CN-121980662-A - Calculation method of mid-span sag change value after main cable of cable hoisting system is transversely moved and transverse movement adjustment method

CN121980662ACN 121980662 ACN121980662 ACN 121980662ACN-121980662-A

Abstract

The invention provides a calculation method of a mid-span sag change value after a main rope of a cable hoisting system is transversely moved and a transverse movement adjustment method, and belongs to the technical field of bridge construction. According to the calculation method of the mid-span sag change value after the main rope of the cable hoisting system is transversely moved, the relation among the rope length of the main rope section, the sag and hanging point coordinates of the main rope section, the unit dead weight of the main rope, the horizontal pulling force and the transverse movement amount of the main rope is established according to the stress rule of the catenary, the mid-span sag change value after the main rope is transversely moved is calculated, and further the mid-span sag of the main rope at the initial position is determined, the repeated adjustment of the main rope line shape is avoided, and therefore the construction efficiency can be accelerated.

Inventors

YANG MINGQIN
ZHOU XIANG
ZHOU TAO
HUANG XIAOLONG
WANG CHUJIE
Zhong Zhiliu
ZHOU GUANGMING
LIANG JING
ZHU JICAI
LUO LIHE
LI SHIYING
WANG YUAN

Assignees

广西路桥工程集团有限公司

Dates

Publication Date: 20260505
Application Date: 20260319

Claims (8)

1. A calculation method of a mid-span sag change value after a main rope of a cable hoisting system is transversely moved is characterized in that the main rope is supported on pulley blocks of main rope saddles of two-bank towers, two ends of the main rope are respectively connected with two-bank ground anchors to form three main rope sections, the main rope sections between the ground anchors and the towers are tail spans, the main rope sections between the two-bank towers are mid-spans, and the main rope is transversely moved between an initial state position and a final state position, and the calculation method of the mid-span sag change value after the main rope of the cable hoisting system is transversely moved comprises the following steps: s1, establishing a relation among the cable length of a main cable segment, the sag and suspension point coordinates of the main cable segment, the unit dead weight of the main cable, the horizontal pulling force and the transverse moving amount of the main cable according to the stress rule of a catenary; s2, substituting the coordinates of two suspension points of the mid-span of the final position and a preset mid-span sag value of the final position into the relational expression, and calculating to obtain mid-span horizontal tension of the final position; s3, substituting the calculated mid-span horizontal tension of the final state position and coordinates of suspension points of the mid-span and the tail span of the final state position into the relational expression to calculate and obtain cable lengths of the mid-span and the tail span of the final state position, wherein the total deformation quantity of a main cable of the final state position subtracted by the sum of the cable lengths of the mid-span and the tail span of the final state position is the stress-free cable length of the final state position; S4, substituting coordinates of suspension points of the middle span and the tail span of the initial position into the relation to obtain a calculation formula of cable lengths of the middle span and the tail span of the initial position, wherein the sum of the cable lengths of the middle span and the tail span of the initial position minus the total deformation quantity of the main cable of the initial position is the stress-free cable length of the initial position; s5, enabling the length of the unstressed cable of the initial state position to be equal to the length of the unstressed cable of the final state position calculated in the step S3, calculating to obtain the midspan horizontal force of the initial state position, substituting the coordinates of the two suspension points of the midspan of the initial state position and the midspan horizontal force of the initial state position obtained by calculation into the relation, and calculating to obtain the midspan sagging of the initial state position; s6, the difference value between the preset midspan sag value of the final state position and the midspan sag of the calculated initial state position is the midspan sag change value after the main rope is transversely moved.
2. The method for calculating a change in the mid-span sag after traversing a main rope of a cable hoisting system according to claim 1, wherein in the step S1, two suspension points of the main rope segment are set to have coordinates (x 1 ,y 1 ）、（x 2 ,y 2 ), the unit dead weight of the main rope is q, the elastic modulus is E, the cross-sectional area is W, L is the span of the main rope segment, c is the height difference between the two suspension points, x is the horizontal coordinate of any point on the main rope segment, For the ordinate of the arbitrary point, θ is the horizontal included angle of the main cable segment at the arbitrary point, and since the main cable follows the stress rule of the catenary, the catenary linear expression of the main cable segment is: (1); parameters in the formula: In the case of the initial state position, ; ; ; ; In the final state of the position, the position of the device, ; ; ; A is the transverse movement amount of the main rope, and H is the horizontal force of the main rope section; The cable length S of the main cable segment is as follows: (2); deriving (1) to obtain the horizontal included angle of any point of the main rope The expression: (3) sag of the main rope segment at this arbitrary point Then expressed by formula (4): (4); Solving the expression of the horizontal coordinate x max of the point at the maximum sag of the main rope segment by solving the equation (4) for the derivative equal to 0: (5); the cable force T at any point is expressed by the formula (6): (6); Sag of the midspan is calculated using point x max of the midspan at maximum sag.
3. The method for calculating the sag change value of the midspan after the main rope of the cable hoisting system moves transversely according to claim 2, wherein in the step S1, the connection points of the main rope and the two-shore ground anchors are set to be a point a and a point D respectively, when the main rope is located at the initial position, the suspension points at the two ends of the midspan are set to be a point B ' and a point C ' respectively when the main rope is located at the final position, the coordinate system is established by taking a point a, a point B and a point D as an origin respectively, namely, the coordinate system is established by taking a point a and a point D respectively as an origin respectively, the coordinate system is established by taking a point B as an origin respectively for the two-tail spans, wherein the X axis is the longitudinal bridge direction, the Y axis is the plumb direction, the coordinates of the point a, the point B, the point C, the point B ' and the point D are known, and the point C ' after the point B moves along the transverse bridge by a distance a, the point C ' reaches the final position after the point a moves along the transverse bridge.
4. The method for calculating the change value of the sag of the mid-span after the main rope of the cable hoisting system moves transversely according to claim 3, wherein the step S2 comprises the following steps of substituting the coordinates of two suspension points of the mid-span of the final position and the preset sag value of the final position into the simultaneous formulas (1) - (5) and calculating to obtain the mid-span horizontal tension of the final position.
5. The method for calculating a mid-span sag variation value after main rope traversing in a cable hoisting system according to claim 4, wherein the step S3 comprises the steps of: Substituting the coordinates of the point B 'and the point C' into a formula (6) and substituting the mid-span horizontal pulling force of the final position calculated in the step S3 to calculate the cable force T CB' at the mid-span point B 'and the cable force T BC' at the mid-span point C'; The main cable saddle pulley at the top of the tower is considered to be absolutely smooth, so that the main cable force between the middle span and the tail span can be completely conducted, and the cable force T AB' = T CB' of the tail span AB 'at the point B' at the tail position and the cable force T DC' = T BC' of the tail span DC 'at the point C' at the tail position are realized; Substituting the cable force T AB' 、T DC' of the tail span at the tail position and coordinate values of two corresponding hanging points of the tail span into a formula (6) to obtain the horizontal pulling force of the tail span at the tail position; and substituting the suspension point coordinates and horizontal tension of the midspan and the tail spans of the final position into the formula (2) to obtain the cable lengths of the midspan and the tail spans of the final position, wherein the total deformation quantity of the main cable of the final position is subtracted from the sum of the cable lengths of the midspan and the two tail spans of the final position to obtain the stress-free cable length of the main cable of the final position.
6. A method of calculating a mid-span sag variation after main rope traversing in a cable lifting system as recited in claim 3, wherein step S4 comprises the steps of: substituting the coordinates of the point C and the point B into the formulas (1) - (6) to obtain the cable length of the midspan of the initial position Sag of midspan The cable force T CB at the midspan point B and the cable force T BC at the midspan point C are related to the horizontal tension of the midspan; The main cable saddle pulley at the top of the tower is considered as absolute smooth, so that the main cable force between the middle span and the tail span can be completely conducted, and the cable force T AB = T CB of the tail span AB at the point B at the initial state position and the cable force T DC = T BC of the tail span DC at the point C at the initial state position are realized; Substituting the cable force T AB 、T DC of the tail span at the initial position and coordinate values of two corresponding hanging points of the tail span into a formula (6) to obtain the relationship between the horizontal tension of the tail span at the initial position and the horizontal tension of the middle span; Obtaining a relation between the length of the midspan at the initial position and the horizontal tension of the midspan according to the formula (2), substituting the relation between the horizontal tension of the tail span at the initial position and the horizontal tension of the midspan into the formula (2), and obtaining the relation between the length of the tail span at the initial position and the horizontal tension of the midspan, wherein the total deformation of the main rope at the initial position subtracted from the sum of the lengths of the midspan at the initial position and the two tail spans is the unstressed rope length at the initial position.
7. The method for calculating a change in sag of a midspan after traversing a main rope of a cable lifting system as recited in claim 1, wherein the deformation amounts of the midspan and the tail span The following formula is used for calculation: (7); Wherein E is the elastic modulus of the main rope, W is the sectional area of the main rope, L is the span of the main rope segment, and the midspan and the tail span of the initial state position and the final state position are respectively corresponding to L, Substituting c into a formula (7) to obtain deformation amounts of the midspan and the tail span of the initial state position and the final state position, and adding the deformation amounts of the midspan and the tail span of the corresponding positions to obtain the total deformation amount of the main rope.
8. The main cable transverse movement adjusting method of the cable hoisting system is characterized by comprising the following steps of: Firstly, calculating and obtaining a mid-span sag change value after the main rope is transversely moved according to the calculation method of the mid-span sag change value after the main rope is transversely moved of the cable hoisting system of claim 1; Secondly, calculating according to a preset midspan sag value of the main rope at the final state position and a midspan sag change value of the main rope after the main rope is transversely moved to obtain a midspan sag value of the main rope at the initial state position; then, installing a main rope at the initial position, and enabling the midspan sag value of the installed main rope to be consistent with the midspan sag value of the main rope at the initial position obtained through calculation; And finally, directly traversing the main rope to the final state position, so that the midspan sag of the main rope at the final state position is ensured to be consistent with the preset midspan sag value of the final state position.

Description

Calculation method of mid-span sag change value after main cable of cable hoisting system is transversely moved and transverse movement adjustment method Technical Field The invention relates to the technical field of bridge construction, in particular to a calculation method of a mid-span sag change value after a main rope of a cable hoisting system is transversely moved and a transverse movement adjustment method. Background The bracket-free construction of the steel tube concrete arch bridge generally adopts a cable hoisting and diagonal buckling method, wherein a main cable is a main stress structure (figure 1) of a cable hoisting system, and the main cable consists of a sealing steel wire rope, so that the stress rule of a catenary is followed. The stress analysis of the catenary is widely applied to the calculation of the main cable of a suspension bridge. In the prior art, the main cable of the suspension bridge has small change along the transverse bridge direction, so the calculation theory is simplified into a two-dimensional model for calculation, but the movement range of the main cable of the cable hoisting system along the transverse bridge direction reaches more than 50 meters, and obviously the influence of transverse movement cannot be ignored. According to catenary characteristics, the initial installation sag of the main rope is a key control factor, and the stress of the main rope in the working condition of the hoisting section is directly determined. When the main cable is traversed, the overall alignment obviously has changed. In the prior art, a main rope of a cable hoisting system is slidably supported on a pulley block of a main rope saddle of a tower frame on two sides, two ends of the main rope are respectively connected with the ground anchors on two sides, a section of the main rope between the ground anchors and the tower frame is a tail span, a section of the main rope between the tower frames on two sides is a middle span, as shown in fig. 1, the installation of the main rope is completed at an initial state position during construction, and then the main rope is moved to a final state position by a traversing system to hoist arch rib sections, so that the front and rear sagging of the main rope before and after traversing mainly changes, and the sagging of the middle span of the main rope changes along with the change of rope force. Because the traditional calculation theory only gives a sag preset value of the midspan of which the main rope is at the final state position and lacks the specific sag of the midspan when the main rope is at the initial state position, in the prior art, the sag of the midspan when the initial state position is estimated generally through construction experience, the main rope is adjusted after the main rope is mounted and reaches the final state position through transverse movement, and the sag of the mounted main rope midspan is ensured to be consistent with the preset sag value. However, since the main cable line shape change is closely related to key parameters such as span, traversing distance, horizontal force and the like, different cable crane arrangements can be referred to with limited value. And as the change value of the midspan sag after the main rope is transversely moved can not be determined, the main rope shape needs to be repeatedly adjusted, and the construction efficiency is reduced. Disclosure of Invention The invention aims to at least solve one of the problems in the background art, and provides a calculation method for a mid-span sag change value of a cable hoisting system after a main cable is transversely moved. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: A calculation method of a mid-span sag change value after a main rope of a cable hoisting system is transversely moved, wherein the main rope is supported on pulley blocks of main rope saddles of two-bank towers, two ends of the main rope are respectively connected with two-bank ground anchors to form three main rope sections, the main rope sections between the ground anchors and the towers are tail spans, the main rope sections between the two-bank towers are mid-spans, and the main rope is transversely moved between an initial state position and a final state position, and the calculation method of the mid-span sag change value after the main rope of the cable hoisting system is transversely moved comprises the following steps: s1, establishing a relation among the cable length of a main cable segment, the sag and suspension point coordinates of the main cable segment, the unit dead weight of the main cable, the horizontal pulling force and the transverse moving amount of the main cable according to the stress rule of a catenary; s2, substituting the coordinates of two suspension points of the mid-span of the final position and a preset mid-span sag value of the final position into the relational expression, and