Concrete floor vibration-proof reinforcement system

Abstract

The application discloses a kind of concrete floor anti-microvibration reinforcement systems, including with existing concrete beam side connection H-shaped steel beam and prestressed screw rod;Steel beam end and concrete beam between being equipped with connecting plate, web two sides are equipped with reinforcing plate, reinforcing plate and wing plate are enclosed into box type structure together;Prestressed screw rod is from rear side opening and passes through connecting plate and is anchored to concrete beam.The size of box type structure, screw rod installation position and prestress are determined according to the target stiffness ratio of steel beam promotion.This application cooperates with prestressed screw rod by box type node, so that newly-added steel beam generates negative bending moment at node, forms bidirectional beam stress system, effectively improves the overall stiffness and anti-microvibration performance of floor.

Description

Technical Field

[0001] This invention relates to building structure reinforcement, and in particular to a system for reinforcing concrete floor slabs against micro-vibration. Background Technology

[0002] With the development of industries such as precision manufacturing and semiconductors, many existing factory structures were not designed with fretting resistance in mind. When equipment is updated or production lines are upgraded, existing floors need to be reinforced to meet stringent fretting resistance requirements. These factory buildings often have one-way floor slabs, whose vibration performance typically cannot meet the demands of high-precision production.

[0003] To improve floor slab stiffness, the industry commonly uses the addition of steel beams. However, traditional reinforcement methods have certain limitations. For example, bonding carbon fiber cloth or adding supporting columns cannot fundamentally change the floor slab's stress system and are insufficient to effectively meet the high bending stiffness requirements for micro-vibration prevention. When using steel beams for reinforcement, if the steel beams are simply supported to the existing concrete beams, bending moments cannot be effectively transferred between them, failing to form a cohesive two-way beam stress system. The significant difference between the nodal stiffness of this connection method and the rotational stiffness of the concrete beams makes it difficult to achieve a matching of bending stiffness between the old and new structures, thus affecting the overall vibration performance and resulting in less than ideal micro-vibration prevention. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a concrete floor slab anti-vibration reinforcement system that can effectively improve the anti-vibration performance of floor slabs and achieve matching and synergistic operation of the bending stiffness of new and old structures.

[0005] Technical solution: The concrete floor slab anti-micro-vibration reinforcement system of the present invention includes: a steel beam and a prestressed bolt connected to the side of the existing concrete beam; the steel beam is made of H-beam, and a connecting plate is provided between the end of the steel beam and the concrete beam and the concrete beam. The web of the end is provided with reinforcing plates on both sides, and the reinforcing plates and the flanges of the steel beam together form a box-shaped structure.

[0006] Two prestressed bolts are symmetrically arranged on both sides of the web of the steel beam; the prestressed bolts are inserted from the opening on the side of the box structure away from the concrete beam and anchored to the pre-set installation position of the concrete beam through the connecting plate, and the prestressed bolts are subjected to a set prestress.

[0007] The cross-sectional dimensions of the box girder, the installation position of the prestressed bolts on the concrete beam, and the magnitude of the applied prestress are determined based on the target increase in bending stiffness ratio of the steel beam.

[0008] By installing reinforcing plates on both sides of the web at the ends of the H-shaped steel beams, the reinforcing plates and flanges together form an open box-shaped structure. This increases the moment of inertia of the steel beam ends relative to the original H-shaped steel section, thereby increasing the rotational stiffness of the joint. The increased rotational stiffness of the joint reduces the deflection of the steel beam, which in turn increases its bending stiffness, providing a structural basis for the transfer of bending moment between the steel beam and the existing concrete beam. Prestressed bolts are inserted through the opening and anchored to the concrete beam through the connecting plate, generating a negative bending moment at the joint, allowing the steel beam to function as a continuous beam. The cross-sectional dimensions of the box-shaped structure, the bolt installation position, and the magnitude of the prestress are all determined based on the target increase in bending stiffness, ensuring that all components of the reinforcement system can be configured collaboratively to achieve the expected increase in bending stiffness in a controllable manner, thus effectively improving the overall bending stiffness and anti-micro-vibration capability of the floor slab.

[0009] Preferably, the formula for calculating the target increase in bending stiffness ratio is:

[0010] ,

[0011] in, For the bending stiffness of the steel beams in the box-type structure, This represents the original bending stiffness of the steel beam; To reflect the parameters of rotational constraint of the box-type structure, Parameters that reflect the prestressing effect of prestressed screws.

[0012] By introducing the formula for the total bending stiffness ratio, the rotational restraint effect provided by the box-type structure (through parameters) is considered. (reflected) and the negative bending moment effect generated by prestress (through parameters) This formula unifies the two reinforcement mechanisms within a single mathematical relationship, enabling a quantitative assessment of their combined effect on improving flexural stiffness. Engineers can use this formula to deduce the required flexural stiffness ratio given a target ratio. and This value guides the design of box-type cross-sectional dimensions and prestress parameters, improving the calculability and predictability of reinforcement scheme design.

[0013] Preferably, the The calculation formula is:

[0014] ,

[0015] in, , Let be the moment of inertia of the box-shaped section at the end of the steel beam. The moment of inertia of the original steel beam section; This refers to the length of the end reinforcement section of the steel beam;

[0016] The calculation formula is:

[0017] ,

[0018] Where b is the flange width of the steel beam, and h is the section height. For the web thickness of the steel beam, The thickness of the flange of the steel beam;

[0019] The calculation formula is:

[0020] ,

[0021] in, To reinforce the thickness of the plate.

[0022] By providing parameters The specific expression was established, and a quantitative relationship between the rotational constraint effect of the box-shaped structure and the cross-sectional geometric parameters was created. Simultaneously, the original cross-sectional moment of inertia was given. and the moment of inertia of the reinforced box section The calculation formula allows engineering designers to directly calculate the required thickness of the H-beam based on standard specifications such as flange width, section height, web and flange thickness, as well as the thickness of the reinforcing plates to be installed. and This allows for a quantitative assessment of the contribution of the end box structure to rotational constraints, providing a direct engineering calculation basis for determining the box section dimensions.

[0023] Preferably, the The calculation formula is:

[0024] ,

[0025] in, The negative bending moment at the end of the prestressed screw after applying prestress; This represents the uniformly distributed load value borne by the steel beam; The span of the steel beam;

[0026] The calculation formula is:

[0027] ,

[0028] in, y represents the prestressing force applied to the prestressed bolt; y is the vertical distance from the centerline of the prestressed bolt to the neutral axis of the concrete beam section.

[0029] By providing parameters The specific expression quantifies the prestressing effect as a function of the negative bending moment at the ends. Load and span The relevant parameters. At the same time, through... The negative bending moment is further decomposed into preload. The product of the product with the eccentricity y allows designers to adjust the product according to the required parameters. The value directly determines the tension control force of the prestressed bolt and its installation height on the concrete beam, providing a clear calculation basis for the selection and positioning of the prestressed bolt.

[0030] Preferably, the reinforcing plate is a steel plate, symmetrically welded to both sides of the web at the end of the steel beam, with its edges flush with the edges of the flanges.

[0031] By symmetrically welding stiffening plates to both sides of the web, with their edges flush with the flanges, the stiffening plates and the original H-beam section can form a complete box-shaped closed profile, ensuring symmetrical stress distribution and avoiding additional torsional stress caused by eccentricity. The welded connection ensures continuous and reliable shear force transfer between the stiffening plates and the H-beam web, allowing the stiffening plates to fully participate in the overall stress distribution of the section and effectively improving the moment of inertia and rotational stiffness of the end sections.

[0032] Preferably, the set prestress is less than the tensile yield strength of the prestressed screw.

[0033] By controlling the applied prestress within the tensile yield strength of the screw, it is ensured that the screw is always within the elastic stress range during operation, avoiding structural damage to the screw due to the prestress exceeding the yield strength. This ensures that the reinforcement system can stably maintain the set prestress level during long-term use, guaranteeing the durability of the reinforcement effect.

[0034] Preferably, the contact surface between the connecting plate and the concrete beam is filled with epoxy resin.

[0035] By filling the contact surface between the connecting plate and the concrete beam with epoxy resin, the micro-voids and unevenness of the contact surface can be filled, increasing the contact area and bonding strength of the interface, reducing the interface fretting and energy dissipation that may occur under vibration load, and improving the integrity of the connection node and the reliability of long-term operation.

[0036] Preferably, the prestressed screw is a screw with a performance grade of not less than Q355.

[0037] Preferably, the prestressed screw is equipped with a nut, which is fastened to the connecting plate to maintain the prestress applied to the prestressed screw.

[0038] Preferably, steel beams are symmetrically arranged on both sides of the existing concrete beam, and prestressed bolts are installed through the steel beams on both sides of the concrete beam.

[0039] Beneficial effects: The combination of box-type structure and prestressed bolts generates negative bending moments at the joints of the newly added steel beams, forming a two-way beam stress system, which effectively improves the overall bending stiffness and anti-micro-vibration capability of the floor slab. Furthermore, the formula for the total bending stiffness ratio and the expressions for its sub-parameters provide engineering calculation basis for the design of box-type cross-section dimensions, the determination of bolt installation positions, and the magnitude of prestress, making the design process of the reinforcement system quantifiable and controllable, and facilitating its application in practical engineering projects. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the overall assembly structure of the concrete floor slab anti-micro-vibration reinforcement system in an embodiment of the present invention;

[0041] Figure 2 This is a three-dimensional exploded perspective view of the steel beam joint.

[0042] Explanation of the reference numerals in the figure:

[0043] 1. Concrete beam, 2. Steel beam, 3. Prestressed bolt, 4. Connecting plate, 5. Web plate, 6. Reinforcing plate, 7. Flange plate, 8. Ordinary bolt. Detailed Implementation

[0044] As shown in the figure, the concrete slab anti-micro-vibration reinforcement system of the present invention includes a steel beam 2 connected to the side of an existing concrete beam 1 and a prestressed bolt 3. The steel beam is made of H-beams, and a connecting plate 4 is provided between the end of the steel beam and the concrete beam. Reinforcing plates 6 are provided on both sides of the web 5 at this end. The reinforcing plates 6 are steel plates, symmetrically welded to both sides of the web 5 at the end of the steel beam, with their edges flush with the edges of the flanges 7. The reinforcing plates 6 and the flanges 7 of the steel beam together form a box-shaped structure.

[0045] Two prestressed bolts 3 are provided, symmetrically arranged on both sides of the web 5 of the steel beam. The prestressed bolts 3 enter through an opening on the rear side of the box girder, i.e., the side furthest from the concrete beam, and pass through the connecting plate 4, anchoring to the pre-set installation position on the concrete beam 1. The prestressed bolts 3 penetrate the concrete beam to apply prestress; the prestressed bolts 3 are subjected to a predetermined prestress value less than the tensile yield strength of the prestressed bolt. The prestressed bolts 3 are equipped with nuts, which are fastened to the connecting plate 4 to maintain the prestress applied to the prestressed bolts 3. Epoxy resin is filled between the contact surfaces of the connecting plate 4 and the concrete beam 1.

[0046] The cross-sectional dimensions of the box girder, the installation position of the prestressed bolts on the concrete beam, and the magnitude of the applied prestress are determined based on the target increase in bending stiffness ratio of the steel beam.

[0047] The mechanical mechanism by which this reinforcement system improves bending stiffness is explained in detail below.

[0048] The steel beams have an H-section, and the span of the reinforced structure is... The flexural stiffness of the section is ,in The elastic modulus of steel; This represents the moment of inertia of the original H-section steel beam. The steel beam is subjected to a uniformly distributed load. This includes the floor slab's self-weight and service load. At the end length of the steel beam... Within the specified range, the H-beam section is reinforced into a box-shaped section by reinforcing plates and flanges to form the box-shaped structure.

[0049] The core mechanical idea of ​​this invention is to improve the overall bending stiffness of the steel beam and system by increasing the angular stiffness of the end nodes and reducing the mid-span deformation of the steel beam under bending moment. Under the equivalent premise of the same column span L and load w, the physical meaning and definition of the relevant stiffness are as follows:

[0050] System bending stiffness K: Defined as the ability of the steel beam and the entire system to resist bending deformation. ,in For mid-span deflection, when the span and load remain constant, the decrease in mid-span deformation δ directly corresponds to an increase in the system's bending stiffness K.

[0051] Equivalent Bending Stiffness (Es*Ieq1, Es*Ieq2, Es*Ieq): This invention significantly improves the angular stiffness of the nodes through the box-type node rotation constraint mechanism and the prestressed negative bending moment mechanism. To quantify this effect, the "equivalent bending stiffness" is introduced, which is strictly defined as: the ideal bending stiffness that a simply supported beam model must possess to achieve the exact same mid-span deformation as after reinforcement by this invention under the same span and load.

[0052] Based on this definition, the suppression effect of each mechanism on mid-span deformation can be rigorously and inversely converted into an intrinsic increase in equivalent bending stiffness, corresponding to a stiffness ratio This refers to the multiple by which the bending stiffness is increased.

[0053] I. Rotation constraint mechanism of box-type nodes

[0054] Moment of inertia of the original H-section The specifications can be directly found in the steel profile specification table, or calculated using the following approximate formula:

[0055] ,

[0056] In the formula, The width of the flange of the steel beam; The height of the cross section; The web thickness of the steel beam; The thickness of the flange of the steel beam.

[0057] The reinforced box-section consists of the original H-beams and reinforcing plates welded to both sides. Assume the thickness of the reinforcing plates is... Height is (Same as H-beams), then the moment of inertia of the box section for:

[0058] ,

[0059] In the formula, In practical engineering, the thickness of the reinforcing plate can also be calculated directly based on the overall geometric dimensions of the box-shaped cross-section. .

[0060] Define the ratio of moments of inertia Obviously This ratio reflects the degree of improvement in the bending stiffness of the steel beam end section.

[0061] The end reinforcement section of the steel beam is equivalent to a rotational spring, and its angular stiffness is... Calculate using the following formula:

[0062] ,

[0063] in, The rotational spring stiffness provided for the node; This refers to the length of the stiffened section at the end of the steel beam. In actual engineering design, this length can be calculated first based on the geometric dimensions of the H-beam cross-section and the stiffened box-section. and Substitute directly into the first equation of the formula to calculate. Alternatively, you can calculate first. Then substitute the values ​​into the second equation of the formula to calculate. The two are completely equivalent.

[0064] Constraint moment generated by angle spring Actual rotation angle of the steel beam end The relationship is Under uniformly distributed load Under the action of the load, the rotation angle at the end of the steel beam is a superposition of the load and the spring moment:

[0065] ,

[0066] Solving the system of equations simultaneously, we obtain the bending moment:

[0067] ,

[0068] First mid-span deflection For uniformly distributed load deflection and The sum of deflections is generated:

[0069] ,

[0070] Define the first equivalent bending stiffness make ,have to:

[0071] ,

[0072] in The first equivalent cross-sectional moment of inertia;

[0073] The ratio of the bending stiffness K1 increased by the box section at the steel end of the steel beam to the original bending stiffness K0 of the steel beam is:

[0074] ,

[0075] in, The specific calculation formula for the parameters reflecting the rotational constraint of the box-type structure is as follows: ;when (i.e., when the ends are completely fixed) That is, the end box joint can increase the bending stiffness of the steel beam to up to 2.5 times that of the original steel beam.

[0076] stiffness Stiffness and deformation are inversely proportional;

[0077] Since the loads are the same, Known The above formula can be derived through derivation, and the same applies to the following text.

[0078] II. Prestressed negative bending moment mechanism

[0079] Prestress is applied at the end of the node by prestressed screws. The vertical distance from the centerline of the screw to the neutral axis of the concrete beam section is: This is called the prestressing eccentricity. The prestressing bolts only need to meet the requirements of vertical distance y and being located above the central axis of the concrete beam. Their position along the length of the concrete beam can be arbitrarily set. The load-bearing capacity of the steel beam is achieved through the remaining ordinary bolts 8 installed on it; generating negative bending moments at the ends. Under the sole action of this negative bending moment;

[0080] Second mid-span deflection for:

[0081] ,

[0082] The second equivalent bending stiffness is:

[0083] ,

[0084] in This is the second equivalent cross-sectional moment of inertia;

[0085] The ratio of the bending stiffness K2 of the prestressed bolt lifting the steel beam to the original bending stiffness K0 of the steel beam is:

[0086] .

[0087] III. Synergistic Effect of Two Mechanisms

[0088] When both the steel beam end box section rotation constraint and prestressed bolts are used, the total mid-span deflection is:

[0089] ,

[0090] Total equivalent bending stiffness:

[0091] ,

[0092] Overall flexural stiffness ratio:

[0093] ,

[0094] in:

[0095] ,

[0096] In the formula The specific calculation formula for the parameters reflecting the prestressing effect is as follows: .

[0097] In practical engineering, the required moment of inertia of the box section can be calculated using the above formula based on the target requirement for the total flexural stiffness ratio after reinforcement. Prestress value and installation eccentricity These key parameters guide the specific dimensional design of the box-type structure, as well as the selection and positioning of the prestressed bolts.

[0098] The above calculation process will be illustrated below through a specific design example.

[0099] Taking HM588×300×12×20 as a steel beam for micro-vibration reinforcement as an example, the steel span... Uniformly distributed load Reinforcing plate thickness Strengthen length .

[0100] Calculate the moment of inertia of the original cross section:

[0101] ,

[0102] Calculated .

[0103] Moment of inertia of box section:

[0104] ,

[0105] Moment of inertia ratio .

[0106] The prestressed bolts use M30 high-strength bolts with pretension. eccentricity The resulting negative bending moment .

[0107] Substitute into the formula to calculate :

[0108]

[0109] The bending stiffness ratio of computer-controlled type 1:

[0110]

[0111] That is, under the action of the end box section alone, the stiffness is increased by about 134%.

[0112] calculate :

[0113]

[0114] The bending stiffness ratio of computer-controlled type II:

[0115]

[0116] That is, under the action of prestress alone, the bending stiffness is increased by about 26.6%.

[0117] The ratio of total flexural stiffness under the combined effect of the two mechanisms:

[0118]

[0119] The reinforcement of the steel beams increased the bending stiffness to 4.63 times that of the original steel beams, which can effectively improve the overall bending stiffness and anti-micro-vibration ability of the floor slab.

Claims

1. A system for reinforcing concrete floor slabs against micro-vibration, characterized in that, include: Steel beams and prestressed bolts are connected to the sides of existing concrete beams; the steel beams are made of H-beams, and a connecting plate is provided between the end of the steel beam and the concrete beam. Reinforcing plates are provided on both sides of the web of this end, and the reinforcing plates and the flanges of the steel beam together form a box-shaped structure. Two prestressed bolts are symmetrically arranged on both sides of the web of the steel beam; the prestressed bolts are inserted from the opening on the side of the box structure away from the concrete beam and anchored to the pre-set installation position of the concrete beam through the connecting plate, and the prestressed bolts are subjected to a set prestress. The cross-sectional dimensions of the box girder, the installation position of the prestressed bolts on the concrete beam, and the magnitude of the applied prestress are determined based on the target increase in bending stiffness ratio of the steel beam.

2. The system according to claim 1, characterized in that, The formula for calculating the target increase in flexural stiffness ratio is as follows: ， in, For the bending stiffness of the steel beams in the box-type structure, This represents the original bending stiffness of the steel beam; To reflect the parameters of rotational constraint of the box-type structure, Parameters that reflect the prestressing effect of prestressed screws.

3. The system according to claim 2, characterized in that: The The calculation formula is: ， in, , Let be the moment of inertia of the box-shaped section at the end of the steel beam. The moment of inertia of the original steel beam section; This refers to the length of the end reinforcement section of the steel beam; The calculation formula is: ， Where b is the flange width of the steel beam, and h is the section height. For the web thickness of the steel beam, The thickness of the flange of the steel beam; The calculation formula is: ， in, To reinforce the thickness of the plate.

4. The system according to claim 2, characterized in that: The The calculation formula is: ， in, The negative bending moment at the end of the prestressed screw after applying prestress; This represents the uniformly distributed load value borne by the steel beam; The span of the steel beam; The calculation formula is: ， in, y represents the prestressing force applied to the prestressed bolt; y is the vertical distance from the centerline of the prestressed bolt to the neutral axis of the concrete beam section.

5. The system according to claim 1, characterized in that: The reinforcing plate is a steel plate, symmetrically welded to both sides of the web at the end of the steel beam, with its edges flush with the edges of the flanges.

6. The system according to claim 1, characterized in that: The set prestress is less than the tensile yield strength of the prestressed screw.

7. The system according to claim 1, characterized in that: The contact surface between the connecting plate and the concrete beam is filled with epoxy resin.

8. The system according to claim 1, characterized in that: The prestressed screw adopts a performance grade of not less than Q355.

9. The system according to claim 1, characterized in that: The prestressed screw is equipped with a nut, which is fastened to the connecting plate to maintain the prestress applied to the prestressed screw.

10. The system according to claim 1, characterized in that: The prestressed screw penetrates the concrete beam.

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