Prestress beam sealing technology for reinforcing existing structure

Abstract

The invention discloses a prestressed beam sealing technology for reinforcing an existing structure. The invention relates to the technical field of design and construction of existing building reinforcement and reconstruction projects. At present, the newly-added steel beam technology is widely applied to the existing structure reinforcing engineering, but the problem of load lag exists, so that the reinforcing efficiency is low, and potential safety hazards of the structure are possibly caused. The puller bolts are arranged between the newly-added steel beam and the existing structure, and the prestress is applied, so that the steel beam enters the working state in time, and the problem of lagging of loading in a traditional method is solved. The method specifically comprises the steps that reinforcing steel beams are arranged below a concrete floor of an existing structure; drilling a hole in the upper flange of the steel beam and mounting a flange stiffening plate; puller bolts are arranged between the steel beam and the floor slab, and prestress is applied by tightening the bolts; and filling a gap between the steel beam and the floor slab with epoxy resin mortar. According to the method, the steel beam is stressed instantly, loading lag is avoided, the reinforcing efficiency is remarkably improved, construction is easy, convenient, economical, safe and feasible, prestress is controllable, and the reinforcing effect is stable.

Description

Technical Field

[0001] The present invention relates to the technical field of design and construction of existing building reinforcement and reconstruction projects, in particular to a prestressed steel beam for existing structure reinforcement projects. Background Art

[0002] Currently, the technology of adding steel beams is widely used in the reinforcement of existing structures, among which the method of adding steel beams is a commonly used reinforcement method.

[0003] However, conventional reinforcement methods using additional steel beams are passive load-bearing methods. The beams only begin to bear vertical loads when additional loads are applied to the superstructure. For the beams to fully realize their capacity, they must undergo a certain degree of bending deformation (generating vertical displacement at midspan). This stress-bearing state is passive and delayed. When no additional loads are applied to the superstructure, the superstructure and reinforced steel beams are in zero-stress contact. This method suffers from delayed load bearing and low reinforcement efficiency. Summary of the Invention

[0004] The present invention aims to overcome these drawbacks by providing a prestressed beam capping technology for reinforcing existing structures. This technology allows newly added steel beams to be immediately operational, without having to wait for the onset of additional loads. This improves reinforcement efficiency, fully leveraging the high bearing capacity of the newly added steel beams and avoiding the problem of the superstructure being subjected to greater loads and deformation while waiting for the beams to function.

[0005] A prestressed beam sealing technology for reinforcing existing structures, characterized in that: in the reinforcement of existing buildings, when adding new steel beams to share the load, tightening bolts are set between the new steel beams and the existing structure, and the bolts are tightened to push the upper structure and squeeze the lower steel beams, so that prestress is generated between the steel beams and the existing structure, and the steel beams can enter the working state in advance. This patent solves the problem of delayed load bearing of conventional new steel beams, that is, it avoids the problem that the existing structure cannot function until the new steel beams are deformed to a certain extent, and realizes that the new steel beams can work as soon as they enter. The use of tightening bolts to apply prestress to the steel beams is the innovation of the present invention, and it is also the distinguishing technical feature compared with the existing technology.

[0006] A preferred solution for prestressed beam sealing technology for reinforcing existing structures is: prestressed beam sealing technology includes superstructure, H-shaped steel beam, tightening bolts, stiffening plates, pads, and epoxy resin mortar. The steel beam is installed under the existing superstructure, and a certain gap is reserved between the two. The upper flange plate of the H-shaped steel beam is drilled with holes at a certain interval to allow bolts to pass through, and nuts are installed on the upper part. Flange stiffening plates are set on both sides of the drilled holes, and the net spacing of the stiffening plates can be greater than the nuts by 2mm; while reinforcing the flange plates, the nuts are prevented from rotating in vain. The bolt rod lifts the superstructure upward, and the nut squeezes the H-shaped steel beam downward. The lifting force matches the deadweight of the superstructure; the steel beam is added and the work is realized. When there is an additional load on the subsequent floor, it will be directly transferred to the steel beam.

[0007] If the superstructure is a concrete floor, steel pads are attached to the bottom of the floor at the locations corresponding to the bolts to eliminate stress concentration and reduce friction. The gap between the steel beam and the floor is filled with epoxy resin mortar.

[0008] The prestressing force can be converted into displacement through structural analysis, i.e., the incremental gap between the superstructure and the steel beam. During construction, simply tightening the bolts according to the designed displacement value will achieve the required prestressing force.

[0009] Compared with the prior art, the present invention has the following beneficial effects: - Steel beams are immediately stressed to avoid delayed loading; - The construction is simple, economical, safe and feasible; - Prestress is controllable and the reinforcement effect is stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a common method of reinforcing steel beams.

[0011] Figure 2 It is a prestressed beam sealing method.

[0012] Figure 3 It is the node sample of prestressed beam sealing method Figure 1 .

[0013] Figure 4 It is the node sample of prestressed beam sealing method Figure 2 .

[0014] Explanation of the accompanying reference numerals: 1. Floor slab; 2. Steel beam; 3. Bolt; 4. Nut; 5. Stiffener; 6. Pad. DETAILED DESCRIPTION

[0015] The present invention is further described below with reference to the embodiments.

[0016] - Install reinforcement steel beams 2 under the concrete floor slab 1 of the existing structure; - Drill holes at a certain interval on the upper flange of the steel beam 2 and install the flange stiffener 5; - Jack bolts 3, including nuts 4, are provided between the steel beam 2 and the concrete floor slab 1; - Paste the spacer steel plate 6 at the position corresponding to the bolts on the bottom surface of the floor; - Prestressing is applied by tightening bolts 3, so that the steel beam 2 enters the working state in advance; - The prestressing force of the steel beam is equal to 1.1 times the deadweight of the superstructure within the subordinate area. This is converted into the deflection and displacement value of the steel beam through structural analysis calculation; - Equivalently control prestressing by controlling displacement during construction; - After adjusting the prestressing of each point of the steel beam, fill the gap between the steel beam and the floor slab with epoxy resin mortar.

[0017] Structural composition - Steel beam: Q355 H-shaped steel (H450×200×9×13), span 6.5m; - Bolts: M20 (grade 8.8), spacing 0.5m; - Stiffening plate: 200×20×5mm Q235; - Spacer steel plate: 100×100×6mm Q235; - Epoxy resin mortar: strength C50, initial setting time 5h.

[0018] Construction steps (1) Steel beam processing: Drill Φ22mm holes on the upper flange and weld stiffeners; (2) Pad pasting: mark the bolt hole positions on the bottom surface of the floor slab and paste the pad; (3) Steel beam installation: Install the steel beam at the set position and height according to the design drawing requirements; (4) Displacement calculation: Load the steel beam with a load of 1.1 times the weight of the floor slab, and analyze and calculate the deflection and displacement of the steel beam; (5) Apply prestress: Tighten the bolts so that the displacement of the steel beam is equal to the value calculated in step 4; (6) Fill the gap: Use epoxy mortar to fill the gap between the steel beam and the floor slab and cure for 24 hours.

[0019] Verify the effect The measured floor deflection was reduced by 35%, and the steel beam stress reached the design value 20% ahead of schedule.

Claims

1. A prestressed beam sealing technology for reinforcing existing structures, characterized by: In the reinforcement of existing buildings, when adding new steel beams to share the load, tightening bolts are set between the new steel beams and the existing structure. By tightening the bolts, prestressing is generated between the steel beams and the existing structure, so that the steel beams can enter the working state in advance. This patent solves the problem of delayed load on conventional new steel beams, that is, it avoids the problem that the existing structure can only function after the new steel beams are deformed to a certain extent, and realizes that the new steel beams can work immediately after they are put into use. The use of tightening bolts to apply prestress to the steel beams is the innovation of this invention and is also the distinguishing technical feature compared with the existing technology. The specific steps include: - Install reinforcement steel beams 2 under the concrete floor slab 1 of the existing structure; - Drill holes at a certain interval on the upper flange of the steel beam 2 and install the flange stiffener 5; - Jack bolts 3, including nuts 4, are provided between the steel beam 2 and the concrete floor slab 1; - Paste the spacer steel plate 6 at the position corresponding to the bolts on the bottom surface of the floor; - Prestressing is applied by tightening bolts 3, so that the steel beam 2 enters the working state in advance. The magnitude of the prestressing force on the steel beam is equal to the deadweight of the superstructure in the subordinate area; - After adjusting the prestressing of each point of the steel beam, fill the gap between the steel beam and the floor slab with epoxy resin mortar.

2. The prestressed beam sealing technology for reinforcing existing structures according to claim 1 is characterized in that: The steel beam 2 is a new bearing body of the reinforcement project. Its specifications and models are determined according to the specific conditions of different projects through structural analysis and calculation. It can be I-beam, H-beam, welded rectangular steel beam, steel truss beam, etc., and the material is Q235, Q355, Q390, Q420.

3. The prestressed beam sealing technology for reinforcing existing structures according to claim 1 is characterized in that: The bolts 3 and nuts 4 are a complete set, serving as the core device for applying prestress. Holes are drilled in the flange of the steel beam 2, through which the bolts 3 pass. Nuts 4 are then installed. By rotating the bolts 4 to adjust their extension, the bolt tips push against the floor slab 1, while the nuts 4 squeeze the steel beam in reverse, thus generating prestress in the beam 2. The specifications of the bolts 3 can be determined based on the weight, stiffness, and spacing of the superstructure. Different projects can use diameters of M16, M20, M22, or larger, made of grade 8.8 or higher, with matching nuts 4.

4. The prestressed beam sealing technology for reinforcing existing structures according to claim 1 is characterized in that: The flange stiffeners 5 are designed to enhance the local compressive strength of the steel beam and limit nut rotation. They are 3mm to 6mm thick, the same height as the nut 4, and the same length as the flange width of the steel beam 2. They are made of Q235 steel. Two stiffeners are provided in a set, positioned on either side of the bolt. The spacing between the two stiffeners is 2-3mm greater than that of the nut 4, facilitating installation and limiting free rotation.

5. The prestressed beam sealing technology for reinforcing existing structures according to claim 1 is characterized in that: The purpose of setting the pad steel plate 6 is to diffuse stress and reduce friction. The thickness is 3mm to 6mm, the shape is a square with a side length of 100mm, and the material is Q235.

6. The prestressed beam sealing technology for reinforcing existing structures according to claim 1 is characterized in that: The epoxy resin mortar is provided to fill the gap between the steel beam 2 and the floor slab 1 so as to evenly transfer the load in the later work. The epoxy resin mortar has a strength grade of C50 or above and an initial setting time of 5 hours.

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