阅读说明：本技术 一种既有建筑结构的改造方法 (method for transforming existing building structure ) 是由 齐贺 田中省 王欣博 杨强 王静贻 杨冰杰 李丹 杨金涛 于 2019-07-27 设计创作，主要内容包括：本发明适用于建筑施工技术领域,提供了一种既有建筑结构的改造方法,其采用钢筋网喷射混凝土或钢筋网批抹灰砂浆加固法加固砌体结构的承重墙体；对无法加固或需要拆除的原有承重墙以及需要改变原有使用空间的部分,增大原有混凝土柱截面,并对混凝土梁、板粘贴碳纤维,承载力不足则新增框架梁柱；对于既有建筑砌体结构使用托换法施工,将墙体承重改为框架承重。本发明在对原有结构扰动最小的情况下,增加既有建筑的结构稳定性和抗震性能,提高其使用寿命并保持建筑物的原有建筑风貌。通过托换法将砌体结构变为框架结构,能够解决原有砌体结构难以满足承载力的要求,提高既有建筑承载力和抗震性,也能变换原有建筑空间,增加既有建筑的实用度。(the invention is suitable for the technical field of building construction, and provides a method for reforming an existing building structure, which adopts a reinforcing mesh sprayed concrete or reinforcing mesh batch plastering mortar reinforcing method to reinforce a bearing wall of a masonry structure; for the original bearing wall which cannot be reinforced or needs to be dismantled and the part which needs to change the original use space, the section of the original concrete column is enlarged, carbon fibers are pasted on the concrete beam and the concrete slab, and a frame beam column is newly added when the bearing capacity is insufficient; the existing building masonry structure is constructed by a underpinning method, and the wall bearing is changed into the frame bearing. The invention increases the structural stability and the anti-seismic performance of the existing building under the condition of minimum disturbance to the original structure, prolongs the service life of the building and keeps the original building appearance of the building. The masonry structure is changed into the frame structure through the underpinning method, the problem that the original masonry structure is difficult to meet the requirement of bearing capacity can be solved, the bearing capacity and the shock resistance of the existing building are improved, the original building space can be changed, and the practicability of the existing building is improved.)

1. a method for retrofitting an existing building structure, comprising the steps of:

Reinforcing the bearing wall of the masonry structure by adopting a reinforcing mesh sprayed concrete or reinforcing mesh batch plastering mortar reinforcing method;

For the part which can not reinforce the bearing wall in the existing building masonry structure or the part which needs to dismantle the original bearing wall and change the original use space, the cross section of the original concrete column is increased, carbon fibers are pasted on the concrete beam and the concrete slab, and a frame beam column is newly added when the bearing capacity is insufficient;

the existing building masonry structure is constructed by a underpinning method, and the wall bearing is changed into the frame bearing.

2. a method of retrofitting an existing building structure as defined in claim 1, wherein said reinforcing mesh bar batch plastering mortar reinforcement method comprises the steps of:

Checking the wall according to a shear bearing capacity control formula, and determining the size, the interval and the plastering thickness of horizontal steel bars and vertical steel bars used by a steel bar mesh;

cleaning the wall surface at the early stage and paving and binding a reinforcing mesh;

watering and wetting the wall surface: before the cement mortar is pressed and plastered, watering and wetting back and forth along the wall surface, and plastering after the wall surface is slightly dry;

layering and plastering cement mortar: the cement mortar must be plastered layer by layer to the designed thickness, and the thickness of each layer is 10-15 mm; the joint parts of the mortar of each layer are required to be staggered, pressed and firmly bonded according to requirements, when the reinforcing mesh cement mortar surface layer is reinforced, a spacing protective layer between the reinforcing mesh and the wall surface is reserved, and the mortar surface layer is smeared in three layers;

After plastering for a period of time, water spraying maintenance is needed to prevent hollowing and cracking;

And (5) wall surface decoration construction.

3. a method for retrofitting an existing building structure as defined in claim 2, wherein said step of applying cement mortar in layers comprises the steps of:

The first layer requires picking up the spacing gap between the reinforcing mesh and the masonry, checking no hollowing and cracking after initial setting, and then smearing to the second layer, requiring mortar to cover the reinforcing mesh, checking no hollowing and cracking after initial setting, and then smearing to the third layer to the designed thickness, when the mortar reaches initial setting, then polishing to enhance the compactness, and if the mortar is not used for polishing, keeping the wall surface to be small, namely smearing and flattening the rough surface layer of the wall surface by iron; the plastering time interval of each layer is within 24 h.

4. A method of retrofitting an existing building structure as defined in claim 1, wherein said method of reinforcing with a mesh reinforcement sprayed with concrete comprises the steps of:

Checking the wall according to a shear bearing capacity control formula, and determining the size, the interval and the thickness of sprayed concrete of horizontal steel bars and vertical steel bars used by a steel bar mesh;

cleaning the wall surface at the early stage and paving and binding a reinforcing mesh;

spraying concrete, wherein the strength of the concrete is C30, and the spraying thickness is not less than 60 mm;

carrying out water spraying maintenance on the surface of the concrete, wherein the maintenance time is not less than 7 d;

leveling the concrete before initial setting to ensure that the thickness of the concrete is not less than 50 mm;

Then, a cement mortar surface layer with the thickness of 10 and the strength of M10 is smeared.

5. A method for renovating an existing building structure as claimed in claim 2 or 4, wherein the pre-wall cleaning and the reinforcement mat laying and binding comprises the following steps:

Original brick wall clearance base plane: attention needs to be paid to prevent the mortar from hollowing, the cleaning of the wall surface of the original masonry is ensured to be clean, and crack pointing or pressure grouting is carried out; then, keeping the wall body fully wet, coating an interface agent, and keeping the steel bars smooth and straight; when plastering, plastering is carried out in layers, each layer is 10-15 mm, and the interval of each plastering is more than 24 h; the mortar is strictly prepared according to the design proportion and added with anti-crack fibers;

Drilling: forming holes by using a percussion drill, wherein the diameter of the through-wall hole is preferably 2mm larger than that of the S-shaped steel bar, the diameter of the anchor bar hole is 1.5-2.5 times of that of the anchor bar, and the hole depth is 100-120 mm;

Cleaning the wall surface;

hanging and paving a reinforcing mesh: when the reinforcing mesh is laid, the vertical reinforcing steel bars are close to the wall surface and supported by reinforcing steel bar heads;

fixing the reinforcing mesh: the anchor bars are inserted into the holes and then filled with cement-based grouting materials, the through-wall anchor bars are firmly fixed with the wall body and filled with cement mortar, the distance is less than or equal to 5mm, the thickness of the outer surface protection layer of the net is more than or equal to 10mm, the steel bars are tied transversely and vertically and are firmly tied with the anchor bars.

6. a method of retrofitting an existing building structure as defined in claim 1, wherein said reinforcing method to increase the cross-sectional area of the existing concrete column comprises the steps of:

Erecting a construction operation platform, making a foundation, cleaning dust and falling blocks on the surface of the concrete column, binding reinforcing steel bars, erecting a formwork, pouring concrete, maintaining and decorating; before binding the reinforcing steel bars, thick chisels need to be cleaned on the surfaces of the concrete columns, and part of the reinforcing steel bars of the columns are exposed, so that new reinforcing steel bars can be bound, and the old concrete columns and the newly poured concrete can be easily bonded.

7. The method for improving the existing building structure according to claim 1, wherein before the carbon fiber is adhered to the concrete beam and the concrete slab, dust and falling blocks need to be cleaned on the surface of the concrete, the incomplete surface of the concrete needs to be repaired, and after the cleaning is finished, primer is coated; and after the carbon fiber cloth is pasted and reinforced, maintaining and coating the surface preservative.

8. A method of retrofitting an existing building structure as claimed in claim 1, wherein said underpinning is by providing an underpinning frame consisting of an upper underpinning clamp beam, a lower underpinning clamp beam, shoulder beams and underpinning columns, transferring the original load borne by the load bearing wall from the upper underpinning clamp beam to the underpinning columns, then to the lower underpinning clamp beam and then to the underlying load bearing structure.

9. The method for improving the existing building structure according to claim 1, wherein after the cross section of the original concrete column is enlarged or the concrete beam is reinforced by carbon fiber, the micro structural change of the reinforced structure is monitored and early warned in real time by using a fiber grating monitoring point pre-embedding technology, and after the requirements on safety and strength are met, the original bearing wall can be dismantled to complete the conversion of a space system.

Technical Field

The invention belongs to the technical field of building construction, and particularly relates to a method for modifying an existing building structure.

Background

with the rapid development of modern economy and the continuous improvement of living standard, the requirements of people on the quality and safety of buildings are higher and higher. At present, a large number of old masonry buildings exist in China, and due to the fact that the requirements for the standard earthquake resistance performance of the old buildings are very limited, the business requirements for structural safety improvement of the buildings are increasingly improved. Particularly, after natural disasters such as severe earthquake of Wenchuan in 2008, government and people consciously pay attention to the maintenance and promotion of the earthquake resistance and the safety performance of the existing building, and according to statistics, the reinforcement and maintenance business of the existing building is increased by nearly 50%.

at present, the existing building structure reinforcing method generally comprises the following steps: the method comprises the steps of changing the section size, adding a steel structure and protection, adding a prestressing method, changing the original structure system, and adding a new composite material reinforcing method. The existing patent technology for reinforcing the existing building structure mainly changes the invention creation of the original structure system, for example, the joist connection prestress in various forms is arranged, the original stress level is cleared up, the integral structure rigidity is improved, the effects of reducing the original structure deformation and improving the stability of the existing building structure are achieved. However, such a method has disadvantages in that it is only suitable for reinforcing the beam slab, and the strength and deformation resistance of the coupling member are high, and at the same time, the size of the indoor ceiling space is increased, and the clear height of the indoor space is reduced. In addition, a new outer casing frame is constructed outside to support the original structure, and the method is also a thought for reinforcing the original structure, but the method has large engineering quantity and high requirement on the surrounding environmental conditions of the existing building, and is only suitable for the existing building with open periphery.

disclosure of Invention

The invention aims to provide a method for transforming an existing building structure, which can solve the problems that the prior art is complex in technology, large in engineering quantity and affects the use space of the original building and the surrounding environment by designing and providing an additional structural member to reinforce the existing building structure.

the invention is realized in such a way that a method for reforming an existing building structure comprises the following steps:

Reinforcing the bearing wall of the masonry structure by adopting a reinforcing mesh sprayed concrete or reinforcing mesh batch plastering mortar reinforcing method;

for the part which can not reinforce the bearing wall in the existing building masonry structure or the part which needs to dismantle the original bearing wall and change the original use space, the cross section of the original concrete column is increased, carbon fibers are pasted on the concrete beam and the concrete slab, and a frame beam column is newly added when the bearing capacity is insufficient;

The existing building masonry structure is constructed by a underpinning method, and the wall bearing is changed into the frame bearing.

Further, the reinforcing method for reinforcing the reinforcing mesh by plastering mortar specifically comprises the following steps:

Checking the wall according to a shear bearing capacity control formula, and determining the size, the interval and the plastering thickness of horizontal steel bars and vertical steel bars used by a steel bar mesh;

Cleaning the wall surface at the early stage and paving and binding a reinforcing mesh;

Watering and wetting the wall surface: before the cement mortar is pressed and plastered, watering and wetting back and forth along the wall surface, and plastering after the wall surface is slightly dry;

Layering and plastering cement mortar: the cement mortar must be plastered layer by layer to the designed thickness, and the thickness of each layer is 10-15 mm; the joint parts of the mortar of each layer are required to be staggered, pressed and firmly bonded according to requirements, when the reinforcing mesh cement mortar surface layer is reinforced, a spacing protective layer between the reinforcing mesh and the wall surface is reserved, and the mortar surface layer is smeared in three layers;

After plastering for a period of time, water spraying maintenance is needed to prevent hollowing and cracking;

And (5) wall surface decoration construction.

further, the concrete steps of the layering and plastering cement mortar are as follows:

The first layer requires picking up the spacing gap between the reinforcing mesh and the masonry, checking no hollowing and cracking after initial setting, and then smearing to the second layer, requiring mortar to cover the reinforcing mesh, checking no hollowing and cracking after initial setting, and then smearing to the third layer to the designed thickness, when the mortar reaches initial setting, then polishing to enhance the compactness, and if the mortar is not used for polishing, keeping the wall surface to be small, namely smearing and flattening the rough surface layer of the wall surface by iron; the plastering time interval of each layer is within 24 h.

Further, the reinforcing method of the mesh reinforcement sprayed concrete specifically comprises the following steps:

checking the wall according to a shear bearing capacity control formula, and determining the size, the interval and the thickness of sprayed concrete of horizontal steel bars and vertical steel bars used by a steel bar mesh;

Cleaning the wall surface at the early stage and paving and binding a reinforcing mesh;

Spraying concrete, wherein the strength of the concrete is C30, and the spraying thickness is not less than 60 mm;

Carrying out water spraying maintenance on the surface of the concrete, wherein the maintenance time is not less than 7 d;

leveling the concrete before initial setting to ensure that the thickness of the concrete is not less than 50 mm;

then, a cement mortar surface layer with the thickness of 10 and the strength of M10 is smeared.

Further, the earlier stage wall surface cleaning and reinforcing mesh laying and binding specifically comprise the following steps:

Original brick wall clearance base plane: attention needs to be paid to prevent the mortar from hollowing, the cleaning of the wall surface of the original masonry is ensured to be clean, and crack pointing or pressure grouting is carried out; then, keeping the wall body fully wet, coating an interface agent, and keeping the steel bars smooth and straight; when plastering, plastering is carried out in layers, each layer is 10-15 mm, and the interval of each plastering is more than 24 h; the mortar is strictly prepared according to the design proportion and added with anti-crack fibers;

Drilling: forming holes by using a percussion drill, wherein the diameter of the through-wall hole is preferably 2mm larger than that of the S-shaped steel bar, the diameter of the anchor bar hole is 1.5-2.5 times of that of the anchor bar, and the hole depth is 100-120 mm;

cleaning the wall surface;

Hanging and paving a reinforcing mesh: when the reinforcing mesh is laid, the vertical reinforcing steel bars are close to the wall surface and supported by reinforcing steel bar heads;

fixing the reinforcing mesh: the anchor bars are inserted into the holes and then filled with cement-based grouting materials, the through-wall anchor bars are firmly fixed with the wall body and filled with cement mortar, the distance is less than or equal to 5mm, the thickness of the outer surface protection layer of the net is more than or equal to 10mm, the steel bars are tied transversely and vertically and are firmly tied with the anchor bars.

further, the reinforcing method for increasing the section area of the original concrete column comprises the following steps:

Erecting a construction operation platform, making a foundation, cleaning dust and falling blocks on the surface of the concrete column, binding reinforcing steel bars, erecting a formwork, pouring concrete, maintaining and decorating; before binding the reinforcing steel bars, thick chisels need to be cleaned on the surfaces of the concrete columns, and part of the reinforcing steel bars of the columns are exposed, so that new reinforcing steel bars can be bound, and the old concrete columns and the newly poured concrete can be easily bonded.

furthermore, before the carbon fibers are adhered to the concrete beam and the concrete slab, dust and falling blocks need to be cleaned on the surface of the concrete, the incomplete surface of the concrete needs to be repaired, and after the cleaning is finished, primer is coated; and after the carbon fiber cloth is pasted and reinforced, maintaining and coating the surface preservative.

furthermore, the underpinning method is a mode that an underpinning frame consisting of an upper underpinning clamping beam, a lower underpinning clamping beam, a shoulder beam and an underpinning column is arranged, the original load born by the bearing wall is transferred to the underpinning column from the upper underpinning clamping beam, then transferred to the lower underpinning clamping beam and then transferred to a lower layer bearing structure.

furthermore, after the cross section of the original concrete column is enlarged or the concrete beam is reinforced by carbon fibers, the micro structural change of the reinforced structure is monitored and early warned in real time by using the fiber grating monitoring point pre-embedding technology, and after the requirements on safety and strength are met, the original bearing wall can be detached, and the conversion of a space system is completed.

Compared with the prior art, the invention has the beneficial effects that:

According to the method for improving the existing building structure, the reinforcing layer made of the steel bar mesh plastering is added to the bearing wall for reinforcing, the concrete beam, the concrete column and the concrete floor slab are bonded with the carbon fiber for reinforcing, the structural stability and the anti-seismic performance of the existing building can be improved under the condition of minimum disturbance to the original structure, the service life of the existing building is prolonged, the original building style of the building is kept, the investment is low, and the benefit ratio is high.

The strength and the extensibility of the component reinforced by sticking the carbon fibers are greatly improved, the bearing capacity, the shearing resistance, the seismic strength and the crack resistance of the component can be improved on the basis of not reducing the building space, and the carbonization of the existing building concrete is avoided. The method for underpinning the original structure can change the masonry structure of the building into a frame structure, improve the bearing capacity and the shock resistance of the existing building on the basis of solving the problem that the original masonry structure is difficult to meet the requirement of the bearing capacity, also can change the original building space, and increases the practicability of the existing building.

the invention comprehensively simplifies the process flow of structure reinforcement from detail to whole from the consideration of the reinforcement of the load-bearing member per se and the consideration of replacement, reconstruction and reinforcement of the whole structure system, improves the operability and convenience, enhances the load-bearing and earthquake-resistant capacity of the existing building per se and prolongs the service life of the building.

drawings

FIG. 1 is a flow chart of a method of retrofitting an existing building structure according to an embodiment of the present invention;

Fig. 2 is a schematic view of a brick wall reinforcing mesh reinforcement according to an embodiment of the present invention;

Fig. 3a and 3b are schematic diagrams of a frame node after being reinforced by the carbon fiber reinforcement method of the embodiment;

FIG. 4 is a schematic view of a building structure after being modified using the frame underpinning method of the present embodiment;

3 FIG. 35 3 is 3a 3 schematic 3 cross 3- 3 sectional 3 view 3 taken 3 along 3 section 3A 3- 3A 3 of 3 FIG. 34 3; 3

Fig. 6 is a schematic cross-sectional view taken along section B-B of fig. 4.

Detailed Description

in order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

in the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention; the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance; furthermore, unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, as they may be fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The embodiment provides a method for transforming an existing building structure, which is used for solving the problems that the existing technology is complex, the engineering quantity is large, and the use space of the original building and the surrounding environment is influenced by designing and providing an additional structural member to reinforce the existing building structure in the prior art.

specifically, please refer to fig. 1, which shows the modification method provided by the present embodiment, specifically including the following steps:

firstly, reinforcing the load-bearing wall of the masonry structure by adopting a reinforcing mesh batch plastering mortar reinforcing method or a reinforcing mesh sprayed concrete reinforcing method.

the reinforcing method for reinforcing the steel bar mesh batch plastering mortar comprises the following steps:

11. the wall body is checked according to a shear bearing capacity control formula, and the size, the distance and the plastering thickness of horizontal steel bars and vertical steel bars used by the steel bar mesh are determined.

12. early-stage wall surface cleaning:

original brick wall surface clearance base face: attention needs to be paid to prevent the mortar from hollowing, the cleaning of the wall surface of the original masonry is ensured to be clean, and crack pointing or pressure grouting is carried out; then, keeping the wall body fully wet, coating an interface agent, and keeping the steel bars smooth and straight; when plastering, plastering is carried out in layers, each layer is 10-15 mm, and the interval of each plastering is more than 24 h; the mortar is strictly prepared according to the design proportion and added with anti-crack fibers; the mortar can be prevented from hollowing, and the strength of the reinforced bearing wall can be prevented from being influenced.

Drilling: and (3) forming holes by using a percussion drill, wherein the diameter of the through-wall hole is preferably 2mm larger than that of the S-shaped steel bar, the diameter of the anchor bar hole is 1.5-2.5 times of that of the anchor bar, and the hole depth is 100-120 mm.

And cleaning the wall surface.

13. Please refer to fig. 2, the steel mesh is laid and bound:

Hanging and paving a reinforcing mesh: the reinforcing mesh comprises vertical reinforcing steel bars 11 and transverse reinforcing steel bars 12, and when the reinforcing mesh is laid, the vertical reinforcing steel bars 11 are supported by the wall surface and reinforcing steel bar heads.

fixing the reinforcing mesh: the anchor bars are inserted into the holes and then filled with cement-based grouting materials, the through-wall anchor bars are firmly fixed with the wall and filled with cement mortar, the distance is less than or equal to 5mm, the thickness of the protective layer on the outer surface of the net is more than or equal to 10mm, the steel bars are bound by tie bars 13, are horizontally flat and vertical and are firmly bound with the anchor bars, and then the steel bar net is reinforced.

14. Watering and wetting the wall surface: before the cement mortar is pressed and plastered, the water is watered back and forth along the wall surface to be wet, and the plastering is carried out after the wall surface is slightly dry.

15. Layering and plastering cement mortar: the cement mortar must be plastered layer by layer to the designed thickness, and the thickness of each layer is 10-15 mm; the joint parts of the mortar of each layer are required to be staggered, pressed and firmly bonded according to requirements, when the reinforcing mesh cement mortar surface layer is reinforced, a spacing protective layer between the reinforcing mesh and the wall surface is reserved, and the mortar surface layer is smeared in three layers; the first layer requires picking up the spacing gap between the reinforcing mesh and the masonry to be solid, checking no hollowing and crack phenomena after initial setting, and then smearing the spacing gap to the second layer, requiring mortar to cover the reinforcing mesh completely, checking no hollowing and crack phenomena after initial setting, and then smearing the spacing gap to the third layer to the designed thickness, when the mortar reaches the initial setting, calendaring for 2-3 times to enhance the compactness, and the finishing must not be performed by adopting clean mortar, so that the wall surface can keep a small rough surface, namely, a rough surface layer of the wall surface is trowelled and flattened by iron; the plastering time interval of each layer is within 24 h.

16. and water spraying maintenance is needed after plastering for 24 hours, hollowing and cracking are prevented, and the maintenance time is not less than 7 d.

17. And (5) wall surface decoration construction.

the reinforcing method of the steel bar mesh sprayed concrete comprises the following steps:

21. The wall body is checked according to a shear bearing capacity control formula, and the size, the distance and the thickness of sprayed concrete of horizontal steel bars and vertical steel bars used by the steel bar mesh are determined.

22. the early-stage wall surface cleaning step and the reinforcing mesh paving and binding step of the reinforcing mesh sprayed concrete reinforcing method are similar to those of a reinforcing mesh cement mortar reinforcing method, and the purpose is to ensure that the wall surface is clean and tidy and the reinforcing mesh is firmly connected with the original wall surface.

23. and (3) spraying the concrete, wherein the strength of the concrete is C30, and the spraying thickness is not less than 60 mm.

24. And (5) carrying out water spraying maintenance on the surface of the concrete, wherein the maintenance time is not less than 7 d.

25. And leveling the concrete before initial setting to ensure that the thickness of the concrete is not less than 50 mm.

26. Then, a cement mortar surface layer with the thickness of 10 and the strength of M10 is smeared.

And secondly, increasing the cross section of the original concrete column for the part which cannot reinforce the bearing wall in the existing building masonry structure or the part which needs to dismantle the original bearing wall and change the original use space, and pasting carbon fibers on the concrete beam and the concrete slab, wherein the newly added frame beam column is not enough in bearing capacity.

The reinforcing method for increasing the section area of the original concrete column comprises the following steps:

the construction method comprises the following steps of erecting a construction operation platform, making a foundation, cleaning dust and falling blocks on the surface of the concrete column, binding reinforcing steel bars, erecting a formwork, pouring concrete, maintaining and decorating. Before binding the reinforcing steel bars, thick chisels need to be cleaned on the surfaces of the concrete columns, and part of the reinforcing steel bars of the columns are exposed, so that new reinforcing steel bars can be bound, and the old concrete columns and the newly poured concrete can be easily bonded.

Before the carbon fibers are adhered to the concrete beam and the concrete slab, dust and falling blocks need to be cleaned on the surface of the concrete, the incomplete surface of the concrete is repaired, and after the cleaning is finished, primer is coated. Please refer to fig. 3a and fig. 3b, which are the frame nodes after being reinforced by adhering carbon fibers 2 (in the embodiment, carbon fiber cloth is used). And (4) curing the reinforced carbon fiber 2, and coating a surface preservative.

The carbon fiber 2 is a high-performance material, has the characteristics of good adhesiveness, heat resistance, corrosion resistance and the like, and has the strength which is more than 10 times that of steel. The strength and the extensibility of the component reinforced by the adhered carbon fibers 2 are greatly improved, the bearing capacity, the shearing resistance, the seismic strength and the crack resistance of the component can be improved on the basis of not reducing the building space, and the carbonization of the existing building concrete is avoided.

After original concrete column carries out the cross-section increase or uses carbon fiber 2 to consolidate to the concrete beam, use the pre-buried technique of fiber grating monitoring point to carry out real time monitoring early warning to the little structural change of structure after consolidating, satisfy security and intensity requirement after, can demolish original bearing wall, accomplish the conversion of space system.

And thirdly, constructing the existing building masonry structure by using a underpinning method, and changing wall bearing into frame bearing.

specifically, referring to fig. 4 to 6, a building structure modified by the framework underpinning method of the present embodiment is shown, in which an underpinning framework composed of an upper underpinning clamping beam 31, a lower underpinning clamping beam 32, a shoulder beam 33, an underpinning column 34 and an underpinning beam 35 is provided, and the original load borne by the load-bearing wall is transferred from the upper underpinning clamping beam 31 to the underpinning column 34, then to the lower underpinning clamping beam 32, and then to the lower layer load-bearing structure.

The method for underpinning the original structure can change the masonry structure of the building into a frame structure, improve the bearing capacity and the shock resistance of the existing building on the basis of solving the problem that the original masonry structure is difficult to meet the requirement of the bearing capacity, also can change the original building space, and increases the practicability of the existing building.

It can be seen that, in the method for modifying the existing building structure provided by this embodiment, the reinforcing mesh plastering reinforcing layer is added to the load-bearing wall for reinforcement, and the carbon fiber 2 is adhered to the concrete beam, the column and the floor slab for reinforcement, so that the structural stability and the seismic performance of the existing building can be increased under the condition of minimal disturbance to the original structure, the service life of the existing building structure can be prolonged by 30 years, the original building appearance of the building can be maintained, the investment is low, and the benefit ratio is high.

in the embodiment, the process flow of the structural reinforcement is comprehensively simplified from details to the whole from the consideration of the reinforcement of the bearing member and the consideration of the replacement, transformation and reinforcement of the whole structural system, the operability and the convenience are improved, the bearing and earthquake resistance of the existing building is enhanced, and the service life of the existing building is prolonged.

the above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.