearing capacity of the rigid plate overall increase with the increase of the thickness of the stiffener;Plate thickness influence on bearing capacity is larger,with the increase of the thickness of the base plate and additional its bearing capacity;2)flexible floor tower when the other parameters constant,along with the increase of thickness of plate,the bearing capacity of flexible plate is small when thickness linear growth trend;Large flexible plate needs to be thicker bottom bearing capacity can be ensured at the same time,the smaller the requirement of flexible threatening the slab thickness is relatively lower;Structure to allow conditions,as far as possible will bolt hole near the boots board layout can improve the bearing capacity of flexible plate.(4)According to the results of theoretical analysis,experimental research and finite element analysis,put forward Suggestions on the rigid and flexible floor tower eight anchor bolt design method.The method simplifies the plate tower complex stress state,consider the stiffener and parameters such as thickness of the plate tower,screw hole spacing,the bearing capacity of the tension,and put forward the concept of the equivalent width coefficient,the bottom bearing side stiffness degradation phenomenon is considered in calculation method,the rigid floor tower and flexible floor tower calculation method.