CN111335168B - Closing method of kilometer-scale hybrid beam cable-stayed bridge - Google Patents

Abstract

The invention discloses a method for closing a kilometer-level hybrid beam cable-stayed bridge. In the benchmark model, the two sides of the closure are linear; after the actual length of the closure is equal to the reference length of the closure, the closure is locked and the jack is removed; after the closure beam is hoisted, the stress-free length of the first set cable is adjusted to the reference value, and the closure is The length of the segment beam is the reference length of the Helongkou; after the bridge is completed, the relative error of the main span steel structure alignment, the relative error of the bridge axis, the relative error of the tower deflection and the cable force error are calculated; it is judged whether the error meets the corresponding set error. Otherwise, adjust until all errors meet the corresponding set errors; set the relative error of the main span steel structure line shape to L/4000, the relative error of the bridge axis to be L/40000, the relative error of tower deflection to be L/10000, and L for the main span length.

Description

Closing method of kilometer-scale hybrid beam cable-stayed bridge

technical field

The invention relates to the field of civil engineering, in particular to a method for closing a kilometer-level hybrid beam cable-stayed bridge.

Background technique

The unique shape and stress characteristics of hybrid girder cable-stayed bridges have been favored by more and more countries in the construction of long-span bridges. Since the 1990s, the bridge type has developed rapidly in my country, from large spans to kilometer spans. With the increase of the span, the construction of the bridge has brought unprecedented challenges.

As one of the important processes in the construction of a hybrid girder cable-stayed bridge, the Helong (Mid-span steel box girder Helong) is a key link in the system conversion, and its quality will be directly related to whether the internal force and alignment of the completed bridge are reasonable.

The traditional method of closing the dragon is mostly based on the double control method mainly based on cable force and elevation. The temperature is matched with the closing dragon. By monitoring the width and shape of the closing opening before closing, the closing temperature is determined and the installation length of the closing opening at this temperature is calculated. With cut dragon. However, due to the great influence of temperature, the trimming of the closing section will change the stress-free state of the components, especially for a cable-stayed bridge with a span of kilometer, the change of the stress-free state of the components will have a greater impact on the internal force and alignment of the completed bridge. , thereby affecting the quality of the bridge.

SUMMARY OF THE INVENTION

In view of the above-mentioned deficiencies in the prior art, the present invention aims to provide a method for closing a kilometer-scale hybrid beam cable-stayed bridge to ensure the quality of the completed bridge.

In order to achieve the purpose of above-mentioned invention and creation, the technical scheme adopted in the present invention is:

A method for closing a kilometer-level hybrid beam cable-stayed bridge is provided, which includes:

S1. Determine the pushing direction of the main beams on both sides of the kilometer-level hybrid girder cable-stayed bridge according to the displacement on one side.

S2. Adjust the stress-free length of the first set cable on the kilometer-level hybrid girder cable-stayed bridge, so that the alignment on both sides of the Helongkou conforms to the alignment on both sides of the Helongkou in the benchmark model;

S3. Perform jacking so that the actual length of the closing port is equal to the reference length of the closing port, then lock the closing port and remove the jacking;

S4. After hoisting the closing section beam, adjust the stress-free length of the first set cable to the reference value, and the length of the closing section beam is the base length of the closing section;

S5. Based on the measurement data of cable force, main girder stress, main girder alignment, cable unstressed length, and pylon alignment of the kilometer-scale hybrid girder cable-stayed bridge after closing, and combined with subsequent construction to predict the relative alignment of the main span steel structure after the bridge is completed Error, relative error of bridge axis, relative error of tower deflection and cable force error;

S6, determine whether the relative error of the main span steel structure alignment, the relative error of the bridge axis, the relative error of the tower deflection and the cable force error meet the corresponding set errors, if so, the closing is completed, otherwise, go to step S7; set the relative alignment of the main span steel structure. The error is L/4000, the relative error of the set bridge axis is L/40000, the relative error of tower deflection is L/10000, and L is the length of the main span;

S7. Adjust the stress-free length of the second set cable on the kilometer-level hybrid beam cable-stayed bridge until all errors meet the corresponding set errors.

Further, in order to ensure reasonable bridge alignment and structural internal force, the cable force error is set to 5%.

Further, the method for determining the push direction is:

If the displacement on one side is negative, push the main beams on both sides to the shore side respectively;

If the displacement on one side is a positive value, push the main beams on both sides to the river side respectively.

Further, in order to avoid excessive jacking and try to ensure that the jacking force can move the main beam, the methods of performing jacking include:

A push device is installed between the first block on the main beam installation platform and the bottom protrusion of the main beam, and a limit device is installed between the second block on the main beam installation platform and the bottom protrusion of the main beam, The second block is opposite to the first block and both are located on the axis of the main beam mounting platform;

Use the jacking device and the limiting device to push the main beam. The maximum jacking force during the jacking process is equal to the preset jacking force. Horizontal component + preset increment.

The stress-free length of the first setting cable is adjusted by adjusting the elongation of the anchor head of the first setting cable, so as to realize the rapid adjustment of the stress-free length of the first setting cable.

The beneficial effects of the present invention are:

(1) Reduce the dependence on temperature, as long as the stress-free alignment of the main girder conforms to the alignment on both sides of the closure in the benchmark model, the closure construction can be carried out at any time.

(2) By adjusting the stress-free length of the first set cable on the kilometer-level hybrid beam cable-stayed bridge, the alignment of the two sides of the closing dragon mouth conforms to the line shape of the two sides of the closing dragon mouth in the benchmark model, and the length of the first set cable is adjusted. The stress-free length is adjusted to the benchmark, which simplifies the traditional tedious process of adjusting the alignment on both sides of the gantry based on cable force and elevation.

(3) On the one hand, it can avoid local changes in the alignment of the closure, resulting in additional stress, which affects the alignment and internal force of the bridge;

Description of drawings

Figure 1 is a schematic diagram of the structure of the kilometer-level cable-stayed bridge in front of Helong when the temperature is lower than the reference temperature;

Figure 2 is a schematic structural diagram of the kilometer-scale cable-stayed bridge shown in Figure 1 after performing jacking;

FIG. 3 is a schematic structural diagram of the arrangement of the jacking device during the jacking process of the main girder on the left side of the kilometer-scale cable-stayed bridge shown in FIG. 1 .

Among them, 1. the main beam installation platform; 2. the second stopper; 3. the limiting device; 4. the pushing device; 5. the first stopper; 6. the bottom of the main beam is convex.

Detailed ways

The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so as to facilitate the understanding of the present invention by those skilled in the art. However, it should be clear that the embodiments described below are only a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments obtained by those skilled in the art without any creative work without departing from the spirit and scope of the present invention defined and determined by the appended claims fall within the protection scope of the present invention.

A method for closing a kilometer-level hybrid beam cable-stayed bridge is provided, which includes:

S1. Determine the pushing direction of the main beams on both sides of the kilometer-level hybrid girder cable-stayed bridge according to the unilateral displacement, the unilateral displacement=(the actual length of the Helongkou - the reference length of the Helongkou)/2.

Specifically, the method for determining the pushing direction is as follows: if the displacement on one side is negative, push the main beams on both sides to the bank side respectively; if the displacement on one side is positive, push the main beams on both sides to the river side respectively. The pushing direction determines the position of the pushing device 4 when the pushing is performed.

As shown in Figure 1 and Figure 2, where D' is the actual length of the closed dragon mouth, and D is the reference length of the closed dragon mouth.

S2. Adjust the stress-free length of the first set cable on the kilometer-level hybrid girder cable-stayed bridge, so that the line shape on both sides of the Helongkou conforms to the line shape on both sides of the Helongkou in the benchmark model. Specifically, the stress-free length of the first set cable can be adjusted by adjusting the elongation of the anchor head of the first set cable, and the cables on each of the 5 beam sections on both sides of the closing opening are usually adjusted.

Traditionally, the alignment of the two sides of the Helongkou in the benchmark model is mainly based on the consideration of the temporary construction load and the calculation of its influence on the cable force and elevation. However, the cable force and elevation have a great relationship with the temporary load during the construction period. At the end, the temporary load has to be removed again. Once the temporary load is removed, the cable force and elevation will change and adjust again, which is obviously cumbersome and troublesome. Simplify the tedious process of continuous adjustment due to temporary load changes, and effectively avoid the impact of temporary construction load changes on the cable force.

S3. Perform jacking so that the actual length of the closing port is equal to the reference length of the closing port, then lock the closing port and remove the jacking.

Specifically, the method for performing push-up includes:

The pushing device 4 is installed between the first block 5 on the main beam installation platform 1 and the bottom protrusion 6 of the main beam, and the second block 2 on the main beam installation platform 1 and the bottom protrusion 6 of the main beam A limiting device 3 is installed therebetween, the second block 2 is opposite to the first block 5 and both are located on the axis of the main beam installation platform 1 .

The main beam is generally installed on the tower beam. When it is necessary to push the main beams on both sides to the river side respectively, as shown in Figure 3, the jacking device 4 is installed on the tower beam near the first stop 5 on the shore side and the main beam. between the bottom protrusions 6, so that the top support direction is toward the river side.

Use the jacking device 4 and the limiting device 3 to push the main beam, the maximum jacking force during the jacking process is equal to the preset jacking force, the preset jacking force = total friction resistance of side span support - side and middle span unbalanced force Cable force horizontal component + preset increment, so as to avoid excessive jacking and reduce construction difficulty. The total frictional resistance of the corresponding side-span supports and the horizontal component of the unbalanced force of the side-middle-span cable force may be different in the calculation of the top thrust of different main beams for the same kilometer-scale hybrid beam cable-stayed bridge.

In one embodiment, the pushing device 4 is a pushing jack, and the limiting device 3 is a pushing jack. According to the theoretical bearing friction coefficient provided by the bearing factory, the friction resistance of the north and south shore bearings is shown in Table 1.

Table 1 Bearing friction resistance table

During the initial push, for the main beam on the north bank: the total frictional resistance of the side-span support - the horizontal component of the unbalanced force cable force in the side-middle span = 6262-4874 = 1388kN, for the main beam on the south bank: the total frictional resistance of the side-span support - the side-middle Horizontal component of cable force across unbalanced force = 6346-4765 = 1581kN. Considering the possible difference between the theoretical bearing friction coefficient and the actual bearing friction coefficient, in order to avoid excessive jacking and at the same time ensure that the jacking force can move the main beam, a preset increment is set so that the main beam on the north bank and the main beam on the south bank can be moved. The preset jacking force of the beam is 1800kN.

However, during the jacking process, the angle of the cable changes, and the horizontal component of the unbalanced cable force on the side and mid-span decreases, so the required jacking force will gradually increase. Under the condition that the single-side jacking amount is 3.6cm, the theoretical calculation shows that the unbalanced cable force of the side and mid-span on the south bank and the north bank is 3072kN. For the main beam on the north bank: the total friction resistance of the side-span bearing - the cable force level of the side-span unbalanced force Component = 6262-3072 = 3190kN, for the main beam on the south bank: the total friction resistance of the side span support - the horizontal component of the unbalanced force on the side and the middle span = 6346-3072 = 3274kN. Considering the appropriate margin, the preset increment is set so that the preset jacking force for the main girder on the north bank and the girder on the south bank is 3500kN.

In view of the discreteness of the friction coefficient, the calculation of the jacking force is difficult to be accurate. In order to prevent insufficient jacking force, auxiliary jacking points are set at two points symmetrical to the axis of the tower beam. When the thrust is insufficient, the auxiliary jacking point is used. The maximum jacking force of the jacking device 4 is not less than 3500kN.

S4. After hoisting the closing section beam, adjust the stress-free length of the first set cable to the reference value, and the length of the closing section beam is the base length of the closing section.

S5. Based on the measurement data of cable force, main girder stress, main girder alignment, cable unstressed length, and pylon alignment of the kilometer-scale hybrid girder cable-stayed bridge after closing, and combined with subsequent construction to predict the relative alignment of the main span steel structure after the bridge is completed Error, relative error of bridge axis, relative error of tower deflection and cable force error. The specific calculation of this step S5 is the prior art.

S6, determine whether the relative error of the main span steel structure alignment, the relative error of the bridge axis, the relative error of the tower deflection and the cable force error meet the corresponding set errors, if so, the closing is completed, otherwise, go to step S7; set the relative alignment of the main span steel structure. The error is L/4000, the relative error of the set bridge axis is L/40000, the relative error of tower deflection is L/10000, and L is the length of the main span.

In order to ensure the reasonable alignment of the bridge and the internal force of the structure, the cable force error is set to 5%, and the cable force error refers to the error between the actual and theoretical values of each cable.

S7. Adjust the stress-free length of the second set cable on the kilometer-level hybrid beam cable-stayed bridge until all errors meet the corresponding set errors. The second cable here does not mean that it is different from the first cable. It is the prior art to adjust the relative error of the main span steel structure line shape, the relative error of the bridge axis, the relative error of the tower deflection and the cable force error to meet the specific preset errors.

The denominators 4000, 40000 and 10000 in the error of this scheme are obtained by the following method:

1) First, use the influence matrix method and the minimum bending energy method to determine the target cable force and target line shape of the bridge;

2) Secondly, carry out the sensitivity analysis of bridge parameters to find out the influence degree of cable force, tower deflection, bridge axis, main girder deformation, and the difference from the target state quantity in step 1), and determine the primary and secondary factors that affect the target state quantity. factors, to provide basis and support for manufacturing, installation, concrete pouring and bridge error analysis, parameter identification and adjustment, and determination of error limits;

3) Furthermore, based on the closing method provided by the present invention, carry out the data collection of manufacturing and processing, installing the stress-free length of the segment stay cable, the structure stress-free linear shape, the cable force and the internal force of the structure, and bring the test data into the nonlinear software NLABS analysis. The nonlinear calculation of the stay cable adopts the catenary theory, and the linear analysis of the main beam adopts the tangent displacement method.

4) As the construction progresses, continuously carry out the data collection of step "3)" and bring it into the NLABS model for calculation and analysis. According to the real-time calculation results, combined with the parameter sensitivity analysis of steps 1) and 2), the influence of the bridge target state error, Judgment and formulate the error limits of the main span steel structure alignment, bridge axis and line tower deviation.

Theoretical analysis and practice show that a kilometer-scale hybrid beam cable-stayed bridge (with a main span of 900-1100m) has similar bridge mechanics, and the closing method provided by the present invention can effectively avoid temporary load changes and temperature changes during construction. The tedious construction process, which leads to uncontrollable errors. For kilometer-level composite beam cable-stayed bridges, due to the large number of segments and the long period of time, if it is controlled like a traditional cable-stayed bridge with a main span of about 400-500m, it may be caused by these temporary loads and changes in construction procedures and environment. This will lead to the emergence of uncertain factors, increase the complexity of regulation, and the accumulation of errors will also increase, which will affect the quality of the bridge.

Claims (5)

1. The closure method of the kilometric hybrid beam cable-stayed bridge is characterized by comprising the following steps:

s1, determining the pushing directions of main beams at two sides of the kilometric mixed beam cable-stayed bridge according to the single-side pushing amount, wherein the single-side pushing amount is (the actual length of the closure opening-the reference length of the closure opening)/2;

s2, adjusting the unstressed lengths of the guys on the two sides of the closure opening on the kilometer-grade mixed beam cable-stayed bridge to enable the line shapes on the two sides of the closure opening to be in line with the line shapes on the two sides of the closure opening in the reference model;

s3, executing pushing to enable the actual length of the closing opening to be equal to the reference length of the closing opening, locking the closing opening and removing the pushing;

s4, after hoisting the closure section beam, adjusting the unstressed lengths of the pull cables on two sides of the closure opening to a reference value, wherein the length of the closure section beam is the reference length of the closure opening;

s5, predicting relative errors of main span steel structure linear shape, bridge axis relative errors, tower deflection relative errors and cable force errors after the bridge is formed by combining subsequent construction based on the measurement data of cable force, main beam stress, main beam linear shape, cable unstressed length and cable tower linear shape after the closure of the kilometer-level mixed beam cable-stayed bridge;

s6, judging whether the main span steel structure linear relative error, the bridge axis relative error, the tower offset relative error and the cable force error meet the corresponding set errors, if so, completing closure, otherwise, entering the step S7; setting the linear relative error of the main span steel structure to be L/4000, setting the axial relative error of the bridge to be L/40000, setting the tower deviation relative error to be L/10000, and setting L to be the main span length;

and S7, adjusting the unstressed length of the stay cable which is not in accordance with the error requirement on the kilometer-grade mixed beam cable-stayed bridge until all errors meet the corresponding set errors.

2. The closure method for kilometer-grade hybrid beam cable-stayed bridges according to claim 1, wherein the set cable force error is 5%.

3. The closure method of the kilometer-grade hybrid beam cable-stayed bridge as claimed in claim 1, wherein the method for determining the pushing direction is as follows:

if the single-side displacement is a negative value, pushing the main beams at the two sides towards the shore side respectively;

if the displacement of the single side is a positive value, the main beams on the two sides are respectively pushed towards the river side.

4. The closure method for kilometer-scale hybrid beam cable-stayed bridges according to any one of claims 1 to 3, wherein the method for performing pushing comprises:

a pushing device (4) is arranged between a first stop block (5) on the main beam mounting platform (1) and a bottom bulge (6) of the main beam, a limiting device (3) is arranged between a second stop block (2) on the main beam mounting platform (1) and the bottom bulge (6) of the main beam, and the second stop block (2) is opposite to the first stop block (5) and is positioned on the axis of the main beam mounting platform (1);

utilize thrustor (4) and stop device (3) to push away the girder, the biggest top thrust that pushes away the in-process equals to predetermine top thrust, predetermines top thrust and is equal to the total frictional resistance of side span support-mid-span unbalanced force cable force horizontal component + predetermines the increment.

5. The closure method of a kilometer-grade hybrid beam cable-stayed bridge, as recited in claim 4, characterized in that the unstressed lengths of the cables at the two sides of the closure opening are adjusted by adjusting the elongation of the cable anchor heads at the two sides of the closure opening.

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