RU2664562C1 - Method of increasing the seismic resistance of large-panel houses without wall columns - Google Patents

Abstract

FIELD: construction.SUBSTANCE: invention relates to the field of construction, namely to the seismic reinforcement of existing large-panel residential buildings, which are erected in the series 1-335c structures without wall columns built in 1960–1965 and which have a seismic resistance deficit. Technical result is achieved by the fact that the method of increasing seismic resistance of large-panel residential buildings without wall columns includes the installation of additional pillars for reinforced concrete run-throughs for unloading wall panels made of gas-ash concrete, while in outer walls of gas-ash concrete within the thickness of wall panels the external spatial frame with rigid frame assemblies is built in, which consists of metal racks that rest on the existing foundation of the residential building, and rail elements, which combine the metal racks into a single frame system due to the device of a special constructive metal element, which is attached to the end of the reinforced concrete run-through using six bolts of the "HILTI" system and made of the vertically positioned metal plate and the stiffener, which is perpendicularly welded to it, which, in turn, is connected from the outside to the racks of the outer frame.EFFECT: technical result is the reduced seismic risk of the existing housing facilities stock of the 1-335c series to an acceptable level.1 cl, 11 dwg

Description

The invention relates to the field of construction and can be used for seismic amplification of existing large-panel residential buildings built in designs of a series 1-335c without wall columns and having a deficiency of seismic resistance.

A known method of reconstruction of existing buildings with reinforcement of structures around the perimeter in urban areas (RF Patent No. 2274718, E04G 23/00, 2006). The reinforcement design is a metal or reinforced concrete spatial frame arranged along the entire perimeter and to the entire height of the building with a gap relative to the existing external walls, having a rigid connection in the nodes and mounted on its own foundation. Horizontal stiffening belts made of metal profile, which serve as supports for additional ceilings, laid in the gap between the frame and the existing building, are attached through holes through bolts to the outer walls at the floor levels of each floor. The load from additional ceilings installed 10-15 cm higher than the ceilings of the main building is transferred to stiffeners, causing compression of existing walls.

The disadvantages of this technical solution include the significant material consumption and the complexity of the work when constructing an existing building, the inability to control the angle of inclination of additional floors during operational loads, a swivel in the level of floors between the main building and the newly built reinforcement system, additional material costs associated with the resettlement of residents for the period production work.

The known invention is a method of reinforcing a large-panel building, which includes steel frame racks installed on their own foundation along the vertical joints of the outer panels and interconnected by horizontal stiffeners parallel to the horizontal joints of the panels. In the transverse direction of the building, the steel frame is pulled together with solid steel bands, passed along the lower surface of the floor slabs and intersecting the inner longitudinal reinforced concrete wall with subsequent fixing of the ends of the bands in horizontal stiffening belts. In the direction of the strands there are compression limiters, consisting of a package of reinforcing bars placed in a steel cage, and fixed on the bottom surface of the floor slab with simultaneous fixation in the horizontal stiffening belt and in the longitudinal inner wall. The longitudinal inner wall is reinforced on both sides by prestressed struts connected to each other at the level of the ceilings and to the reinforcement frame of the end panels. The frame, steel bands, stops and struts form a single structure with external panels, an internal longitudinal wall and floor slabs (RF Patent No. 2081274, MNC E04G 23/00, 1997).

The disadvantages of this method of seismic amplification include high metal consumption, the need to have highly qualified personnel capable of performing high-quality work on prestressing reinforcement at a construction site, and additional material costs associated with relocation of residents for the period of building reinforcement.

There is also a method of increasing the earthquake resistance of existing buildings (RF Patent No. 2005155, Е04Н 9/02 2000) by erecting reinforcement elements along the walls of the building. With a gap relative to the existing walls, along the contour of the building to the entire height, starting with the edged foundation, formwork is installed and a reinforcing wall is erected, leaving vertical channels for concreting buttresses in it. In the transverse and longitudinal directions, prestressed horizontal bands are passed through the existing building, the ends of which anchor in the channels of the reinforcing elements. On the outer surface of the walls, vertical and horizontal grooves are punched, which, while monolithic reinforcing walls, buttresses and an additional monolithic coating, form reinforced concrete dowels. As a result, all structures are rigidly interconnected. The free ends of the prestressed horizontal cords of the outer end walls of the building are attached to the inner bearing longitudinal wall.

The disadvantages of this method are similar to the disadvantages of the previous method of seismic amplification, which include: high material consumption, the complexity of the work on the construction site; essentially point bonds in the form of monolithic dowels connect the old weakened external walls with new reinforcing elements, which does not provide equal strength designs; a large amount of wet processes and additional costs for electrical heating of concrete in winter conditions; increase in terms of production of work associated with technological interruptions necessary for hardening concrete in joints; additional material costs for resettlement of residents for the period of seismic reinforcement of the building.

A known method of reconstruction of existing large-panel residential buildings by dismantling balcony structures, the device of a continuous extension to the facade of glazed loggias and superstructures from 4 to 7 additional floors (Patent KZ No. 29984, E04G 23/00 2006.01). The built-in part of the building is a monolithic reinforced concrete frame, consisting of columns, which are also the side walls of the attached loggias along the facades of the existing large-panel building, monolithic ribbed ceilings and coverings, and masonry from piece materials or a monolith from light concrete can serve as wall filling. At the same time, the loads from the additionally built-up floors are transferred to the side walls of the newly built loggias, which directly rely on separately arranged bored pile foundations.

The main disadvantage of this method of seismic amplification is the mismatch of the building being reconstructed in this way to none of those listed in Table. 7 SP-14.13330.2014 “Construction in seismic areas” of structural types of buildings. Therefore, for the reconstruction of each residential building requires the preparation of special technical conditions (STU), or the possibility of applying this method of amplification is limited to non-seismic areas.

A well-known method of seismic amplification of existing large-panel buildings with an incomplete frame is a constructive solution with the device of prestressed wall columns, which allow unloading load-bearing external walls made of gas and ash concrete, which have significant physical wear and damage, by extension of elevator shafts and bay windows outside the contour of an existing building and by attic floors ( A.V. Petrov, A.G. Petunia, Construction Bulletin of the Baikal Region No. 2 (13), 2013, pp. 24-28). During the reconstruction, the exfoliated part of the outer layer of the gas-ash-concrete wall panel is removed with its subsequent restoration by gunning using a newly installed reinforcing mesh and the monolithic bay windows are simultaneously installed along the building contour, and in buildings with an incomplete frame, an additional device of internal stiffness diaphragms at the level of each floor is installed. For 5-story buildings, the attic superstructure is one floor, for 4-story buildings - two floors.

The disadvantages of this method of seismic amplification include: a large volume of wet processes and the complexity of their production in the autumn - winter period at the construction site; the complexity of the work related to the prestressing of the reinforcement in the existing house, the additional weakening of the outdoor gas-reinforced concrete wall panels during the conversion of windows into doorways for a bay window, the additional material costs of resettling residents for the period of the building's seismic reinforcement.

This technical solution is the closest to the invention, therefore, it is a prototype for it.

The objective of the invention is to develop a method of increasing the seismic resistance of existing large-panel residential buildings without wall columns, which allows to maintain the spatial stability of the building while reducing the bearing capacity of both individual structural elements and the building as a whole due to the physical and seismic wear that the building has been exposed to for several decades, without resorting to the resettlement of residents during seismic reinforcement of the building.

The technical result of the invention is:

- reduction of seismic risk of the existing housing stock of series 1-335с to an acceptable level.

The technical result is ensured by the fact that along the axes of the outer contour of the building, a system of metal racks is built in the outer walls of isosceles, which are combined using horizontal metal strapping into a spatial frame system and are based on the existing foundation of a residential building. Along the axes, at the level of the floors of each floor, a special structural metal element is arranged, which is fastened on one side to the end of the reinforced concrete run using HILTI bolts, and on the other, to the elements of the external frame, which essentially serves as a continuation of the run. Thus, the main part of the vertical load, which was perceived by previously weakened outer walls of gas-concrete, is transferred to the metal posts of the outer frame. Vertical loads from interfloor ceilings are perceived by bearing transverse girders with subsequent transfer of loads to additionally installed metal racks of the external frame and to existing reinforced concrete columns of the internal frame of the building. An incomplete internal frame with reinforced concrete columns along the middle axis, supplemented by an external frame with metal columns, forms a complete frame capable of absorbing all vertical loads without the participation of external wall panels. Horizontal seismic loads in the transverse direction are perceived by the external end walls of gas-concrete, the internal intersection walls of heavy concrete and the ventilation panels of heavy concrete installed along the borders of staircases. In the longitudinal direction, horizontal seismic loads are perceived by the external metal frame, while the outer walls of gas-concrete take part in the work of the building in the longitudinal direction. In general, the proposed system forms a closed external metal frame with rigid frame units, which provides increased seismic resistance of a residential building, the level of seismic amplification of which is assigned on the basis of seismic risk calculations taking into account the residual life of it. Moreover, an acceptable level of seismic risk is assumed to be no higher than ⁵ выше10 ^-5 (1 / year), i.e. five affected by the earthquake per 100 thousand people during the year.

The presence of new distinctive features in comparison with the prototype determines the conformity of the claimed technical solution to the criterion of "novelty."

The proposed set of essential features has an "inventive step", because allows you to provide a new technical result, unknown from the existing level of technology in this field at the filing date of this application.

The invention is illustrated by the drawings.

FIG. 1 - installation plan of a typical floor of an apartment building of a series 1-335с, reinforced by elements of an external framework;

FIG. 2 - a diagram of the installation locations of the external frame - metal racks and horizontal strapping on the facade of the building;

FIG. 3 - node supporting the reinforced concrete run on the outer wall panels of gas-ash concrete (outside view), developed according to the standard design;

FIG. 4 - special structural unit;

FIG. 5 - connection node of the outer frame with reinforced concrete run (outside view);

FIG. 6 - connection node run with an external frame (view from the inside of the building);

FIG. 7 - metal rack of the outer frame;

FIG. 8 is a view AA in FIG. 7. Horizontal section of the metal rack construction;

FIG. 9 - horizontal element of the metal strapping of the outer frame;

FIG. 10 - connection of the external frame with seismic amplification elements. Fragment of the facade.

FIG. 11 is a test diagram of a special structural unit with static load.

The design of FIG. 1 and FIG. 2, which increases the seismic resistance of existing residential buildings of the 1-335s series, is achieved due to the device in the outer walls 1 along the axes of the building with an external spatial frame made of metal profile, consisting of racks 2 and elements of horizontal strapping 3, as well as a special structural metal unit 4, which is artificially created by the continuation of reinforced concrete run 5, rigidly connected both with the newly erected supporting frame, and with transverse runs 5 inside the building and transmitting the main part of the vertical load Vises from reinforced concrete run 5 to metal racks of the outer frame 2.

In FIG. 1 shows the installation plan of a typical floor of a residential building of the 1-335c series, reinforced with elements of the external frame. To the initial structural scheme of a building with an incomplete internal frame, consisting of reinforced concrete columns 6 with a section of 300 × 400 mm, spaced along the middle axis of the building, and transverse reinforced concrete runs 5 with a section of 200 × 350 mm, supported by columns 6 and supporting external walls made of gas-ash concrete 1, reinforcement is added in the form of an external frame, consisting of metal posts 2, horizontal strapping 3 (not shown in Fig. 1) and special structural units 4. In places where there are no columns 6, reinforced concrete smoke is used as support for floor slabs ventilation panels 7, which are the walls of the stairwell, intersection walls or end and longitudinal outer walls of gas-concrete 1, which are connected with the elements of the external frame.

In FIG. 2 shows a diagram of the installation locations of the external frame - metal racks 2 and horizontal strapping 3 on the example of the facade of a 3-storey residential building. Metal racks 2 made of equal-angle corners 8 with a section of 100 × 100 × 10 mm are built into the outer walls 1, and elements of horizontal metal strapping 3 of unequal corners 9 with a section of 80 × 125 × 8 mm combine the racks into a single spatial system of the external frame. Additional spatial immutability of the seismic amplification system is ensured by attaching the vertical 2 and horizontal 3 frame elements to the outer wall panels 1 using metal embedded parts 10, welded with a certain step to the elements of the external frame.

In FIG. Figure 3 shows a design, non-reinforced unit for supporting the reinforced concrete run 5 on the outer wall panels of gas-ash concrete 1. Structurally, the outer wall panels 1 have nests with a depth of 250 mm into which the reinforced concrete run 5 is installed during installation of the building, followed by welding of embedded parts. The sealing of the seam between the wall panels 1 is conventionally not shown.

In FIG. 4 - shows a special structural unit 4, consisting of a vertically arranged metal plate 11 with a cross section of 200 × 350 × 10 mm and a stiffener 12 perpendicularly welded to it in the form of a vertical plate with a size of 155 × 510 mm and a thickness of 10 mm, which, in turn, the outer side is connected to the posts of the outer frame 2 by welding. In addition, the vertically located plate 11 is fastened to the end of the reinforced concrete run 5 with six bolts of the HILTI system 13 and to a horizontal metal plate 14 of 100 × 125 × 10 mm in size, which serves as an additional connecting element when installing the upper metal rack of the frame 2 of the next floor.

In FIG. 5 shows the connection unit of the external frame with reinforced concrete run 5 (view from the outside of the building), and in FIG. 6 the same node is presented from the inside of the building. In both figures, all structural elements are located that are located in the area of the connection unit 4 at the level of overlap: reinforced concrete run 5, rigidly connected by bolts of the HILTI system 13 with a vertical metal plate 11 and with a stiffener 12 perpendicular to it, which, in in turn, connected to the rack 2 and the horizontal strapping 3 of the external metal frame. In addition, in FIG. 6 shows the design position of the supporting metal plate 14 when installing the metal rack 2 of the upper floor.

In FIG. 7 depicts a metal post 2 of the outer frame 2690 mm long, made of two isosceles corners 8, interconnected by welding using patch elements 15 with a cross section of 100 × 100 × 6 mm. On both sides of the rack frame 2, protruding on the surface of the outer wall 1, metal embedded parts 10 are welded at a distance of 1500 mm from each other, which serve to fix the vertical position of the rack 2 and its connection with the outer wall panels of gas-concrete 1.

FIG. 8 is an explanation of FIG. 7, in which view A-A shows a horizontal section of the structure of a metal stand 2, consisting of two equal-angled corners 8 with a section of 100 × 100 × 10 mm, interconnected by means of an overlay metal element 15 with a section of 100 × 100 × 6 mm.

In FIG. 9 shows a horizontal element of the metal strapping 3 of the outer frame, which has a structural solution similar to the metal rack 2 in FIG. 7. The strapping element consists of two rolling corners 9 with a cross section of 80 × 125 × 8 mm, joined together by welding using the patch element 15. Also, on both sides of the strapping 3, protruding on the surface of the outer wall 1, at a distance of 1500 mm from each other welded metal embedded parts 10 to ensure its horizontal position and communication with the panels of the outer wall of gas-concrete 1.

In FIG. 10 shows a fragment of the facade in a perspective view, which presents a constructive solution for the seismic amplification of residential buildings. The external frame of the metal profile, consisting of racks 2 and straps 3, built into the outer walls 1 along all axes of the building, has a rigid connection with the internal transverse reinforced concrete girders 5 through a special structural metal element 4, which transfers the bulk of the vertical load from the reinforced concrete girders 5 to metal racks of the outer frame 2.

In FIG. 11 shows a test diagram of a special structural unit 4 for control static load. The main power element of the test bench is a metal traverse 16, made of two channels No. 30 and fixed to the power floor 17 using 4 rods 18 made of ∅25 mm reinforcing steel of A400 class. Using the traverse 16, the hydraulic jack 19 of the DG-50 brand creates a vertical static load on the reinforced concrete run 5 with a length of 3000 mm, which, in turn, transfers it to the metal posts 2 of the outer frame through a special structural unit 4. The control static load on the special structural unit 4 should be at least 140 kN, at which the force on the jack 19 will be 280 kN. By changing the pressure level in the hydraulic network of the pumping station, it is possible to assess the reserves of the bearing capacity of the connection “reinforced concrete run - special structural unit - column of the external frame”.

The given set of essential features characterizing the proposed constructive solution, increasing the level of seismic resistance of existing residential buildings of the 1-335s series without wall columns, is not described in the literature. The novelty of the solution lies in the fact that on all axes of the building an external spatial frame of metal profiles is built into the external walls, which, through special structural elements rigidly connected to the internal girders, perceives the vertical load transmitted from the floor slabs to the reinforced concrete girders. The internal incomplete reinforced concrete frame of an existing building, supplemented by an external spatial metal frame, forms a full frame of a residential building, capable of absorbing both vertical loads without the participation of external gas-concrete concrete wall panels, which are significantly weakened, and horizontal seismic loads in the longitudinal direction.

Therefore, the claimed technical solution meets the condition of patentability "industrial applicability".

The fundamental principles of seismic amplification are:

- Fulfillment of all repair and restoration work only from the external contour of a residential building without intrusion of the technological process into internal residential premises.

- Carrying out work on seismic amplification on the principle of "dry construction", that is, on bolts, without the use of wet processes, with the exception of repair of wall panels in places of exfoliation of the outer finishing layer.

Strict compliance with the requirements of the Federal Law on Energy Efficiency of Construction Facilities 261-FZ.

Description of the technology for increasing the seismic resistance of large-panel residential buildings of the 1-335s series without wall columns

1. Initially, repairs are carried out related to the mechanical removal of the exfoliated outer layer of gas and concrete with a thickness of up to 130 mm and the external reinforcing mesh, which has undergone corrosion, from the end wall panels. Then, several layers of fiberglass are glued along the outer surface leveled with a cement-sand mortar, which acts as an external reinforcement in addition to the reinforcing mesh located closer to the inner surface of the wall panel and not affected by corrosion, which is confirmed by a mass examination of the outer walls.

2. The elimination of accumulated defects in damaged sections of the external walls along the longitudinal facades of the house, as a rule, in the area of lintels and window sashes, is carried out by the method of “applications”, which are subsequently protected from external influences by means of hinged front-wall facades.

3. Further, as a result of clearing the vertical joints between the outer wall panels to the entire height of the floor, sinuses of rectangular section with a width of 40 mm and a depth of 100 mm are formed. In the zones of intersection of vertical and horizontal seams, at the place of installation of the run, using a disk tool, the outer layer of wall panels is cut to a depth of 140 mm to expose the end of the run.

4. Using 6 ∅16 mm HILTI bolts to the end of the reinforced concrete run, a metal plate is fixed with a section of 200 × 350 × 10 mm - an element of a special structural unit.

5. Then, in the sinuses between the outer wall panels, racks of the 1st floor of the outer frame are installed, consisting of two steel corners with a section of 100 × 100 × 10 mm, interconnected with a gap of 12 mm, using patch metal plates; in the upper part of the rack there are 2 plates with a section of 100 × 125 × 10 mm for the joint device of the metal rack of the upper floor frame.

6. In the upper part, stiffeners are arranged on the posts of the external frame in the form of a vertical plate 500 × 155 mm in size and 10 mm thick and are bolted to the plate of a special structural unit at the end of the run and to the corners of the metal frame of the frame.

7. Installation of the outer metal rack frame of the upper floors with a height of 2690 mm is carried out similarly to the installation of the rack of the 1st floor, while the upper part of the stiffener of the lower tier is passed between the corners of the upper metal rack. The base plate of the lower strut of the external frame is connected to a similar part of the upper strut of the external frame with bolts.

8. The connection of metal racks of the external frame into a single spatial structure is provided due to horizontal metal strapping, consisting of two rolling corners with a section of 80 × 125 × 8 mm, united by overhead elements for welding, and arranged at the level of horizontal seams. The specified system is an external metal frame with rigid frame assemblies - a “bandage” for a residential building, which ensures the transfer of the main part of the vertical load from the external wall panels to the columns of the external frame and is a constructive implementation of the principle of seismic amplification of a residential building.

9. Fulfillment of the requirements of Law 261-ФЗ on energy efficiency of construction projects is carried out by installing one of the systems of suspended ventilated facades of the strategic offensive air forces on the external enclosing structures - wall panels made of gas and ash concrete.

Claims (2)

1. A method of increasing the seismic resistance of large-panel residential buildings without wall columns, which consists in installing additional support racks for reinforced concrete runs for unloading wall panels of gas and ash concrete, characterized in that an external spatial frame with rigid frame is embedded in the outer walls of gas and ash concrete within the thickness of the wall panels nodes, consisting of metal racks resting on the existing foundation of a residential building, and elements of horizontal strapping, combining metal racks into a single frame system due to the device of a special structural metal element attached to the end of the reinforced concrete run with six bolts of the HILTI system and made of a vertically located metal plate and a stiffener perpendicularly welded to it, which, in turn, is connected from the outside with racks of an external framework. 2. The method according to p. 1, characterized in that the vertical and horizontal elements of the frame to the outer wall panels are attached using metal embedded parts.

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