A voided arch bridge system connected by UHPC wet joints and its construction method

Abstract

An open-spandrel arch bridge system connected by UHPC wet joints and a construction method thereof. The system includes a concrete foundation, abutments, arch seats arranged on the foundation soil, a prefabricated and assembled rib arch arranged on the arch seats, spandrel piers composed of capping beams, precast columns and bottom beams, and deck slabs; the prefabricated and assembled rib arch is prefabricated in three sections, and the precast segments are connected by UHPC wet joints; the main arch ring is constructed by the cable-suspended erection method, and then the superstructure on the arch is constructed on the main arch ring; the present invention applies UHPC wet joints to the connection between precast arch ring segments, gives full play to the superior performance of UHPC, can effectively reduce the lap length of the reserved steel bars at the joints, enhance the bonding strength between each arch ring segment and the wet joint segment, and ensure the performance of the components under normal working conditions and extreme load actions; the prefabricated and assembled construction can greatly improve the construction efficiency and shorten the construction period.

Description

Technical Field

[0001] The present invention relates to the technical field of arch bridges, and particularly to a spandrel arch bridge system connected by UHPC wet joints and a construction method thereof. Background Art

[0002] Arch bridges are one of the main structural forms of highway bridges in China. Among them, reinforced concrete arch bridges make full use of the mechanical advantages of concrete and steel, effectively improving the economic performance of arch bridges and expanding their application scope. They are widely used in mountainous areas across valleys in China. However, since the main arch ring cannot bear force before closure, most of the main arch ring construction is carried out by means of erecting scaffolds and casting or masonry on site. The construction process is relatively cumbersome and often requires processes such as foundation treatment, scaffold erection, and scaffold preloading. Foundation treatment is troublesome in areas with poor geological conditions, and accidents are likely to occur during scaffold removal. Moreover, scaffolds cannot be erected in areas that need to cross canyons, rivers, etc., which limits the application scope of reinforced concrete arch bridges. Compared with beam bridge construction, the degree of mechanization is low, dust and noise pollution are serious, the development progress of prefabricated construction is lagging behind, and the technological innovation of construction methods is slow, which is not conducive to the development of bridge industrialization and prefabrication.

[0003] With the continuous and rapid development of the national economy, the improvement of energy conservation and environmental protection requirements in engineering construction, and the continuous increase of labor costs, the research and application of concrete prefabricated construction technology in China have gradually heated up. Promoting bridge prefabricated construction has become an irresistible trend. Bridge prefabricated construction can save resources, reduce pollution, improve the working conditions of workers, and reduce the labor intensity of workers in the construction industry, which also meets the requirements of new industrialization, informatization, and greening, and is an inherent need for China's economic development. Therefore, finding a prefabricated and assembled arch bridge structure with fast construction, strong bearing capacity, and wide application scope has become an important task for engineering and technical personnel. Summary of the Invention

[0004] In response to the transformation and upgrading of the bridge engineering construction industry from a traditional industry to factory production, prefabricated construction, and green construction, and to solve the problems of complex construction technology and long construction period of arch bridges, the purpose of the present invention is to provide a spandrel arch bridge system connected by UHPC wet joints and a construction method thereof. Applying ultra-high performance concrete UHPC to the arch bridge system can reduce the length of the wet joint section and the anchorage length of the reinforcement at the joint, enhance the flexural performance of the joint, reduce on-site construction time, and optimize the traditional spandrel arch bridge structure and construction method under medium and small spans.

[0005] To achieve the above object, the technical solution of the present invention is realized as follows:

[0006] An open-spandrel arch bridge system connected by UHPC wet joints, comprising a concrete foundation 1 arranged on the foundation soil layer, an arch abutment 2 and a bridge abutment 3 arranged on the concrete foundation 1, an arch ring 4 assembled by precast reinforced concrete is arranged on two arch abutments 2, and a spandrel pier 6 and a bridge deck 7 are arranged on the arch abutment 2;

[0007] The arch ring 4 is divided into three segments, and is spliced by side segments 10 on both sides and a middle segment 11 through a UHPC wet joint 5. Both the side segments 10 and the middle segment 11 are composed of two arch ribs 8 and a cross tie beam 9, and the cross section of the arch rib 8 is rectangular.

[0008] The UHPC wet joint 5 is formed by pouring ultra-high performance concrete. The connection structures on both sides of the UHPC wet joint 5 are diamond-shaped. The main reinforcement of the side segments 10 and the middle segment 11 extends out and is welded on one side. The compressive strength of the UHPC material is not less than 130 Mpa, and the steel fiber content is not less than 0.02%. To ensure the bearing capacity and durability requirements of the wet joint, the length L of the UHPC wet joint 5 is calculated and determined according to the following formula:

[0009]

[0010] In the formula:

[0011] L is the length of the UHPC wet joint (mm);

[0012] f is the ultimate tensile strength of the longitudinal reinforcement (Mpa);

[0013] c is the concrete cover thickness (mm);

[0014] d is the diameter of the reinforcement (mm);

[0015] When the wet joint length calculated according to the above formula is less than 10d, 10d is taken as the UHPC wet joint length.

[0016] The structures of the bridge abutment 3 and the arch abutment 2 are cast with ordinary reinforced concrete materials. The embedded reinforcement 12 of the arch abutment 2 extends out and is welded at the butt joint with the side segment 10, and is welded with the reinforcement of the side segments 10 on both sides after the arch ring 4 is closed and connected by pouring ordinary concrete.

[0017] The spandrel pier 6 is cast with ordinary reinforced concrete materials and is connected to the arch ring 4 through a bottom beam 14. A bottom beam core 16 is arranged at the lower end of the spandrel pier 6, and the longitudinal reinforcement extends out from the periphery of the bottom beam core and is welded with the reinforcement extending out of the bottom beam 14 and then concrete is poured; a notch 19 is precast at the upper end of the spandrel pier 6, and the longitudinal reinforcement of the column in the notch 19 is welded with the reinforcement extending out from the bottom surface of the capping beam 17 and then sealed with high-strength mortar.

[0018] Based on the above, a construction method for an open-spandrel precast assembled arch bridge system connected by ultra-high performance concrete (UHPC) wet joints:

[0019] Step 1: Excavate the foundation pit, construct the concrete foundation 1, and pour the arch seats 2 and the abutments 3; simultaneously precast the arch ribs 8;

[0020] Step 2: Move the precast arch ribs 8 to the site through transportation equipment, lift the side segments 10 to the installation positions, and temporarily fix the arch ribs 8 using buckles. Lift the middle segments 11, adjust the arch axis and elevation, chisel off the surface concrete at the joints by 5 - 10 mm, clean it thoroughly, keep the surface wet, weld the main bars of the wet joints, with the single-sided welding length not less than 10d, where d is the diameter of the steel bar (mm), formwork and pour the UHPC wet joints 5. After completion of closure, pour the cross girders 9, weld the reserved steel bars 12 of the arch seats 2 and the main bars of the arch ring 4, and pour the arch foot concrete 13 to complete the closure of the hinge;

[0021] Step 3: Weld the steel bars of the bottom beam 14 and the precast column steel bars, and pour the column bottom concrete; weld the column steel bars in the notch 19 and the extended steel bars 18 from the bottom surface of the capping beam, and seal the notch 19 with high-strength mortar. The length of the steel bar welding shall meet the specification requirements;

[0022] Step 4: Lift the deck slabs 7 to complete the construction of the bridge deck system and add railings.

[0023] The present invention applies UHPC materials to the joint structure of the open-spandrel arch bridge, making full use of the advantages of UHPC such as high compressive and flexural strength, super toughness, good durability, and small shrinkage, reducing problems such as easy cracking and damage at the joints of traditional arch bridges due to the low bond strength between the cast-in-place concrete and the original concrete cross-section at the joints between segments, effectively ensuring the interface connection strength and the cross-section impermeability; and the UHPC material can reach sufficient strength in a relatively short curing time. Combined with the prefabricated and assembled construction method, it can greatly improve the construction efficiency, shorten the construction period, and obtain greater economic benefits. Therefore, the invention has great practical value and good economic benefits, especially having a broad application prospect in the field of arch bridge construction technology. Brief Description of the Drawings

[0024] Figure 1 It is a structural schematic diagram of the open-spandrel arch bridge system connected by UHPC wet joints according to the present invention.

[0025] Figure 2 It is a schematic diagram of each precast segment of the main arch ring of the present invention.

[0026] Figure 3 It is a cross-sectional schematic diagram of the arch rib of the precast arch ring segment of the present invention.

[0027] Figure 4 It is a schematic diagram of the wet joint structure of the precast arch ring segment of the present invention.

[0028] Figure 5It is a schematic diagram of the arch foot section joint structure of the present invention.

[0029] Figure 6a This is a schematic diagram of the joint structure of the prefabricated column and the bottom beam of the present invention.

[0030] Figure 6b This is a cross-sectional view of the joint between the prefabricated column and the bottom beam of the present invention.

[0031] Figure 7 This is a schematic diagram of the joint structure of the prefabricated column and the cap beam of the present invention.

[0032] Figure 8a - Figure 8f The present invention is a schematic diagram of the construction process of a hollow prefabricated assembled arch bridge system using UHPC wet joint connection.

[0033] Among them: 1. Concrete foundation; 2. Arch seat; 3. Abutment; 4. Arch ring; 5. UHPC wet joint; 6. Pier pier; 7. Bridge slab; 8. Arch rib; 9. Transverse tie beam; 10. Side section; 11. Middle section; 12. Steel bars; 13. Arch foot concrete; 14. Bottom beam; 15. Wet joint between bottom beam and pier pier; 16. Bottom beam grinding core; 17. Cap beam; 18. Steel bars extending from the bottom surface of the cap beam; 19. Notch. DETAILED DESCRIPTION

[0034] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0035] like Figure 1 As shown, a hollow arch bridge system using UHPC wet joint connection includes a concrete foundation 1 set on the foundation soil layer, an arch seat 2 and abutment 3 set on the foundation 1, a reinforced concrete prefabricated arch ring 4 set on the two arch seats 2, and a pier 6 and a bridge slab 7 are set on the arch seat 2.

[0036] like Figure 2 , Figure 3 As shown, the arch ring 4 is divided into three sections, which are formed by side sections 10 and a middle section 11 on both sides being spliced together through UHPC wet joints 5. The side section 10 and the middle section 11 are both composed of two arch ribs 8 and a transverse tie beam 9, wherein the cross section of the arch rib 8 is a rectangle.

[0037] like Figure 4 As shown, the UHPC wet joint 5 is formed by pouring ultra-high performance concrete. The connection structure on both sides of the wet joint 5 is a rhombus. The main reinforcement of the side section 10 and the middle section 11 is extended and welded on one side. The compressive strength of the UHPC material is not less than 130Mpa, and the steel fiber content is not less than 0.02%. In order to ensure the bearing capacity and durability requirements of the wet joint, the length L of the UHPC wet joint 5 can be calculated and determined according to the following formula:

[0038]

[0039] In the formula:

[0040] L is the length of the UHPC wet joint (mm);

[0041] f is the ultimate tensile strength of the longitudinal reinforcement (Mpa);

[0042] c is the concrete cover thickness (mm);

[0043] d is the diameter of the reinforcement (mm);

[0044] When the wet joint length calculated according to the above formula is less than 10d, 10d is taken as the UHPC wet joint length.

[0045] As Figure 5 shown, the structures of the abutment 3 and the arch seat 2 are cast with ordinary reinforced concrete materials. The embedded reinforcement 12 of the arch seat 2 extends and is welded at the butt joint with the side section 10. After the arch ring 4 is closed, it is welded with the reinforcement of the two side sections 10 and connected by casting ordinary concrete.

[0046] As Figure 6a , Figure 6b , Figure 7 shown, the spandrel pier 6 is cast with ordinary reinforced concrete materials and is connected to the arch ring 4 through the bottom beam 14. A bottom beam core 16 is arranged at the lower end of the spandrel pier 6. The longitudinal reinforcement extends from the periphery of the bottom beam core and is welded to the reinforcement extending from the bottom beam 14, and then concrete is cast; a notch 19 is precast at the upper end of the spandrel pier 6. The longitudinal reinforcement of the column in the notch 19 is welded to the reinforcement extending from the bottom surface of the capping beam 17 and then sealed with high-strength mortar.

[0047] Referring to Figure 8a - Figure 8f , a construction method of an open-spandrel precast segmental arch bridge system using ultra-high performance concrete (UHPC) wet joints includes the following steps:

[0048] Step 1: Remove the obstacles around the bridge site to create a working surface for construction; excavate the foundation pit, construct the foundation 1, and cast the arch seat 2 and the abutment 3; conduct a trial pull of the ground anchor, perform a counter-tensioning with the buckle, and conduct a trial lift of the main cable system; precast the arch rib 8 synchronously.

[0049] Step 2: Move the precast arch rib 8 to the site through transportation equipment, lift the side section 10 to the installation position, and temporarily fix the arch rib 8 using the buckle. Lift the middle section 11, adjust the arch axis and elevation, chisel off the surface concrete at the joint by 5 - 10 mm, clean it, keep the surface wet, weld the main reinforcement of the wet joint, with the single-sided welding length not less than 10d, where d is the diameter of the reinforcement (mm), formwork and pour the UHPC wet joint 5, and pour the cross beam 9 after closure; weld the reserved reinforcement 12 of the arch seat 2 and the main reinforcement of the arch ring 4, and pour the arch foot concrete 13 to complete the closure of the hinge.

[0050] Step 3: Weld the steel bars of the bottom beam 14 and the abdominal hole pier 6, and pour concrete at the wet joint 15 between the bottom beam and the abdominal hole pier; weld the steel bars in the notch 19 and the steel bars extending from the bottom surface of the capping beam 18, and seal the notch 19 with high-strength mortar.

[0051] Step 4: Hoist the bridge deck slab 7, complete the construction of the bridge deck system and add railings.

Claims

1. A voided arch bridge system connected by UHPC wet joints, comprising a concrete foundation (1) arranged on a foundation soil layer, an arch abutment (2) and a bridge abutment (3) arranged on the concrete foundation (1), an arch ring (4) prefabricated and assembled with reinforced concrete is arranged on two arch abutments (2), and a spandrel pier (6) and a deck slab (7) are arranged on the arch abutment (2), characterized in that, The arch ring (4) is divided into three sections, which are formed by splicing side sections (10) and a middle section (11) on both sides through UHPC wet joints (5), and the side sections (10) and the middle section (11) are both composed of two arch ribs (8) and a transverse tie beam (9), wherein the cross section of the arch rib (8) is rectangular; The UHPC wet joint (5) is formed by pouring ultra-high performance concrete. The connection structure on both sides of the UHPC wet joint (5) is a rhombus. The main reinforcement of the side section (10) and the middle section (11) is extended and welded on one side. The compressive strength of the UHPC material is not less than 130Mpa, and the steel fiber content is not less than 0.02%. In order to ensure the bearing capacity and durability requirements of the wet joint, the length L of the UHPC wet joint (5) is calculated and determined according to the following formula: Where: L is the length of UHPC wet joint (mm); f is the ultimate tensile strength of the longitudinal reinforcement (Mpa); c is the thickness of the concrete cover (mm); d is the diameter of the steel bar (mm); When the wet joint length calculated by the above formula is less than 10d, take 10d as the UHPC wet joint length; The abutment (3) and the arch seat (2) are cast with ordinary reinforced concrete materials. The pre-buried steel bars (12) of the arch seat (2) extend out and are welded at the joint with the side section (10). After the arch ring (4) is closed, it is welded with the steel bars of the side sections (10) on both sides and cast with ordinary concrete for connection. The pier (6) is cast with ordinary reinforced concrete material and connected to the arch ring (4) through a bottom beam (14). A bottom beam grinding core (16) is arranged at the lower end of the pier (6). Longitudinal steel bars extend from the periphery of the bottom beam grinding core and are welded to the steel bars extending from the bottom beam (14) before concrete is cast. A notch (19) is prefabricated at the upper end of the pier (6). The longitudinal steel bars of the columns in the notch (19) are welded to the steel bars extending from the bottom surface of the cap beam (17) and then sealed with high-strength mortar.

2. The construction method of a voided arch bridge system connected by UHPC wet joints according to claim 1, characterized in that The following steps are involved: Step 1: excavation of foundation pit, construction of concrete foundation (1), pouring of arch seat (2) and abutment (3); simultaneous prefabrication of arch rib (8); Step 2: Move the prefabricated arch rib (8) to the site by means of transportation equipment, hoist the side section (10) to the installation position, and temporarily fix the arch rib (8) with a buckle, hoist the middle section (11), adjust the arch axis and elevation, chisel off 5 to 10 mm of the surface concrete at the joint, clean it, keep the surface moist, weld the main reinforcement of the wet joint, and the single-sided welding length is not less than 10 d, where d is the diameter of the steel bar (mm), support the formwork and cast the UHPC wet joint (5), cast the transverse tie beam (9) after closing, weld the steel bars (12) reserved for the arch seat (2) and the main reinforcement of the arch ring (4), and cast the arch foot concrete (13) to complete the hinge closure; Step 3: Weld the steel bars of the bottom beam (14) and the prefabricated column steel bars, and pour concrete at the bottom of the column; weld the column steel bars in the notch (19) and the steel bars (18) protruding from the bottom of the cap beam, and seal the notch (19) with high-strength mortar. The welding length of the steel bars must meet the requirements of the specification; Step 4: hoist the bridge deck (7), complete the bridge deck construction and add railings.

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