Structural Design And Mechanical Analysis Of Self-elevating Tower Crossing Frame

In order to meet the need of construction safety protection of transmission lines,a new type of self-elevating tower crossing frame is designed.The steel frame is composed of self-supporting tower and crossbeam.The tower is set up by standard segments with self-elevating systems.Therefore,the working height and the working direction can be adjusted flexibly according to the actual situation.The tower is made up of 3m long standard segments and the maximum working height of the tower is 60 m.The crossing frame is erected on both sides of the crossed object,and the crossbeams on both sides are connected in the air to form an 80 m span sealing structure.This structure makes full use of the advantages of convenient construction of the standard section,and reduces the time and cost of the crossing construction.The technical parameters and load conditions of the self-elevating tower crossing frame are introduced.Based on the strength condition,the standard section of tower and the cross beam boom of box type and U section type are designed,and the finite element analysis model of span frame is established.According to different working conditions,the most unfavorable stress ratio of each position is calculated.Combined with the structural mechanical properties and structural requirements,the section is selected for the requirements of overall stability.According to the characteristics of the self-elevating tower crossing frame,the mechanical properties of the two types of crossing frame under different working conditions,such as stress ratio,displacement and buckling coefficient,are analyzed.The U-shaped boom structure uses small amount of steel and can make full use of the advantages of small displacement change of the regular triangle boom,which can effectively control the deformation of the cross-frame structure,and is more suitable for railway,highway and electric power lines.Referring to the common structure type of tower crane turntable,according to the design criterion of steel structure,which is economical,reasonable,safe and applicable,and ensuring the quality,a double rotary turntable mechanism is designed,that is,a pair of planetary pinions arranged symmetrically.The three-dimensional finite element model of rotating mechanism is established.The strength,stiffness and stability of the turntable are analyzed in order to ensure the stability of the rotary process.The structure of the span frame is reasonable,safe and reliable.It plays an important role of safety protection in the transmission line crossing project,and has high application and popularization value.