JPH0447073A - Method of adding story to low building - Google Patents

Abstract

PURPOSE: To promote earthquake resistance by building a footing around the existing building close to it and erecting a floor addition overlapping frame girder on the footing to provide expansion and contraction joints of structure between the existing building and a column. CONSTITUTION: A footing 12 of a new building is built in the neighborhood of the footing 11 of the existing building, a partition wall 13 of a thin and hard material is provided between the footings 11 and 12, a non-slip plate 14 is provided to the outside of the new footing 12. A column 5 is erected on the footing 12, a floor addition frame bearing girder 2 is firmly connected to the frame column 5 at the top of the existing building 4, and the weight of a floor addition structure is borne on the girder 2 to transfer to a ground bedrock through the column 5. Then, a temporaty beam 6 is provided to the column 5 in every floor to connect in the longitudinal direction of each of the buildings. By the constitution, an additional floor can be added to the low-rise building.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to construction sites, in particular the conversion of existing low-rise buildings into high-rise buildings, i.e. the addition of additional floors to existing low-rise buildings. Regarding things.

BACKGROUND OF THE INVENTION Adding additional levels to existing low-level buildings is an emerging theme in the development of urban structures throughout the world. With the increase in urban population, cities are forced to expand, but due to the limitations of developed areas, the area of cities cannot be enlarged at will. Therefore, it is necessary to appropriately limit development within the city limits. This means that there are demands to increase the height of buildings, especially in cities where original buildings are generally very low, and the contradiction between reality and demand is most pronounced. Until now, the answer to this contradiction has consisted of: That is, ■. Demolishing the original low-rise building and rebuilding a new high-rise building in its place. This not only creates problems in relocating occupants to other locations and disposing of waste from the construction site, but also leads to the removal of some of the buildings far beyond the end of their useful life. However, problems arise that must be overcome. This results in waste and waste, and creates several social problems that are difficult to solve.

2. Increase the height of the original building. Currently, it mainly consists of two methods. i.) Keep the original building and add 1-2 floors to it.

口) Adding further layers using a pure frame structure.

In method a), the weight of the additional storey is supported by the original building structure. However, since the supporting capacity of the original building structure is quite limited, only one or two storeys can be added at most.

Obviously, this cannot meet the demands of increasing building height. In this method, the weight of the added storey is transferred to the foundation through the frame structure because the design does not take into account that the path of force transmission of the additional storey structure is absolutely precise and clear. ie there is no disruption of the force transmission path. Other than that, no measures have been taken to avoid possible foundation slippage during an earthquake.

Therefore, this kind of layer-added structure not only presents an inherent flaw in the principle of structural design mechanism, ie, disrupts the force transmission path of the structure, but also has very low malleability.

The object of the present invention is to provide a method for adding additional stories to an existing low-story building in order to increase the height of the existing low-story building, the weight of the newly added multi-story building part being is transmitted to the ground foundation via a weight-bearing frame structure specifically connected to the original building rather than being supported by the original building, thereby reducing the burden of additional monolithic force transmission in any situation. To provide a method to prevent routes from being confused. At the same time, the present invention includes three categories of patented technology, namely "impact resistance and shock absorption device for buildings"
(China Patent No. 87100151), “Impact Insulator for Buildings” (China Patent No. 88108470.0) and “Between new and old buildings when increasing the height of the old building” to realize the above-mentioned special connection. 'Coupler' (China Patent Application No. 89106137.1) is incorporated. In addition, an anti-slip plate is provided in the stress superimposed area of the ground foundation, thereby substantially increasing the seismic capacity of the monolithic structure of the low-rise building with additional floors.

Means for Solving the Problems The method according to the invention to achieve the above-mentioned object is as follows.

A foundation is laid closely around the original building on which several additional storey supporting frame columns are erected. Structural expansion and contraction joints are provided between the original building and the columns, and these joints can be filled with compressible material.

A storey addition frame support girder is rigidly connected to the frame columns above the roof of the original building, such that the weight of the storey addition structure is carried by the girders and transferred to the ground foundation through the frame columns. . The bottom surface of the girder and the top surface of the original building are separated by a space, the size of which is greater than the settlement of the storey addition.

The frame columns are connected to the columns of the original building at the floor locations of each floor of the original building as a "connector between new and old buildings when increasing the height of the old building" (China Patent Application No. 8910B137.1) ), and the ends of the frame columns are fixed ends, whereas the ends of the columns of the old building are hinged ends that are movable in the vertical direction, but are not allowed to move laterally.

Close to the outside of the foundation of the tiered additional support frame column and below the bottom of the foundation, an anti-slip board for the ground base soil, for example using a reinforced concrete board, is provided.

A bulkhead made of rigid, thin material is installed between the original building foundation and the new addition's foundation for supporting frame columns.

In order to increase the stability of the newly added layer support frame columns,
The frame columns are longitudinally connected to each other along the original building at the level of each of their corresponding floor locations by plate beams.

It is not difficult to understand that the original building structure is essentially stable after many years of use, so that it can be thought of as a non-deformable rigid body. During the early stages of use, storey additions may exhibit foundation settlement and self-deformation of structural members after the action of loads, resulting in relative vertical displacements between the new and old buildings. As a result, if appropriate measures are not taken or special connections are not provided between the old and new buildings, the weight of the new building will be forced firmly down onto the old building, This will cause a disruption of the path of force transmission and an increase in stress within the old and new structures. However, since there is some space between the bottom surface of the additional storey frame support girder and the top surface of the original building, the Since there is a "connector between the new and old structure when increasing the height, it not only avoids the above-mentioned drawbacks, but also shortens the free length of the storey addition frame column, improving the stability of the storey addition structure and the old building. to improve the overall seismic capacity of the building.

Furthermore, as mentioned above, an anti-slip board for the ground base soil is provided, which prevents the ground soil under the new building foundation from being compressed away from the original building, thereby It can prevent the foundation from slipping. This also improves the building's ability to withstand expansion.

Besides, since the foundations of old and new buildings are placed close to each other, the span length of the girders is shortened, and they are separated from each other by bulkheads, so it is important that the foundations of new buildings are stable. It is possible to prevent the building from being affected by the foundation of the old building before it reaches its original state.

The methods, objects and advantages of the invention will now be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals apply to the same or corresponding parts.

EXAMPLE Referring now to FIG. 7, in order to reduce the span length of the additional storey support girder, the foundation 12 of the new building is as close as possible to the foundation 11 of the original building; The foundation of the original building! A portion of 11 can be removed when it is not a supporting foundation as shown in FIG. 7a. In order to avoid settling of the foundation of the new building during the early stages of use, which may damage the foundation of the original building, a bulkhead 13 made of thin rigid material is provided between the two foundations. In order to prevent the ground soil of the new building foundation from being compressed away from the original building, which would cause the foundation of the additional floor structure to slip, an anti-slip plate 1 for the ground foundation soil was installed.
4 is provided outside the layer addition structure and below the bottom of its foundation as shown in FIGS. 7 and 11.

In order to better understand the need to provide anti-slip plates 14 for ground base soil, further explanation is made as follows. The foundation of the original building has become stable after many years of use, and its stress distribution is shown in Figure 10a, but the foundation of the new building has not yet become stable at the initial stage of use. , when the two foundations are brought into action together with each other, the stress of the storey addition has little effect on the stress distribution of the original building foundation, whereas the stress transferred from the foundation of the storey addition has little effect on the stress distribution of the original building foundation. The reaction caused by the stress in the original building's foundation acting on the stress changes the stress distribution in the storey addition when it acts in isolation. This change in stress distribution compresses the ground soil beneath the foundation of the storey addition laterally away from the original building foundation, or rather in the direction of the storey. However, if it is a one-way compression or a two-way compression, it does not affect the load limit value, at which the load is very large, for example during an earthquake, and it can lead to slipping of the foundation of the storey addition. , and foundation slippage may cause the layered addition to crack, twist, or tilt. Therefore, outside the layered additional structure and under the bottom of its foundation, an anti-slip board for the ground base soil is provided, forming an enclosure for this foundation and as mentioned above when the layered additional structure acts on the foundation. Ensure that the foundation is not compressed laterally to avoid the occurrence of harmful conditions.

When the ground foundation is a rock bed, it is better to adopt an insulated foundation under the column, and when the ground foundation is a soil bed, it is better to adopt a reinforced concrete strip foundation. When the strip foundation under the column cannot meet the requirements, it is possible to supplement with perforated piles or internal piles, but it is not allowed to adopt driven piles. Although groundwater pumping is a convenient method for building foundations with additional storeys, it is unacceptable to use groundwater pumping when the groundwater level is high. Since it tends to change the stress state of the ground base of the original building, it can adversely affect the overall structure of the storey addition. In this situation, it is better to adopt the underwater concreting method.

For the construction of the foundation, it is preferable to adopt the divisional construction method. After one segment is excavated and concreted, the next segment begins to be excavated and concreted, and so on. In the excavated foundation bit, sheet pile walls 25 are supported by braces 22 against the original building foundation walls and the story addition frame.

During the rainy season, a rainwater shelter is erected to prevent too much rainwater from flowing into the foundation bit 23, as shown in FIG.

An embodiment of the invention is illustrated in FIG. On the foundation of the above-described storey addition around the original building 4, reinforced concrete columns 5 are cast, which together with the upper storey addition 1 form an integral structure.

Above the top of the original building, the storey addition support girders 2 are rigidly connected to the above-mentioned frame columns, so that the weight of the storey addition is supported by the girders 2 and transmitted to the ground foundation via the columns 5. be done. There is some space or gap between the bottom surface of the girder 2 and the top surface of the original building 4, the size of which is larger than the amount of settlement of the additional storey structure. In order to increase the stability of the overall structure, it is necessary to connect the additional storey structure with the original building 4. Although the structure of the original building is stable after many years of use, the additional storey structure is also not stable in the early stages of use, probably due to settling of the foundation or self-deformation of some of its components when subjected to loads;
If the two are rigidly connected, it will certainly cause a disruption of the force transmission path and worsen the stress situation. To solve this problem, the frame columns 5 are connected to the columns of the original building 4 at the closure of each floor of the original building 4 as a "connector between the new and old structures when increasing the height of the old building" The end of the frame pillar 5 is a fixed end, and the end of the original building pillar is a hinged end that is movable in the vertical direction, but is not allowed to move laterally. In order to strengthen the stability of the additional storey supporting frame columns 5, the frame columns are connected in the length direction of the building by plate beams 6 at respective corresponding closing levels of each storey of the original building 4. In order to improve the seismic capacity of the multi-level monolithic structure, a "building impact insulator" (China Patent No. 88108470.0) is provided outside the ground foundation.

FIG. 5 shows another embodiment of the invention. The upper tier additional structure 1 is a composite structure, which consists of a single deck support frame structure 10
(Column 5, girder 2, plate beam 6, "connector between new and old building" 3
) and superimposed on the lower single deck support frame structure 10 via a Building Impact Resistance and Shock Absorption Device 8.

In other respects it is the same as the embodiment shown in FIG.

FIG. 6 shows a third embodiment of the invention. The upper tier additional structure 1 has a frame structure, which is a single deck support frame structure 10
and also superimposed on a single deck support frame structure 10 via a Building Impact Resistance and Shock Absorption Device 8.

The size of the span length of the additional storey support girder depends on the width of the original building. Girders of different span lengths are classified into two categories: regular span and oversized span girders. So-called normal spans have a height/span ratio H/L that is reasonable for use with respect to story height. Girder 2 height/span ratio H/
When L is ≦(178-1/12), it is possible to adopt a straight uniform cross-section girder. On the other hand, according to the design, the value obtained by subtracting the girder height from the story height and the thickness of the floor slab is the usable story height, for example, from the story height of 2.9 m to the girder height of 1 m, the floor The actual usable height is 1.76m after subtracting the slab thickness of 0.12m and the ground thickness.
get. Obviously, this usable height is not reasonable for use in construction. However, it cannot be increased by increasing the story height because increasing the story height makes the story height different from the story height of the original building. In this case it is appropriate to use non-uniform cross-section girders with oversized spans. Below is an analysis of the design and construction of two categories: regular span girders and oversized spans.

(1) Digit of normal span B. Use multi-decker frame superimposed support girders.

In order to save molding plates, to make the construction eight-crystalline, and to maximize structural integrity, the frame girder is generally a superimposed type girder made by double casting. . A so-called superimposed type of girder is a girder on which part of its height is first precast and on which a prefabricated floor plate is placed. After the floor plates have been installed, the concrete above the girder is poured to reach the design height. In this way, the integration of the connections between the girders, plate beams and columns takes place. The prefabricated girder can be of prestressed concrete and can form a prestressed concrete superimposed girder with subsequent cast concrete. Regarding the design of superimposed girders, reference may be made to the design materials on superimposed girders of high-rise buildings. The storey addition structure uses superimposed girders, and the requirements of construction conditions are high, such as strong filling and hoisting capacity, large site size and convenient transportation. In limited conditions, superimposed girders can be cast in situ.

using cast-in-place rectangular support girders.

When the foundation condition is good and the span length is not too long,
It is possible to use uniform rectangular girders as layered additional structure support girders, and the internal forces of the girders are calculated according to the method of calculating frame structures.

(2) When the span length of the girder layer addition structure with oversized span is relatively long, various rectangular girders cannot be used and non-uniform cross-sectional shapes are adopted for the supporting girders. This means that the height of the girder H> (1/8
~1/12) This is because L affects the usable height of the structure hierarchy. This is advantageous for load carrying capacity and allows the weight of the structure itself to be reduced and the usable space of the structure to be increased, as shown in FIG.

There is an additional layer structure on the roof of the original building.

The load for each floor of the layered additional structure is transmitted to the columns 5 via the girders 2. The original building is generally divided into buildings with flat roofs and buildings with pitched roofs. For flat roofs, hollow floor slabs of reinforced concrete are commonly used, so it can be fully utilized. The girders are cast in-situ on top of the flat roof to enhance full load carrying capacity. Next, the first floor brick wall section of the storey addition is placed on the girders and the floor slab is placed on the second floor girder. During structural treatment, since there is a relative displacement of the additional storey structure with respect to the original building, gaps are provided between the brick top surface of the additional storey and the bottom surface of the board beams and second storey; This prevents downward compressive deformation of the additional storey structure from acting on the original building before the additional storey structure becomes stable. The protected gap is filled with an easily compressible material such as foamed concrete bricks or air-entrained concrete bricks or the like.

When the original building is a building with a pitched roof, by adopting a split construction method to design and construct the storey addition in the same manner as described above for the original building with a flat roof. It is necessary to transform the roof into a flat roof. If the original building is a five-story building, remove a portion of the roof and upper part of the walls to reduce the aspect ratio of the columns, adapt the cross-sectional dimensions of the columns to the overall appearance of the structure, and It is necessary to leave space for additional storey girders and foam concrete bricks. The layout of the additional storey structure is in principle the same as the original building.1. Minimize design and construction difficulties by making maximum use of the original building's water supply, software systems, staircases, electrical circuits, etc.

The nodes of the layered addition structure must have sufficient strength.

It is necessary to perform strength calculations for the construction and service phases. The first thing to do when calculating strength is
Identify the internal forces, i.e. shear forces, moments and axial forces at the nodes, as well as the direction of force transmission at the nodes, and identify bending failures, warping failures, shear failures, nodal core failures, failures of welds or reinforcing rods, and main reinforcement rods. The purpose is to analyze various possible forms of failure of the joints, such as bowing, locking failure, failure of stirrups, and then determining the necessary calculation formulas and measurements for construction.

Nodes between girders and columns are generally critical locations for structural failure. Therefore, nodal reinforcement must be taken into account when calculating the nodal strength. In order to improve the impact resistance capacity of the structure, the nodes must have the necessary ductility.

In addition, the present invention provides an elevated highway and a three-dimensional view.A in FIG. 1 is a front view of the original building, b in FIG. 1 is a side view of the original building, and a in FIG. FIG. 2b is a side view of the building with additional stories according to the invention; FIG. 3 is a schematic diagram of the structure of the invention; FIG. 5 is a schematic diagram showing a newly added full frame structure in close proximity around the original building having a building impact insulator device according to the invention; FIG. FIG. A superimposed storey addition frame structure having an ``impact resistance and absorption device for buildings'' and ``impact insulation for buildings'' according to the invention and a newly added single deck support frame in close proximity around the original building. FIG. 7a is a schematic diagram showing the foundations of the new and old buildings, the bulkhead between the two foundations, and the anti-slip plate for the ground foundation soil, with a part of the foundation of the old building shown. Figure 7b is a schematic diagram showing the foundations of the new and old buildings, the bulkhead between the two foundations, and the anti-slip plate for the ground foundation soil, with part of the foundation of the old building partially removed. It is a diagram that maintains its original shape, and Figure 8 shows the original building foundation, sheet pile walls, bracing in the foundation groove of the additional floor frame structure, and the rainwater protection shelter above the foundation groove. Fig. 9 is a three-dimensional assembly drawing showing the long span non-uniform cross-section girder, plate girder, and additional floor support frame columns, and Fig. 10 a shows the stable foundation of the original building. Fig. 10b is a compressive stress distribution diagram of the frame structure with additional floors after the foundation has become stable under the separated load; FIG. 3 shows the anti-slip plate for the ground foundation soil installed outside the foundation of the frame structure and below the bottom of the foundation and the foundation of the original building;

1... Upper floor additional structure, 2... Tier additional support frame column resistance and shock absorption device, 1o... Lower single deck support frame structure, 14... Anti-slip plate.

Claims (10)

[Claims] (1) A method of adding floors to a low-rise building to increase the height of the original low-rise building, in which a foundation is laid close to the original building (4), and a foundation is placed on top of the foundation. erecting additional storey superimposed frame girders (5), providing structural expansion and contraction joints between the original building and the columns and filling these joints with compressible material, above the roof of the original building; The additional storey frame support girder (2) is rigidly connected to the frame column (5), so that the weight of the additional storey structure is supported by the girder and transmitted to the ground foundation via the frame column (5), and the girder (2) Create a gap between the bottom surface of the original building and the top surface of the original building, and make the size of the gap larger than the amount of settlement of the additional layer structure; The frame column (5) is connected to the column of the original building in the floor area of each floor of the original building by a "connector between structures", and the end of the frame column (5) is a fixed end. At the same time, the end of the original building column is a hinged end that can be moved vertically but not allowed to move laterally, and that it is located close to the outside of the foundation of the additional floor support frame column (5) and of the foundation. Anti-slip plate for ground base soil under the bottom (14)
A method for adding floors to a low-rise building, which consists of: installing a bulkhead made of hard and thin material between the foundation of the original building and the supporting frame columns. 2. The method of adding stories to a low-rise building according to claim 1, characterized in that the supporting frame columns (5) are connected to the upper story addition structure (1) to form an integrated structure. (3) The upper storey addition structure (1) is a composite structure, which is separated from the lower single-deck support frame structure (10) and connected to the lower single-deck support frame structure (10) via a "building impact resistance and shock absorption device" (8). The method for adding a story to a low-rise building according to claim 2, characterized in that the method is superimposed on one deck support frame structure (10). (4) the upper tier additional structure (1) is a frame structure, which is separate from the lower single deck support frame structure (10) and
3. The method for adding a layer to a low-rise building according to claim 2, characterized in that the structure is superimposed on the lower single deck support frame structure (10) through a building impact resistance and shock absorption device (8). . (5) Height H of digit (2) is H≦(1/8 to 1/12)L
When , a uniform rectangular girder of prestressed concrete girder consisting of a regular span or a pre-assembled girder of prestressed concrete with double cast superimposed girder or post-cast concrete is used as girder (2) used, digit (2)
4. Claims 1 to 4 characterized in that when the height H of is H > (1/8 to 1/12) L, an oversized span with a non-uniform cross section is used as a girder (2). any one of
How to add floors to low-rise buildings as described in Section. (6) The supporting frame columns (5) are connected to each other in the longitudinal direction of the building by plate beams (6) at the floor floor level of each corresponding story of the original building. 5. The method for adding floors to a low-rise building described in any one of paragraphs 5. (7) When the original building is a building with a sloped roof, a split construction method is adopted to transform the roof into a flat roof to reduce the height of the frame columns (5), thereby increasing the upper level A method for adding floors to a low-rise building according to any one of claims 1 to 6, characterized in that the construction of an additional structure (1) is facilitated. (8) The method for adding floors to a low-rise building according to any one of claims 1 to 7, characterized in that the foundation is concreted by a dividing method. (9) According to any one of claims 1 to 8, characterized in that when the construction of an additional storey is carried out in a location with a high groundwater level, underwater concreting is employed to create the foundation of the new building. How to add floors to low-rise buildings as described. (10) The method for adding floors to a low-rise building as set forth in any one of claims 1 to 9, wherein the building is a raised highway or a grade crossing.