A shear connector and a structural element with such a shear connector

Abstract

A shear connector (1) to connect a UHPC / UHPFRC girder (3) and a slab of standard concrete wherein the shear connector (1) has a longitudinal shape and along its length, a part (2) to be embedded in the UHPC / UHPFRC girder (3) as well as a part (4) to be embedded in standard concrete are arranged over each other. The shear connector (1) is made of the UHPC / UHPFRC material and the part (2) to be embedded in the UHPC / UHPFRC girder (3) is provided with through holes (5) and the part (4) to be embedded in standard concrete forms shaped projections (6).

Description

[0001] A shear connector and a structural element with such a shear connector

[0002] Technical field The invention relates to a shear connector to connect a UHPC / UHPFRC girder and a slab of standard concrete wherein the shear connector has a longitudinal shape and along its length, a part to be embedded in the UHPC / UHPFRC girder, as well as a part to be embedded in standard concrete are arranged over each other. The invention further relates to a structural element with such a shear connector.

[0003] Background art

[0004] Coupling is a technical term describing a rigid, or semi-rigid connection / interconnection ensuring static cooperation of different materials or different layers of identical or similar materials.

[0005] A simply supported bent girder is generally loaded in such a way that its top layers are subject to pressure while its bottom layers are subject to tension. This results in the need to select materials or structures that resist pressure well for the top layers and materials or structures that resist tension well for the bottom layers.

[0006] However, the top any bottom layers need to be connected, or coupled.

[0007] In the construction practice, such coupled structures frequently consist of a steel girder on the top of which, there is a concrete slab. In other cases, the bottom girder is also made of concrete, such a solution being advantageous that it is prestressed, which gives the concrete girder the necessary compressive capacity for tensile stress transfer.

[0008] In the construction practice, steel products are used almost always, e.g. coupling pins or shear connectors, which are usual for bottom girders made of steel. Concreting reinforcement, which protrudes from the bottom girder, is used for bottom girders made of concrete.

[0009] The bottom girder may be made of ultra high performance concrete, or possibly of ultra high performance fibre reinforced concrete. In specialized literature, this well-known material is referred to as UHPC, or UHPFRC, respectively, and therefore, in the text below, it is commonly referred to as UHPC / UHPFRC wherein this designation in the text refers to both the UHPC material and the UHPFRC material. These are composite materials based on cements, fine aggregate and chemical additives with a very low water ratio that have a high compressive strength. A usual limit quoted in reference literature is 150 MPa and more. They have a very high residual tensile strength or tensile bending strength after the occurrence of a crack with a high fracture energy and high ductility. If the bottom girder consists of a UHPC / UHPFRC girder, coupling pins cannot be connected to it.

[0010] When UHPC / UHPFRC is used, there is an effort to eliminate concreting reinforcement. In such a case, protruding concreting reinforcement is not advantageous to useto couple the two used materials.

[0011] In such a case, a steel shear connector can be embedded in the UHPC / UHPFRC girder, but then this UHPC / UHPFRC girder would have to be additionally reinforced with concreting reinforcement, or a steel bar having uneconomical dimensions would have to be used. The problem is local tension of the concrete when stressed by a narrow shear connector. At the same time, a corroding and less durable element would be used in a very durable UHPC / UHPFRC girder. Thus, it is the object of the invention to provide such a shear connector that would not have the above-mentioned drawbacks of the prior art.

[0012] Summary of the invention The above-mentioned object is achieved through a shear connector to connect a UHPC / UHPFRC girder and a siab of standard concrete wherein the shear connector has a longitudinal shape and along its length a part to be embedded in the UHPC / UHPFRC girder as well as a part to be embedded in standard concrete are arranged over each other according to the invention the principle of which is that it is made of the UHPC / UHPFRC material and the part to be embedded in the UHPC / UHPFRC girder is provided with through holes and the part to be embedded in standard concrete forms shaped projections.

[0013] An advantage of a shear connector made of the UHPC / UHPFRC material is that it does not corrode, has very high durability, has the same inherent parameters as the girder, especially the modulus of elasticity, and therefore, it has suitable static characteristics.

[0014] The through holes make it possible to avoid reinforcing the girder with standard reinforcement.

[0015] In a preferred embodiment, the shaped projections have a mushroom-like shape and are arranged at intervals after each other.

[0016] The gaps between the shaped projections allow direct insertion of concreting reinforcement into the slab of standard concrete. In another preferred embodiment, the part to be embedded in the UHPC / UHPFRC girder is provided with a series of recesses arranged at intervals at its bottom edge.

[0017] The said object is also achieved through a structural element that comprises a siab of standard concrete that is supported by multiple UHPC / UHPFRC girders according to the invention the principle of which Is that the UHPC / UHPFRC girders and the slab of standard concrete are bound by multiple shear connectors according to any of the preceding embodiments arranged in series after each other.

[0018] The shear connectors transfer longitudinal shear forces at the interface of the materials of the coupled cross-section, thus ensuring their firm connection.

[0019] Brief Description of Drawings

[0020] The invention will be described in detail with reference to embodiment examples of a shear connector according to the invention and a structural element using such a shear connector according to the invention, the embodiment examples being shown in the attached drawings wherein individual figures represent:

[0021] Fig. 1 - a shear connector according to the invention in a side view;

[0022] Fig. 2 - the shear connector according to the invention in an axonometric view;

[0023] Fig. 3 - a UHPC / UHPFRC girder with a shear connector according to the invention;

[0024] Fig. 4 - a structural element comprising a slab of standard concrete that is supported by multiple UHPC / UHPFRC girders.

[0025] Examples of embodiments

[0026] The shear connector 1 according to Fig. 1 and 2 for the connection of a UHPC / UHPFRC girder 3 and a slab 8 of standard concrete has a longitudinal shape and along its length, a part 2 to be embedded in the UHPC / UHPFRC girder 3 as well as a part 4 to be embedded in standard concrete are arranged over each other. The shear connector 1 is made of the UHPC / UHPFRC material and the part 2 to be embedded in the UHPC / UHPFRC girder 3 is provided with through holes 5 and the part 4 to be embedded in standard concrete forms shaped projections 6.

[0027] 5 In the preferred embodiment of Fig. 1 and 2, the shaped projections 6 have a mushroom-like shape and are arranged at intervals after each other.

[0028] The part 2 to be embedded in the UHPC / UHPFRC girder 3 is provided with a series of semicircular recesses 7 arranged at intervals at its bottom edge.

[0029] 10

[0030] Fig. 3 shows an embodiment example of a prefabricated UHPC / UHPFRC girder 3 that has an embedded series of shear connectors 1 of Fig. 1 and 2 arranged after each other on its top side. is Fig. 4 schematically shows a cross-section of a road bridge that comprises a slab 8 of standard concrete that is supported by multiple UHPC / UHPFRC girders 3 of Fig. 3. The slab 8 of standard concrete is bound with the UHPC / UHPFRC girders 3 with multiple shear connectors 1 arranged after each other in a series.

[0031] 2G List of reference signs

[0032] 1 shear connector

[0033] 2 part to be embedded in the UHPC / UHPFRC girder

[0034] 3 UHPC / UHPFRC girder

[0035] 4 part to be embedded in standard concrete

[0036] 25 5 through hole

[0037] 6 shaped projection

[0038] 7 recess

[0039] 8 slab of standard concrete

Claims

CLAIMS1. A shear connector (1 ) to connect a UHPC / UHPFRC girder (3) and a slab of standard concrete wherein the shear connector (1 ) has a longitudinal shape and along its length, a part (2) to be embedded in the UHPC / UHPFRC girder (3) as well as a part (4) to be embedded in standard concrete are arranged over each other, characterized in that it is made of the UHPC / UHPFRC material and the part (2) to be embedded in the UHPC / UHPFRC girder (3) is provided with through holes (5) and the part (4) to be embedded in standard concrete forms shaped projections (6),2. The shear connector according to claim 1 , characterized in that the shaped projections (6) have a mushroom-like shape and are arranged at intervals after each other.

3. The shear connector according to claim 1 or 2, characterized in that the part(2) to be embedded in the UHPC / UHPFRC girder (3) is provided with a series of recesses (7) arranged at intervals at its bottom edge.

4. A structural element comprising a slab (8) of standard concrete that is supported by multiple UHPC / UHPFRC girders (3), characterized in that the UHPC / UHPFRC girders (3) and the slab (8) of standard concrete are bound with multiple shear connectors (1) according to any of claims 1 , 2 and 3 arranged after each other in a series.

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