Patent Application
20240159062
The present invention relates to the technical fields of Mechanics and Construction, because it provides a T-type shear connector; a floor system consisting of metallic elements and concrete slab, which comprises the T-type shear connector; and a method for the construction of said floor system.
Currently, Nelson type connectors or bolts are used to join the steel beams to the concrete of a slab, which are very efficient in forming a composite behavior between steel and concrete elements. However, their fabrication is by means of a cold punching or steel casting process, which is relatively expensive. Another disadvantage of Nelson type connectors is that due to their structural design there is a group factor that penalizes their strength when they are placed close together to increase the capacity of the connection. Additionally, increasing the diameter of such Nelson bolts to increase the capacity of the connection can cause the crushing of the concrete to become critical to the design.
Another connector used is the so-called Channel type, which is fabricated with rolled sections, but is not efficient at the type of stresses it is subjected to when forming the composite action between the concrete slab and the steel beam. For the channel connector, the design is controlled by a combination of relatively high bending and shear stresses affecting the channel web. The web of the channels is the thinnest part, which makes it the weakest part of the section to resist this type of stress.
Khorramian et al. (Dec. 7, 2015), disclosed a study of the application of angled shear connectors in inclined positions, where it is described that angled steel profile has been used in different positions as L-shaped or C-shaped shear connectors. In this study, the behavior of inclined shaped angle shear connectors under monotonic loading was investigated using experimental thrust tests. Eight thrust specimens were tested to investigate the effects of different angle parameters on the maximum load capacity of the connectors. Two different inclination angles of 112.5 and 135° between the angle leg and the steel beam were considered. In addition, the sizes and lengths of the angles were varied. Two different failure modes consisting of concrete crushing-splitting and connector fracture were observed. As the connector size increased, the maximum load increased in most cases. In general, 135-degree inclined angle shear connectors have higher strength and stiffness than the 112.5 type°.
Patent document KR1170897B1 discloses a beam-slab joint structure using a composite beam that does not require a separate fireproof coating and can reduce the floor height. The wing plate is composed of an inclined surface extending obliquely downward from one end of an upper horizontal plate and a fixed surface extending horizontally from the end of the inclined surface, and a plurality of concrete filler holes are drilled in the inclined surface, and the fixed surface is the lower horizontal plate and the upper steel beams placed between horizontal plates. With a formwork plate attached to the wing plate at the bottom of the steel beam and concrete filling the space surrounded by the upper horizontal plate, the wing plate and formwork plate, make them integrate with the steel beam, and the formwork plate is removed after concrete curing, and the fixed surface is the lower horizontal plate and the upper steel beams are placed between the horizontal plates.
In order to counteract the aforementioned drawbacks, a T-type shear connector was developed, which is useful in the construction of a floor system.
The characteristic details of the present invention are detailed in the following description, examples and figures, the purpose of which is only to demonstrate its conception and some of its embodiments, wherein:
The present invention relates to a T-type shear connector for joining beams and/or metal elements to a concrete slab; said T-type shear connector is an alternative to Nelson-type bolts and shear connectors based on Channel-type sections that are used to achieve composite behavior between steel elements and concrete elements to resist effects of different types of structural loading.
Thus a first object of the present invention is a T-type shear connector, which is composed of:
One embodiment of the T-type shear connector of the present invention is where the length of the second quadrilateral plate (2) is 32.33% less than the length of the first quadrilateral plate (1); although there is also the embodiment where the length of the first plate (1) is twice the length of the second plate (2), such that the three ends of the T-type shear connector have the same length relative to each other.
A mode of the T-type shear connector, in question, is when the quadrilateral plates (1 and 2) have different widths from each other; although the mode is not ruled out when they have equal widths from each other said plates (1 and 2).
A further variant of the T-type shear connector of the present invention, is when the quadrilateral plates (1 and 2) have different widths or thicknesses from each other, but can also have equal widths or thicknesses from each other.
A further embodiment of such a T-type shear connector is where the plates (1 and 2) are manufactured from a material resistant to bending, compression and shear; for example, a metallic material, which may be steel, most preferably A992 grade 50 steel.
In yet another embodiment of the connector according to the present invention, it is when both quadrilateral plates (1 and 2) are: rectangular, quadrangular, trapezoidal, a combination of these shapes, or any other shape that allows for the configuration and operation of said connector.
A further variant of the connector according to the present invention is when it further comprises, in addition, a strong fixing element (not illustrated) for joining and strongly fixing the quadrilateral plates (1 and 2) to each other. This embodiment refers to when the connector is manufactured with two separate plates; as it can also be manufactured in one piece by means of a mold, lamination process, etc.
The means of strong fixation (not illustrated) can be selected from the following group: welds, glues or adhesives, assembly mechanisms, tongue and groove systems, a combination of these, to name a few examples.
A second object of the present invention is a floor system made up of metallic elements (3, 4 and 6) and concrete slab (5), where said floor system comprises, at least, a T-type shear connector, such as the one proposed and described in the present invention, for joining the metallic elements (3 and 4) with the concrete slab (5); where the T-type shear connector is fixed on the metallic elements (3 and 4) by means of the free end of the second quadrilateral plate (2) and any of the ends of the first quadrilateral plate (1), remaining in a tilted position and embedded in the concrete slab (5). The metallic elements are: metallic beams (4), metallic slabs (3) and/or reinforcement meshes (6), preferably.
The fastening of the T-type shear connector with the metallic elements (3 and 4) must be by means of any strong fastening element (7), such as: welding, glue or adhesive, an assembly mechanism, a tongue-and-groove system, a combination among them, etc.
The present invention has as a third object, a method for constructing the floor system, in accordance with the present invention, wherein said method comprises the following stages:
The strong fastening element (7) that can be used to join the T-type shear connector with the metallic elements (3 and 4), can be welding, glue or adhesive, an assembly mechanism, a tongue and groove system, etc.
One of the advantages of the T-type connector over the Nelson and Channel type connectors is the mechanical behavior. The Nelson and Channel type connectors are controlled by the combination of bending and shear stresses; while the T-type connector withstands a combination of axial and bending stresses because it is used in a tilted position, where the steel is better able to resist the combination of stresses because of the tilted position.
Nelson Bolts are very efficient in forming a composite behavior between steel and concrete elements. However, they are expensive to manufacture because they are fabricated by means of a steel casting or cold punching process. Whereas, the T-type connectors of the present invention can be manufactured by cutting from rolled sections, which is a more efficient and economical process.
Another advantage of the T-Side connectors over the Nelson Bolt is that for the structural design of the Nelson Bolt there is a group factor that penalizes its strength when placed close together to increase the capacity of the connection. In contrast, the T-type connector only requires an increase in its dimensions, but it will remain a single connector. In addition, increasing the diameter of the Nelson Bolts to increase the capacity of the connection may cause the crushing of the concrete to become critical; but increasing the dimension of the T-type connectors maintains the same relationship, so it does not increase the probability of concrete crushing.
For the channel connector, its design is affected by a combination of relatively high bending and shear stresses, affecting the channel web. The web of the channels is the thinnest part, which makes it the weakest part of the section to resist this type of stress. For the T-type connector, its design is affected by tension in its second piece (2) or by a combination of relatively high axial and bending stresses and a relatively low shear stress at the ends, which make contact with the metallic elements (3 and 4), of the pieces (1 and 2).
The following examples are included for illustrative purposes only, as a demonstration of the conception and some preferred embodiments of the present invention; therefore, they are not to be considered as limiting the scope of said invention.
A T-type shear connector was fabricated using a first rectangular plate (1) of 103.0×50.0×10.3 mm; and a second rectangular plate (2) of 69.7×50.0×6.7 mm; both plates were made of A992 grade 50 steel with a yield strength of 3,515 Kg/cm2. The second rectangular plate (2) was welded perpendicularly and transversely through one of its ends in the middle part of the first rectangular plate (1), with a weld E7018 of a nominal resistance of 4,900 Kg/cm2, thus forming a T-shaped piece, see figures.
The T-shear connector obtained had the following structural characteristics: a weight of 0.60 Kg, whose technical effects were: a connecting capacity of 14,934 Kg, which was 27.3% higher with respect to the channel type shear connectors; although it is true that its weight increased by 11.2% with respect to the weight of the channel type shear connectors, but it still showed an increase in efficiency of 14.47%. This T-type shear connector had a tensile rupture capacity of the second plate (2), in its tilted position, of 15.081 kg (1.5 kg).
The floor system was built using steel beams (4), on which a ribbed steel plate (3) was placed, and in each of its channels was welded 1 T-type shear connector described in the previous example, which was positioned in a tilted way, that is, two of the ends of the T-type connector were fixed to the beam through the steel plate (3), see
This example illustrated a composite action consisting of the concrete slab (5) subjected to compression, the steel beam (4) subjected to tension and the T-type shear connectors joining them to generate a single element resisting bending stresses. The stresses of the T-type shear connector elements fabricated according to example 1, withstood the following stresses in their tilted position and immersed in the concrete slab (5), shown in Tables 1, 2 and 3.
Khorramian K, Maleki S, Shariati M, Ramli Sulong NH (2015) Behavior of Tilted Angle Connectors. PLoS ONE 11(2): e01448945.
| Number | Date | Country | Kind |
|---|---|---|---|
| MX/A/2021/003332 | Mar 2021 | MX | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/MX2022/050019 | 3/16/2022 | WO |
