Pre-tensioning method UHPC-pi beam structure

Abstract

The utility model discloses a pre-tensioning method UHPC-Pi beam structure, which relates to the technical field of precast beams, and comprises single beam components and a connecting mechanism, the single beam components are symmetrically arranged, the single beam components are arranged in a T shape, each single beam component is composed of a panel, a web and a horseshoe plate, the top end of the horseshoe plate is fixedly connected with the bottom end of the panel, and the connecting mechanism is fixedly connected with the web. The bottom end of the horseshoe plate is fixedly connected with the top end of the web plate, a first reinforcing mechanism is arranged between the panel and the horseshoe plate, a second reinforcing mechanism is arranged between the horseshoe plate and the web plate, and the connecting mechanism is arranged between the single beam assemblies. The two single-beam assemblies are connected through the connecting mechanism, so that the two T-shaped single-beam assemblies are combined into the pi shape, the pi-shaped beam structural design reduces the material consumption, the structural appearance is lighter and more attractive, transportation and installation are convenient, the characteristics of high strength, high durability and high corrosion resistance of UHPC materials are fully utilized, the later maintenance cost of a beam body is reduced, and the construction cost is reduced. The service life of the beam body is greatly prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of prefabricated beams, in particular to a pre-tensioned UHPC-π beam structure. Background Art

[0002] Precast beam structures used in conventional bridge applications usually adopt two tensioning processes: ordinary reinforced concrete post-tensioning and pre-tensioning. The post-tensioning tensioning process is suitable for large prestressed concrete structures and cast-in-place structures at the construction site, and the pre-tensioning tensioning process is suitable for small prestressed concrete components produced in factories. Because ordinary reinforced concrete prestressed structures have a large number of steel bars, a large beam body weight, and high transportation and installation requirements, large equipment is required to complete transportation and installation during the hoisting stage, and there is also a high safety risk. From the perspective of completed operation, conventional reinforced concrete precast beams have poor durability, steel bars are prone to rust, the structural bearing capacity is reduced, the operation and maintenance workload is large, and the maintenance cost is high. For this reason, we propose a pre-tensioned UHPC-π beam structure. Utility Model Content

[0003] The purpose of the utility model is to provide a pre-tensioned UHPC-π beam structure to solve the problems raised in the above background technology.

[0004] To achieve the above purpose, the utility model provides the following technical solution: a pre-tensioned UHPC-π beam structure, comprising:

[0005] A single beam assembly, wherein the single beam assembly is symmetrically arranged, the single beam assembly is T-shaped, and the single beam assembly consists of a panel, a web and a horseshoe plate, the top end of the horseshoe plate is fixedly connected to the bottom end of the panel, the bottom end of the horseshoe plate is fixedly connected to the top end of the web, a first reinforcing mechanism is arranged between the panel and the horseshoe plate, and a second reinforcing mechanism is arranged between the horseshoe plate and the web;

[0006] A connecting mechanism is arranged between the single beam components.

[0007] Preferably, the connection mechanism comprises a splicing plate, one side of the splicing plate is connected to one of the panels, and the other side of the splicing plate is connected to another of the panels.

[0008] Preferably, the lengths of the panel and the splicing plate are both 10 meters, the thicknesses of the panel and the splicing plate are both 0.09 meters, the width of the panel is 0.9 meters, the width of the splicing plate is 0.46 meters, and the thickness of the panel is 0.1 meters.

[0009] Preferably, the first reinforcement mechanism includes a first chamfer, and the first chamfer is arranged at the connection between the panel and the horseshoe plate, and the size of the first chamfer is 10 meters × 0.135 meters × 0.05 meters.

[0010] Preferably, the second reinforcement mechanism includes a second chamfer, and the second chamfer is arranged at the connection between the horseshoe plate and the web plate, and the size of the second chamfer is 10 meters × 0.135 meters × 0.05 meters.

[0011] Preferably, a third chamfer is provided on both sides of the bottom end of the web, and the size of the third chamfer is 10 m×0.025 m×0.025 m.

[0012] Technical effects and advantages of the utility model:

[0013] The utility model connects two single beam components through a connecting mechanism, so that the two T-shaped single beam components are combined into a π-shaped structure. The structural design of the π-shaped beam reduces the material consumption, makes the structure appearance lighter and more beautiful, and is convenient for transportation and installation. It fully utilizes the high strength, high durability and high corrosion resistance of UHPC materials, reduces the later maintenance costs of the beam body, and greatly improves the service life of the beam body. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the front structure of the utility model.

[0015] In the figure: 101, single beam assembly; 201, spliced ​​plate; 301, panel; 302, web; 303, horseshoe plate; 401, first chamfer; 402, second chamfer; 501, third chamfer. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0017] The utility model provides Figure 1A pre-tensioned UHPC-π beam structure shown includes a single beam component 101 and a connecting mechanism. The single beam component 101 is symmetrically arranged and T-shaped. The single beam component 101 is composed of a panel 301, a web 302 and a horseshoe plate 303. The top of the horseshoe plate 303 is fixedly connected to the bottom of the panel 301, and the bottom of the horseshoe plate 303 is fixedly connected to the top of the web 302. A first reinforcing mechanism is arranged between the panel 301 and the horseshoe plate 303, and a second reinforcing mechanism is arranged between the horseshoe plate 303 and the web 302. Two single beam components 101 are connected by the connecting mechanism, so that two T-shaped single beam components 101 are combined into a π-shaped structure. The structural design of the π-shaped beam reduces the amount of materials used, makes the structure more lightweight and beautiful, and is easy to transport and install. It fully utilizes the high strength, high durability and high corrosion resistance of UHPC materials, reduces the later maintenance costs of the beam body, and greatly improves the service life of the beam body.

[0018] The connecting mechanism is arranged between the single beam components 101, and the connecting mechanism includes a splicing plate 201. One side of the splicing plate 201 is connected to one of the panels 301, and the other side of the splicing plate 201 is connected to another one of the panels 301. The two panels 301 are connected by the splicing plate 201 to form a π beam. The beam structure is designed without web reinforcement. Some internal steel bars are set as embedded steel bars, which are distributed in the top panel and the joints. The prestressed steel strand adopts φ15.2 mm high-strength and low-relaxation steel strand. The pre-tensioned double "T" beam is designed with 16 steel strands each, and the tensioning force of a single steel strand is N=182KN.

[0019] The lengths of the panel 301 and the splicing plate 201 are both 10 meters, the thicknesses of the panel 301 and the splicing plate 201 are both 0.09 meters, the width of the panel 301 is 0.9 meters, the width of the splicing plate 201 is 0.46 meters, and the thickness of the panel 301 is 0.1 meters.

[0020] Among them, the first reinforcement mechanism includes a first chamfer 401, which is arranged at the connection between the panel 301 and the horseshoe plate 303, and the size of the first chamfer 401 is 10 meters × 0.135 meters × 0.05 meters. The second reinforcement mechanism includes a second chamfer 402, which is arranged at the connection between the horseshoe plate 303 and the web 302, and the size of the second chamfer 402 is 10 meters × 0.135 meters × 0.05 meters. The connection strength between the panel 301 and the horseshoe plate 303 and between the horseshoe plate 303 and the web 302 is increased by the first chamfer 401 and the second chamfer 402, so that the strength of the π beam is higher and it is more stable to use. Among them, third chamfers 501 are opened on both sides of the bottom end of the web 302, and the size of the third chamfer 501 is 10 meters × 0.025 meters × 0.025 meters.

[0021] The construction method of π beam is as follows:

[0022] The entire π beam is prefabricated in the factory building. First, the tensioning pedestal is built, and then the single "T" structure is prefabricated by the pre-tensioning method. After steaming and curing, the two single "T"s are spliced ​​into a π beam in the form of a joint. After the joint curing is completed, it is transported to the site for installation. The tensioning pedestal includes an enlarged pedestal foundation, a force transfer column, a steel beam, a steel anchor box, etc. The enlarged pedestal foundation and the force transfer column adopt C30 reinforced concrete structure. The enlarged foundation of the pedestal end is 150 cm × 170 cm × 250 cm, and the cross-sectional size of the force transfer column is 50 cm × 60 cm. In order to prevent the force transfer column from becoming unstable, a connecting ground beam is set every 5 meters of the force transfer column, and there are 3 ground beams in the middle. The cross-sectional size of the ground beam is 20 cm × 40 cm. The bottom plate of the pedestal adopts a customized steel formwork, and the tensioning beam uses a steel box beam welded from Q345 steel plates. The beam size is 56 cm × 90 cm × 270 cm.

[0023] The controlled tensioning stress of prestressed steel strands is σcon=1 web 302Mpa, and the total controlled tensioning force of single T-beam is 2916KN. Four 250t jacks are used for single-end synchronous tensioning. When the elastic modulus and design strength of the π beam reach 75% of the design, the steel strand tensioning construction is carried out. Four 250t jacks are used for single-end synchronous tensioning. After the steel strands are relaxed, they are cut off with a grinding wheel cutting machine.

[0024] Template making:

[0025] The bottom formwork and side formwork of the double T beam are made of standardized steel formwork. The thickness of the steel formwork panel is not less than 5 mm. The wet joint and cross beam formwork are constructed with wooden formwork and floor-standing steel pipe brackets. The joint and cross beam formwork are processed according to the size.

[0026] Main beam formwork installation:

[0027] The template uses assembled steel templates, and the outer template uses an integral large template. The template must be shaped before trial assembly. The joints of the two templates are polished with a grinder to avoid misalignment of the concrete surface, which affects the appearance quality of the component.

[0028] When installing the template, first install the bottom model steel bracket, then install the bottom template, remove the scum from the joints of the bottom template and make it close. Check the double-sided adhesive sealing strips on both sides of the bottom template to ensure that both sides of the bottom template are smooth and straight. Install the outer template, use double-sided foam adhesive at the joints between the templates, and apply mold release agent to the template. Use special standard parts to fix the web of the template on both sides. The distance between the buckle positions of the width standard parts is the width of the web, and the side template is horizontally connected through the tie rod under the bottom template.

[0029] Installation of π beam joints and transverse beam formwork:

[0030] The width of the π beam joint is 46.25 cm, the thickness is 9 cm, the thickness of the cross beam is 40 cm, 15 mm bamboo plywood is used as the panel, 50 mm × 70 mm square wood is used as the back rib, and the spacing between the ribs is no more than 25 cm. The joint template uses a floor-standing steel pipe bracket with a horizontal spacing of 60 cm and a vertical spacing of 90 cm.

[0031] Installation of embedded steel bars:

[0032] For the installation of embedded reinforcement in the main beam top plate, 16mm diameter threaded steel bars are used. The transverse embedded reinforcement is installed and distributed longitudinally from the end to the other end. The installation sequence is to first pass the two ends of the reinforcement through the embedded holes in the side molds on both sides of the top plate. The spacing between the side mold embedded holes is 10cm. After the reinforcement is punched, the two ends of the reinforcement are bent vertically by 9cm and horizontally by 31cm. The longitudinal spacing of the reinforcement is 10cm. For the installation of the longitudinal embedded reinforcement in the main beam top plate, two 16mm diameter threaded steel bars are distributed and tied and fixed to each other on the transversely bent horizontal reinforcement at both ends.

[0033] Concrete pouring:

[0034] 1UHPC mixing

[0035] The main beam UHPC is uniformly mixed by a mixing station. The mixing of UHPC is carried out by adding water to the premix according to the mix ratio to ensure the mixing time, so that UHPC has good workability and sufficient strength. The expansion of UHPC is 500-650 mm.

[0036] 2UHPC pouring

[0037] ① Use a gantry crane to transport concrete. First, fix the hopper on the transport trolley, pour the concrete from the mixer into the hopper, and transport it to the construction site by the transport trolley. The gantry crane lifts the hopper to the template for unloading. During the transportation process, the hopper door must be closed to prevent leakage of material. The trolley must be stable during the movement to prevent the material from shaking out of the hopper due to excessive vibration.

[0038] ② Precautions for pouring concrete of main beam: pour the single "T" bottom web first, and then pour the panel after the "T" bottom web is poured. The pouring time should be selected during the period of low temperature on the day. When pouring, the material should be laid in a longitudinally movable layered manner to ensure that the steel fiber is evenly distributed. When pouring, follow the instructions of the on-site construction worker to discharge the material to the designated location. The discharge speed should be uniform and gentle to prevent concrete from spilling or overflowing. After each bucket of material is poured, turn on the vibrator near the discharge port and vibrate for 90 seconds to 120 seconds. If the interval between the two bucket materials is long, turn on the vibrator at the discharge port for 30 seconds when pouring the second bucket material.

[0039] ③After pouring, spray the curing agent on the top surface and cover it with a film. When the strength reaches about 45MPA, remove the outer formwork. After removing the formwork, it is necessary to mark it in time, and the marking content should include the bridge name, beam number, production date, etc.

[0040] Steaming:

[0041] After the single "T" beam is cast, when the strength reaches 60MPa, it is concentratedly steamed by covering the scaffold with tarpaulin. During steaming, pay attention to covering the top of the beam with plastic film or other coverings to prevent dripping from causing water marks or pits. During steaming, pay attention to the heating and cooling speed. The heating should not be too fast. Ensure that the heating speed is within 10℃ / h. After heating to 90℃, keep the temperature for 48h, and then cool it down at 15℃ / h to ensure the steaming effect and safety of the components.

[0042] T beam splicing:

[0043] After the prestressed tendons of the single "T" beam are released, the two single "T" beams are moved and spliced ​​to form a π beam structure. The embedded steel bars are spliced, and the joints and partitions are installed using a fixed wooden formwork. After the process is inspected and qualified, the UHPC concrete is poured. After pouring, the curing agent is sprayed on the top surface of the joint and covered with a film. When the strength reaches about 45MPA, the outer formwork is removed and spray curing is carried out.

[0044] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A pre-tensioned UHPC-π beam structure, characterized in that: include: A single beam assembly (101), wherein the single beam assembly (101) is symmetrically arranged, the single beam assembly (101) is T-shaped, the single beam assembly (101) is composed of a panel (301), a web (302), and a horseshoe plate (303), the top end of the horseshoe plate (303) is fixedly connected to the bottom end of the panel (301), the bottom end of the horseshoe plate (303) is fixedly connected to the top end of the web (302), a first reinforcing mechanism is arranged between the panel (301) and the horseshoe plate (303), and a second reinforcing mechanism is arranged between the horseshoe plate (303) and the web (302); A connecting mechanism, wherein the connecting mechanism is arranged between the single beam components (101).

2. A pre-tensioned UHPC-π beam structure according to claim 1, characterized in that: The connection mechanism comprises a splicing plate (201), one side of the splicing plate (201) being connected to one of the panels (301), and the other side of the splicing plate (201) being connected to another of the panels (301).

3. A pre-tensioned UHPC-π beam structure according to claim 2, characterized in that: The lengths of the panel (301) and the splicing plate (201) are both 10 meters, the thicknesses of the panel (301) and the splicing plate (201) are both 0.09 meters, the width of the panel (301) is 0.9 meters, the width of the splicing plate (201) is 0.46 meters, and the thickness of the panel (301) is 0.1 meters.

4. The pre-tensioned UHPC-π beam structure according to claim 1, characterized in that: The first reinforcement mechanism comprises a first chamfer (401), the first chamfer (401) being arranged at the connection between the panel (301) and the horseshoe plate (303), and the dimensions of the first chamfer (401) are 10 meters×0.135 meters×0.05 meters.

5. The pre-tensioned UHPC-π beam structure according to claim 1, characterized in that: The second reinforcement mechanism comprises a second chamfer (402), the second chamfer (402) being arranged at the connection between the horseshoe plate (303) and the web plate (302), and the size of the second chamfer (402) being 10 m×0.135 m×0.05 m.

6. The pre-tensioned UHPC-π beam structure according to claim 1, characterized in that: A third chamfer (501) is provided on both sides of the bottom end of the web (302), and the dimensions of the third chamfer (501) are 10 m×0.025 m×0.025 m.

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