Ballast area structure of a steel truss girder cable-stayed bridge and its construction method

Abstract

The present invention relates to a counterweight area structure of a steel truss girder cable-stayed bridge and a construction method thereof. A counterweight area structure of a steel truss girder cable-stayed bridge includes a bottom plate and two side plates. The bottom plate and the side plates are both arranged between two adjacent floor system cross beams of the steel truss girder. The bottom plate, the two side plates, the corresponding two adjacent floor system cross beams and the steel bridge deck of the steel truss girder can enclose a closed structure, and a counterweight body is filled in the closed structure. It simplifies the connection structure between the counterweight area and the steel girder, has a high steel utilization rate and less steel consumption; it has a larger construction space, fewer construction steps, is simpler in construction and has a higher installation efficiency; and it enables the steel bridge deck and the underlying floor system at the closed structure to not require post-maintenance.

Description

Technical Field

[0001] The present invention relates to the technical field of counterweight for cable-stayed bridges, and particularly to a counterweight area structure and a construction method thereof for a steel truss girder cable-stayed bridge. Background Art

[0002] The problem of reaction force of multi-line long-span steel truss girder cable-stayed bridges is very prominent. Adding a counterweight area to the side span is the most common and effective method for steel truss girder cable-stayed bridges to eliminate reaction force and provide pressure reserve under the operating state.

[0003] The existing counterweight area structures of steel truss girder cable-stayed bridges mainly include two types: deck counterweight and counterweight box arranged in the deck system. A counterweight box is arranged below the deck system: that is, between the longitudinal or transverse beams of the deck system, a counterweight box is added, and counterweight concrete is poured into the counterweight box. As Figure 1 shown, below the deck slab 2 is the deck system composed of longitudinal and transverse beams. A counterweight box 3 is arranged in the deck system. It is necessary to arrange components for supporting the counterweight box 3 between the longitudinal beams or transverse beams 1 of the deck system. For example, several small longitudinal beams 5 are bolted to the transverse beam 1 of the deck system, and the counterweight box 3 is supported on the small longitudinal beams 5. All the weights are borne by the small longitudinal beams 5. This structure has the following problems:

[0004] (1) The installation of the counterweight box 3 can only be carried out after the construction of the small longitudinal beams 5 is completed. The connection is complex, the steel consumption is large, and the counterweight box 3 is only a container and does not make full use of steel. In addition, the construction space above the small longitudinal beams 5 is limited, the construction difficulty of the counterweight box 3 is large and the process is relatively complex.

[0005] (2) A plurality of counterweight boxes 3 are arranged along the transverse direction of the bridge. The capacity of a single counterweight box 3 is small and the counterweight efficiency is low. After the counterweight box 3 is arranged, the space below the deck system is limited, which brings inconvenience to the subsequent maintenance of this part. And in order to meet the subsequent maintenance of the deck slab 2, a certain space needs to be reserved above the counterweight box 3, such as a space with a height of 1 - 1.5 m, so that the vertical range where the counterweight box 3 can be arranged on the bridge is small. In order to increase the counterweight, it is necessary to increase the transverse beam 1 of the deck system or increase the unit weight. Since the installation space of the steel truss girder counterweight box 3 is extremely limited, in order to save the material consumption of the counterweight area and reduce the volume of the counterweight area, the existing counterweight area materials of steel truss girder cable-stayed bridges mainly adopt two types: iron sand concrete and barite concrete. In terms of counterweight materials, the greater the unit weight of the heavy concrete 4, the greater the pumping difficulty, especially in the case of a relatively high bridge height. Usually, a special pumping process needs to be adopted, and compared with ordinary concrete, the heavy concrete 4 is more expensive. Summary of the Invention

[0006] The object of the present invention is to provide a ballast area structure and a construction method thereof for a steel truss girder cable-stayed bridge, aiming at the problems existing in the ballast area structure of the existing steel truss girder cable-stayed bridge. In the existing structure, several small longitudinal girders are bolted to the cross girders under the deck system, and several ballast boxes are supported on the small longitudinal girders, which has complex connections, a large amount of steel consumption, low steel utilization rate, and is difficult and complex in construction and maintenance.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A ballast area structure for a steel truss girder cable-stayed bridge includes a bottom plate and two side plates. The bottom plate and the side plates are both arranged between two adjacent cross girders of the steel truss girder. The bottom plate, the two side plates, the corresponding two adjacent cross girders and the steel bridge deck of the steel truss girder can enclose a closed structure, and the closed structure is filled with ballast.

[0009] The ballast can be formed by pouring ballast materials such as concrete and mortar in the prior art; the unit weight of the ballast and the closed structure are designed according to the actual construction situation, and the bottom plate and the side plates are designed according to the actual construction situation.

[0010] For the ballast area structure of the steel truss girder cable-stayed bridge in this solution, a closed structure is formed by the bottom plate, the two side plates, the corresponding two adjacent cross girders and the steel bridge deck of the steel truss girder, so that the space between two adjacent cross girders can be filled with ballast materials, and the ballast area structure is combined with the steel truss girder to achieve the ballast function.

[0011] For the ballast area structure of the steel truss girder cable-stayed bridge, the bottom plate and the two side plates are both supported by the cross girders of the deck system, so there is no need to separately set small longitudinal girders for support; and the closed structure is a large and closed ballast box, which is formed by means of the deck system and the bridge deck of the steel truss girder, simplifying the connection structure between the ballast area and the steel girder; moreover, the deck system and the bridge deck of the steel truss girder are not only part of the bridge structure but also part of the ballast box of the ballast, with high steel utilization rate; and the overall volume of the closed structure is larger than that of the ballast box between two adjacent cross girders in the prior art, which can reduce the unit weight of the ballast materials and thus reduce the cost, without the need to increase the ballast like the prior art by increasing the height of the cross girders of the deck system or significantly increasing the height of the cross girders of the deck system; the above reasons result in less steel consumption for the ballast area structure. And because there is no need to set small longitudinal girders, only the bottom plate and the side plates need to be installed between two adjacent cross girders, providing a larger construction space, fewer construction steps, and simpler construction; the bottom plate and the side plates can be installed in time after installing two adjacent cross girders, improving the installation efficiency. After the closed structure is filled with ballast materials, the ballast materials can directly support the steel bridge deck, effectively improving the fatigue characteristics of the steel bridge deck, so that neither the steel bridge deck nor the underlying deck system at the closed structure needs to be maintained later, and the entire ballast area structure also does not need maintenance.

[0012] Preferably, the lower part of the ballast body is a normal concrete layer, and the upper part is a self-compacting cement mortar layer.

[0013] By adopting a closed structure, the total volume of all ballast boxes between two adjacent bridge deck crossbeams in the present solution is larger than that of the prior art. Under the condition of ensuring the same ballast weight, it is possible to use normal concrete and self-compacting cement mortar with a smaller unit weight than heavy concrete to achieve ballast. The normal concrete layer at the lower part inside the closed structure has strong bearing capacity, and the self-compacting cement mortar layer is conducive to filling the upper part of the closed structure, while ensuring safety and compactness. Compared with heavy concrete, filling the internal space of the closed structure with the normal concrete layer and the self-compacting cement mortar layer is simpler in construction, and the cost of the materials themselves is also lower, thus saving construction costs.

[0014] Preferably, the top surface height of the normal concrete layer is not higher than the bottom of the U-rib of the steel bridge deck.

[0015] The U-rib is a U-shaped stiffening rib arranged longitudinally along the bottom surface of the steel bridge deck. The actual height of the normal concrete layer is determined according to the specific ballast weight, but the top surface height of the normal concrete layer should not be higher than the bottom of the U-rib of the steel bridge deck, so that the self-compacting cement mortar can better fill the corners such as the U-rib of the bridge deck, improving the filling effect inside the closed structure.

[0016] Preferably, the side plate is provided with a manhole, and the top of the manhole is higher than the top surface of the normal concrete layer, and the normal concrete layer is poured through the manhole.

[0017] Construction workers can enter the manhole to pour normal concrete, which is convenient for pouring the normal concrete layer, and can improve the pouring quality. Moreover, there is no need to separately open redundant pouring ports on the side plate for pouring the normal concrete layer, which can improve the integrity of the closed structure.

[0018] Preferably, a number of first stiffening ribs are provided above the bottom plate, and a number of second stiffening ribs are provided on the inner side of the side plate.

[0019] The strength and stiffness of the bottom plate can be enhanced by the first stiffening ribs, and the strength and stiffness of the side plate can be enhanced by the second stiffening ribs. The first stiffening ribs are arranged on the top surface of the bottom plate, making the connection between the bottom plate and the ballast material inside the closed structure closer; the second stiffening ribs are arranged on the inner side of the side plate, making the connection between the side plate and the ballast material inside the closed structure closer; the integrity and stability of the ballast area structure can be improved.

[0020] Preferably, several of the first stiffeners are arranged longitudinally along the bridge, and the first stiffeners are connected to the corresponding joint plates of the cross beams of the deck system by first high-strength bolts; both longitudinal sides of the side plates are respectively connected to the web stiffeners of two cross beams of the deck system by second high-strength bolts.

[0021] The joint plate is vertically arranged at the corner of the web and the lower flange of the cross beam of the deck system. Along the longitudinal direction of the bridge and corresponding to the position of the joint plate, a first stiffener is arranged on the top surface of the bottom plate. While ensuring sufficient reinforcement of the bottom plate, it can also stably connect the bottom plate and the cross beam of the deck system through the first high-strength bolts. The inner side of the side plate refers to the side of the side plate facing the inside of the closed structure. The web of the cross beam of the deck system has a vertically arranged web stiffener, which makes the connection between the side plate and the cross beam of the deck system more stable through the second high-strength bolts. Through the first stiffener, the first high-strength bolts and the second high-strength bolts, the installation quality of the bottom plate and the side plate can be better, thereby improving the quality of the closed structure, making the ballast area structure of the steel truss girder cable-stayed bridge described in this solution better applicable to the bridge formed by piecemeal assembly of members.

[0022] Preferably, the second stiffeners are arranged vertically. Since the vertical height of the side plate is higher than that of the existing ballast box, by arranging the vertical second stiffeners, the side plate can be better strengthened.

[0023] Preferably, the thickness of the bottom plate is 10 - 16 mm, and the thickness of the side plate is greater than or equal to 10 mm. After being strengthened by the above-mentioned first stiffeners and second stiffeners, it is possible to use thinner bottom plates and side plates, that is, a bottom plate with a thickness of 10 - 16 mm can be used, and a side plate with a thickness of greater than or equal to 10 mm can be used. Furthermore, the steel consumption can be reduced, the cost can be saved, and it is more convenient for hoisting the side plate and the bottom plate.

[0024] A construction method for the ballast area structure of a steel truss girder cable-stayed bridge includes the following steps:

[0025] S1. Construct the bottom plate, two side plates, two cross beams of the deck system and the steel bridge deck in each ballast area beam section to form a closed structure;

[0026] S2. After the main girder of the cable-stayed bridge is closed, first pour a layer of ordinary concrete into the closed structure, and then pour a layer of self-compacting cement mortar.

[0027] Compared with the construction of the existing ballast box, through the above method, the ballast area structure of the steel truss girder cable-stayed bridge in the present invention can be constructed safely and quickly, and its construction is simpler.

[0028] Preferably, in step S2, the ordinary concrete layer is constructed in two layers. First, pour the first layer on the bottom plate, and after the strength of the first layer reaches the standard, pour the second layer on the first layer.

[0029] Through the above construction method, the bearing capacity of the first layer of ordinary concrete is effectively utilized, so that the relatively thin bottom plate and the first stiffening rib only need to be able to bear the weight of the first layer of ordinary concrete. After the first layer of ordinary concrete is formed, the steel-concrete structure formed with the bottom plate can effectively bear the total weight of the second layer of ordinary concrete and the self-compacting cement mortar layer.

[0030] Preferably, in the step S2, the ordinary concrete layer is poured through a manhole, and the manhole is located on one of the side plates;

[0031] During the pouring process of the second layer, when the height of the poured ordinary concrete is higher than the bottom of the manhole, the ordinary concrete is poured in a way of gradually plugging the manhole upwards until the pouring of the second layer is completed, and then the manhole is completely plugged;

[0032] After the strength of the second layer reaches the standard, a pouring hole is opened in the steel bridge deck, and the self-compacting cement mortar layer is poured through the pouring hole until the closed structure is filled, and then the pouring hole is closed.

[0033] When the height of the poured ordinary concrete is higher than the bottom of the manhole, as the pouring height increases, the manhole is gradually plugged until the pouring of the second layer is completed. Pouring the ordinary concrete layer through the manhole on the side plate can better ensure the pouring quality during the layered pouring of the ordinary concrete layer, and the manhole will be closed after the pouring of the second layer of the ordinary concrete layer. The entire closed structure is completely closed and pouring cannot be carried out. A pouring hole is opened above the steel bridge deck corresponding to between its U ribs and between the U ribs and the longitudinal beam of the bridge deck. The pouring hole is preferably 4 - 6 cm, and the self-compacting cement mortar layer is poured through the pouring hole, which can more conveniently, quickly and with high quality fill the closed structure, avoiding incomplete filling at the U ribs and the longitudinal beam of the bridge deck. This construction method of cooperating the manhole with small pouring holes can minimize the opening of a large number of relatively large pouring openings in the ballast area structure, ensure the integrity of the ballast area structure, and improve the quality of the ballast area structure.

[0034] Preferably, in step S1, when the steel truss beam is constructed to the ballast area beam section, after hoisting two adjacent bridge deck cross beams, the bottom plate and the side plate are hoisted between the corresponding two adjacent bridge deck cross beams to form the closed structure.

[0035] When the construction site for the beam segment in the ballast area is limited, or large lifting equipment cannot be transported to the construction site of the beam segment in the ballast area, it is impossible to assemble the beam segment in the ballast area on the ground and then conduct overall hoisting. By hoisting the bottom plate and side plates in a timely manner after hoisting two adjacent crossbeams of the deck system, the closed structure can be formed, which can avoid being restricted by the construction site, eliminate the need to use large lifting equipment, and the construction steps are simpler. Moreover, this assembly method will not affect the quality of the closed structure.

[0036] Preferably, in step S1, when installing the bottom plate and side plates between two adjacent crossbeams of the deck system, the first high-strength bolts and the second high-strength bolts are initially tightened, and after the construction of the beam segment in the ballast area is completed, the first high-strength bolts and the second high-strength bolts are tightened.

[0037] Among them, the first high-strength bolts are used to connect the first stiffening rib to the corresponding joint plate. The first stiffening rib is arranged along the longitudinal bridge direction on the bottom plate, and the joint plate is vertically arranged at the corner of the web and the lower flange of the crossbeam of the deck system; the second high-strength bolts are used to connect the longitudinal bridge sides of the side plate to the web stiffening plates of two adjacent crossbeams of the deck system respectively, and the web stiffening plates are vertically arranged on the web of the crossbeam of the deck system.

[0038] Through the above construction method, it is convenient to adjust the connection of the bottom plate and the side plates.

[0039] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0040] 1. For the ballast area structure of the steel truss girder cable-stayed bridge of the present invention, a closed structure is formed by the bottom plate, two side plates, two adjacent crossbeams of the deck system corresponding thereto, and the steel deck plate of the steel truss girder, so that the space between two adjacent crossbeams of the deck system can be filled with ballast materials, enabling the ballast area structure to be combined with the steel truss girder. Moreover, the filling volume of the ballast materials in the closed structure is larger, which can better achieve the increase of the ballast weight; there is no need to separately set small longitudinal beams for support, and the closed structure is formed by means of the deck system and the deck plate of the steel truss girder, which simplifies the connection structure between the ballast area and the steel girder, has a high steel utilization rate, and reduces the steel consumption; and the total capacity of the closed structure is large, eliminating the need to increase the ballast like the prior art by increasing the height of the crossbeam of the deck system or significantly increasing the height of the crossbeam of the deck system, thereby reducing the steel consumption. And because there is no need to set small longitudinal beams, only the bottom plate and side plates need to be installed between two adjacent crossbeams of the deck system, resulting in a larger construction space, fewer construction steps, and simpler construction; the bottom plate and side plates can be installed in a timely manner after installing two adjacent crossbeams of the deck system, which can improve the installation efficiency. After the closed structure is filled with ballast materials, the ballast materials can directly support the steel deck plate, effectively improving the fatigue characteristics of the steel deck plate, so that neither the steel deck plate nor the underlying deck system at the closed structure needs to be maintained later, and the entire ballast area structure also does not need maintenance.

[0041] 2. The bearing capacity of the ordinary concrete layer at the lower part inside the closed structure is strong. The self-compacting cement mortar layer is beneficial to filling the upper part of the closed structure, while ensuring safety and compactness. Compared with heavy concrete, filling the internal space of the closed structure through the ordinary concrete layer and the self-compacting cement mortar layer is simpler in construction, and the cost of the materials themselves is also lower, thus being able to save construction costs.

[0042] 3. The construction method of the ballast area structure of the steel truss girder cable-stayed bridge described in the present invention can construct the ballast area structure of the steel truss girder cable-stayed bridge in the present invention safely and quickly compared with the construction of the existing ballast box, and its construction is simpler.

[0043] 4. The construction method of using manholes in cooperation with small pouring holes can minimize the opening of a large number of relatively large pouring ports in the ballast area structure, ensure the integrity of the ballast area structure, improve the quality of the ballast area structure, and opening pouring holes above the steel bridge deck corresponding to the space between its U-shaped ribs or between the U-shaped ribs and the longitudinal girders of the bridge deck can more conveniently, quickly and with high quality fill the upper U-shaped ribs and other corners of the closed structure with self-compacting cement mortar, so that the closed structure is filled. Description of the Drawings

[0044] Figure 1 is a schematic structural diagram of the ballast area structure of the existing steel truss girder cable-stayed bridge;

[0045] Figure 1 In the figure: 1 - crossbeam of the bridge deck system; 2 - bridge deck; 3 - ballast box; 4 - heavy concrete; 5 - small longitudinal girder.

[0046] Figure 2 is a schematic cross-sectional structural diagram of the ballast area structure of the steel truss girder cable-stayed bridge described in Embodiment 1;

[0047] Figure 3 is Figure 2 the sectional view at A - A in the figure;

[0048] Figure 4 is Figure 2 the sectional view at B - B in the figure;

[0049] Figure 5 is a schematic plan view of the ballast area structure of the steel truss girder cable-stayed bridge described in Embodiment 1.

[0050] Figure 2 - 5Chinese icons: 1 - cross beam of bridge deck system; 2 - steel bridge deck; 21 - U rib; 22 - longitudinal beam of bridge deck; 3 - bottom plate; 4 - first stiffening rib; 5 - side plate; 6 - normal concrete layer; 61 - first layer; 62 - second layer; 7 - self - compacting cement mortar layer; 8 - first high - strength bolt; 10 - second high - strength bolt; 11 - joint plate; 12 - manhole; 13 - second stiffening rib. Detailed implementation manners

[0051] The present invention will be described in detail below with reference to the accompanying drawings.

[0052] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0053] Embodiment 1

[0054] This embodiment provides a ballast area structure of a steel truss girder cable - stayed bridge. Refer to Figure 2 - 4 , which includes a bottom plate 3 and two side plates 5. The bottom plate 3 and the side plates 5 are both arranged between two adjacent cross beams 1 of the bridge deck system of the steel truss girder. The bottom plate 3, the two side plates 5, the corresponding two adjacent cross beams 1 of the bridge deck system and the steel bridge deck 2 of the steel truss girder can enclose a closed structure, and the closed structure is filled with ballast.

[0055] The ballast can be formed by pouring ballast materials such as concrete and mortar; the unit weight of the ballast is determined according to the required reaction force reserve, and the bottom plate 3 and the side plates 5 are designed according to the ballast weight.

[0056] For the ballast area structure of the steel truss girder cable - stayed bridge in this solution, a closed structure is formed by the bottom plate 3, the two side plates 5, the corresponding two adjacent cross beams 1 of the bridge deck system and the steel bridge deck 2 of the steel truss girder, so that the space between two adjacent cross beams 1 of the bridge deck system can be filled with ballast materials, making the ballast area structure combined with the steel truss girder to achieve the ballast function.

[0057] In this embodiment, by adopting a closed structure, compared with the total volume of all ballast boxes between two adjacent bridge deck crossbeams 1 in the prior art, the total volume is larger. When ensuring the same ballast weight, it is possible to use ordinary concrete and self-compacting cement mortar with a smaller unit weight than heavy concrete to achieve ballast. Therefore, a better structure can be adopted, such that the lower part of the ballast body is an ordinary concrete layer 6 and the upper part is a self-compacting cement mortar layer 7. The ordinary concrete layer 6 at the lower part inside the closed structure has strong bearing capacity, and the self-compacting cement mortar layer 7 is beneficial to filling the upper part of the closed structure, while ensuring safety and compactness. Moreover, compared with heavy concrete, filling the internal space of the closed structure with the ordinary concrete layer 6 and the self-compacting cement mortar layer 7 is simpler in construction and lower in material cost itself, thereby being able to save construction costs. In addition, the actual height of the ordinary concrete layer 6 is determined according to the specific ballast weight, but the top surface height of the ordinary concrete layer 6 should not be higher than the bottom of the U-rib 21 of the steel bridge deck 2, so that the U-rib 21 of the bridge deck and other corner parts can be better filled with self-compacting cement mortar, improving the filling effect inside the closed structure.

[0058] In this embodiment, the bottom plate 3 and the side plate 5 are both provided with stiffening structures, and the stiffening structures are used to strengthen the bottom plate 3 and the side plate 5, so that the bottom plate 3 and the side plate 5 can bear the overall pressure of the ordinary concrete layer 6 and the self-compacting cement mortar layer 7.

[0059] As Figure 2 、 3 As shown in FIGS. 4 and 5, a vertical joint plate 11 is provided along the longitudinal bridge direction at the corner of the web and the lower flange of the bridge deck crossbeam 1. The stiffening structure of the bottom plate 3 is a number of first stiffening ribs 4 arranged corresponding to the joint plate 11. The first stiffening ribs 4 are arranged along the longitudinal bridge direction, and the first stiffening ribs 4 and the corresponding joint plate 11 are connected by first high-strength bolts 8. Arranging the first stiffening ribs 4 on the top surface of the bottom plate 3 along the longitudinal bridge direction and corresponding to the position of the joint plate 11 can not only ensure sufficient strengthening of the bottom plate 3, but also facilitate the more stable connection between the bottom plate 3 and the bridge deck crossbeam 1. And the first stiffening ribs 4 are arranged on the top surface of the bottom plate 3, making the connection between the bottom plate 3 and the ordinary concrete layer 6 closer, improving the integrity and stability of the ballast area structure.

[0060] The inner side of the side plate 5 refers to the side of the side plate 5 facing the inside of the closed structure. As Figure 4As shown, the web of the cross beam 1 of the bridge deck system has vertically arranged web stiffeners. The two longitudinal bridge sides of the side plate 5 are respectively connected to the web stiffeners of the two cross beams 1 of the bridge deck system through the second high-strength bolts 10, making the connection between the side plate 5 and the cross beam 1 of the bridge deck system more stable. And the stiffening structure of the side plate 5 is a number of second stiffening ribs 13. The second stiffening ribs 13 are vertically arranged inside the side plate 5. Since the vertical height of the side plate 5 is higher than the height of the existing ballast box, by arranging the vertical second stiffening ribs 13, the side plate 5 can be better strengthened. And by arranging the second stiffening ribs 13 inside the side plate 5, the side plate 5 can be more closely connected to the normal concrete layer 6 and the self-compacting cement mortar layer 7, improving the integrity and stability of the ballast area structure.

[0061] After being strengthened by the above-mentioned first stiffening ribs 4 and second stiffening ribs 13, it is possible to use a bottom plate 3 and a side plate 5 with a relatively thin thickness. That is, a bottom plate 3 with a thickness of 10 - 16 mm can be used, and a side plate 5 with a thickness greater than or equal to 10 mm can be used. Furthermore, the steel consumption can be reduced, the cost can be saved, and it is more convenient for the hoisting of the side plate 5 and the bottom plate 3.

[0062] And a manhole 12 is provided on the side plate 5. The top of the manhole 12 is higher than the top surface of the normal concrete layer 6. In this embodiment, each closed structure has only one side plate 5 provided with one manhole 12. Through the manhole 12, the normal concrete layer 6 is poured. Construction workers can enter the manhole 12 to pour the normal concrete, which is convenient for the pouring of the normal concrete layer 6, and can improve the pouring quality. Moreover, there is no need to separately open redundant pouring ports on the side plate 5 for pouring the normal concrete layer 6, which can improve the integrity of the closed structure.

[0063] The ballast area structure of the steel truss girder cable-stayed bridge described in this embodiment has a simple structure and is convenient to install. This ballast area structure makes better use of the main structure of the steel truss girder. Only by adding a bottom plate 3 and side plates 5 to connect the crossbeams 1 of the bridge deck system and cooperating with the steel bridge deck 2 to form an integral closed structure as the ballast area, the connection structure between the ballast area and the steel truss girder is simplified. And it is connected by the first high-strength bolts 8 and the second high-strength bolts 10, which can be installed in blocks and is convenient for construction. Moreover, its structure has clear force transmission, does not change the force system and mechanical properties of the steel truss girder, and the cable force still maintains the force transmission path from the chord to the bridge deck. It has good economy. Compared with the traditional ballast box, it can save more than 40% of steel. Two kinds of ballast materials are used. The bottom ordinary concrete layer 6 has strong bearing capacity, and the top self-compacting cement mortar layer 7 is convenient for pouring through small holes opened on the top plate, ensuring the compactness. And this ballast area structure has strong safety. After the ordinary concrete of the ordinary concrete layer 6 is formed, it forms an integral body with the bottom plate 3, and is connected to the crossbeam 1 of the bridge deck system by the first high-strength bolts 8. Even if the first high-strength bolts 8 fail, this ballast area structure can effectively support on the lower flange of the crossbeam 1 of the bridge deck system and will not fall off. And it also has the characteristics of maintenance-free and strong durability. The closed structure is filled with ordinary concrete and self-compacting cement mortar, and no maintenance is required; the steel bridge deck 2 is supported by the closed structure, the ordinary concrete layer 6 and the self-compacting cement mortar layer 7 inside it, and its mechanical properties are improved and its durability is enhanced. And the outer surface of the closed structure is smooth and clean, which is convenient for maintenance.

[0064] Embodiment 2

[0065] This embodiment provides a construction method for the ballast area structure of a steel truss girder cable-stayed bridge, which is used to construct the ballast area structure of the steel truss girder cable-stayed bridge as described in Embodiment 1, and includes the following steps:

[0066] S1. During the construction of each ballast area beam segment, construct the bottom plate 3, two side plates 5, two crossbeams 1 of the bridge deck system and the steel bridge deck 2 to form a closed structure;

[0067] S2. After the main girder of the cable-stayed bridge is closed, first pour the ordinary concrete layer 6 into the closed structure, and then pour the self-compacting cement mortar layer 7.

[0068] Among them, the closed structure can be installed in a variety of ways, as follows:

[0069] Method 1: In step S1, when constructing each ballast area beam segment, first assemble the steel bridge deck 2, all the crossbeams 1 of the bridge deck system, the bottom plate 3 and the side plates 5 between two adjacent crossbeams 1 of the bridge deck system in the ballast area beam segment to form an integral beam segment. The integral beam segment includes several closed structures, and then hoist the integral beam segment;

[0070] The first method is to assemble each beam segment in the weight-bearing area on the ground. When assembling, the bottom plate 3 and the side plates 5 are installed on the ground to form several closed structures, and then the whole is hoisted. This construction method is carried out on the ground, and the construction is safer, but it requires a large assembly site and large lifting equipment.

[0071] When the construction site of the beam segment in the weight-bearing area is limited, or the large lifting equipment cannot be transported to the construction site of the beam segment in the weight-bearing area, it is impossible to assemble the beam segment in the weight-bearing area on the ground and then hoist it as a whole. At this time, the second method is used to install the bottom plate 3 and the side plates 5.

[0072] The second method is as follows: In step S1, when the steel truss girder is constructed to the beam segment in the weight-bearing area, after hoisting two adjacent bridge deck cross beams 1, the bottom plate 3 and the side plates 5 are hoisted between the corresponding two adjacent bridge deck cross beams 1 to form the closed structure. The second method is a better implementation method. By hoisting the bottom plate 3 and the side plates 5 in time after hoisting two adjacent bridge deck cross beams 1 to form the closed structure, it can avoid being restricted by the construction site, and there is no need to use large lifting equipment, and the construction steps are simpler.

[0073] In this embodiment, when there are the first high-strength bolts 8 and the second high-strength bolts 10 in Embodiment 1, in step S1, when installing the bottom plate 3 and the side plates 5 between the corresponding two adjacent bridge deck cross beams 1, the first high-strength bolts 8 and the second high-strength bolts 10 are initially tightened. After the construction of the beam segment in the weight-bearing area is completed, the first high-strength bolts 8 and the second high-strength bolts 10 are tightened to form a stable closed structure.

[0074] After the main girder of the cable-stayed bridge is closed, preparations are made to pour the ordinary concrete at the bottom layer. Before pouring, it is necessary to seal the gaps between the side plates 5 of the closed structure and the bridge deck cross beams 1 and between the side plates 5 and the steel bridge deck 2.

[0075] After the sealing treatment is completed, the underlying ordinary concrete is poured through the manhole. The ordinary concrete layer 6 is poured in a full-section layered manner. In this embodiment, a preferred implementation method is adopted. In step S2, the ordinary concrete layer 6 is constructed in two layers. First, the first layer 61 is poured on the bottom plate 3. After the strength of the first layer 61 reaches the standard, the second layer 62 is poured on the first layer 61. During the pouring of the second layer 62, when the height of the poured ordinary concrete is higher than the bottom elevation of the manhole 12, a part of the bottom of the manhole 12 is blocked first, and then the ordinary concrete is poured. When the ordinary concrete is about to overflow from the manhole 12, a part of the manhole 12 is blocked upward again, and then the ordinary concrete is poured. The ordinary concrete is poured by gradually blocking the manhole 12 upward until the second layer 62 is poured, and then the manhole 12 is completely blocked; the bearing capacity of the ordinary concrete of the first layer 61 is effectively utilized, so that the relatively thin bottom plate 3 and the first stiffening rib 4 only need to be able to bear the weight of the ordinary concrete of the first layer 61. The steel-concrete structure formed by the ordinary concrete of the first layer 61 and the bottom plate 3 after molding can effectively bear the total weight of the ordinary concrete of the second layer 62 and the self-compacting cement mortar layer 7. Dividing the ordinary concrete layer 6 into two layers for construction makes the required thickness of the bottom plate 3 thinner and the required strength of the first stiffening rib 4 smaller, which can save steel and make the installation of the bottom plate 3 and the first stiffening rib 4 easier.

[0076] After the strength of the second layer 62 reaches the standard, pouring holes are opened above the steel bridge deck 2 corresponding to between its U-ribs 21 and between the U-ribs 21 and the deck longitudinal girder 22. The self-compacting cement mortar layer 7 is poured through the pouring holes until the closed structure is filled. Among them, the size of the pouring hole is 4 - 6 cm, preferably 5 cm, and an exhaust pipe and a pouring pipe are provided. Micro-expansion self-compacting cement mortar is used for pressure pouring to ensure that the weight box is fully filled. Pouring the self-compacting cement mortar layer 7 through the pouring holes can fill the closed structure more conveniently, quickly and with high quality, and avoid incomplete filling of the corner parts of the U-ribs 21 and the deck longitudinal girder 22. This construction method using the manhole 12 and small pouring holes can minimize the opening of a large number of relatively large pouring openings in the ballast area structure, ensure the integrity of the ballast area structure, and improve the quality of the ballast area structure.

[0077] After the closed structure is filled, the pouring holes on the steel bridge deck 2 are blocked to complete the construction of the ballast area structure.

[0078] In order to test the safety and feasibility of the bottom plate 3 and the deck system cross beam 1 of the ballast area structure, the stress of the ballast area structure is calculated and analyzed, and all meet the stress requirements. After the closed structure is fully filled, the fatigue characteristics of the steel bridge deck 2 can be effectively improved, making the bridge deck structure maintenance-free.

[0079] Compared with the construction of the existing ballast boxes, the construction method of the ballast area structure of the steel truss girder cable-stayed bridge in this embodiment can construct the ballast area structure of the steel truss girder cable-stayed bridge in the present invention safely and quickly, and the construction is simpler.

[0080] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A construction method for the ballast area structure of a steel truss girder cable-stayed bridge, characterized in that The ballast area structure of the steel truss girder cable-stayed bridge includes a bottom plate (3) and two side plates (5). The bottom plate (3) and the side plates (5) are both arranged between two adjacent crossbeams (1) of the bridge deck system of the steel truss girder. The bottom plate (3), the two side plates (5), the corresponding two adjacent crossbeams (1) of the bridge deck system and the steel bridge deck (2) of the steel truss girder can enclose a closed structure, and a ballast body is filled in the closed structure; the lower part of the ballast body is a normal concrete layer (6), and the upper part is a self-compacting cement mortar layer (7). The construction method includes the following steps: S1. Construct the bottom plate (3), two side plates (5), two crossbeams (1) of the bridge deck system and the steel bridge deck (2) in each ballast area beam segment to form a closed structure; S2. After the main girder of the cable-stayed bridge is closed, first pour the normal concrete layer (6) into the closed structure, and then pour the self-compacting cement mortar layer (7); In step S2, the normal concrete layer (6) is constructed in two layers. First, pour the first layer (61) on the bottom plate (3). After the strength of the first layer (61) reaches the standard, pour the second layer (62) on the first layer (61).

2. The construction method of the ballast area structure of the steel truss girder cable-stayed bridge according to claim 1, characterized in that, The top surface height of the normal concrete layer (6) is not higher than the bottom of the U-rib (21) of the steel bridge deck (2).

3. The construction method of the ballast area structure of the steel truss girder cable-stayed bridge according to claim 1, characterized in that, The side plate (5) is provided with a manhole (12), the top of the manhole (12) is higher than the top surface of the normal concrete layer (6), and the normal concrete layer (6) is poured through the manhole (12).

4. The construction method of the ballast area structure of the steel truss cable-stayed bridge according to any one of claims 1-3, characterized in that A number of first stiffening ribs (4) are arranged above the bottom plate (3), and a number of second stiffening ribs (13) are arranged on the inner side of the side plate (5).

5. The construction method of the ballast area structure of the steel truss girder cable-stayed bridge according to claim 4, characterized in that A number of the first stiffening ribs (4) are arranged along the longitudinal bridge direction, and the first stiffening ribs (4) are connected to the corresponding joint plates (11) of the crossbeams (1) of the bridge deck system by first high-strength bolts (8); both longitudinal bridge sides of the side plate (5) are respectively connected to the web stiffening plates of the two crossbeams (1) of the bridge deck system by second high-strength bolts (10).

6. The construction method of the ballast area structure of the steel truss girder cable-stayed bridge according to claim 4, characterized in that The thickness of the bottom plate (3) is 10-16 mm, and the thickness of the side plate (5) is greater than or equal to 10 mm.

7. The construction method of the ballast area structure of the steel truss girder cable-stayed bridge according to claim 1, characterized in that, In step S2, the normal concrete layer (6) is poured through the manhole (12), and the manhole (12) is arranged on the side plate (5); During the pouring process of the second layer (62), when the height of the poured normal concrete is higher than the bottom of the manhole (12), the manhole (12) is gradually blocked upward to pour the normal concrete until the pouring of the second layer (62) is completed, and then the manhole (12) is completely blocked; After the strength of the second layer (62) reaches the standard, a pouring hole is opened in the steel bridge deck (2), and the self-compacting cement mortar layer (7) is poured through the pouring hole until the closed structure is filled, and then the pouring hole is closed.

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