Mechanical Properties And Its Application Of New Connected Nodes Between Main Members And Diagonal Members And Between Main Members And Foundation In Iron Tower

Due to the increasing span of transmission lines,the external load on the tower is getting bigger and bigger.The requirement of the transmission capability of the tower connection node is higher and higher.At present,the domestic and foreign research on the connection node theory is not perfect,and irrationality in design,In this paper,two new types of connection nodes are designed,the feasibility of the new connected node is verified by theoretical analysis,finite element simulation and experimental results.The iron tower with small slenderness ratio,The connection node are generally unstable control;The iron tower with large slenderness ratio,the connection node will be changed from instability control to strength and instability.However,there are some deficiencies in the strength and stability of Gusset single Plate Connections to Slotted Tubes.And the global stiffness of Gusset single Plate Connections to Slotted Tubes is small.So that it is easy to lateral buckling out of plane,also prone to premature failure of strength.Iron tower for strictly controlling fatigue,the fatigue failure of the welding zone of Gusset single Plate Connections to Slotted Tubes,limit application of Gusset single Plate Connections to Slotted Tubes in the narrow base tower and fan tower,To this end,this paper presents a new connection node: Gusset double Plate Connections to Slotted Tubes,That is to say,the stress on section of angle steel is close to uniform distribution by changing the distribution of bolts,Because the gusset plate is bear eccentric load to axial load.Through comparison,For gusset plate,the gusset plate is bear eccentric load under external load,The additional bending moment caused by eccentric load will increase the additional stress of the gusset plate.therefore,the bearing capacity of the gusset plate is reduced.At the same load,the maximum stress of Gusset single Plate Connections to Slotted Tubes is at least 4 times the maximum stress of Gusset double Plate Connections to Slotted Tubes,the uneven distribution of the stress along the thickness direction of the gusset plate is very unfavorable to the strength of the welding zone between the gusset plate and the steel pipe,it can easily lead to fatigue failure of welding zone;For angle steel,under the condition of eccentric tension and compression,the stress distribution on section of the angle steel is not uniform,the maximum stress on section is 2.5 times of the average stress.Firstly,As an important connection between upper structure and foundation of iron tower,the force transfer mechanism of the eight foundation bolts bottom plate is analyzed.The mechanical model of the eight foundation bolts node is proposed,The mechanical model is analyzed by finite element.The inner full scale test is carried out.The experimental data are agreement with the finite element results,It can also reflect the real deformation and stress of the eight foundation bolts node.The ultimate bearing capacity of the iron tower is at least 1.7 times the design load.Based on the finite element numerical simulation and experimental results,The expression of thickness of bottom plate is put forward.Compared to thickness of bottom plate by the current standard designed,The thickness of bottom plate designed by formula in this paper can be reduced about 33%.