Self-balancing buckling and hanging system for weak bridge pier arch rib of through arch bridge in plain soft foundation area

Abstract

The invention discloses a plain soft foundation area through type arch bridge weak pier arch rib self-balancing buckling system which comprises two sets of ejector rods arranged in the length direction of a bridge, the ejector rods penetrate through an ejector rod limiting truss, the ejector rod limiting truss is fixedly connected with an approach bridge cover beam below a T-shaped beam, back cable anchor boxes are fixed to the ejector rods, and the back cable anchor boxes are fixedly connected with the T-shaped beam. A lower anchoring point of the back cable is fixed on the back cable anchor box, an ejector rod end limiting device is arranged on the top face of an end cross beam, close to the main bridge, of the approach bridge, and the tail end of the ejector rod abuts against the ejector rod end limiting device on the end cross beam. According to the structure, due to the fact that the ejector rods are limited by the ejector rod limiting trusses, the ejector rods are prevented from floating up and floating up under the pulling force effect of the back cables, deformation of the ejector rods in the length direction is not restrained, and therefore thrust generated by deformation of the ejector rods is prevented from being finally transmitted to the lowermost weak bridge pier through the approach bridge T beam; therefore, the weak bridge pier may be damaged under the action of large thrust. By means of the structure, large-area new temporary facilities can be avoided, and occupied land and resource waste are reduced.

Description

Technical Field

[0001] The invention relates to a self-balancing buckling system for weak piers and arch ribs of a through-type arch bridge in a plain soft foundation area, belonging to the technical field of bridge structures. Background Art

[0002] During the construction of a bottom-supported arch bridge, if the area it crosses (such as a water source, a historical and cultural relic protection area, or a navigation channel) cannot be supported by a bracket to push the upper arch frame, a buckle tower structure is required. The arch rib segments are stabilized by the buckle hanging system connected to the buckle tower structure. At the same time, in order to ensure the verticality of the buckle tower structure, a back cable is required. The upper end of the back cable is anchored to the tower frame and the lower end is anchored to the anchor. When building a bridge in a mountainous area, the lower end of the back cable can be anchored to the rock mass with an anchor cable structure. When building such a bridge in a plain area, only gravity anchors can be applied on the ground on the approach side of both banks to fix the back cable. However, when the ground on the approach bridge side is a soft foundation structure (such as silty soil layer) and there are large areas of basic farmland near the bridge site, the construction of temporary gravity anchors requires "large-scale excavation and construction", which not only increases the workload but also causes a lot of damage to the farmland. In this case, what kind of structure should be used to achieve back cable fixation while avoiding damage to the farmland has become a technical problem that the industry urgently needs to solve. Summary of the invention

[0003] The purpose of the present invention is to provide a self-balancing buckling system for weak pier arch ribs of a bottom-supported arch bridge in a plain soft foundation area. By arranging a top rod and a top rod limiting truss on the approach bridge, the back cable is fixed on the top rod, and the back cable can be anchored without the need for gravity anchors, and the whole process can avoid damage to the land on the approach bridge side.

[0004] The technical solution of the present invention is as follows: a self-balancing buckling system for the arch rib of a weak pier of a bottom-supported arch bridge in a plain soft foundation area, comprising two groups of top rods arranged along the length direction of the bridge, the two groups of top rods are respectively placed on the left and right sides of the surface of the T-beam of the approach bridge, the top rods pass through a top rod limiting truss, the top rod limiting truss passes through the T-beam of the approach bridge through a fixing device and is vertically tied to the approach bridge cap beam below it, a back cable anchor box is fixed on the top rod, the lower anchor point of the back cable is fixed on the back cable anchor box, and the upper anchor point is fixed on the buckling tower, a top rod end limit device is arranged on the top surface of the end cross beam of the approach bridge close to the main bridge, and the end of the top rod abuts against the top rod end limit device on the end cross beam.

[0005] In the aforementioned self-balancing buckle system for the weak pier and arch rib of the bottom-supported arch bridge in the soft foundation area on the plain, the fixing device includes embedded steel bundle anchors and prestressed steel bundles in the approach bridge cap beam, vertical holes are reserved on the cross beam at the end of the approach bridge T-beam, the prestressed steel bundle vertically passes through the approach bridge T-beam and is anchored on the top rod limiting truss, and the tensioning end of the prestressed steel bundle is located on the top surface of the top rod limiting truss.

[0006] In the aforementioned self-balancing buckling system for the weak pier arch rib of the bottom-supported arch bridge in the plain soft foundation area, the top rod limiting truss includes a top pressure beam, and two parallel bottom pad beams are arranged below the top pressure beam. The top pressure beam and the two bottom pad beams, as well as the two bottom pad beams, are fixedly connected together through connecting rods. The connecting rods divide the top rod limiting truss into a plurality of penetration cavities, and the top rod passes through the penetration cavities; a plurality of prestressed steel bundle penetration holes are arranged on the top pressure beam.

[0007] In the aforementioned self-balancing buckle system for the weak pier arch rib of the bottom-supported arch bridge in the plain soft foundation area, polytetrafluoroethylene gaskets are arranged on the top pressure beam, bottom cushion beam and connecting rod at the penetration cavity; the top pressure beam and the bottom cushion beam, as well as the two bottom cushion beams, are fixedly connected together via oblique reinforcing rods.

[0008] In the aforementioned self-balancing buckling system of the weak pier and arch rib of the bottom-supported arch bridge in the soft foundation area of ​​the plain, a top rod transverse stabilization frame is also provided in the middle span area of ​​the T-beam of the approach bridge. The bottom of the top rod transverse stabilization frame is fixedly connected with the embedded parts on the surface of the T-beam of the approach bridge. The structure of the top rod transverse stabilization frame is similar to the structure of the top rod limiting truss, and the top rod also passes through the top rod transverse stabilization frame.

[0009] In the aforementioned weak pier and arch rib self-balancing buckle system of the through-type arch bridge in the plain soft foundation area, prestressed steel strand penetration holes are arranged on the top compression beams on both sides of each penetration cavity.

[0010] In the aforementioned self-balancing buckling system for weak pier arch ribs of bottom-supported arch bridges in plain soft foundation areas, the top rod is composed of a steel pipe and a steel box top rod with a square cross-section structure connected to each other, wherein the steel box top rod is arranged at the position of the top rod limiting truss.

[0011] In the aforementioned self-balancing buckling system for the weak pier arch rib of the bottom-supported arch bridge in the plain soft foundation area, the back cable anchor box includes a back cable anchor end at the lower end, and two connecting plates are connected to the back of the back cable anchor end. The connecting plates are inserted into the interior of the steel box top rod through two openings on the top surface of the steel box top rod, and the pin shaft passes through the steel box top rod and the connecting plate to connect the two together.

[0012] In the aforementioned self-balancing buckle system for the arch rib of the weak pier of the bottom-supported arch bridge in the plain soft foundation area, the steel box top rod includes a steel box top plate and a steel box bottom plate arranged in parallel, two steel box side plates and a steel box middle plate are arranged between the steel box top plate and the steel box bottom plate, and reinforcing steel plates are also connected to the steel box top plate, steel box bottom plate and steel box side plates in the middle of the steel box top rod.

[0013] In the aforementioned self-balancing buckle system for the weak pier and arch rib of the bottom-supported arch bridge in the plain soft foundation area, the top rod end limit device includes a main bridge end cross beam, and a plurality of top rod reaction frames are fixedly arranged on the top of the main bridge end cross beam, and the end of the top rod is against the top rod reaction frame; the buckle tower uses the arch bridge main pier cap as the foundation.

[0014] Beneficial effects of the present invention: Compared with the prior art, the present invention arranges a steel pipe top rod on the top surface of the approach bridge, the buckle tower of the buckle hanging system is arranged on the top surface of the main pier pedestal of the main bridge, and a top rod reaction frame (i.e., a top rod end limit device) is arranged on the cross beam at the end of the main bridge, so that the horizontal component of the anchoring of the lower end of the back cable of the arch rib buckle hanging system and the horizontal component of the buckle cable are balanced at the piers of the main bridge, reducing the unbalanced horizontal force of the main pier and making maximum use of the constructed permanent structure as a temporary structure for the construction of subsequent permanent structures.

[0015] Specifically, in the structure of the present invention, a top rod is arranged along the length direction of the approach bridge, and the top rod is inserted into a top rod limiting truss. The top rod limiting truss is fixed to the approach bridge T-beam and the approach bridge cover beam through a prestressed steel bundle, and then the back cable is connected and fixed to the top rod through a back cable anchor box. Since the top rod is limited by the top rod limiting truss, the top rod is prevented from floating upward under the tension of the back cable, and in the length direction, only a top rod end limiting device is arranged at the top rod end to limit it, and its deformation in the length direction is not constrained, thereby preventing the thrust generated by its deformation from being finally transmitted to the lowest pier through the approach bridge T-beam, causing the pier to be damaged under the action of a large thrust.

[0016] The structure of the present invention can avoid the construction of large-scale temporary facilities, reduce the occupation of cultivated land and waste of resources, realize the "permanent and temporary combination" construction, protect the environment, save resources, and reduce the construction cost of the industry. It has good promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the overall structure of the entire bridge; Figure 2 It is a structural schematic diagram of the present invention; Figure 3 for Figure 2 A schematic diagram of a top view structure; Figure 4 for Figure 3 A partial enlarged schematic diagram of Figure 5 for Figure 4 A single cross-sectional structural diagram of ; Figure 6 It is a schematic diagram of the connection structure between the steel box top rod and the top rod limiting truss; Figure 7 It is a schematic diagram of the top structure of the steel box top rod; Figure 8 for Figure 7 AA section view; Fig. 9 It is a top view of the top rod limiting truss; Fig.10 This is the elevation view of the top rod limiting truss; Fig.11 for Fig.10 BB section view; Fig.12 It is a structural schematic diagram of the back cable anchor box; Fig.13 Schematic diagram of the installation structure of the top rod lateral stabilizer frame.

[0018] Figure markings: 1-top rod, 2-approach bridge T-beam, 3-top rod limiting truss, 4-approach bridge cover beam, 5-back cable anchor box, 6-back cable, 7-prestressed steel bundle, 8-top pressure beam, 9-bottom cushion beam, 10-connecting rod, 11-prestressed steel bundle insertion hole, 12-PTFE gasket, 13-oblique reinforcement rod, 14-steel pipe, 15-steel box top rod, 16-back cable anchor end, 17-connecting plate, 18-pin shaft, 19-main bridge end cross beam, 20-top rod reaction frame, 21-steel box top plate, 22-steel box bottom plate, 23-steel box side plate, 24-steel box middle plate, 25-reinforced steel plate, 26-top rod lateral stabilization frame, 27-embedded parts, 28-opening. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0020] Embodiments of the present invention: A self-balancing buckle system for weak piers and arch ribs of a through arch bridge in a plain soft foundation area, such as Figure 1-13 As shown, it includes 2 groups of top rods 1 arranged along the length direction of the bridge. As shown in the figure, each group is composed of 3 top rods 1. The 2 groups of top rods 1 are respectively placed on the left and right sides of the surface of the approach bridge T-beam 2, and are respectively arranged corresponding to the two sides of the buckle tower. Each group of top rods 1 passes through a plurality of spaced top rod limiting trusses 3. Each top rod limiting truss 3 is arranged on the approach bridge T-beam 2 just above the approach bridge cover beam 4. The top rod limiting truss 3 passes through the approach bridge T-beam 2 through a fixing device and is vertically tied and fixedly connected with the approach bridge cover beam 4 located below it. A back cable anchor box 5 is fixed on the top rod 1, and the lower anchor point of the back cable 6 is fixed on the back cable anchor box 5, and the upper anchor point is fixed on the buckle tower. A top rod end limit device is arranged on the top surface of the end cross beam of the approach bridge close to the main bridge, and the end of the top rod 1 is against the top rod end limit device on the end cross beam.

[0021] In the structure of the present invention, a top rod 1 is provided along the length direction of the approach bridge, and the top rod 1 is inserted into the top rod limiting truss 3, and the top rod limiting truss 3 is fixed on the approach bridge T-beam 2 and the approach bridge cover beam 4. Since the top rod 1 is limited in the vertical direction by the top rod limiting truss 3, the top rod 1 is prevented from floating upward under the tension of the back cable 6, and in the length direction, only a top rod end limiting device is provided at the end of the top rod 1 to limit it. The deformation of the top rod 1 in the length direction is not constrained by the components, and the component of the tension of the back cable 6 in the horizontal direction finally acts directly on the top rod end limiting device at its head end through the top rod 1, and its thrust toward the main bridge is resisted by the top rod end limiting device. Since the deformation of the top rod 1 in the length direction is not constrained by any component, its thrust toward the main bridge will not be transmitted to the approach bridge T-beam 2, the approach bridge cover beam 4 and the piers under the approach bridge cover beam 4 through the components.

[0022] When the piers under the approach bridge are set in some areas with complex terrain, such as silt areas, the piers are relatively weak in their ability to withstand thrust. At this time, the piers are weak pier structures. The above-mentioned structure of the present invention can prevent the horizontal thrust borne by the top rod 1 from being transmitted to the weak piers and T-beams 2 and approach bridge cover beams 4 at the bottom, causing the weak piers and T-beams 2 and approach bridge cover beams 4 to be damaged under the action of a larger thrust.

[0023] The fixing device includes embedded steel bundle anchors and prestressed steel bundle 7 in the approach bridge cap beam 4, vertical holes are reserved on the end cross beams of the approach bridge T beam, and the prestressed steel bundle 7 vertically passes through the reserved vertical holes in the approach bridge T beam 2 and is anchored on the top rod limiting truss 3, and the tensioning end of the prestressed steel bundle 7 is located on the top surface of the top rod limiting truss 3. The fixed connection between the top rod limiting truss 3 and the approach bridge cap beam 4 and the approach bridge T beam 2 is achieved through this structure.

[0024] The top rod limiting truss 3 includes a top pressure beam 8, and two parallel bottom cushion beams 9 are arranged below the top pressure beam 8. The bottom cushion beams 9 are supported on the approach bridge T beam 2. The top pressure beam 8 and the two bottom cushion beams 9, as well as the two bottom cushion beams 9, are fixedly connected together through a connecting rod 10, so that the side of the top rod limiting truss 3 forms a triangular structure. The connecting rod 10 divides the top rod limiting truss 3 into three penetration cavities, and each penetration cavity corresponds to a top rod 1. The top rod 1 passes through the penetration cavity, and the bottom of the top rod 1 is supported on the bottom cushion beam 9, and the top is pressed by the top pressure beam 8, so as to achieve the vertical direction of the top rod 1. A plurality of prestressed steel beam penetration holes 11 are arranged on the top pressure beam 8 to fix the top rod limiting truss 3 from the top.

[0025] A polyfluoro gasket 12 is fixedly arranged on the top pressure beam 8, the bottom cushion beam 9 and the connecting rod 10 at the penetration cavity. The polyfluoro gasket 12 contacts the outer wall of the top rod 1. Because the top rod 1 will be deformed toward the main bridge under the tension of the back cable 6, the deformation will cause a slight displacement of the top rod 1. The polyfluoro gasket 12 is arranged to prevent the top rod 1 from directly contacting the top pressure beam 8, the bottom cushion beam 9 and the connecting rod 10, so as to prevent them from being worn, and to prevent excessive friction between them, which will affect the displacement of the top rod 1 toward the main bridge.

[0026] The top pressure beam 8 and the bottom cushion beam 9, as well as the two bottom cushion beams 9, are fixedly connected together via oblique reinforcing rods 13 to improve the overall strength of the top rod limiting truss 3 and prevent the top rod limiting truss 3 from being deformed after being subjected to the upward extrusion force of the top rod 1.

[0027] A top rod transverse stabilizing frame 26 is also provided in the middle span area of ​​the approach bridge T beam 2. The top rod transverse stabilizing frame 26 is provided in an area where no top rod limiting truss 3 is provided. The bottom of the top rod transverse stabilizing frame 26 is fixedly connected to the embedded part 27 on the surface of the approach bridge T beam 2. The structure of the top rod transverse stabilizing frame 26 is similar to that of the top rod limiting truss 3. The difference is that the top rod transverse stabilizing frame 26 does not need to be provided with a prestressed steel bundle penetration hole 11, and the top rod 1 also passes through the top rod transverse stabilizing frame 26. The top rod transverse stabilizing frame 26 is provided mainly to support the top rod 1 to prevent its bottom from contacting the surface of the approach bridge T beam 2, resulting in its horizontal displacement being hindered by the approach bridge T beam 2, and at the same time to prevent the surface of the approach bridge T beam 2 from being worn. In addition to playing a vertical limiting role, the top rod limiting truss 3 also plays a supporting role.

[0028] Prestressed steel bundle penetration holes 11 are provided on the top compression beams 8 on both sides of each penetration cavity, and six prestressed steel bundles 7 are provided corresponding to the three penetration cavities, so that each position of the top rod limiting truss 3 is firmly fixed.

[0029] The mandrel 1 is composed of a steel pipe 14 and a steel box mandrel 15 with a square cross section, and flange plates are provided at both ends of the steel pipe 14 and the steel box mandrel 15. After the bolts pass through the flange plates, two adjacent steel pipes 14 or adjacent steel pipes 14 and steel box mandrel 15 can be connected together. The steel box mandrel 15 is arranged at the position of the mandrel limiting truss 3. The reason why the steel box mandrel 15 with a square cross section is arranged is to ensure that the contact between the mandrel limiting truss 3 and the mandrel 1 is a surface-to-surface contact, so that the mandrel 1 can be better limited by the mandrel limiting truss 3.

[0030] The back cable anchor box 5 includes a back cable anchor end 16 at the lower end. The back cable anchor end 16 is composed of two parallel and spaced steel plates, which are densely covered with through holes. The back cable 6 can be anchored on the back cable anchor end 16 after passing through the through holes. Two connecting plates 17 are connected to the back of the back cable anchor end 16. The two connecting plates 17 and the back cable anchor end 16 form a U-shaped structure. The two connecting plates 17 are inserted into the steel box top rod 15 through two openings 28 opened on the top surface of the steel box top rod 15, and then the pin 18 passes through the steel box top rod 15 and the connecting plates 17 to connect the two together, thereby realizing the connection between the back cable anchor box 5 and the steel box top rod 15. The reason why the back cable anchor box 5 is set at the steel box top rod 15 is that the steel box top rod 15 is just set with a top rod limiting truss 3 to press it, and this place can best withstand the tension of the back cable 6.

[0031] The steel box top rod 15 includes a steel box top plate 21 and a steel box bottom plate 22 which are arranged in parallel. Two steel box side plates 23 and a steel box middle plate 24 are arranged between the steel box top plate 21 and the steel box bottom plate 22. A reinforcing steel plate 25 is also connected to the steel box top plate 21, the steel box bottom plate 22 and the steel box side plates 23 in the middle of the steel box top rod 15. Since the middle part of the steel box top rod 15 needs to be connected to the back cable anchor box 5 and needs to withstand a large tensile force, a reinforcing steel plate 25 is also arranged to improve its tensile resistance.

[0032] The ram end limiting device includes a main bridge end cross beam 19, and a plurality of ram reaction frames 20 are fixedly arranged on the top of the main bridge end cross beam 19. The end of the ram 1 is against the ram reaction frame 20, and the ram reaction frame 20 will transfer the thrust in the direction of the main bridge to the main bridge end cross beam 19, while both ends of the main bridge end cross beam 19 also bear the thrust in the direction of the approach bridge applied by the rib buckle back cable. The two thrusts are offset here, so that the horizontal force of the entire arch bridge structure is balanced.

[0033] The upper anchor point of the back cable 6 is fixed on the buckle tower, and the buckle tower uses the arch bridge main pier cap as a foundation.

Claims

1. The self-balancing buckle system for weak piers and arch ribs of through-type arch bridges in plain soft foundation areas is characterized by: The invention comprises two groups of top rods (1) arranged along the length direction of the bridge. The two groups of top rods (1) are respectively placed on the left and right sides of the surface of the approach bridge T-beam (2). The top rods (1) pass through the top rod limiting trusses (3). The top rod limiting trusses (3) pass through the approach bridge T-beam (2) through a fixing device and are vertically tied to the approach bridge cap beam (4) below it. A back cable anchor box (5) is fixed on the top rod (1). The lower anchor point of the back cable (6) is fixed on the back cable anchor box (5), and the upper anchor point is fixed on the buckle tower. A top rod end limiting device is arranged on the top surface of the end cross beam of the approach bridge close to the main bridge. The end of the top rod (1) abuts against the top rod end limiting device on the end cross beam.

2. The self-balancing buckle system for weak piers and arch ribs of through-type arch bridges in plain soft foundation areas according to claim 1 is characterized by: The fixing device comprises a pre-buried steel bundle anchor and a prestressed steel bundle (7) in the approach bridge cap beam (4); a vertical hole is reserved on the end cross beam of the approach bridge T-beam; the prestressed steel bundle (7) vertically passes through the approach bridge T-beam (2) and is anchored on the top rod limiting truss (3); the tensioning end of the prestressed steel bundle (7) is located on the top surface of the top rod limiting truss (3).

3. The self-balancing buckle system for weak piers and arch ribs of through-type arch bridges in plain soft foundation areas according to claim 2 is characterized by: The top rod limiting truss (3) comprises a top pressure beam (8), two parallel bottom cushion beams (9) are arranged below the top pressure beam (8), the top pressure beam (8) and the two bottom cushion beams (9), as well as the two bottom cushion beams (9) are fixedly connected together via a connecting rod (10), the connecting rod (10) divides the top rod limiting truss (3) into a plurality of penetration cavities, and the top rod (1) passes through the penetration cavities; a plurality of prestressed steel strand penetration holes (11) are arranged on the top pressure beam (8).

4. The self-balancing buckle system for weak piers and arch ribs of through-type arch bridges in plain soft foundation areas according to claim 3 is characterized by: A polytetrafluoroethylene gasket (12) is provided on the top pressure beam (8), the bottom cushion beam (9) and the connecting rod (10) at the penetration cavity; the top pressure beam (8) and the bottom cushion beam (9), as well as the two bottom cushion beams (9), are fixedly connected together via an oblique reinforcing rod (13).

5. The self-balancing buckle system for weak piers and arch ribs of through-type arch bridges in plain soft foundation areas according to claim 3 is characterized by: A top rod transverse stabilizing frame (26) is also provided in the middle span area of ​​the approach bridge T-beam (2). The bottom of the top rod transverse stabilizing frame (26) is fixedly connected to an embedded part (27) on the surface of the approach bridge T-beam (2). The structure of the top rod transverse stabilizing frame (26) is similar to that of the top rod limiting truss (3). The top rod (1) also passes through the top rod transverse stabilizing frame (26).

6. The self-balancing buckle system for weak piers and arch ribs of through-type arch bridges in plain soft foundation areas according to claim 3 is characterized by: Prestressed steel strand penetration holes (11) are provided on the top compression beams (8) on both sides of each penetration cavity.

7. The self-balancing buckle system for weak piers and arch ribs of through-type arch bridges in plain soft foundation areas according to claim 3 is characterized by: The top rod (1) is composed of a steel pipe (14) and a steel box top rod (15) having a square cross-section, which are connected to each other, wherein the steel box top rod (15) is arranged at the position of the top rod limiting truss (3).

8. The self-balancing buckling system for weak piers and arch ribs of through-type arch bridges in plain soft foundation areas according to claim 7 is characterized by: The back cable anchor box (5) comprises a back cable anchor end (16) at the lower end, and two connecting plates (17) are connected to the back of the back cable anchor end (16). The connecting plates (17) are inserted into the interior of the steel box top rod (15) through two openings (28) on the top surface of the steel box top rod (15), and the pin shaft (18) passes through the steel box top rod (15) and the connecting plates (17) to connect the two together.

9. The self-balancing buckle system for weak piers and arch ribs of through-type arch bridges in plain soft foundation areas according to claim 7 is characterized by: The steel box top rod (15) comprises a steel box top plate (21) and a steel box bottom plate (22) arranged in parallel, two steel box side plates (23) and a steel box middle plate (24) are arranged between the steel box top plate (21) and the steel box bottom plate (22), and a reinforcing steel plate (25) is also connected to the steel box top plate (21), the steel box bottom plate (22) and the steel box side plates (23) in the middle of the steel box top rod (15).

10. The self-balancing buckling system for weak piers and arch ribs of through arch bridges in plain soft soil areas according to claim 1 is characterized by: The push rod end limit device comprises a main bridge end cross beam (19), a plurality of push rod reaction frames (20) are fixedly arranged on the top of the main bridge end cross beam (19), and the end of the push rod (1) abuts against the push rod reaction frame (20); the buckle tower uses the arch bridge main pier cap as a foundation.

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