WO1997039198A1

WO1997039198A1 - Construction system based on lightweight concrete grill-plates

Info

Publication number: WO1997039198A1
Application number: PCT/SI1997/000012
Authority: WO
Inventors: Ante Mihanovic; Bozenko Jelic; Zdravko Mestrovic
Original assignee: Damjanic, Frano
Priority date: 1996-04-15
Filing date: 1997-04-11
Publication date: 1997-10-23
Also published as: AU2188397A; HRP960170A2

Abstract

The construction system based on the lightweight concrete grill-plate structures is rational for building ceilings, floors, roofs, complete houses and halls, quay of small harbor and small bridges. The building can be multistorey, up to ten-storey, and layout dimensions are up to 60 x 60 m. The construction of quay in the small harbors is based on the grill-plate beam system. The construction of small bridge structures is based on the system of grill-plate beams connected longitudinally or laterally. The general structures can be constructed monolithically, precast or semi-precast. These elements are competitive for building many kinds of structures due to their low weight, which is 3 times lower than in conventional reinforced concrete, excellent insulation properties and low cost of construction. They are a combination of reinforcement steel and lightweight concrete with a density lower than 1500 kg/m3 and compressive strength higher than 2 MPa. Their bearing capacity, in slabs and beams 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 of the reinforcement bars in the compressive and shear regions. The regular form of the elements makes the application of different construction methods possible for building structures of various forms which enables architects and engineers a greater creative freedom.

Description

CONSTRUCTION SYSTEM BASED ON LIGHTWEIGHT CONCRETE GRILL - PLATES

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 ststructures 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 ructures such as walls, ceilings, floors roofs and single elements.

Technical problem This patent involves grill-plate bearing elements of completely reinforced lightweight concrete structures which can be efficiently used in monolithic, precast or combined type of construction of various lightweight structures like slabs, ceilings, roofs, houses and halls, quay of the harbour, small bridges and similar structures. This patent solves the problem of quick and rational building of lightweight concrete 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.), Solite (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.: [1].

(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, PCT/SI97/00003 and PCT/SI97/00009. The difference between this patent and PCT/SI97/00002 which contains a lightweight beam of I type is that in this patent the inverse T type beam is used and the finalized slab is covered by the monolithic thin concrete, normal or lightweight, plates.

The difference between this patent and PCT/SI97/00003 which contains a TT type slab with ribs in one direction, is that in this patent the slab is semi-precast consist of the ribs in two orthogonal directions what forms the grill-plates structures. The difference between this patent and PCT/SI97/00009 which contains a solid slab or a slab whose internal ribs reinforcement is formed on the framed principle and with partially formed polystyrene blocks, is that in this patent the semi-precast slab consists of ribs in two directions, whose rib reinforcement is formed on the truss principle and polystyrene block are structural part of the slab during construction. 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:

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

Publishers Ltd., 1978. [2] 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 grill-plate structural elements as parts of lightweight concrete structures.

The principle of complete reinforcement has been applied to lightweight concrete semi-precast solid slabs, precast or monolithic grill-plates and grill-beams, ceilings, floors, roofs, houses and halls, quay of the harbor and small bridges. 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 protection against heat, noise and humidity. Lightweight concrete elements have a low density implying 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 construction system ensures quick, efficient and low cost assembly.

Description of Drawings The drawings present a new system of grill-plates bearing elements of completely reinforced lightweight concrete structures. Each drawing shows one possible way to apply the system and does not limit the rights contained in the patent claims. Drawing 1 shows a longitudinal-section and cross-section through the lightweight concrete semi-precast thin rib slab, Drawing 2 shows a longitudinal-section and cross-section through the lightweight concrete grill-plate structure supported in the total thickness, Drawing 3 shows a longitudinal-section and cross-section through the lightweight concrete grill-plate structure supported in the partial of thickness, Drawing 4 shows a longitudinal-section and cross-section through the lightweight concrete grill-plates structure prepared for connection to other structural members, Drawing 5 shows a cross-section through the lateral ribs of the lightweight concrete grill-plates beam designed for quays of the harbor, Drawing 6 shows a cross-section through the lateral ribs of the lightweight concrete grill-plates beam designed for ceiling structures of the houses and halls, Drawing 7 shows a cross-section through the lateral ribs of the lightweight concrete grill-plates beam designed for the small bridges, Drawing 8 shows a cross-section through the house structures whose ceilings and roof are designed as lightweight concrete grill-plates and grill-plate beam, Drawing 9 shows a cross-section through the one span of the house structure near the column, Drawing 10 shows a cross-section through the one span house structure in the middle of the span, Drawing 11 shows the layout of the one field ceiling structures formed of the four grill-plate beams and grill-plate, Drawing 12 shows the layout of the one field ceiling structures formed of the two grill-plate beams and grill-plate, Drawing 13 shows the layout of the one field ceiling structures formed of the grill- plate, Drawing 14 shows the side-view of the quay structures, Drawing 15 shows the details of the connection of the quay structures, Drawing 16 shows a cross-section through structures of the quay, Drawing 17 shows the side-view of the one span bridge structures, Drawing 18 shows the side-view of the two span bridge structures, Drawing 19 shows a cross-section through structures of the small bridge. Detailed Description of the Patent The new construction system of complete reinforced lightweight concrete grill-plate elements which is presented in Drawings 1-19, consists of the following elements: semi-precast thin rib slab (1), precast or monolithic grill-plates (2,2A,2B,2C), precast or monolithic grill-plates beam (3,3A,3B,3C,3D), the construction system of buildings and halls (4), quay of the harbor (5) and small bridges (6).

Drawing 1 shows a longitudinal-section and a cross-section of the semi-precast lightweight concrete thin ribs slab (1), whose thickness and spans are chosen in accordance with resistance and stability conditions, temperatures conditions, fires and moistures protection in the building. Thickness from h=0.1-0.3 m, and spans > 12.0 m, are recommended. The slabs consist of the following elements: precast ribs (1.1), lateral monolithic ribs (1.2), ceiling filler (1.3) and thin compressive plate (1.4). The distance of main ribs d=40-80 cm, rib bandwidth b=8-15 cm, plaster thickness z=1-2 cm and thickness of compressive slab 3,5-6 cm are recommended. The precast lightweight concrete rib is made of reinforced framework and lightweight concrete of lower zone (1.1). The lightweight concrete is made with a recommended density lower than 1500 kg/m3 and compressive strength higher than 2 MPa. The mains ribs reinforcement is formed as a truss structure with a filler in forms of 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 (1.7) consist of at least one bar , lower zone (1.5) consist of at least two bars, and the reinforcement of the filling (1.6) consist of at least one bar. It is recommended to chose two bars in lower zone and two bars in the filler.

The reinforcement framework is connected by welding, depending upon the type of the concrete used the reinforcement is protected by coatings. The lateral ribs are formed inside of the main ribs. Its reinforcement can be chosen different, from one bar in lower zone up to complete truss. The distance between lateral ribs a=1.5 -2.0 m is recommended.

The slab filler (1.3) is made as the polystyrene block or similar material, covered by the plaster layer from the lower side. The recommended thickness of plaster is 2-4 cm, so as to ensure the fire protection. The recommended plaster material is lightweight concrete. The compressive slab (1.4) is made of welded wire fabric and normal or lightweight concrete. Concrete properties have to ensure deformability conditions of semi- precast ribs slab.

The way of construction of slab is as follows: Precast main ribs and lightweight slab fillers are cast firstly. In the meantime the preparing of slab supports over wall or similar structure shall be finished. After that placing of main ribs follows. Then slab filler is placed. On the edge of slab filler volume of lateral rib is formed. Then lateral rib reinforcement is placed. The concreteing of the ribs volume and compressive thin slab follows. The ending of structure is made by placing of the plaster from lower side.

Drawing 2 shows longitudinal-section and cross-section through grill-plates (2). It consists of at least two longitudinal ribs (2.1), at least two lateral ribs (2.2) and a thin slab (2.3). The distance between longitudinal and lateral ribs a=1.0-2.5 m is recommended. Longitudinal and lateral ribs are orthogonal. The recommended rib depth b=6-30 cm. The height of ribs is h=0.15-2.5 m and it depends on the main slab span. The slab spans of -25 m are recommended. The recommended thin slab thickness is t=4-40 cm but it is chosen according to the fire, moisture and noise protection.

The rib lightweight concrete is made with a density lower than 1500 kg/m3, compressive strength higher than 2 MPa, tensile strength higher than 1 MPa and shear strength higher than 0.1 MPa.

The longitudinal ribs reinforcement forms complete truss whose upper zone (2.5) and lower zone (2.4) consist of at least one bar and truss diagonals (2.6), by part, are in form of V, X or N, where truss is placed in one plane at least. The lateral rib reinforcement is placing inside of the reinforcement of longitudinal rib and it forms complete truss whose upper zone (2.8) and lower zone (2.7) consist of at least one bar and truss diagonals (2.9), by part, are in form of V, X or N, where truss is placed in one plane at least.

The reinforcement of the both ribs is connected by welding. After welding the reinforcement is covered by coating in case where lightweight concrete is not protective against corrosion.

The thin slab (2.3) is reinforced by welded wire fabric, in both zones if necessary (2.10). It is concrete by lightweight or normal concrete.

Drawing 3 shows a longitudinal-section and a cross-section of the grill-plates supported by the part of height. In this case last field of reinforcement truss is omitted and support is strengthened by steel plates (2.12). In the case where grill-plates (2B) shall be continued, as shown on drawing 4, connecting must be made by welding upper and lower reinforcement bars at the end or by standard anchoring in the normal concrete.

The grill-plate beams (3,3A,3B,3C) are special type of grill-plates in case where one span is dominant. The cross-section of the grill-plate beam (3) related to the structures of the quay in small harbor and small bridges are shown on drawing 5. It consists of two main ribs on recommended distance of d=1.0-3.0 m and recommended span of 0-30 m.

Drawing 6 shows a cross-section of the grill-plate beams prepared as supporter to other structures to one side (3A) or to the both sides (3B). The supporting is realized by separate notch which is reinforced by separate reinforcement (2.14) connected to the ribs reinforcement.

Drawing 7 shows a cross-section of the grill-plate beams (3C) related to the structures of the small bridges. The specialty of this beam is in that the thin slab (2.3) takes loads like console. The console span k and its thickness must be related to the distance between ribs d and rib height h.

Construction procedure of the framed houses and halls (4) is shown on drawing 8. The system (4) consist of the concrete column foundations (4.1 ), reinforced concrete column (4.2), reinforced concrete capital (4.3), lightweight concrete grill-plate beams (3,3A,3B) and the lightweight concrete grill-plates (2,2A,2B). The facade wall panel are placed to close house or hall, see (z) on drawing 8. The house can be up to ten- storey high. Limit of the house or hall lay out is 60 x 60 m. The recommended high of flat h=3.0-4.0 m and the internal span L=5.0-15.0 m.

The procedure of the construction which is subject of the innovation follows. It starts by placing the column footings (4.1 ). The columns are placed in the footings. If the columns are precast, they can be higher than one flat. In the slab level, the column concrete is omit. The steel mold of column capital is placed. This mold is temporary supporter of the grill-plates beam or grill-plate also. After that reinforcement of the capital is placed and complete nodes are concreted. The next flat is finished by this procedure. In the end the facade wall panel is placed. The details of the placing of the flat slab are shown on drawings 9 and 10. There are a few ways for that placing. The first procedure includes placing of the tour grill-plate beams onto the capital molds and placing grill-plates after that, see drawing 11. Another procedure includes placing of the two grill-plate beams onto the capital molds and placing grill-plates after that, see drawing 12. Third procedure includes placing of the grill-plates directly to the capital molds, see drawing 13. Drawing 14 shows a quay of small harbor (5) built by using the lightweight concrete grill-plate beams. The construction procedure follows. The structure supports have to be prepared firstly. The placing of the monolithic or precast grill-plate beams (3) must be done. Then anchoring of the reinforcement anchors (5.7) each other and with anchors from supports (5.9) by monolithic connections by lightweight or normal concrete must be done, see drawing 15. The protective layer (5.1 ), anchors (5.4), water and electrical box (5.3) and installation equipment (5.5) shall be placed. Drawings 17 and 18 show a small bridge structure (6) constructed by using the lightweight concrete grill-plate beams. The construction procedure follows. The structures supports have to be prepared firstly. Then placing of the monolithic or precast grill-plate beams (3) must be done. The grill-plate beam consist of a two or more main ribs. The grill-plate beams laterally can be connected by monolithic concrete and adequate reinforcement. The grill-plate beams longitudinally can be connected also, in case of the two or more bridge spans. Finally the protective layer (6.1) and bridge balustrade shall be placed.

One of the possible methods for the production of a lightweight body is lightweight concrete based on the aggregate made as expanded polystyrene. If the lightweight concrete is made of the light expanded polystyrene aggregate, then the density should be higher than 800 kg/m3 if elements are structural or 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 system of the monolithic or precast grill-plate lightweight concrete elements from this patent.

Claims

PATENT CLAIMS

1.) The construction system based on the grill-plate elements of completely reinforced lightweight concrete structures as presented in Drawing 1-19 characterized in that it contains the semi-precast lightweight concrete thin rib slab (1), precast or monolithic lightweight concrete grill-plate (2,2A,2B), precast or monolithic lightweight concrete grill-plate beams (3,3A,3B,3C), used to construct ceilings, roofs, houses and halls (4), quays of small harbor (5) and small bridges (6).

2.) The lightweight concrete slab (1 ), according to patent claim 1, whose spans and thickness are chosen according to the requirements of mechanical resistance and stability and physical conditions of the building, characterized by the fact that it consists of main precast ribs (1.1) made from reinforcement framework and lightweight concrete with a density lower than 1500 kg/m3, compressive strength higher than 2 MPa, lateral monolithically ribs (1.2) made from reinforcement and lightweight or normal concrete, precast light filler (1.3) made from polystyrene or similar material covered by plaster or concrete layer on the lower side and compressive thin plates (1.4) made from lightweight or normal concrete.

3.) The precast lightweight rib according to patent claim 2 whose height and width and axial length are chosen according to the requirements of mechanical resistance and stability, whose reinforcement is connected by welding and protected by coatings, if necessary, characterized by the fact that its self-bearing in all construction phases, 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 plane, so that the reinforcement of the upper zone (1.7), lower zone (1.5) and the reinforcement of the filling (1.6) consist of at least one bar.

4.) The lightweight concrete grill-plates (2.2A.2B) and grill-plate beams (3,3A,3B,3C) according to patent claim 1 whose height, width and length of the rib and thickness of compressive thin slab are chosen according to the requirements of mechanical resistance and stability and temperature, fire and moisture condition, whose reinforcement is protected by coatings, if necessary, characterized by the parallel edges and by the fact that it consists of at least two longitudinal ribs (2.1) and at least one lateral rib (2.2), that is made of reinforcement framework and lightweight concrete with a density lower than 1500 kg/m3, compressive strength higher than 2 MPa, tensile strength higher than 1 MPa and shear strength higher than 0.1 MPa, that they have the thin compressive slab (2.3) over ribs, reinforced by welded wire fabric in both zone made from lightweight or normal concrete.

5.) The longitudinal ribs (2.1 ) according to patent claim 4 whose reinforcement is connected by welding characterized by the fact that their reinforcement forms complete truss whose upper zone (2.5) and lower zone (2.4) consist of at least one bar and truss diagonals (2.6), by part, are in form of V, X or N, where truss is placed in one plane at least.

6.) The lateral ribs (2.2) according to patent claim 4 whose reinforcement is connected by welding characterized by the fact that their reinforcement is placed inside of longitudinal ribs, and it forms complete truss whose upper zone (2.8) and lower zone (2.7) consist of at least one bar and truss diagonals (2.9), by part, are in form of V, X or N, where truss is placed in one plane at least.

7.) The procedure of the house and hall construction (4) based on usage of the grill- plate elements according to patent claim 1 characterized by the fact that it includes placing of the column footings (4.1 ), precast or monolithic, placing of the monolithic column (4.2) flat by flat or the precast column, one or more flat height, with holes in flat slab level, placing mold of the column capital (4.3) which is temporary support for grill-plates (3A,3B) and grill-plate beam (2), what is connected by the monolithic concrete of column capital.

8.) The procedure of the flat slab construction according to patent claim 7 characterized by the fact that grill-plates (2) are placed direct to the mold of column capital or that grill-plates (2) are placed on the two grill-plate beam (3A.3B) parallel to two flat slab sides or that grill-plates (2) are placed on the four grill-plate beams (3A,3B) along the four flat slab sides.

9.) The procedure of the construction of a quay of small harbor by using the grill- plate beams, according to patent claims 1 , 4 and 5, whose bearing structure is placed onto prepared supports is characterized by the placing monolithic or precast grill- plate beams (3), then anchoring of the reinforcement anchors (5.7) each other and with anchors from supports (5.9), then monolithic connecting by lightweight or normal concrete (5.8) and placing final layer (5.1 ) and building anchors (5.4) and water and electrical box (5.3) and installation equipment (5.5) in the prepared openings in lateral ribs.

10.) The procedure of the small bridge construction by using the grill-plate beams, according to patent claims 1 , 4 and 5, whose bearing structure is placed onto prepared supports and covered by protection layer (6.1 ) with placed bridge balustrade is characterized by placing the monolithic or precast grill-plate beams (3), consisting two or more main ribs (2.1), over the bridge span, which if necessary can be laterally connected by monolithic concrete, which in case of two or more spans can be monolithized in longitudinal directions at supports place (6.3).