WO1997035078A2

WO1997035078A2 - Bearing elements of completely reinforced lightweight concrete structures

Info

Publication number: WO1997035078A2
Application number: PCT/SI1997/000009
Authority: WO
Inventors: Ante Mihanovic
Original assignee: Damjanic, Frano
Priority date: 1996-03-19
Filing date: 1997-03-11
Publication date: 1997-09-25
Also published as: WO1997035078A3; AU2111297A; HRP960128A2

Abstract

The bearing elements of completely reinforced lightweight concrete structures consist of slabs (1), linear beams (2-7), columns (8-11) and wall (12, 13) which are either monolithic, precast or combine; they are components used for building various structures such as slab structures or structures with bearing walls, frame structures, arch structures, grill structures or shells. These elements are competitive for building all kinds of structures due to their low weight, which is 4 times lower than in conventional reinforced concrete, good insulation properties and low cost of construction. They are a combination of reinforcement steel and lightweight concrete body. Their bearing capacity, in slabs (1) and walls (12, 13), and especially in beams (2-7) and columns (8-11), is ensured by their reinforcement framework which is always designed as a structure within a structure. The method of placement and continuation of the reinforcement ensures local stability or the reinforcement bars in the compressive and shear regions. The regular form of the elements makes possible the application of different construction methods for building structures of various forms which enables architects and engineers to have greater creative freedom.

Description

BEARING ELEMENTS OF COMPLETELY REINFORCED LIGHTWEIGHT CONCRETE STRUCTURES

Technical field

The technical field is very well defined according to IPC subgroups E 04 B 1/00 and E 04 B 2/00 which contain general structures such as walls, ceilings, floors roofs and single elements.

Technical problem This patent involves bearing elements of completely reinforced lightweight concrete structures such as: slabs, girders, columns and walls which can be efficiently used in monolithic, precast or combined type of construction of various lightweight structures like slabs structures and structures with bearing walls, frame structures, arch structures, grids, shell and complex structures. This patent solves the problem of quick and rational building of lightweight concrete structures by using new methods of design and construction. The adaptability of the elements to different forms and functions of the structures contributes to their rationality and has wide applicability.

State of the art A general review of the development of reinforced lightweight concrete dates back to the end of the nineteenth century. At the beginning of the 20th century (1907) The British Museum was built using lightweight concrete technology based on clinker concrete. In the mid 1930s, aerated concrete was introduced into Europe, mainly in Sweden After War World II the production and application of lightweight elements made of expanded clay, shale, foamed slag and pumice, expanded becoming lighter and automatically achieving better insulation properties especially the temperature insulation property with insignificant decrease in mechanical strength. Expanded polystyrene lightweight concrete, as a special type of lightweight concrete, was introduced into Germany in 1951. The existing lightweight concrete systems which solve, to a certain extent, the mentioned technical task are Ytong (Europe), Leca (Germany), Lytag (Britain) and systems based on expanded clays such as Aglite (Britain), Gravelite (U.S.A.), Soiite (Canada) and Liapor (Sweden) and systems based on the use of lightweight concrete made with fly ash. There are no similar solutions as those obtained by this patent in civil engineering since all previous systems were based on the significant contribution of lightweight concrete in taking over the internal forces, stresses.

According to the concept applied in this patent the reinforcement takes over the stresses while the lightweight concrete has a secondary role. The technical task of constructing large spans has been solved for lightweight concrete systems in different ways in the following cases:

(1 ) by using Aglite technology in a multistory building in London, Ref.: [1].

(2) by using Lytag technology as in the 60-storey Marina City Towers and Water Tower Plaza, the highest lightweight concrete building in the world, both in Chicago, Ref.: [1],

(3) by using Leca technology in the BMW Office Building in Munich, Ref.: [l].

(4) Generally in high buildings, see [2].

(5) Generally in the construction of bridges, see [3].

The general concept of this patent is similar to the idea in the patent application PCT/SI97/00002 and PCT/SI97/00003. The difference between this patent and PCT/SI97/00002 which contains a lightweight beam of I type is that in this patent the I type beam is stabilized in the plane of the flansh by specific joints or mesh. The difference between this patent and PCT/SI97/00003 which contains a T type beam with non parallel belts and with a secondary reinforcement in the form of a mesh is that in this patent the reinforcement is not place and the stabilization of the cord in its place is performed by a grid reinforce structure. Lightweight concrete as structural and insulation material is incorporated in the technical codes of all developed countries. A special treatment of these structures is proposed by "Eurocode" 2 , see [4].

References:

[1] Short A., W. Kinniburgh, Lightweight Concrete, third edition, Applied Science

Publishers Ltd., 1978. 12] Bobrowski J., Outstanding Applications of Lightweight Concrete and an appreciation of likely future developments, in Lightweight Concrete (The Concrete Society, The Construction Press Ltd, Lancaster, England, 1980) 239-260. [3] Roberts J. E., Lightweight Concrete Bridges for California highway system, in

Structural Lightweight Aggregate Concrete Performance, Hole, T. A. Vaysburd, A.M., Edt. (ACI, SP-136, Detroit, 1992) 255-271. [4] Eurocode 2: Design of concrete structures - Part 1 -4; General rules - Lightweight aggregate concrete with closed structures, ENV 1992-1 -4:1994. Essential Features of the Patent

The main feature of this patent is the application of the principle of complete reinforcement of lightweight concrete to the single structural elements as parts of lightweight concrete structures.

The principle of complete reinforcement has been applied to lightweight concrete slabs, beams, columns and walls, ceiling and roof beams. This principle enables an almost complete transfer of compressive, tensile and shear stresses onto the reinforcement. Hence, the lightweight concrete body become a secondary structural media for local and global stabilization and take on the role of an anti- corrosive as well as protect against heat, noise and humidity. Lightweight concrete elements have a low density which implies a reduction in the dead load and, hence, less reinforcement and improvement of insulation properties.

The system offers the possibility for the efficient completion of precast lightweight concrete elements or monolithic elements or combined. This precast system ensures quick, efficient and low cost assembly.

Description of Drawings The drawings present a new system of completely reinforced lightweight concrete elements. Each drawing shows one possible way to apply the system and does not limit the rights contained in the patent claims. . Drawing 1 gives an axonometric presentation of structures built with lightweight concrete structural elements, . Drawing 2 shows a cross-section through a lightweight slab and its section, . Drawing 3 shows the cross-sections of a beam: rectangular, I and T type, . Drawing 4 shows cross-sections of beams: rectangular, with the form of a trapezoid or triangle, . Drawing 5 shows a longitudinal cross-section through a straight beam, . Drawing 6 shows a cross-section of columns, rectangular, triangle and I type, . Drawing 7 shows the layout and side-view of the reinforcement framework of the columns: rectangular, I type and triangle. . Drawing 8 shows the vertical cross-section through the precast and monolithic walls, . Drawing 9 shows a horizontal cross-section of a lightweight concrete wall. Detailed Description of the Patent

The new system of complete reinforced lightweight concrete elements is presented in Drawings 1-9, consists of the following elements: slab (1 ), beams (2), (3),(4),(5),(6) and (7), columns (8),(9),(10) and (11) and walls (12) and (13); they are formed by monolithic, precast or combined procedures, as composite elements combined from a completely reinforced steel framework and lightweight concrete body made as lightweight concrete with a recommended density lower than 1500 kg/m3, compressive strength higher than 0.5 MPa, tensile strength higher than 0.1 MPa, shear strength higher than 0.02 MPa and initial modulus of elasticity 10000 MPa > E > 500 MPa.

Drawing 1 gives an axonometric presentation of two structure which have been built exclusively with reinforced lightweight concrete bearing elements. Drawing 2 presents the cross-section through a slab (1 ) whose thickness and width, which are changeable, are chosen in accordance with the requirements of mechanical resistance and stability and temperatures and moistures content conditions in the building. The slab mid-surface can be either fiat or curved and is supported by at least one discrete or continuous support (1.5). Slab (1) has a mesh reinforcement of the upper zone (1.1) and of the lower zone (1.2), and reinforcement ties (1.3) at intervals which ensure the stability of compressive bars, so that the reinforcement forms a Vurendel frame in each of the two main directions while shear stresses of the slab are transferred in combination of the ties and the lightweight concrete body (1.4).

Beams as bearing elements (2), (3), (4), (5), (6) and (7) are presented in Drawing 3,4 and 5. The lightweight concrete body has either a rectangular cross-section (2) and (5), or a trapezoid (6) or triangular (7) cross-section, and the longitudinal axis is either straight or curvilinear in sections which can be supported at one or several points (2.5); between the bars of the reinforcement framework there are openings of arbitrary shape (2.6). which is not arbitrary. The opening between the bars have the function of reducing the weight of the structure and placing installations. The reinforcement framework is continued by welding, depending upon the type of the concrete used, and the reinforcement is protected by coatings. In beams with great dimensions a secondary reinforcement can be used (2.6) which is not obligatory for all types of beams.

The dimensions of the cross-section and the length of the axis are chosen in accordance with the requirements of mechanical resistance and stability and their longitudinal edges are either parallel or non parallel. The main reinforcement is f ormed as a truss structure with a filling in forms V,X or N, by part, and the reinforcement of the filling is places in at least one plane, so that the reinforcement of the upper zone (N.1 ) (where N is equal 2,3,4,5,6, or 7), lower zone (N.2) and the reinforcement of the filling (N.3) consist of at least one bar, while the reinforcement of the upper and lower zones stiffened by ties (N.4) which form local frames or trusses, which is not obligatory.

Walls as supporting elements (12) and (13) are presented in Drawing 8 and 9. The dimensions, height, width and thickness which can be changeable, are chosen in accordance with the geometry of the space they occupy and the computations of mechanical resistance and stability and physical characteristics of the building. The middle surface is either flat or curved, and its sections are supported by at least one discrete or continuous support. (12.5). the reinforcement can be protected by coatings if necessary, but it is not obligatory. The walls have mesh reinforcement of the left (12.1 ) and right zone (12.2) and reinforcement joints (12.3) at intervals which ensure the stability of compressive bars so that the reinforcement forms a Vurendel frame in each of two main directions, while shear stresses of the slab are transferred in combination of the ties and the lightweight concrete body (12.4).

Under specific static conditions when the wall transfer the stresses to its planes (13), then there are strengthened horizontal bars at the floor level (12.6), along the boundaries there is a local column (12.7) with a concrete body built of lightweight concrete with a density higher than 1500 kg/m3 or normal concrete, which is not obligatory and, if necessary, there is a diagonal reinforcement (12.8) from one floor to another which is not obligatory.

When a precast or combined alternative is chosen for the construction of the structure or its greater part the precast elements should be made in advance in separate molds. During this process anchors are left at the end of the elements so that they can be joined to other section into a logical system. Subsequently they are taken to the construction site and placed at designated places, it necessary supports. The connection to other sections or monolithic parts is performed by connecting the anchor first by welding if monolitization is made with lightweight concrete and by overlapping if the process is performed with concrete of normal weight.

In the monolithic alternative of construction it is necessary to place first the mold of the section to be performed. Subsequently, the reinforcement framework is placed into the mold, if possible previously precast and brought in sections. The reinforcement is joined by welding if those places will be covered with lightweight concrete or by overlapping as classical endings if concrete of normal weight is used.

The supporting elements dealt with in this patent can be used for various structures, such as slabs and shell, structures with bearing walls, frame structures, arch structures, grid structures and various combinations.

The methods of continuation and monolitization will not be dealt with in this patent.

One of the possible methods for the production of a lightweight body is lightweight concrete based on expanded polystyrene (styroconcrete). If the lightweight concrete body is made as light styroconcrete then the density should be higher than 800 kg/m3 if exposed to any kind of fire load.

Industrial application

The application of this patent in industry is evident. The proposed lightweight concrete elements are applicable in practice as a new method for constructing various structures based on single monolithic or precast bearing lightweight concrete elements form this patent.

Claims

PATENT CLAIMS

1.) Bearing elements of completely reinforced lightweight concrete structures as presented in Drawing 1-13 characterized in that they are built as slabs (1 ), beams (2),(3),(4),(5),(6) and (7), columns (8),(9),(10) and (11 ) and walls (12) and (13), by monolithic, precast or combined procedures, consisting of completely reinforced steel framework and lightweight concrete body made as lightweight concrete with a density lower than 1500 kg/m3, compressive strength higher than 0.6 MPa, tensile strength higher than 0.1 MPa, shear strength higher than 0,02 MPa and initial modulus of elasticity 15000 MPa > E > 300 MPa.

2.) The slab (1 ), according to patent claim 1 , whose length, width and thickness, which can be changeable, are chosen according to the requirements of mechanical resistance and stability and physical characteristics of the building, whose reinforcement is protected by coatings, if necessary, characterized by the fact that its mid-surface is either flat or curved in sections, is support by at least one discrete or continuous element (1.5), it has a mesh reinforcement of the upper (1.1 ) zone and of the lower zone (1.2) and reinforcement ties (1.3) at intervals which ensure the stability of the compressive bars so that the reinforcement forms a Vurendel frame in each of the two main directions, while the shear stresses of the slab are transferred in combination of the ties and the lightweight concrete body.

3.) The beams (2), (3), (4), (5), (6) and (7) according to patent claim 1 , whose reinforcement continues and is joined by welding, and protected by coatings, if necessary, with a secondary reinforcement (2/6), which is not obligatory, characterized by the lightweight concrete body has either a rectangular cross- section (2) and (5), or a trapezoid (6) or triangular (7) cross-section, and the longitudinal axis is either straight or curvilinear in sections which can be supported at one or several points (2.5); between the bars of the reinforcement framework there are openings of arbitrary shape (2.6). which is not arbitrary.

4.) The beam with a rectangular cross-section (2) and (5), according to patent claim 3 whose height and width of the cross-section and axial length are chosen according to the requirements of mechanical resistance and stability, characterized by the fact that its longitudinal boundaries along the sections are either parallel or non parallel, whose main reinforcement is in the form of complete truss beam with a filling of V,X or N form, by part, and the reinforcement of the filling is placed in at least one place, so that the reinforcement of the upper zone (2.1 ), lower zone (2.2) and the reinforcement of the filling (2.3) consist of at least one bar, while the reinforcement of the upper and lower zones in planes is stiffened by ties (2.4) which form local frames or trusses, which is not obligatory.

5.) The beam of T type (cross-section), according to patent claim 3, whose height and thickness of the cord (3.8) and rib (3.9) and axial length are chosen according to requirements of mechanical resistance and stability, characterized by the fact that its longitudinal edges along the sections are either parallels or non parallel (polygonal), whose main reinforcement is formed as a complete truss beam with a filling in section of the V,X or N form, while the reinforcement of the filling is placed in at least one plane, so that the reinforcement of the upper zone (3) and lower zone (3.2) and the reinforcement of the filling (3.3) consist of at least one bar and the reinforcement of the upper zone in the plane of the flansh is stiffened by ties (3.4) which form a local frame or truss, which is not obligatory.

6.) The beam of I cross-section (4), according to patent claim 3, whose height and thickness of the ribs and flansh and the axial length are chosen according to the requirements of mechanical resistance and stability, characterized by the fact that the upper and lower longitudinal edges are parallels, whose main reinforcement is formed as truss beam with the filling of V,X or N type, and the reinforcement of the filling is placed in at least one plane, so that the reinforcement of the upper zone (4.1 ) and lower zone (4.2) and the reinforcement of the filling (4.3) consist of at least one bar and the reinforcement of the upper and lower zone in their planes are stiffened by ties which form local frames or trusses, which is not obligatory.

7.) The beam with a trapezoid cross-section (6), according to patent claim 3, whose height and thickness at the bottom and top, and the axial length are chosen according to the requirements of mechanical resistance and stability, characterized by the fact that its longitudinal edges are either parallel or non parallel, whose main reinforcement is formed into at least one complete truss beam with the filling with V,X or N form, by part, while the reinforcement of the filling is placed in at least one plane, so that the reinforcement of the upper zone (6.1 ) and of the lower zone (6.2) and the reinforcement of the filling (6.3) consist of at least one bar and the reinforcement of the upper and lower zones in its planes is stiffened by ties (6.4) which form local frames or trusses, which is not obligatory.

8.) The beam with a triangular cross-section (7), according to patent claim 3, whose height and width as well as the axial length are chosen according to the request of mechanical resistance and stability, characterized by the fact that its upper and lower edges are either parlor or non parallels, and its reinforcement of the upper zone (7.1) consists of at least one bar, the reinforcement of the lower zone (7.2) consist of at least one bar and the reinforcement of the filling (7.3) which consists of at least one bar, whose reinforcement is formed into a complete truss with the filling of the V,X or N form, by part, while the reinforcement of the filling is placed in at least one plane and the reinforcement of the upper zone in its place is stiffened by ties (7.4) which form a local frame or a truss.

9.) Columns (8),(9),(10) and (11), according to patent claim 1 , whose reinforcement continues is welded, and is protected by coatings, if necessary, which has a secondary reinforcement (8.6), which is not obligatory, characterized by the fact that the lightweight concrete body has the cross-section in the form of a rectangle (8) and (10), I type (9) or the form of a triangle (11 ), and the longitudinal axis is either straight, polygonal or curvilinear; the columns are fixed at least at one place (8.5) and between the bars of the reinforcement framework there are empty openings or other filled with various materials. (8.6), with arbitrary shapes, which is not obligatory.

10.) The column with a rectangular cross-section (8) and (10), according to patent claim 9, whose thickness and width and axial height are chosen according to the requirements of mechanical resistance and stability, characterized by the fact that its longitudinal edges are either parallel or non parallels, whole main reinforcement has the form of a complete truss beam with the filling of V,X or N type, by part, and the reinforcement of the filling is placed in at least one plane, so that the reinforcement of the left zone (8.1 ), right zone (8.2) and the reinforcement of the filling (8.3) consist of at least one bar and the reinforcement of the left and right zones are stiffened, in their planes, by ties (8.4) which form local frames or trusses, which is not obligatory.

11.) The column of I cross-section (9), according to patent claim 9, whose width and thickness of the ribs (9.8) and belts (9.9), and the axial height are chosen according to the requirements of mechanical resistance and stability, characterized by the fact that its edges along the sections are either parallel or non parallels, whose main reinforcement is formed as a complete truss beam with the filling in of V, X or N form, by part, while the reinforcement of the filling is placed in at least one plane, so that the reinforcement of the left zone (9.1) , right zone (9.2) and the reinforcement of the filling (9.3) consist of at least one bar, while the reinforcements of the upper and lower zone are stiffened, in their planes, by joints (9.4) which form local frames or trusses, which is not obligatory.

12.) The column with a triangular cross-section (11), according to patent claim 9, whose height and width and the axial length are chosen according to the requirements of mechanical resistance and stability, characterized by the fact that its edges, by part, are either parallel or non parallel and its has the reinforcement of the left zone (11.1) which consists of at least one bar, the reinforcement of the right zone (11.2) which consists of at least one bar and the reinforcement of the filling (11.3) which consists of at least one bar whose reinforcement if formed as a complete truss beam with the filling in the sections of the V, X or N form, while the reinforcement of the filling is placed in at least one place and the reinforcement f the left zone, in its plane, is stiffened by joints (11.4) which form a local frame or truss.

13.) The walls (12) and (13), according to patent claim 1 , whose height, width and thickness can be changed according to the requirements of mechanical resistance and stability and physical properties of the building, whose reinforcement can be protected by coatings, which is not obligatory, characterized by the fact that their mid-surface is either flat or curved, are supported by at least one discrete or continuous support (12.5), that the mesh reinforcement of the left zone (12.1) and of the right zone (12.2), and the reinforcement of the ties (12.3) are placed at intervals which ensure the stability of the compressive bars so that the reinforcement forms a Vurendel frame in each of the two main directions, while the shear stresses of the slab are transferred in combination of the ties and the lightweight concrete body (12.4).

14.) The wall (13). according to patent claim 13, where there are great internal forces in the plane of the wall, characterized by the fact that at the floor level there strengthened horizontal bars (12.6), along the boundaries there is a local column (12.7) which has a lightweight concrete body made of lightweight concrete with a density greater than 1500 kg/m3 or normal concrete, which is not obligatory, with a diagonal reinforcement (12.8) from one floor to another, which is not obligatory.