Hidden masonry parapet wall anti-seismic reinforcement construction method applying vertical prestress

Abstract

The invention discloses an anti-seismic reinforcement construction method for a hidden masonry parapet wall applying vertical prestress, door-shaped reinforcement structures are mounted on the outer sides of the two ends of a bearing wall and the parapet wall, a plurality of springs in a compressed state are mounted, and the anti-seismic reinforcement construction method comprises the following steps: 1, determining the rigidity and the number of the springs; 2, positioning the steel base plate; 3, mounting a steel base plate; fourthly, steel pipes of the door-shaped reinforcing structure are installed; fifthly, H-shaped steel of the door-shaped reinforcing structure is installed; and 6, installing and fixing the spring. On the basis of reduction of damage to waterproofing of an original roof, a door-shaped reinforcing structure is installed on the outer side of a load bearing wall and the outer side of a parapet wall, a plurality of springs in a compressed state are installed, the springs are fully used for improving the vertical pressure stress of the parapet wall, friction force is generated on the shearing face of the parapet wall, and the meshing effect between aggregates is enhanced; and crack development, shear slippage and inclined crack penetration in the parapet wall are inhibited, and damage is delayed, so that the shear resistance is improved, and the anti-seismic bearing capacity of the parapet wall can be remarkably improved during an earthquake.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of Tibetan masonry parapet wall seismic reinforcement, and particularly relates to a Tibetan masonry parapet wall seismic reinforcement construction method with vertical prestress. BACKGROUND

[0002] The parapet wall refers to the low wall around the roof of a building, the top of a staircase or the edge of a roof terrace, and is usually arranged on the upper part of the bearing wall. Its main functions include: 1. Safety protection: preventing people from falling from a high place and ensuring personal safety. 2. Architectural aesthetics: as a component of the building facade, it plays a role in decoration and edge collection. 3. Waterproof closing: as the end part of the roof waterproof material, it prevents rainwater from seeping in.

[0003] There are many masonry parapet walls in Tibetan architecture. The Dingri earthquake found that under the action of earthquakes, parapet walls that are not specially designed or improperly constructed are extremely fragile non-structural components. According to the principle of structural dynamics, after the seismic wave is input into the main body of the building, a whipping effect will occur at the top. As the topmost part of the building, the parapet wall will bear several times the seismic acceleration of the main body, resulting in a sharp increase in its inertia force, and it is extremely prone to damage. Many parapet walls have been severely damaged due to the lack of anchoring measures, low material strength, excessive height, poor construction quality, and other reasons, causing great loss of life and property safety to the public. The specific analysis has the following shortcomings: 1. Poor stability: the parapet wall is usually high and towering, and the connection with the roof structure (such as the tieback in masonry structures) is often insufficient or improperly constructed, forming a cantilever structure with the head heavier than the feet, which has extremely poor stability; 2. Weak integrity: traditional masonry parapet walls are built with bricks, blocks and other materials, which have low tensile and shear strength, and their integrity is very poor, making them prone to collapse and collapse under the action of earthquakes; 3. Weak connection with the main structure: the connection between the parapet wall and the roof floor or ring beam is a weak link in seismic resistance, and the new and old concrete joint surface and the masonry and concrete joint surface are prone to cracking, leading to connection failure.

[0004] Therefore, how to reinforce the parapet wall against earthquakes has become a major problem after the earthquake. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a Tibetan masonry parapet wall seismic reinforcement construction method with vertical prestress to overcome the shortcomings of the prior art. This method proposes to install a door-shaped reinforcement structure on the outside of the bearing wall and the parapet wall, and install multiple springs in a compressed state, fully utilizing the spring to apply vertical prestress to the parapet wall, generating friction on the shear surface of the parapet wall, and inhibiting the development of cracks, shear slip and penetration of diagonal cracks inside the parapet wall. This method can significantly improve the seismic bearing capacity of the parapet wall during an earthquake, solving the problem of ineffective reinforcement of masonry parapet walls in the prior art and the problem of large damage to the original roof waterproofing by existing reinforcement methods.

[0006] To solve the above technical problems, the technical scheme adopted by the present application is: a Tibetan masonry parapet anti-seismic reinforcement construction method for applying vertical prestress, characterized in that the method is to install door-shaped reinforcement structures on the outer sides of both ends of the load-bearing wall and the parapet, install a plurality of springs in a compressed state between the door-shaped reinforcement structures and the top of the parapet for anti-seismic reinforcement, and further provide steel backing plates between the springs and the top of the parapet, and the method comprises the following steps: Step one, determine the stiffness and number of springs: Given that the length of the parapet is L, and the interval of the springs is assumed to be l , then the number of springs n = L / l + 1, and the effective contact area of the spring with the top surface of the parapet is set to A, according to the requirements of the Code for Design of Masonry Structures GB 50003-2011, the horizontal cross-sectional average compressive stress generated by the spring should not be greater than 0.8 f , wherein f is the compressive strength design value of the parapet, then the vertical prestress N provided by each spring should not be greater than 0.8 f· A / n, and the compression amount of the spring to be used is set to x, then the maximum stiffness k of the spring required is N / x, and the maximum stiffness of the spring is obtained; Step two, position the steel backing plate: weld threaded anchor rods at the lower part of the steel backing plate, then use a chalk line to position the steel backing plates with the same number of threaded anchor rods as the number of springs obtained in step one according to the interval of the springs, and mark the installation positions of the steel backing plates and the threaded anchor rods on the top surface of the parapet; Step three, install the steel backing plate: according to the installation positions of the steel backing plates and the threaded anchor rods marked in step two, drill holes at the corresponding threaded anchor rod installation positions on the top of the parapet, then inject structural adhesive into the holes, after that, insert the threaded anchor rods of the steel backing plate into the holes, and finally perform maintenance to obtain a parapet with installed steel backing plates; Step four, install the steel pipes of the door-shaped reinforcement structure: drill holes on the outer sides of both ends of the parapet with installed steel backing plates and the load-bearing wall obtained in step three, then inject structural adhesive into the holes, after that, sequentially insert two steel pipes into the holes through threaded rods to fix them, and obtain two fixed steel pipes; Step five, install the H-shaped steel of the door-shaped reinforcement structure: weld H-shaped steel at the ends of the two fixed steel pipes obtained in step four, and weld stiffening ribs at the web of the H-shaped steel at each position corresponding to the spring, and obtain a door-shaped reinforcement structure; Step six, install and fix the spring: according to the clearance height between the bottom surface of the H-shaped steel in the door-shaped reinforcing structure obtained in step five and the steel backing plate, select a plurality of springs with a length meeting the requirements and meeting the rigidity and quantity requirements obtained in step one, then compress each spring and temporarily wrap it with iron wire to obtain a compressed spring, weld the compressed spring on the H-shaped steel and the steel backing plate in the door-shaped reinforcing structure obtained in step five, and finally cut off the temporarily wrapped iron wire to complete the application of the vertical prestress of the Tibetan masonry parapet wall.

[0007] The application is based on reducing the damage to the original roof waterproof, and proposes to install a door-shaped reinforcing structure on the outer side of both ends of the load-bearing wall and the parapet wall, and install a plurality of springs in a compressed state between the door-shaped reinforcing structure and the top of the parapet wall for seismic reinforcement, wherein a steel backing plate is further arranged between the spring and the top of the parapet wall, so that the vertical prestress provided by the spring is uniformly applied to the parapet wall, and the effect of seismic resistance is ensured. According to the shear capacity calculation formula of the masonry wall in the Code for Design of Masonry Structures GB 50003-2011 , wherein, f v is the shear capacity of the parapet wall masonry itself, a mus 0 is the part of the improved bearing capacity due to the increase of the vertical prestress of the spring, which fully utilizes the spring to improve the vertical compressive stress of the parapet wall, generates friction on the shear surface of the parapet wall masonry, enhances the interlocking action between the aggregates, suppresses the development of cracks, shear slip and penetration of diagonal cracks in the parapet wall masonry, delays the damage, and thus improves the shear capacity, which can significantly improve the seismic bearing capacity of the parapet wall in an earthquake.

[0008] According to the known length L of the parapet wall, the spacing of the spring is assumed to be l , the number of springs n=L / l +1 is obtained, then according to the requirements of the Code for Design of Masonry Structures GB 50003-2011, the average compressive stress σ0 of the horizontal section generated by the design value of the permanent load should not be greater than 0.8 f , wherein f is the design value of the compressive strength of the masonry, the effective contact area of the spring and the top surface of the parapet wall is set as A, and based on this, the maximum vertical prestress N=0.8 f· A / n provided by each spring is obtained, and then according to the set compression amount x of the spring, the maximum stiffness k=N / x of the spring is obtained.

[0009] The application is characterized in that the spring spacing is controlled, the construction is facilitated, the springs do not interfere with each other, the wall is less damaged, the best stability effect is ensured, the spring compression amount is controlled, the compression stress provided by the spring has the best reinforcing effect, and the stability of the spring is ensured.

[0010] The application is characterized in that the effective contact area in step one is the area of contact between the spring and the steel pad. l The spring spacing is controlled, the construction is facilitated, the springs do not interfere with each other, the wall is less damaged, the best stability effect is ensured, the spring compression amount is controlled, the compression stress provided by the spring has the best reinforcing effect, and the stability of the spring is ensured.

[0011] The application is characterized in that the effective contact area in step one is the area of contact between the spring and the steel pad.

[0012] It should be noted that the outer diameter of the spring is 40mm smaller than the side length of the steel pad, and the area of contact between the spring and the steel pad is a circular ring with a width of 1mm.

[0013] The application is characterized in that the steel pad in step two is a square with a thickness of 3mm to 5mm, the side length is the same as the thickness of the parapet wall, four threaded anchor rods are welded to the lower part of each steel pad, the diameter of the threaded anchor rod is 10mm to 12mm, and the length is not less than 200mm. The application is characterized in that the parameters of the steel pad and the threaded anchor rod are controlled, which are used to more evenly and stably apply the compression stress provided by the spring to the parapet wall, and ensure the effect of earthquake resistance.

[0014] The application discloses a vertical pre-stress applied Tibetan masonry parapet wall anti-seismic reinforcing construction method, and relates to the technical field of building construction.

[0015] The vertical pre-stress applied Tibetan masonry parapet wall anti-seismic reinforcing construction method has the characteristics that the steel pipe is a rectangular steel pipe with a section length of not less than 350 mm, a section width of not less than 250 mm and a wall thickness of not less than 6 mm, the length of the steel pipe is not less than 2.5 times the height of the parapet wall, the length of the top of the steel pipe that is higher than the top surface of the parapet wall is 550 mm to 600 mm, the diameter of the threaded screw rod is 10 mm to 12 mm, and the interval between adjacent threaded screw rods is 300 mm to 350 mm.

[0016] The vertical pre-stress applied Tibetan masonry parapet wall anti-seismic reinforcing construction method has the characteristics that the H-shaped steel has a section height of not less than 400 mm, a flange width of not less than 300 mm, an web thickness of not less than 10 mm and a flange thickness of not less than 16 mm, two stiffening ribs with a thickness of 3 mm to 5 mm are welded to the web of the H-shaped steel at positions corresponding to the springs, and the interval between the two stiffening ribs is 100 mm to 120 mm.

[0017] Compared with the prior art, the application has the following advantages: 1. Based on reducing damage to the original roof waterproofing, this invention proposes installing a portal-shaped reinforcement structure on the outer sides of both ends of the load-bearing wall and the parapet wall. Multiple compressed springs are installed between the portal-shaped reinforcement structure and the top of the parapet wall for seismic reinforcement. A steel pad is also placed between the springs and the top of the parapet wall to uniformly apply the compressive stress provided by the springs to the parapet wall. This fully utilizes the springs to increase the vertical compressive stress of the parapet wall, generating friction on the shear surface of the parapet wall masonry, enhancing the interlocking effect between aggregates, inhibiting the development of cracks, shear slip, and the penetration of diagonal cracks within the parapet wall masonry, thus delaying failure and improving shear resistance. During earthquakes, this significantly improves the seismic bearing capacity of the parapet wall.

[0018] 2. The present invention welds threaded anchor rods to the lower part of the steel pad, which facilitates a stable connection between the steel pad and the parapet wall, thereby further and evenly applying the compressive stress provided by the spring to the parapet wall and preventing the steel pad from shifting laterally.

[0019] 3. This invention combines the room's span dimensions with the spring spacing to ensure optimal stability. By controlling the spring compression, it ensures that the compressive stress provided by the spring has the best reinforcement effect, while also guaranteeing the spring's stability.

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the Tibetan-style masonry parapet wall seismic reinforcement structure with vertical prestress applied according to the present invention.

[0022] Explanation of reference numerals in the attached figures: Detailed Implementation

[0023] Figure 1 This is a schematic diagram of the seismic reinforcement structure of Tibetan-style masonry parapet walls with vertical prestressing according to the present invention. Figure 1 As can be seen, a portal-shaped reinforcement structure is installed on the outer sides of both ends of the load-bearing wall 1 and the parapet wall 2. Multiple springs 3 in a compressed state are installed between the portal-shaped reinforcement structure and the top of the parapet wall 2 for seismic reinforcement. A steel pad 4 is also set between the spring 3 and the top of the parapet wall 2. Threaded anchor rods 5 are welded to the lower part of the steel pad 4. The portal-shaped reinforcement structure is composed of two steel pipes 6 and H-beams 8 welded to the ends. The two steel pipes 6 are fixed to the load-bearing wall 1 and the parapet wall 2 by multiple threaded bolts 7. Stiffening ribs 9 are welded to the web of each H-beam 8 at a position corresponding to the spring 3.

[0024] Example 1 This embodiment includes the following steps: Step 1: Calculate the stiffness and number of springs: The length of the parapet is L=9900mm, and the interval of the spring is assumed to be l =1100mm, then the number of the spring is n=L / l +1=10, the thickness of the parapet is 240mm, the effective contact area of the spring and the top surface of the parapet is assumed to be the contact area of the spring and the steel pad, and the outer diameter of the spring is 40mm smaller than the side length of the steel pad, and the contact area of the spring and the steel pad is a circular ring with a width of 1mm, then the effective contact area is A=625.2mm 2 The vertical compressive stress generated by the spring should not be greater than 0.8 f , wherein f is the compressive strength design value of the parapet f =0.4×10 6 Pa, then the maximum vertical pressure provided by each spring is N=0.8 f· A / n=20×10 6 N, and the compression amount of the spring is assumed to be x=200mm, then the maximum stiffness of the spring to be used is k=N / x=100000N / mm; Step two, positioning the steel pad: four threaded anchor rods with a diameter of 10mm and a length of 250mm are welded at the lower part of a square steel pad with a thickness of 3mm and a side length equal to the thickness of the parapet, then the same number of steel pad welded with threaded anchor rods is positioned using a line pencil according to the number of springs and the interval of the springs, and the installation position of the steel pad and the threaded anchor rod is marked on the top surface of the parapet; Step three, installing the steel pad: according to the installation position of the steel pad and the threaded anchor rod marked in step two, holes are drilled at the corresponding threaded anchor rod installation position on the top of the parapet, after drilling, the holes are cleaned with a non-falling hair brush, the diameter of the holes is 2mm larger than the diameter of the threaded anchor rod, and the depth of the holes is 10mm greater than the length of the threaded anchor rod, then structural adhesive is injected into the holes, and when the adhesive in the holes reaches 80%, the threaded anchor rods of the steel pad are immediately inserted into the holes, and finally curing is performed to obtain a parapet with installed steel pads; Step four, installing the steel pipe of the door-shaped reinforcing structure: holes are drilled on the outer side of both ends of the parapet with installed steel pads obtained in step three and the load-bearing wall, then structural adhesive is injected into the holes, and then two steel pipes are sequentially fixed by inserting threaded screws into the holes, the steel pipes are rectangular steel pipes with a cross-sectional length of 370mm, a cross-sectional width of 270mm, and a wall thickness of 7mm, the length of the steel pipes is 2.6 times the height of the parapet, and the length of the steel pipes above the top surface of the parapet is 600mm, the diameter of the threaded screws is 10mm, and the interval of adjacent threaded screws is 330mm, to obtain two fixed steel pipes; Step 5: Install the H-beams for the portal reinforcement structure: Weld H-beams with a cross-sectional height of 400mm, a flange width of 300mm, a web thickness of 10mm, and a flange thickness of 16mm to the ends of the two fixed steel pipes obtained in Step 4. Weld two stiffening ribs with a thickness of 3mm and a spacing of 100mm to the web of each H-beam corresponding to the spring position to obtain the portal reinforcement structure. Step Six: Install and Fix Springs: Based on the clearance height between the bottom surface of the H-beam and the steel pad in the portal reinforcement structure obtained in Step Five, select multiple springs with sufficient length and stiffness and quantity to meet the requirements obtained in Step One. Then, compress each spring and temporarily wrap it with wire to obtain a compression spring. Weld the compression springs onto the H-beam and steel pad in the portal reinforcement structure obtained in Step Five. Finally, cut the temporarily wrapped wire to complete the seismic reinforcement of the Tibetan-style masonry parapet wall with vertical prestress.

[0025] Example 2 This embodiment includes the following steps: Step 1: Calculate the stiffness and number of springs: Given that the length of the parapet wall is L = 12000 mm, and assuming the spring spacing is... l =1000mm, then the number of springs n=L / l +1=13, the thickness of the parapet wall is 200mm, the effective contact area between the spring and the top surface of the parapet wall is set to the area of ​​contact between the spring and the steel pad, and the outer diameter of the spring is 40mm smaller than the side length of the steel pad. The contact area between the spring and the steel pad is a ring with a width of 1mm. Then the effective contact area is A=499.5mm². 2 The vertical compressive stress generated by the spring should not exceed 0.8. f ,in f Design value of compressive strength for parapet wall f =0.3×10 6 If Pa, then the maximum vertical pressure N provided by each spring is 0.8. f· A / n = 9.22 × 10 6 N, with the spring compression set to x = 150 mm, then the maximum stiffness of the spring to be used is k = N / x = 61466 N / mm; Step 2, Positioning the steel pad: Weld four threaded anchor rods with a diameter of 12mm and a length of 230mm to the bottom of a square steel pad with a thickness of 5mm and a side length the same as the thickness of the parapet wall. Then, according to the number of springs and the spacing of the springs obtained in Step 1, position the steel pad with the same number of welded threaded anchor rods as the number of springs using a chalk line. Mark the installation positions of the steel pad and threaded anchor rods on the top surface of the parapet wall. Step 3: Install steel pads: According to the installation positions of the steel pads and threaded anchors noted in Step 2, drill holes at the corresponding threaded anchor installation positions on the top of the parapet wall. After drilling, use a lint-free brush to remove dust from the holes. The diameter of the hole should be 1mm larger than the diameter of the threaded anchor, and the depth should be 20mm larger than the length of the threaded anchor. Then inject structural adhesive into the holes. When the adhesive reaches 75% of the hole, immediately insert the threaded anchor of the steel pad into the hole. Finally, perform curing to obtain the parapet wall with the steel pad installed. Step 4: Install the steel pipes for the portal reinforcement structure: Drill holes on the outer sides of both ends of the parapet wall and the load-bearing wall obtained in Step 3 for installing the steel pads. Then inject structural adhesive into the holes. Next, insert two steel pipes into the holes one by one using threaded screws for fixation. The steel pipes are rectangular steel pipes with a cross-sectional length of 360mm, a cross-sectional width of 260mm, and a wall thickness of 6mm. The length of the steel pipe is 2.7 times the height of the parapet wall, and the top of the steel pipe extends 570mm above the top surface of the parapet wall. The diameter of the threaded screw is 11mm, and the spacing between adjacent threaded screws is 300mm, resulting in two fixed steel pipes. Step 5: Install the H-beams for the portal reinforcement structure: Weld H-beams with a cross-sectional height of 420mm, a flange width of 320mm, a web thickness of 12mm, and a flange thickness of 18mm to the ends of the two fixed steel pipes obtained in Step 4. Weld two stiffening ribs with a thickness of 5mm and a spacing of 120mm to the web of each H-beam corresponding to the spring position to obtain the portal reinforcement structure. Step Six: Install and Fix Springs: Based on the clearance height between the bottom surface of the H-beam and the steel pad in the portal reinforcement structure obtained in Step Five, select multiple springs with sufficient length and stiffness and quantity to meet the requirements obtained in Step One. Then, compress each spring and temporarily wrap it with wire to obtain a compression spring. Weld the compression springs onto the H-beam and steel pad in the portal reinforcement structure obtained in Step Five. Finally, cut the temporarily wrapped wire to complete the seismic reinforcement of the Tibetan-style masonry parapet wall with vertical prestress.

[0026] Example 3 This embodiment includes the following steps: Step 1: Calculate the stiffness and number of springs: Given that the length of the parapet wall is L = 16500 mm, and assuming the spring spacing is... l =1500mm, then the number of springs n=L / l +1=12, the thickness of the parapet wall is 190mm, the effective contact area between the spring and the top surface of the parapet wall is set to the area of ​​contact between the spring and the steel pad, and the outer diameter of the spring is 40mm smaller than the side length of the steel pad. The contact area between the spring and the steel pad is a ring with a width of 1mm. Then the effective contact area is A=468.1mm. 2The vertical compressive stress generated by the spring should not exceed 0.8. f ,in f Design value of compressive strength for parapet wall f =0.36×10 6 If Pa, then the vertical pressure provided by each spring is N = 0.8. f· A / n = 11.23 × 10 6 Given N, and setting the spring compression to x = 190 mm, the required spring stiffness is k = N / x = 59128 N / mm. This gives the spring stiffness and quantity. Step 2, Positioning the steel pad: Weld four threaded anchor rods with a diameter of 11mm and a length of 240mm to the bottom of a square steel pad with a thickness of 4mm and a side length the same as the thickness of the parapet wall. Then, according to the number of springs and the spacing of the springs obtained in Step 1, position the steel pad with the same number of welded threaded anchor rods as the number of springs using a chalk line. Mark the installation positions of the steel pad and threaded anchor rods on the top surface of the parapet wall. Step 3: Install steel pads: According to the installation positions of the steel pads and threaded anchors noted in Step 2, drill holes at the corresponding threaded anchor installation positions on the top of the parapet wall. After drilling, use a lint-free brush to remove dust from the holes. The diameter of the hole should be 3mm larger than the diameter of the threaded anchor, and the depth should be 15mm larger than the length of the threaded anchor. Then inject structural adhesive into the holes. When the adhesive reaches 85% of the hole, immediately insert the threaded anchor of the steel pad into the hole. Finally, perform curing to obtain the parapet wall with the steel pad installed. Step 4: Install the steel pipes for the portal reinforcement structure: Drill holes on the outer sides of both ends of the parapet wall and the load-bearing wall obtained in Step 3 for installing the steel pads. Then inject structural adhesive into the holes. Next, insert two steel pipes into the holes one by one using threaded screws for fixation. The steel pipes are rectangular steel pipes with a cross-sectional length of 350mm, a cross-sectional width of 250mm, and a wall thickness of 7mm. The length of the steel pipe is 2.5 times the height of the parapet wall, and the top of the steel pipe extends 550mm above the top surface of the parapet wall. The diameter of the threaded screw is 12mm, and the spacing between adjacent threaded screws is 350mm, resulting in two fixed steel pipes. Step 5: Install the H-beams for the portal reinforcement structure: Weld H-beams with a cross-sectional height of 410mm, a flange width of 310mm, a web thickness of 11mm, and a flange thickness of 18mm to the ends of the two fixed steel pipes obtained in Step 4. Weld two stiffening ribs with a thickness of 4mm and a spacing of 110mm to the web of each H-beam corresponding to the spring position to obtain the portal reinforcement structure. Step Six: Install and Fix Springs: Based on the clearance height between the bottom surface of the H-beam and the steel pad in the portal reinforcement structure obtained in Step Five, select multiple springs with sufficient length and stiffness and quantity to meet the requirements obtained in Step One. Then, compress each spring and temporarily wrap it with wire to obtain a compression spring. Weld the compression springs onto the H-beam and steel pad in the portal reinforcement structure obtained in Step Five. Finally, cut the temporarily wrapped wire to complete the seismic reinforcement of the Tibetan-style masonry parapet wall with vertical prestress.

[0027] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A construction method for applying vertical prestress to a Tibetan masonry parapet for seismic reinforcement, characterized in that, The method is characterized in that door-shaped reinforcing structures are installed on the outer sides of the two ends of the bearing wall and the parapet wall, a plurality of springs in compression are installed between the door-shaped reinforcing structures and the top of the parapet wall, and steel backing plates are arranged between the springs and the top of the parapet wall. Step one: determine the stiffness and quantity of the springs; The length of the daughter wall is known as L, the interval of the spring is assumed as l , the number of the spring n=L / l +1, the effective contact area of the spring and the top surface of the daughter wall is set as A, according to the requirement of the Code for Design of Masonry Structures GB 50003-2011, the horizontal cross-section average compressive stress generated by the spring should not be greater than 0.8 f , wherein f is the design value of the compressive strength of the daughter wall, the vertical prestress N provided by each spring should not be greater than 0.8 f· A / n, the compression amount of the spring to be used is set as x, the maximum stiffness k of the spring required is N / x, and the maximum stiffness of the spring is obtained. Step two: position the steel backing plates; weld threaded anchor rods at the lower part of the steel backing plates, and then position the steel backing plates with the same number of welded threaded anchor rods as the number of springs by using a line marker according to the number and spacing of the springs obtained in step one, and mark the installation positions of the steel backing plates and the threaded anchor rods on the top surface of the parapet wall; Step three: install the steel backing plates; according to the installation positions of the steel backing plates and the threaded anchor rods marked in step two, drill holes corresponding to the threaded anchor rod installation positions on the top of the parapet wall, then inject structural glue into the holes, and then insert the threaded anchor rods of the steel backing plates into the holes, and finally perform maintenance to obtain the parapet wall with installed steel backing plates; Step four: install the steel pipes of the door-shaped reinforcing structures; drill holes on the outer sides of the two ends of the parapet wall with installed steel backing plates and the bearing wall, then inject structural glue into the holes, and then sequentially insert two steel pipes into the holes through threaded rods to fix the two steel pipes, thereby obtaining two fixed steel pipes; Step five: install the H-shaped steel of the door-shaped reinforcing structure; weld the H-shaped steel at the end of the two fixed steel pipes obtained in step four, and weld stiffening ribs at the web of the H-shaped steel corresponding to each spring, thereby obtaining the door-shaped reinforcing structure; Step six: install and fix the springs; select a plurality of springs with lengths meeting the requirements of the clear height between the bottom surface of the H-shaped steel of the door-shaped reinforcing structure and the steel backing plate, and the stiffness and quantity obtained in step one, then compress each spring and temporarily wrap it with iron wire, obtain the compressed spring, weld the compressed spring on the H-shaped steel and the steel backing plate of the door-shaped reinforcing structure obtained in step five, and finally cut off the temporarily wrapped iron wire, thereby completing the seismic reinforcement of the concealed masonry parapet wall with applied vertical prestress.

2. The construction method for applying vertical pre-stress to the Tibetan masonry parapet for seismic reinforcement according to claim 1, characterized in that, The spring distance in step one l Take 1000m~1500m, compression x take 150mm~200mm.

3. The construction method for applying vertical pre-stress to the Tibetan-style masonry parapet for seismic reinforcement according to claim 1, characterized in that, The effective contact area in step one is the area of contact between the spring and the steel backing plate.

4. The construction method for applying vertical pre-stress to the Tibetan masonry parapet for seismic reinforcement according to claim 1, characterized in that, The steel backing plate in step two is square, has a thickness of 3mm-5mm, has a side length same as the thickness of the parapet wall, has four threaded anchor rods welded at the lower part of each steel backing plate, the threaded anchor rods have a diameter of 10mm-12mm and a length not less than 200mm.

5. The construction method for applying vertical pre-stress to the Tibetan-style masonry parapet for seismic reinforcement according to claim 1, characterized in that, In step three, the holes are cleaned of floating dust by using a non-falling hair brush after drilling, the diameter of the holes is 1mm-3mm larger than the diameter of the threaded anchor rods, the depth of the holes is 10mm-20mm greater than the length of the threaded anchor rods, and the structural glue is injected into the holes, and the threaded anchor rods of the steel backing plates are immediately inserted into the holes when the glue injection in the holes reaches 75%-85%.

6. The construction method for applying vertical pre-stress to the Tibetan masonry parapet for seismic reinforcement according to claim 1, characterized in that, The steel pipe in step four is a rectangular steel pipe with a cross-section length of not less than 350 mm, a cross-section width of not less than 250 mm and a wall thickness of not less than 6 mm, the length of the steel pipe is not less than 2.5 times of the parapet height, the length of the top of the steel pipe above the top surface of the parapet is 550 mm to 600 mm, the diameter of the threaded screw rod is 10 mm to 12 mm, and the distance between adjacent threaded screw rods is 300 mm to 350 mm.

7. The construction method for applying vertical pre-stress to the Tibetan masonry parapet for seismic reinforcement according to claim 1, characterized in that, The H-shaped steel in step five has a cross-section height of not less than 400 mm, a flange width of not less than 300 mm, a web thickness of not less than 10 mm, a flange thickness of not less than 16 mm, two stiffening ribs with a thickness of 3 mm to 5 mm are welded at the web of each corresponding position of the H-shaped steel with respect to the spring, and the distance between the stiffening ribs is 100 mm to 120 mm.

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