C-sections and composite decks formed by cold-formed sheets for a system of composite reinforced concrete columns

Abstract

The present application relates to reinforced concrete columns classed in the category of reinforced concrete according to the NSR-10 and ACI-318 standards, in which the tubular channel is formed by sections with cold-roll sheets (CR) which form C-sections with a core and at least on skid which projects into the inner space of the column, coming into contact with the concrete. The skid comprises along its length a series of perforations through which concrete can pass, allowing a composite column to be formed once the concrete has set, in which steel and concrete work together and mutually strengthen their qualities to such an extent that the thickness of the sheet can be reduced, rendering the product economically viable. Moreover, the invention relates to the composite deck comprising these C-sections and a concrete core confined in the inner space of the tubular channel.

Description

TECHNICAL FIELD[0001]The present application relates to composite reinforced concrete columns, which are classified as reinforced concrete under standards NSR-10 and ACI-318, in which the tubular channel consists of sections made of Cold Roll (CR)-type sheets, forming channel sections having a web and at least one flange projecting toward the internal space of the column, wherein said flange enters in contact with the concrete, and comprises a series of perforations through which the concrete may pass, so that the concrete hardens to form a composite column the components of which work in concert, enhancing the qualities of both steel and concrete, so that the thickness of the steel sheet may be reduced, which makes it possible for the product to be economically viable. Preferably, the channel sections of the present invention are open sections having an “L”, “C”, or “U” shape. Likewise, a part of the present application is an integral and built-in structural system based on said co...

AI Technical Summary

Benefits of technology

[0044]Steel on the exterior entails treating the steel to prevent corrosion and so forth, such as with resins or other expensive materials. Galvanized is not used because the sheet thickness required according to the standard is very expensive. The column defined herein allows the thickness of the sheet to be reduced sufficiently to permit using galvanized steel or stainless steel.

Problems solved by technology

One of the causes that explain that fact, arises from the costs.

That this procedure has been kept almost unaltered for more than one hundred years, apart from revealing the absence of significant improvements, implies that the process conserves two activities that have the nature of a craft, namely the carpentry in wood or metal and the ironworking, with the consequent implications: high labor consumption at the site with higher risk of errors, longer execution times and, consequently, high direct and administrative costs.

It exclusively provides the structural tubular channel as an option to replace the reinforcing bars, constitutes a severe economic disadvantage.

The reduction of it ironworking activity that its use would entail is not enough to equalize its cost as compared to the reinforcing bars.In addition to the above, the yield strengths of the steel in reinforcing bars, which are greater than those of structural tubular profiles, determine larger sections of tubular channels than those required by the reinforcing bars, and consequently, higher consumption of tubular steel, with higher unit values than in the case of reinforcing bars.Likewise, the concept of transferring stress “ .

. . ” entails an additional cost for this component of the composite section.In addition to the costs indicated, the requirement is imposed of treatments for surface protection against corrosion.

In addition to the economic issue, the worldwide use of this type of columns remains very limited because the system does not work efficiently as a composite section; that is, stress transfer between the two components, namely the concrete and the steel tubular channel or encased steel profile, which is essential for the section to have a composite character and for the components to work efficiently in concert, does not occur effectively, because when the concrete sets, due to the nature of the chemical reaction, the concrete retracts and detaches from the internal walls of the tubular channel or the surface of the encased profile, eliminating the direct contact between the two components.

The compressive strength of the concrete is disregarded and the solution is not economically efficient.

The parameters indicated above introduce higher costs in the column fabrication process, which renders this solution uncompetitive for a high cost input such as tubular profiles.

Although such columns are an alternative for steel and concrete columns, their interaction is not strong enough for the column to function as a composite element that has a combined effect.

In summary, I-shaped encased composite systems are very expensive, and circular or square systems require shear bolts that are distributed along the length of the column.

Consequently, existing systemsare not viable because the required minimum thickness to be categorized as a composite column is 4.8 mm, which increases costs because it is much more expensive than rods.Steel on the exterior entails treating the steel to prevent corrosion and so forth, such as with resins or other expensive materials.

Galvanized is not used because the sheet thickness required according to the standard is very expensive.

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