A BUILDING STRUCTURE, PARTICULARLY A ROAD BRIDGE STRUCTURE, AND A METHOD OF MAKING SUCH A BUILDING STRUCTURE

Abstract: A building structure, such as a road bridge, has a lower part, e.g. a reinforced concrete beam (2, 3, 4, 8), and an upper part (23, 24) separated from each other by means of a liquid-impermeable membrane (9) which consists of a non-adhesive, low friction sheet material and is formed with hood portions (16) tightly enclosing block-like elements (11) projecting upwards from the upper surface of the lower part (2, 3, 4, 8). The hood-clad elements (11, 16) again fit tightly in recesses formed in the upper part (23, 24). Horizontal forces are transferred from the upper to the lower part via the flanks of the block-like elements (11), thus perpendicularly to the membrane material. In a practical method of making the structure, the block-like elements (11) are first attached to the lower part on top of a full sheet of membrane material, and pre-formed hood portions (16) of the same membrane material are then applied to the block-like elements (11) and sealed to the sheet (9).

Description: A building structure, particularly a road bridge struc¬ ture, and a method of making such a building structure. The invention relates to a building structure of the kind set forth in the introductory part of claim 1. A particularly important field of use of such a building struture is for road bridges, and the invention will in the following be described with particular reference to that field of use, but it will be realized that the invention may likewise be used for other building struc¬ tures where similar problems exist. A road bridge structure covering a span of a bridge typically comprises a lower part consisting of a sup¬ porting beam of reinforced concrete and an upper part comprising e.g. a base layer of concrete and a top layer of asphalt. It is important that rainwater or other liguids collect¬ ing on the surface of the road bridge should be drained away as quickly as possible through the layers of the upper part, which is the reason for constructing these layers from liquid permeable materials. It is equally important, however, to prevent the pen¬ etration into the beam of water, oil or chemicals, that may occur on the surface of the top layer, e.g. as a consequence of rainfall, melted snow or ice, thawing salt, exhaust and leakage from vehicles passing the bridge, wreckage of chemical cargo vehicles, or environ¬ mental conditions, such as acid rain. This is the reason for interposing a liquid-impermeable membrane between the two parts. A road bridge building structure of the kind set forth in the introductory part of claim 1 is known from German patent no. 3339638. In this known structure the membrane consists of a strongly adhesive layer of material, e.g. consisting of blocks of bitumen-butadiene-styrol-butadiene embedded in a matrix of bitumen, and the force transfer means con¬ sist of bolts or iron rods embedded in the concrete of the lower part and extending into the layers of the upper part. A strongly adhesive layer on a bituminous basis has the disadvantage that the layer will unavoid¬ ably be subjected to a certain amount of shearing forces in some situations of load and/or temperature variations, whereby after a period of ageing small cracks may be formed impairing the liquid-impermeability of the layer. Besides the layer cannot be expected in the long run to maintain a perfect liquid proof seal against the bolts or iron rods piercing the layer. A further disadvantage is that the upper surface of the beam must be thoroughly cleaned, degreased and dried up before the adhesive layer can be applied. In the case of repair or renovation of the layers of the upper part, the adhesive membrane has to be chipped off together with the upper layers, to which it adheres, thus expos¬ ing the surface of the beam to wheather conditions during the period of repair or renovation. It is the object of the invention to provide a building structure having improved properties in respect of the factors mentioned above. This object is achieved by means of the features set forth in the charactericing clause of claim 1. A membrane as therein defined will not be subjected to substantial tearing or shearing forces in its own plane, but practically only to compressional forces perpen¬ dicular to its plane. Synthetic thermoplastic sheet or cloth materials having the properties of non-adhesiveness and low friction are available in the trade. Particular reference is made to that marketed by Du Pont under the registered trademark Hypalon ® . This material is impervious to water and oils and has a high resistance to a wide range of chemicals, including acids and dissociated salts. Moreover, it is unaffected by both high and low temperatures and has a very long lifetime. It can easily be pressed into the shape of hoods with collars, and the latter can be heat- sealed to the plane sheet laid out on top of the lower part. The non-adhesion and low friction of the membrane to- wards the upper part can be further secured by means of a lubricant. It will be realized that horizontal forces are trans¬ ferred from the upper part to the flanks of the project- ing elements through the hood areas enclosing the flanks, and thus perpendicularly to the membrane ma¬ terial in these areas. When applying the membrane to the surface of the lower part, it is not necessary beforehand to clean, degrease and dry up that surface because no adhesion is to be established. _ In the case of repair or renovation of the layers of the upper part, the membrane incl. the hoods, can be left in position to protect the beam against the intrusion of rain water or other liquids during the period of repair of renovation. The invention also relates to a method of making a building structure of the kind referred to. The method is characterized by the steps set forth in claim 3. By this method the correct positioning of the block-like elements relative to the lower part is greatly facili- tated, because no great accuracy is required in perform¬ ing the steps. The invention will now be further described with ref¬ erence to an example illustrated in the accompanying drawings in which Figs. 1-5 are vertical longitudinal sections through a bridge structure in various stages of its production and Fig. 6 is a vertical cross section through the bridge structure. In Fig. 1, 1 is the bottom of a shuttering in which a reinforced concrete beam is to be moulded. 2 is the principal reinforcement, 3 iron bars supporting a soft iron distributory reinforcement 4 adjacent to the con¬ templated upper surface of the beam. An anchor 5 having a threaded bore is welded (at 6) to the reinforcement 4. The bore is closed by a plastic cap 7 to prevent the penetration of concrete during moulding. In Fig. 2, the beam 8 has been moulded and cured, and the shuttering 1 has been removed. Lengths of membrane cloth have been rolled out, and holes 10 have been cut in the cloths above the anchors 5 so that the cloth can now lie smoothly on top of the beam. The lengths of cloth are heat-sealed together along their edges to form a continuous sheet in the whole width of the beam. In Fig. 3, the caps 7 have been removed, and concrete blocks 11 have been fastened to the anchors by means of steel screws 15. The blocks 11 may alternatively consist of any other suitable material having the required mechanical strength and may e.g. be of a circular, oval or rectangular configuration in horizontal plane. Hoods 16 of the membrane material have been placed on and around the blocks 11, and their collars 17 have been sealed to the cloth 9 by hot airblast and pressure. Now, as illustrated in Fig. 4, mats 18 of a draining hygrophilic material are placed on top of the membrane 9, and a layer of draining concrete 23 is moulded, whereby recesses are formed which fit around the hood- clad blocks 11. As an intermediary step, a reinforcement ring 19 connected by stays 21 to an upper ring 20 may first be placed around each block 11, and a body of expanding mortar 22 may be moulded to ensure a particu¬ larly firm and permanent grip around the blocks 11. As a last step, as illustrated in Fig. 5, a top layer 24 of asphalt is laid out in adhesive engagement with the concrete layer 23. Fig. 6 illustrates a manner of efficiently draining off water from the hygrophilic layer 18 to a gutter 26.

Claims: CLAIMS: 1. A building structure comprising an upper part (23, 24) having an exposed upper surface and consisting of liquid-pervious building materials suitable for the intended use of the structure, a lower part (2,3,4,8) forming a structural support of the upper part, a liquid-impervious membrane (9) interposed between the lower part (2,3,4,8) and the upper part (23,24) for the purpose of preventing the penetration of liquid through the upper part (23,24) to the lower part (2,3,4,8), and force transfer means (5,11,15) anchored in the lower part (2,3,4,8) and extending upwards into the body of the upper part (23,24) for the purpose of transferring surface-parallel forces directly from the upper part (23,24) to the lower part (2,3,4,8), characterized in that said force transfer means consist of distributed block-like elements (11) projecting upwards from the upper surface of the lower part (2,3,4,8) and fitting tightly in hood portions of the membrane (16), which again fit tightly in recesses formed in the upper part (23,24), and that the membrane consists of a non-ad¬ hesive material and has practically zero friction at least towards the areas of the upper part (23,24) with which it is in contact. 2. A building structure as in claim 1, characterized in that the block-like elements (11) are constructed with flank portions which are perpendicular to the upper surface of the upper part (23,24) and have a sufficient size to enable the totality of block-like elements (11) to take up the maximum forces in any surface-parallel direction, for which the building structure is designed, without exceeding the permissible pressure on the mem- brane material of the hood portions surrounding the block-like elements (11). 3. A method of making a building structure as in claim 1, comprising the steps of (1) providing a lower part (2,3,4,8) having the required supporting capacity and having a substantially flat surface, (2) applying a non-adhesive, liquid-impervious sheet material (9) to said substantially flat surface in such a manner as to form a continuous covering of the entire area of that surface, (3) fastening block-like elements (11) on top of said sheet material by fastening means (5,15) extending through holes cut in the sheet material (10) into said lower part (2,3,4,8) and mechanically secured therein, (4) pulling a hood (16) made from the same sheet ma¬ terial down around each of said block-like elements (11), said hood (6) having a configuration closely fitting around that of the element (11), (5) sealingly connecting a lower marginal portion of each hood (17) with the flat sheet material in the area immediately surrounding the respective block-like el¬ ement (11) by a welding or sealing process appropriate for establishing a permanent liquid proof seal, (6) applying liquid-pervious building materials (23,24) to form an upper part of the building structure on top of said liquid-impervious membrane (9) and up to a level above the top of said hood-clad block-like elements (11,16). 4. A method as in claim 3 for making a building struc¬ ture as in claim 1 having a lower part in the form of a reinforced concrete beam (2,3,4,8), characterized in that before pouring the concrete to form the beam, anchors (5) are fastened to an upper portion of the pre¬ paratorily set-up reinforcement iron structure (4), e.g. by welding (6) in horizontal positions corresponding to the contemplated positions of the block-like elements and in a vertical position such as to be firmly embedded in the concrete of the beam (8), when poured, and to extend upwards approximately to the contemplated upper level of the reinforced concrete beam, and that after concrete has been poured up to that level and has hardened, steps (2)-(6) of claim 3 are carried out, said anchors (5) having threaded bores to receive screws or bolts (15) constituting the fastening means of step (3). 5. A method as in claim 4, characterized in that before carrying out step (6) of claim 3 a body of expanding mortar (22) is moulded around each hood-clad block-like element (11,16) such as to embed an reinforcement ring (19) held in position to encircle the block-like element (11,16) at some distance therefrom.

Inventors: THYGESEN SOEREN, THYGESEN, SOEREN
Applicants: THYGESEN SOEREN, THYGESEN, SOEREN
Application year: 1990
Main classification: E01D19
IPC codes: E01D19