Dynamic compensation synchronous construction method for asymmetric cantilever unbalanced bending moment of cable-stayed bridge

Abstract

This invention relates to a synchronous construction method for dynamic compensation of unbalanced bending moments in the asymmetric cantilever of a cable-stayed bridge. The cantilever beam segments of the side spans are cast in place using hanging baskets, while the cantilever beam segments of the mid-span are hoisted using a bridge deck crane. A mobile counterweight is installed on the main beam of the mid-span, which can travel back and forth along the crane's track. The counterweight's traveling wheels are driven by a motor. During the construction of the cantilever beams in the side and mid-spans, the counterweight is moved to an appropriate position on the main beam to accurately compensate for the unbalanced bending moments in the side and mid-span cantilever beams, ensuring the smooth implementation and construction safety of the "cantilever casting in the side spans and synchronous cantilever assembly in the mid-span" construction scheme for the asymmetric cable-stayed bridge.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of bridge construction, and relates to a cable-stayed bridge construction, in particular to a dynamic compensation synchronous construction method for asymmetric cantilever unbalanced bending moment of a cable-stayed bridge. BACKGROUND

[0002] The main girder of a cable-stayed bridge is usually a steel girder, a concrete girder or a steel-concrete composite girder. For a cable-stayed bridge with asymmetric structure, the main span adopts a steel girder or a steel-concrete composite girder, and the side span adopts a concrete girder. At present, the construction method of "firstly constructing the side span beam support and then suspending and pouring the middle span beam segment" is generally adopted in the construction, but this method is difficult to implement when the side span is located in a steep mountain, a deep valley or a deep river channel, because it is difficult to set up the support.

[0003] In view of the above problems, the construction idea of "suspension pouring of the side span and synchronous suspension and pouring of the middle span" has been proposed in the industry, but the following problems are faced: due to the difference between the continuous loading of the cantilever pouring of the concrete girder of the side span and the instantaneous loading of the hoisting of the steel girder of the middle span, and the weight difference between the concrete girder segment and the steel girder segment, there is an unbalanced bending moment in the process of the synchronous construction of the cantilever of the middle span and the side span, and therefore, on the one hand, stronger temporary anchoring measures need to be configured at the root of the girder, and on the other hand, counterweights need to be arranged on the cantilever of the side with lighter weight to compensate for the unbalanced bending moment.

[0004] There are some technical solutions for compensating for the unbalanced bending moment of asymmetric cantilevers by counterweights in the prior art, such as the "large-span asymmetric section cable-stayed bridge counterweight control construction method" disclosed in patent CN101424072A, which is to first construct the side span by the support method to the closure, then construct each segment of the cantilever of the middle span, first determine the counterweight girder segment of the side span, then remove the support under the counterweight girder segment, and set counterweights on the counterweight girder segment of the side span. Obviously, this method is not suitable for the technical idea of the synchronous cantilever construction of the side span and the middle span. Patent CN219951698U provides a counterweight device for asymmetric main girders of a cable-stayed bridge, which includes an outer water tank and an inner water tank. The outer water tank is placed on the ground, and the inner water tank is placed in the outer water tank and hung below the counterweight girder segment. Water is injected into the inner water tank as a counterweight, and water is injected into the outer water tank to provide a certain buoyancy to the inner water tank. The weight of the counterweight is dynamically adjusted by adjusting the amount of water in the inner and outer water tanks. This type of counterweight can be used for the synchronous cantilever construction of the side span and the middle span in theory, but the installation position of the counterweight is fixed. As the length of the cantilever increases during construction, the weight of the counterweight also needs to be continuously increased, which can reach hundreds of tons, and will have an adverse effect on the structure of the girder segment on which the counterweight is hung.

[0005] Obviously, the existing technical solutions for compensating for the unbalanced bending moment of asymmetric cantilevers by counterweights cannot meet the construction idea of "suspension pouring of the side span and synchronous suspension and pouring of the middle span". SUMMARY

[0006] The purpose of the present application is to solve the above problems, provide a method for dynamic compensation of asymmetric cantilever unbalanced bending moment of cable-stayed bridge, meet the requirements of asymmetric cantilever synchronous construction of cable-stayed bridge, and ensure construction efficiency and safety.

[0007] The technical solution of the present application is as follows:

[0008] A method for dynamic compensation of asymmetric cantilever unbalanced bending moment of cable-stayed bridge, characterized in that it comprises the following steps:

[0009] (1) A tower area beam segment construction support is erected on the side span and the midspan side of the pier column below the cable tower, the 0# block and the side span 1# beam segment concrete pouring are completed on the support, the midspan steel-concrete composite beam segment is installed, and the tower beam temporary anchoring is tensioned;

[0010] (2) The midspan side support is removed, two bridge deck crane sliding rails are laid on the bridge deck in the bridge direction, the bridge deck crane is installed on the sliding rails, the midspan 1# segment steel beam is hoisted by the bridge deck crane, and the first pair of cable-stayed cables is installed and tensioned on the side span 1# beam segment and the midspan 1# segment;

[0011] (3) A counterweight is arranged on the midspan main beam, two groups of electric walking wheels are arranged on the two sides of the bottom of the counterweight, and the walking wheels on the two sides are supported on the two sliding rails respectively; the side span side support is removed, and the side span cantilever pouring hanging basket is installed on the side span 1# beam segment;

[0012] (4) The side span 2# beam segment is cantilever poured by the hanging basket, during the side span concrete pouring process, as the weight of the side span end increases, the counterweight is driven to move forward a certain distance towards the midspan direction, the midspan side bending moment is compensated, and the side span and the midspan bending moment reach balance;

[0013] (5) The bridge deck crane moves forward, hoists the midspan 2# segment, and simultaneously drives the counterweight to move backward a certain distance towards the side span direction; after the midspan 2# segment is hoisted, the second pair of cable-stayed cables is installed and tensioned;

[0014] (6) The above steps (4) and (5) are cycled until the bridge closure.

[0015] The present application provides compensation bending moment for the lighter end of the cantilever of the cable-stayed bridge by arranging a movable counterweight on the lighter cantilever of the cable-stayed bridge, dynamically adjusts the position of the counterweight in real time according to the bending moment compensation requirements, controls the unbalanced bending moment of the side and midspan main beams of the asymmetric cable-stayed bridge within a safe range during the cantilever construction of the main beam of the asymmetric cable-stayed bridge, and ensures the smooth implementation of the construction scheme of the asymmetric cable-stayed bridge. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is the construction process flowchart of the present application;

[0017] Figure 2is the state diagram of the 0# block, the edge span 1# beam segment and the steel-concrete combined segment of the bridge in the construction of the support method;

[0018] Figure 3 is the state diagram of the 1# steel beam in the middle span hoisted by the bridge deck crane;

[0019] Figure 4 is the state diagram of the setting of the hanging basket in the edge span and the setting of the sliding type counterweight on the beam in the middle span;

[0020] Figure 5 is the state diagram of the 2# beam segment in the edge span suspended and cast by the hanging basket and the forward movement of the counterweight in the middle span to compensate for the unbalanced bending moment;

[0021] Figure 6 is the state diagram of the 2# steel beam in the middle span hoisted by the bridge deck crane and the backward movement of the counterweight to compensate for the unbalanced bending moment;

[0022] Figure 7 is the state diagram of the subsequent beam segment in the edge span suspended and cast by the hanging basket and the forward movement of the counterweight in the middle span to compensate for the unbalanced bending moment again. DETAILED DESCRIPTION

[0023] Figure 1 is the construction flowchart of the present application, and the specific implementation is as follows:

[0024] (1) As shown in Figure 2 , first, the tower area beam segment construction support 2 is erected on the side of the pier column in the edge span and the side in the middle span under the cable tower 1, the 0# block 3 and the edge span 1# beam segment 4 are completed on the support, the steel-concrete combined beam segment 5 is installed in the middle span, and the temporary anchoring of the tower beam is tensioned.

[0025] (2) As shown in Figure 3 , the side support in the middle span is removed, two bridge deck crane sliding rails 6 are laid on the bridge deck in the middle span, the bridge deck crane 7 is installed on the sliding rails, and the 1# segment steel beam 8 in the middle span is hoisted by the bridge deck crane 7; after the hoisting of the 1# segment steel beam 8 is completed, the first pair of inclined cables 9 is installed and tensioned on the edge span 1# beam segment and the middle span 1# segment.

[0026] (3) As shown in Figure 4 , since the weight of the concrete beam in the edge span is greater than the weight of the steel beam in the middle span, in order to keep the balance of the cantilever bending moment of the edge span and the middle span, the counterweight 10 is arranged on the main beam in the middle span; two groups of electric walking wheels are arranged on the bottom of the two sides of the counterweight 10, the walking wheels on the two sides are respectively supported on the two sliding rails 6, and the walking wheels are driven to walk along the sliding rails through the control system;

[0027] The side support in the edge span is removed, and the edge span suspended and cast hanging basket 11 is installed on the 1# beam segment in the edge span.

[0028] (4) As shown in Figure 5As shown, the side span No. 2 beam segment 12 is cantilevered using the hanging basket 11. During the concrete pouring process of the side span beam segment, as the weight at the end of the side span increases, the unbalanced bending moment between the side span and the middle span increases. Therefore, the counterweight 10 is driven to gradually move forward a certain distance towards the middle of the span (the arrow in the figure indicates the direction of movement) to compensate for the bending moment at the middle of the span, so that the bending moments of the side span and the middle span can be balanced.

[0029] In a specific implementation of this invention, during the casting of the side span beam segment, the distance the counterweight moves forward towards the center of the span is determined by calculation, and the calculation method is as follows:

[0030] The maximum bending moment of the side span is calculated based on the cantilever length, weight, and weight of the beam segment to be poured in the side span. The bending moment of the mid-span cantilever is calculated based on the cantilever length and weight, and the bending moment difference between the side span and the mid-span is further calculated. Then, based on the weight of the counterweight, the position of the counterweight on the mid-span main beam is calculated to achieve bending moment balance between the mid-span and the side span. During the pouring of the cantilever beam segment of the side span, the counterweight is gradually moved to the set position until the cantilever beam of the side span is completed, at which point the counterweight is exactly moved to the set position on the mid-span main beam.

[0031] To further precisely control the movement distance of the counterweight, the weight of the beam segment to be poured in the side span can be pre-divided into multiple weight nodes from 0 to the total weight, and the position of the counterweight on the main beam at the mid-span of each weight node of the corresponding beam segment to be poured is calculated to achieve the cantilever bending moment balance of the side span and the middle span. The above data is input into the counterweight movement motor control system. During the pouring of the beam segment in the side span, the volume of concrete poured is used to monitor each weight node reached by the poured beam segment, and the counterweight is simultaneously controlled to move to the position of each weight node of the corresponding beam segment.

[0032] (5) Figure 6 As shown, the bridge deck crane 7 moves forward to lift the second segment 13 of the middle span. Due to the increase in weight of the middle span caused by lifting the second segment, the bending moment of the counterweight on the cantilever of the middle span at its current position on the main beam of the middle span is greater than the bending moment that needs to be compensated to maintain the balance between the side span and the middle span. Therefore, the counterweight needs to be moved backward a certain distance to reduce the bending moment compensated by the counterweight and to restore the balance of the bending moments of the cantilever of the side span and the middle span.

[0033] After the hoisting of segment 13 of the mid-span 2# was completed, the second pair of stay cables 9 were installed and tensioned;

[0034] In a specific implementation of this invention, when hoisting the mid-span beam segment, the distance the counterweight moves backward in the direction of the side span is determined by calculation, and the calculation method is as follows:

[0035] According to the length and weight of the side span cantilever, the maximum bending moment of the side span is calculated, according to the length, weight of the cantilever and the weight of the to-be-lifted beam segment, the bending moment of the cantilever in the middle span is calculated, the bending moment difference of the side span and the middle span is further calculated, and then according to the weight of the counterweight, the position of the counterweight on the main beam in the middle span is calculated to achieve the balance of the bending moment in the middle span and the side span; the deck crane slowly lifts the middle span beam segment, and the counterweight gradually moves to the set position while lifting, until the beam segment is completely suspended, and the counterweight is just moved to the set position on the main beam in the middle span.

[0036] To further accurately control the moving distance of the counterweight, the weight of the to-be-lifted beam segment in the middle span can be evenly divided into multiple weight nodes from 0 to the full weight, and the positions of the counterweight on the main beam in the middle span corresponding to each weight node of the to-be-lifted beam segment to achieve the balance of the bending moment of the side span and the middle span are calculated; during the lifting of the beam segment, the deck crane loads the lifting force in stages according to the divided weight nodes of the lifted beam segment, and synchronously controls the movement of the counterweight to the position corresponding to each weight node of the lifted beam segment.

[0037] (6) As shown in Figure 7 , the above steps (4) and (5) are cycled to construct, the subsequent beam segments of the side span are poured, and the subsequent beam segments of the middle span are lifted, until the bridge is closed.

Claims

1. A method for synchronous construction of dynamic compensation for unbalanced bending moment in asymmetric cantilever cable-stayed bridges, characterized in that, Includes the following steps: (1) Erect construction scaffolds for the tower area beam segments on the side span and mid-span of the pier column below the tower, and complete the concrete pouring of block 0 and side span beam segment 1 on the scaffolds. Install the steel-concrete composite beam segment in the mid-span and tension the temporary anchorage of the tower beam. (2) Remove the mid-span side support, lay two bridge deck crane slide rails along the bridge direction on the mid-span bridge deck, install the bridge deck crane on the slide rails, and use the bridge deck crane to lift the steel beam of segment 1 in the mid-span; install and tension the first pair of stay cables on the side span segment 1 and the mid-span segment 1. (3) Set a counterweight on the main beam of the middle span. Two sets of electric walking wheels are set on both sides of the bottom of the counterweight. The walking wheels on both sides are supported on two slide rails respectively. Remove the side support of the side span and install the side span cantilever hanging basket on the No. 1 beam segment of the side span. (4) The side span No. 2 beam segment is cast using a hanging basket. During the concrete pouring process of the side span, as the weight of the side span end increases, the driving counterweight is gradually moved forward a certain distance towards the middle of the span to compensate for the side bending moment at the middle of the span, so that the bending moments of the side span and the middle span can be balanced. (5) The bridge deck crane moves forward to hoist the No. 2 segment of the middle span, while simultaneously driving the counterweight to move a certain distance backward towards the side span; after the No. 2 segment of the middle span is hoisted, the second pair of stay cables are installed and tensioned; (6) Repeat the above steps (4) and (5) until the bridge is closed.

2. The synchronous construction method for dynamic compensation of unbalanced bending moment in a cable-stayed bridge with asymmetric cantilever as described in claim 1, characterized in that: In step (4), when the side span beam segment is poured, the distance by which the counterweight moves forward towards the middle of the span is determined by calculation, and the calculation method is as follows: The maximum bending moment of the side span is calculated based on the cantilever length, weight, and weight of the beam segment to be poured in the side span. The bending moment of the mid-span cantilever is calculated based on the cantilever length and weight, and the bending moment difference between the side span and the mid-span is further calculated. Then, based on the weight of the counterweight, the position of the counterweight on the mid-span main beam is calculated to achieve bending moment balance between the mid-span and the side span. During the pouring of the cantilever beam segment of the side span, the counterweight is gradually moved to the set position until the cantilever beam of the side span is completed, at which point the counterweight is exactly moved to the set position on the mid-span main beam.

3. The synchronous construction method for dynamic compensation of unbalanced bending moment in a cable-stayed bridge with asymmetric cantilever as described in claim 2, characterized in that: The weight of the beam segment to be poured in the side span is evenly divided into multiple weight nodes from 0 to the total weight, and the position of the counterweight on the main beam at the mid-span is calculated for each weight node of the beam segment to be poured in order to achieve the balance of the cantilever bending moment in the side span and the middle span. During the pouring of the beam segment in the side span, the volume of concrete poured is used to monitor each weight node reached by the poured beam segment, and the counterweight is moved to the position of each weight node of the corresponding beam segment in a synchronous manner.

4. The synchronous construction method for dynamic compensation of unbalanced bending moment in a cable-stayed bridge with asymmetric cantilever as described in claim 1, characterized in that: In step (5), when hoisting the mid-span beam segment, the distance the counterweight moves backward in the direction of the side span is determined by calculation, and the calculation method is as follows: Based on the cantilever length and weight of the side span, the maximum bending moment of the side span is calculated. Based on the cantilever length, weight, and weight of the beam segment to be lifted, the bending moment of the cantilever at mid-span is calculated. The bending moment difference between the side span and the mid-span is further calculated. Then, based on the weight of the counterweight, the position of the counterweight on the mid-span main beam is calculated to achieve bending moment balance between the mid-span and side span. The bridge crane slowly lifts the mid-span beam segment, while controlling the counterweight to gradually move towards the set position until the lifted beam segment is completely suspended and the counterweight has just moved to the set position on the mid-span main beam.

5. The synchronous construction method for dynamic compensation of unbalanced bending moment in a cable-stayed bridge with asymmetric cantilever as described in claim 4, characterized in that: The weight of the beam segment to be hoisted in the middle span is evenly divided into multiple weight nodes from 0 to the total weight, and the position of the counterweight on the main beam at the middle span for each weight node of the corresponding beam segment to be hoisted is calculated to achieve the balance of the cantilever bending moment of the side span and the middle span. During the lifting of the beam segments, the bridge deck crane applies lifting force in stages according to the weight nodes of the beam segments to be lifted, and simultaneously controls the counterweight to move to the position of each weight node of the corresponding beam segment.

Images