A prestressed beam sealing technology for existing structure reinforcement

Abstract

A prestressed beam sealing technology for existing structure reinforcement. The present application relates to the field of design and construction technology of existing building reinforcement reconstruction engineering. At present, the technology of adding new steel beam is widely used in existing structure reinforcement engineering, but there is a problem of load lag, which leads to low reinforcement efficiency and may cause safety hazards of the structure. The present application solves the problem of load lag in traditional methods by setting a jacking bolt between the new steel beam and the existing structure and applying prestress, so that the steel beam enters the working state immediately. The construction process is to lay the reinforcement steel beam under the existing structure concrete floor, drill holes on the flange of the steel beam at intervals and assemble the jacking bolt with nut, and install the flange stiffener simultaneously; paste the gasket steel plate on the floor bottom surface corresponding to the bolt position, apply prestress by means of the jacking bolt, after the prestress adjustment is completed, fill the gap between the steel beam and the concrete floor with mortar or grouting material. The present application can realize efficient prestressed reinforcement of existing building structure, avoid load lag, and significantly improve the reinforcement efficiency.

Description

Technical Field

[0001] This utility model relates to the design and construction technology of existing building reinforcement and renovation projects, and in particular to a prestressed steel beam for existing structure reinforcement projects. Background Technology

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

[0003] However, the conventional method of adding new steel beams for reinforcement is a passive load-bearing method. The steel beams only begin to bear vertical loads after an additional load is applied to the superstructure. For the steel beams to fully utilize their capacity, they need a certain degree of bending deformation (vertical displacement at mid-span). This stress state is passive and delayed. When no new load is applied to the superstructure, there is zero stress contact between the superstructure and the reinforced steel beams. This method suffers from load lag and low reinforcement efficiency. Summary of the Invention

[0004] This invention aims to overcome the aforementioned shortcomings and provide a prestressed beam sealing technology for strengthening existing structures. This technology allows newly added steel beams to enter a working state immediately, without waiting for new loads to occur. It improves strengthening efficiency, fully utilizes the high load-bearing capacity of the new steel beams, and avoids the problem of the superstructure bearing larger loads and undergoing greater deformation while waiting for the steel beams to function.

[0005] A prestressed beam sealing technology for strengthening existing structures is characterized in that: when the load is shared by adding new steel beams in the strengthening of existing buildings, tightening bolts are set between the new steel beams and the existing structure. By adjusting the tightening bolts, the upper structure is pushed and the lower steel beam is squeezed, so that prestress is generated between the steel beams and the existing structure, and the new steel beams can be put into operation immediately.

[0006] A prestressed beam sealing technology for reinforcing existing structures is characterized by comprising a superstructure concrete slab, steel beams, tightening bolts, nuts, flange stiffening plates, spacer steel plates, and mortar. Specifically, it includes the following steps: installing reinforcing steel beams under the concrete slab of the superstructure; drilling holes at regular intervals in the upper flange of the steel beams and installing tightening bolts (including nuts); installing flange stiffening plates; attaching spacer steel plates to the corresponding positions of the tightening bolts on the bottom surface of the concrete slab; applying prestress by adjusting the tightening bolts, with the magnitude of the prestress in the steel beam equal to the self-weight of the superstructure within the subordinate area; and filling the gap between the steel beam and the concrete slab with mortar (or other materials that meet strength and durability requirements, such as grouting material).

[0007] A prestressed beam sealing technology for strengthening existing structures is characterized in that: the specifications and models of the newly added steel beams are determined by structural analysis and calculation according to the specific conditions of different projects, and can be I-beams, H-beams, welded rectangular steel beams, steel truss beams, etc., with materials of Q235, Q355, Q390, and Q420.

[0008] A prestressed beam sealing technology for reinforcing existing structures is characterized in that: the specifications of the tightening bolts can be determined based on the analysis of the self-weight, stiffness, and spacing of the superstructure; depending on the project, they can be M16, M20, M22 or larger diameters, made of grade 8.8 or higher material, and the nuts are matched with the specifications of the tightening bolts.

[0009] Flange stiffeners are used to improve the local compressive strength of steel beams and limit the free spin of nuts. They are 3mm to 6mm thick, with the same height as the nut and the same length as the flange width of the steel beam, and are made of Q235 steel. A set of two flange stiffeners is placed on either side of the nut, with the distance between the two stiffeners 2-3mm greater than the distance between the nut. The flange stiffeners are welded to the steel beam.

[0010] Steel shims are attached to the corresponding positions of the bolts on the bottom surface of the concrete floor slab. The steel shims are used to diffuse stress and reduce friction on the contact surface. They are 3mm to 6mm thick, square in shape with a side length of 50 to 100mm, and made of Q235 steel.

[0011] The gap between the steel beam and the floor slab is filled with mortar (or other materials that meet the requirements of strength and durability, such as grouting material).

[0012] The magnitude of the prestress applied by the tightening bolts is equal to the self-weight of the tributary area structure, which can be converted into displacement through structural analysis, i.e., the increase in the gap between the superstructure and the steel beams. During construction, simply adjusting the tightening bolts according to the displacement design value achieves the specified value of prestress.

[0013] Compared with the prior art, the present invention has the following beneficial effects: - The steel beams are subjected to load immediately, avoiding load lag; - The construction is simple, economical, safe, and feasible; - The prestress is controllable, and the reinforcement effect is stable. Attached Figure Description

[0014] Figure 1 shows the common method for reinforcing newly added steel beams.

[0015] Figure 2 shows the prestressed beam sealing method.

[0016] Figure 3 shows the detailed joint of the prestressed beam sealing method. Figure 1 .

[0017] Figure 4Detailed specifications of prestressed beam sealing method nodes Figure 2 .

[0018] Explanation of reference numerals in the attached drawings: 1. Concrete floor slab; 2. Steel beam; 3. Tightening bolt; 4. Nut; 5. Flange stiffening plate; 6. Steel plate pad. Detailed Implementation

[0019] The present invention will be further described below with reference to embodiments.

[0020] - Install reinforcing steel beams 2 under the existing concrete floor slab 1; - Drill holes at certain intervals on the upper flange of steel beam 2 and install tightening bolts 3, including nuts 4; - Install flange stiffening plate 5; - Attach the pad steel plate 6 at the position corresponding to the bolt 3 on the bottom surface of the concrete floor slab 1; - By adjusting the tightening bolt 3, prestress is applied, allowing the steel beam 2 to enter the working state ahead of time; - The magnitude of the prestressing force on the steel beam is equal to the self-weight of the superstructure within the subordinate area. This is then converted into the deflection displacement value of the steel beam through structural analysis calculations. - Prestress is controlled during construction by controlling displacement equivalently; - After adjusting the preload at each point of the steel beam, fill the gap between the steel beam and the floor slab with mortar.

[0021] Structural composition - Steel beams: Q355 H-beams (H450×200×9×13), span 6.5m; - Bolts: M20 (8.8 grade), spacing 0.5m; - Flange stiffening plate: 200×20×5mm Q235; - Spacer plate: 100×100×6mm Q235; - Mortar: Strength M15, initial setting time 2h.

[0022] Construction steps (1) Steel beam fabrication: Drill Φ22mm holes in the upper flange and weld stiffening plates; (2) Shim plate attachment: Mark the bolt hole positions on the bottom surface of the floor slab and attach the shim plate; (3) Steel beam installation: Install the steel beams at the designated positions and heights according to the design drawings; (4) Displacement calculation: The steel beam is loaded with the self-weight load of the floor slab belonging to the steel beam, and the deflection displacement of the steel beam is analyzed and calculated. (5) Apply prestress: Adjust the tightening bolts to make the displacement of the steel beam equal to the value calculated in step 4; (6) Filling gaps: Use mortar to fill the gaps between the steel beams and the floor slab.

[0023] Verification effect Actual measurements showed a 35% reduction in floor slab deflection and that the steel beam stress reached the design value 30% ahead of schedule.

Claims

1. A prestressed beam sealing technology for strengthening existing structures, characterized in that: In the reinforcement of existing buildings, when the load is shared by adding new steel beams, tightening bolts (3) and nuts (4) are set between the new steel beams (2) and the existing structure. By adjusting the tightening bolts (3), prestress is generated between the steel beams (2) and the existing structure. Specifically, the work includes the following tasks: - A reinforcing steel beam (2) is installed under the existing concrete floor slab (1); - Drill holes at certain intervals on the upper flange of the steel beam (2) and install top bolts (3), including nuts (4); - Install flange stiffening plates (5); - Attach a pad steel plate (6) to the corresponding position of the bolt (3) on the bottom surface of the concrete floor slab (1); - By adjusting the tightening bolt (3) to apply prestress, the steel beam (2) is brought into working state in advance. The magnitude of the prestress of the steel beam (2) is equal to the self-weight of the superstructure in the subordinate area. - After adjusting the preload at each point of the steel beam (2), the gap between the steel beam (2) and the concrete floor slab (1) is filled with mortar.

2. The prestressed beam sealing technology for strengthening existing structures according to claim 1, characterized in that, The steel beam (2) is a new load-bearing structure for the reinforcement project. Its specifications and models are determined by structural analysis and calculation based on the specific circumstances of different projects. The steel beam is an I-beam and the material is Q235, Q355, Q390, or Q420.

3. The prestressed beam sealing technology for strengthening existing structures according to claim 1, characterized in that, The specifications of the tightening bolt (3) are determined based on the analysis of the self-weight, stiffness and arrangement spacing of the upper structure. The material is grade 8.8 or above, and the nut (4) matches it.

4. The prestressed beam sealing technology for strengthening existing structures according to claim 1, characterized in that, The flange stiffening plate (5) has a thickness of 3mm to 6mm, a height of the same as that of the nut (4), and a length of the same as that of the flange plate of the steel beam (2). It is made of Q235 steel. There are two flange stiffening plates (5) in a set, distributed on both sides of the nut (4). The distance between the two flange stiffening plates (5) is 2 to 3mm larger than that of the nut (4). The flange stiffening plate (5) is welded to the steel beam (2).

5. The prestressed beam sealing technology for strengthening existing structures according to claim 1, characterized in that, The pad steel plate (6) has a thickness of 3mm to 6mm, a square shape with a side length of 50 to 100mm, and is made of Q235 steel.

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