WO2017149462A1

WO2017149462A1 - C-sections and composite decks formed by cold-formed sheets for a system of composite reinforced concrete columns

Info

Publication number: WO2017149462A1
Application number: PCT/IB2017/051179
Authority: WO
Inventors: Daniel JEANGROS FRANCO; Carlos JIMENEZ SARTA
Original assignee: Soluciones E Innovaciones Estructurales S.A.S.
Priority date: 2016-03-02
Filing date: 2017-02-28
Publication date: 2017-09-08

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 (1) and at least one skid (2) which projects into the inner space of the column, coming into contact with the concrete (4). The skid (2) comprises along its length a series of perforations (3) 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

COLLABORATED SHEETS AND COLLABORATING SHIRTS IN COLD FORMED FOR AN ARMED CONCRETE COMPOSITE COLUMN SYSTEM

The present application refers to columns composed of reinforced concrete, which according to NSR-10 and ACI-318, are classified within the category of reinforced concrete, in which the tubular is formed by sections in Cold Roll (CR) type sheets. , which form perlines with a soul and at least one skate that projects to the internal space of the column, coming into contact with the concrete, and said skate comprises a series of perforations that allow the concrete to pass through them, achieving that once the concrete sets, a composite column is formed that works in solidarity, enhancing the qualities of steel and concrete, to the point that the thickness of the sheet can be reduced, which allows the product to be economically viable,. Preferably, the perlines of the present invention are open perlines in the form of "L", "C", "U". Likewise, an integral and constructive structural system based on these columns is part of this application.

In the construction sector concrete or concrete columns and columns with steel structures are known, the latter offer a series of advantages that can be summarized as follows: a) Due to the nature of the material: steel, mathematical analysis models , are more representative of the real models,

b) The industrial character in the manufacturing and assembly processes, translates into speed of execution,

i c) Derived from the previous reason, the final product can reach quality levels that are very difficult to obtain, with the use of a material such as concrete,

d) Significant lower weight of the structural mass, which translates into lower demands due to inertial effects of seismic events,

e) Derived from the above, lower loads to the ground and consequently the foundation solutions,

f) 100% recyclable material. Despite its better performance, the diffusion of steel columns, particularly in countries with poor development of the steel industry, such as Colombia, remains incipient, despite the globalization of the economy. One of the causes that explain this fact lies in the costs. A widely known and applied alternative is the construction of reinforced concrete and steel columns, which basically maintains the same construction procedure that is applied from the beginning of its use, to the end from the 19th century: a) Preliminary activity of blacksmithing: elaboration, forming and assembly of the reinforcement system,

b) Carpentry activity: assembly, adjustment and plumbing of the format, c) Concrete emptying activity: preparation of the working system at height, emptying and vibrating the concrete,

d) Waiting time to guarantee sufficient setting, for the release, and e) Release activity.

The fact of maintaining an almost unalterable procedure for more than a hundred years, apart from revealing the absence of significant improvements, implies the process conserves two activities of artisanal nature: wood or metal carpentry and blacksmithing, with the implications that are proper : high labor consumption on the site with the highest risk of errors, longer execution times and, consequently, high direct and administrative costs.

However, structurally the components whose demands are tension or bending type, are more efficient in steel profiles. The same is not true for compression or flexural compression requirements, typical in columns, where conventional steel profiles, such as type I sections, shown in Figure 1, are more vulnerable to torsional buckling, which limits their compression resistance capacity, while the square, rectangular or circular sections, typical of reinforced concrete columns, there is no such limitation. Additionally, the concrete offers a good compressive strength at lower costs. The foregoing determines that, for the usual requirements in the columns, the alternative in reinforced concrete generally offers lower costs, than its current equivalent in steel profiles.

On the other hand and from a structural and functional point of view, it is observed that, if reinforced, consisting of steel bars, a concrete coating must be provided, which as specified in title C.1 .7.7.1 of the NSR-10 standard, it must not be less than ios 40mm, whose basic function is to protect it from corrosive processes and, eventually, as a short-term thermal insulator, against a conflagration event.

Complementing the function of this coating concrete, the NSR-10 title: C.10,8.2, C.10.8,3, C, 10.8.4: in one of its paragraphs it states: "The basic idea of: C, 10.8, 2, C. 10.8.3, C. 10.8.4, it is appropriate to design a column of sufficient dimensions to withstand the increased load, and then simply add concrete around the designed section, without increasing the reinforcement, so that it is inside of the minimum percentages required by C, 10.9, 1, It should not be considered that the additional concrete resists load ". For a square column of 250mm side, the covering section for the minimum: 40mm, represents 54% of the total section of the column. More than half of the entire section is not used in terms of compressive strength.

In an effort to find an option that combines the efficient compressive capacity of concrete in "full ^" sections, with the efficient strength of tensile steel, but that maintains the advantages of rapid execution of steel construction systems, eliminating formwork process that requires columns in reinforced concrete, composite columns have been produced and analysis models and procedures have been defined, systematized in construction standards, such as the AISC-LRFD, for the use of tubular with concrete cores or of composite sections that require formwork, as well as the columns shown in Figure 1, which are an example of the current technique.

The alternative, registered by standard AC1-318 and the corresponding Colombian: NSR ~ 10, as well as by almost all international standards, which replaces carpentry and blacksmithing activities, by industrial processes, correspond to the category of composite columns and within these, tubular ios with concrete cores. In it, the format is formed by the tubular which in turn fulfills the function of reinforcement, so that the two activities of an artisanal nature, merge into one, with the main component: tubular, industrial production.

The NSR-10 standard, in its title C10.13.1, describes the sections composed as follows: "... Compressed elements subjected to compression shall include all those elements that are longitudinally reinforced with structural steel profiles, pipes or tubes with or without longitudinal bars ". Obviously these are continuous closed sections. Later in the title: CR10.13.2 states: "The same rules used to calculate the resistance, using the load-moment interaction, for reinforced concrete sections can be applied to composite sections. The interaction diagrams for concrete filled pipes (composite sections), are identical to those of the ACI Design Handbook ... ". The titles: CR.10.13.3 and CR.10.13.4, Specify the stress transfer systems between the core concrete and the steel tubular as follows: "... The direct connection, to transfer the forces between the steel and the concrete can be developed, by protrusions, plates or reinforcing bars welded to the profile or structural tube before placing the concrete ... "The title: C.10.13.6.1, establishes the minimum thickness values, with the equations, which are reproduced below, the first of these equations is for Rectangular or square sections and while the second corresponds to the circular sections.

In eüas, the variables are, e: minimum thickness for the length side; bo diameter: D, f _y : yield strength of steel, E _s : modulus of elasticity of steel. So, for example, for a square section with a minimum indicated length of 250mm, by standard f _y = 413Mp and Es = 200,000Mp, the minimum wall thickness will be «6.55mm.

The previous criteria of the norm, constitute the foundations of the application of the columns of compound sections and obviously, their level of development in the present, that they imitate severely their application, for the following reasons of economic type:

The definition established in the title: C10.13.1, states: "... pipes or tubes with or without reinforcing bars ...", refers to structural tubular, with wall thicknesses equal to or greater than 6mm. Having the structural tubular exclusively, as a replacement option for the reinforcement in bars, constitutes a severe economic disadvantage. The cost per unit weight of the structural tubular, exceeds that of the reinforcement bar, by more than 40%. The reduction of the activity of blacksmithing that would imply its use, is not enough to equate its cost against the reinforcement in bars. In addition to the above, the creep limits of steels for reinforcing bars, greater than those corresponding to structural tubular profiles, determine larger sections of tubular, than those required by bars, and consequently greater consumption of tubular steel, with unit values greater than reinforcement bars.

Likewise, the stress transfer scheme: "... by means of protrusions, plates or reinforcing bars associated with the profile or structural tube ../ 'imply an additional cost to this component of the composite section.

In addition to the indicated costs, the requirement of treatments for surface protection, against corrosion processes. In the case of a tubular "reinforcement" of pillars or columns, fundamental components in the stability of the structural system that conform, it demands high performance surface protection, which guarantees its useful life.

Although, studies conducted in Spain, by CIDECT (International Committee for the Development and Study of Tubular Construction) in the 1970s, established that tubular filled concrete could resist fire, with temperatures of the order of ios 600 ° C, for up to 90 minutes, the protection of the tubular reinforcement, against conflagration events is necessary.

In addition to the economic issue, the worldwide use of this type of columns is still very limited, because the system does not work efficiently, as a composite section, that is, the transfer of tensions between the two components: concrete and tubular steel or the embedded steel profile, essential for the section to have a composite character and work in a solidary manner and consequently efficient, does not occur effectively, because when the concrete sets, due to the nature of the chemical reaction, retracts and detaches itself from the inner walls of the tubular or from the surface of the embedded profile, eliminating direct contact between the two components. The compressive strength capacity of! In particular, it is practically despised and the solution is not economically efficient.

As an alternative to guarantee solidarity work, the 2010 AISC standard specifies the use of shear connectors to guarantee the transfer of tensions between the concrete and the steel tubular or the embedded profile. On this subject, the AISC-360-10 ¹ standard establishes that ios "steel anchors used to transfer longitudinal cuts must be distributed within the length of the load introduction, which must not exceed a distance of twice the minimum dimension transverse of composite members embedded above and below the load transfer region The anchors used to transfer longitudinal cuts should be used on at least two sides of the steel element in a generally symmetrical configuration on the axis of the steel section. spacing of steel anchors, both inside and outside the length of the load introduction, must satisfy Section i 8.3e. "

In addition to the above and in relation to the "Filled Composite Members", the AISC-360-10 standard states: "Where required, steel anchors that transfer the longitudinal cuts shall be distributed within the length of introduction to the load, the which shall not exceed a distance of twice the minimum transverse dimension of rectangular steel members or twice the diameter of round steel members, both above and below the load transfer region. The spacing of steel anchors within the length for the introduction of loads must be met in Section I8.3e. "

¹ A! SC-360-10. Chapter I. Section 18. Page 171, related to the "Design of composite section members". Number! 4. "Requirements for Detachment". 4th. "Embedded composite members" and 4b. "Composite Members Relénos" The parameters indicated above introduce higher costs in the manufacturing process of the column, which in a high-cost input such as tubular profiles, makes this solution not competitive. Among the documents related to this type of columns is the patent application JPH03144047 of KAWASAK! STEEL CO, which reports a composite column that improves the transfer of stress between a beam and a pillar, the support beam is welded to a square steel tube, and the concrete that is placed in said steel tube. The system consists of a metal tube with a square section (1 1) to which beam supports (12) are welded. The metal tube (1 1) is filled with concrete (15) through the through holes (14) located on faces of said tube. After the concrete (15) is cured the through members (14) are blocked. This conformation causes the dispersion of the tensile force, exerted on the supports (12) and prevents deformation outside the piano of the lateral part of the steel tube (1 1). The beam supports (12) are tied to another section of themselves by means of bolts

Another document that refers to a composite system is patent application KR20120099822, which refers to a method of construction of a prefabricated steel column with reinforced concrete using L-shaped and open steel profiles to significantly reduce construction time , allowing the formation of a panel area of a PSRC column to absorb a vertical error. In a preferred form of the invention, four profiles of L-shaped steels (1 1) are placed vertically in the corners of a rectangular cross section. Auxiliary reinforcing bars (12) are added to the gaps between the L-shaped steels and are surrounded by tie rods (13). The steel plates (15) are welded to the outer sides of the L-shaped steel profiles and the auxiliary reinforcing bars. Jan! In the prior art, composite columns have been found such as those reported by ACESCO ² , who disclosed a composite column consisting of open profiles made of steel sheets, type CR or HR, especially in the form of "C", which are attached to along the joints of the C sections, forming a tubular section embedded with concrete. Although these 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 works in solidarity.

Likewise, GERDAU CORSA ³ offers among its products columns whose structural member design is formed by steel profiles that work together with reinforced concrete elements, or with coatings or fillings of this material. Specifically, it refers to composite columns, formed by steel profiles, rolled or made with sections or plates, screwed or welded, or by tubes or members of hollow rectangular rectangular cross-section of steel, drowned in reinforced concrete or filled with this material, and beams or beams, open-hearted reinforcements or stringers, called "joist", which are made of steel and are drowned in reinforced concrete or that support a slab, interconnected so that the two materials work together. Like ACESCO, GERDAU CORSA refers to a composite column, with a peripheral system of steel sheets, type CR or HR, which are joined by welding type 70XX, along the joints of the "C" sections, with an intermittent weld bead, 50mm every 250mm, creating an interior space occupied by concrete

Despite the existence of composite columns with different types of profiles, including some similar to those of the present invention such as ACESCO and GERDAU

CORSA, all columns with tubular and concrete core require the presence of welded attachments inside the walls of the tubular, as provided by the current standard for this category of composite sections: NSR-10 titles: CR.10.13. 3 and CR.10.13.4.

Thus, in the state of the art there is still a need to have a system of composite columns, whose profiles act in solidarity with the concrete, working efficiently so that the transfer of stresses between the two components: concrete and tubular or the steel profile achieves sufficient contact so that they interact with each other so that their capacity for compressive strength of concrete and the tensile strength of the steel work alone, maintaining the advantage of the speed of execution of construction systems in steel, but that is economically profitable, In summary, the compound systems embedded in the form of 1, are very expensive and the circular or square, require shear pins that are distributed along the column. Consequently, existing systems

• They are not viable because the minimum thickness to be categorized as a composite column must be 4, Smm which increases costs because it is much more expensive than the rods

• Steel outside involves the treatment of steel to prevent corrosion and others, such as resins or others that are expensive. They do not use galvanized because the thickness required by the sheet according to the standard is very expensive. The column defined here allows to reduce the thickness of the sheet that allows the use of galvanized steel or stainless steel.

® Additionally, these columns require welding to join the bolts or projections that increase the amount of material and time required for its construction. FIGURE 1, illustrates examples of composite columns existing in the state of the art with steel profiles of different shapes, H-shaped, circular or rectangular with an interior space filled with concrete.

FIGURE 2A. It shows a cross section of an L-shaped collaborating perlin, according to the present application

FIGURE 2B. Show a transverse cut! of a C-shaped collaborating perlin, in accordance with the present application

FIGURE 2C. It shows a cross section of a U-shaped collaborating perlin, according to the present application

FIGURE 3A. It shows the side view of an L-shaped collaborating perlin, according to the present application

FIGURE 3B. It shows the side view of a C-shaped collaborating perlin, according to the present application

FIGURE 3C. It shows the side view of a U-shaped collaborating perlin, according to the present application FIGURE 4A. It shows a top view of the column of the present invention, composed of four collaborating perlines in the form of L (1A) and four collaborating perlines in the form of C (1 B), where the skates of the components A and B have been joined and the concrete is set within its internal space. FIGURE 4B. It shows a top view of the column of the present invention, composed of four collaborating U-shaped perlines (1 C), where the tabs of components A and B have been joined and the concrete is set within the internal space of the same.

FIGURE SA. Top view of the column of the present invention, composed of four collaborating perlines in the form of L (1A) and four collaborating perlines in the form of C (1 B), showing the sections of the concrete bridges, which cross the perforations practiced on the skates of the collaborating perlines,

FIGURE 5B. Top view of the column of the present invention, composed of four U-shaped collaborating perlines (1 C), showing the sections of the concrete bridges, which cross the perforations performed on the skates of the collaborating perlines.

FIGURE S. Shows a scheme and the photo of an essay performed on the concrete core. FIGURE 7. Shows a detail of the connection between the collaborating shirt and a pedestal.

FIGURE 8. Shows a detail of the connection between the collaborating shirt and a beam.

FIGURE 9. Analysis using the finite element method, in the program

STAAD.Pro V8i, to simulate the behavior of one of the faces of a collaborating perlin, internally restricted by the concrete core. The boundary conditions for the nodes are freedom of movement along the Z axis, which corresponds to the vertical displacement of the body of the column, but unable to move along the X axis, due to the presence of the concrete core. FIGURE 10. Table showing the degrees of freedom defined for the lateral nodes.

FIGURE 1 1. Analysis using the finite element method, in the program

STAAD.Pro V8i, to simulate the behavior of one of the faces of a collaborating perlin, subjected to the necessary load to carry the section of foil away from creep and distributed over the lateral nodes of the model, of as follows: upper half of ateral nodes with loads oriented in the -Z direction. Lower half of lateral nodes with loads oriented in the + Z direction.

FIGURE 12. Results of the analysis of wrinkles and displacements in X, Y and Z.

FIGURE 13. Shows a column-beam connection. FIGURE 14. Shows the anchor length (1 1).

The present invention relates to collaborating perlines formed from steel sheets, preferably Cold Rol! (CR), which comprise a soul (1) and at least one skate (2) that projects, towards the internal space of the column, coming into contact with the concrete (4) and said skate (2) comprises along its length a series of perforations (3), as shown in figures 2 and 3. These perforations allow the concrete to pass through them before solidifying, and once it sets, a bridge is formed (5 ) of concrete, marked by circles in Figure 5, which ensures that a composite column constructed with the perlines of the invention works in solidarity, enhancing the qualities of steel and concrete, to the point that the thickness of the sheet can be reduced, which allows the product to be economically viable. These periines are produced in galvanized steel or stainless steel whose thickness fluctuates between 0 , 45mm and 3mm. In contrast, the current state of the art that handles equivalent solutions of composite section with thicker tubular or compact section and tension transfer devices consisting of attachments that require welding, which ultimately results in an increase in costs, causing These columns are not flashy as it is unprofitable.

The aforementioned periines (1) are L-shaped (see figure 3A and 4A), C-shaped (see figure 3B and 4B) or U-shaped (see figure 3C and 4C) and have a pair of skates (2) on each One of its ends.

In a preferred embodiment of the invention, the width of the core (1) of the periines must be less than 150 mm, the width of the skates (2) is between 50 mm and 75 mm, preferably the skates (2) have 75mm of width and the perforations (3) are distributed equally along the skate and centered in relation to the lateral edges of the skate. Elias have a diameter that ranges between 25 mm and 38 mm, even better, said diameter is 2Srnm, the distance (L) between one drilling center and another is 1 to 2 times the diameter of the perforations, preferably said distance of separation is 75 mm and the distance between the center of the perforation (3) and the edges of the skate (2) is 37.5 mm.

Likewise, an integral and constructive structural system based on said periines for the construction of composite columns is part of the present application. Said composite columns are made up of collaborating shirts comprising different combinations of the perlines of the present invention. To form the tubular, the skates (2) of the perlines are provisionally joined by an epoxy resin adhesive or type 70XX welding, so that the perforations (3) of adjacent skates coincide to allow the flow of concrete through it, and the perlines create an empty space inside to form a tubular section with the dimensions of the column. The definitive union of the pemiles that make up the tubular occurs after emptying the concrete in the empty space and that it is set, by means of the mooring of the through sections of the concrete core that cross the perforations (3), creating a bridge ( 5) that consolidates the system composed of COLLABORATING PERLINES-CONCRETE NUCLEUS, achieving the connection and interaction required for the composite column to function as such and to ensure that the components act in solidarity. The transfer of tensions between the core and the collaborating perlines will be given by the shear resistance of the sections of the concrete bridges, which cross the perforations (3) and are embedded in the concrete core, as shown in the Figures 5A and 5B.

In the case of steel sheets in "L", "C" or "U" of figures 2 and 3, so that the work between the concrete and the section of the steel sheet is balanced, it should be given that: when the concrete (2) that crosses the perforations, fails by shear, the steel of the sheet (1) will be entering creep, therefore, the maximum capacity of each component in the section will be taking advantage.

In a preferred alternative of the invention, the column tubular comprises four L-shaped collaborating perlines (1A), located in the corners, joined to four C-shaped collaborating perlines (1 B) that occupy the central part, such as It is shown in Figure 5A. In another embodiment of the present invention, the tubular comprises four collaborating U-shaped perlines (1 C), as shown in Figure 5B. Now, the structural system integrates! and constructive of the present application also includes the concrete core. In one embodiment of the invention, the mixing design for the concrete core will be for a compressive strength of 40! Vlp. In a preferred alternative, the concrete mixture has a water / cement ratio = 0.4, comprises a super plasticizer additive, a water reducing additive based on modified polycarboxylates or the like, has a consumption of 16mi / kg of cement, and includes a thick aggregate such as fractured boulder, with a maximum size of 15mm, and circular section metal fibers with anchor hooks at their ends, classification I, ASTIV1 A820-1 1, with the following properties: diameter: G.75mm ± G .03mm, length: 60mm ± 0.03mm, minimum tensile strength: 1 .100Mp. Proportion of metallic fiber consumption: 160Kg / m3.

For that concrete with that proportion of metallic fiber, it is essential to make laboratory tests to determine its resistance to shear, which is increased with that aggregate. Shear test standard: JSC SF ~ 6. Figure 6 shows a scheme and the photo of an essay. In said test the test piece is a beam of 500mmx150mmx150mm and the test is pure shear, which yields a conservative result in the case of elements simultaneously subjected to compression, such as that corresponding to the present development. In the study: "ENERGY OF FRACTURES IN MODE II OF THE CONCRETE OF NORMAL RESISTANCE REINFORCED WITH SHORT STEEL FIBERS", carried out by the Engineers: Fabián Augusto Lamus Báez and Sergio Mauricio Segura Arenas, page 168, See Appendix: 1, it is established that The concrete qualifies for a shear strength of: 15.46 ± 0.85Mp, which is the strength of the concrete used in the columns of the present invention.

Finally, the construction method comprising the following steps is part of the object here: to. Prepare the perlines in the form of L and C or in the form of U, depending on the type of column to be built;

b. Provisionally join the skates (2) of the perlines by means of an adhesive or weld, ensuring that the perforations (3) of the adjacent skates coincide leaving a hollow space, through which the concrete flows, and creating an empty space inside the perlines joined to form the tubular;

C. Fill the interior space of the tubular with concrete; Y

d. Wait for the concrete to set, so that when solidifying the through sections of the concrete core that pass through the perforations (3) generate bridges (5) that definitively join the perlines and consolidate the column composed of

COLLABORATING PERLINES-CONCRETE NUCLEUS.

EXAMPLES

Example 1. Construction details

UNION COMPOSITE-PEDESTAL FOUNDATION COLUMN: Applies to both reinforced concrete and steel structures. As shown in Figure 7, the structural connection is given by the extension of the first reinforcement section of the column (6) that comes from the pedestal (7), in a length not less than the development length (61) of the larger diameter bar, inside the concrete core (4) of the composite section (6). Said column (6) is attached to the pedestal (7) by leveling nuts (71), adjusting nuts (72) and anchor bolts (73). The base plate frame (8) fulfills only the function of facilitating the positioning of the collaborating shirt.

JOINED BEAM OR Slab COLUMN UNION: Applies to reinforced concrete structures, specifically slabs or slabs (9). Figure 8 shows that the structural connection is given by the extension of the last section and first reinforcement section (62) of the immediately following column (6), in a length not less than the length of development (61) of the bar of greater diameter, within the concrete core of the composite section, of the consecutive columns formed by the collaborating sleeve (63).

UNION COMPOSITE-BEAM OR Slab COLUMN: Applies to steel structures. In Figure 8 it can be seen that the structural connection is made by through bars that connect the steel beams in line. As in the previous case, the column (6) is attached to the plate (9) by leveling nuts (91), adjusting nuts (92) and anchor bolts (73),

Example 2. Analytical basis of development and advantages:

DESIGN CRITERIA: Norms: ACI-318-1 1 and NSR-10, Chapter: "Composite Section Columns" and AISI norm, as regards COLLABORATING PERLINES.

STEEL OF THE COLLABORATING PEARLS: As defined above: Lamina Coid Rol! in ASTM A572 galvanized steel with thicknesses: G.45mm - 2mm. o Stainless 302, with thicknesses between: 0.5mm ~ 1.5mm. For its analysis applies the standard for cold formed steels: AISI. This regulation, in the subtitles: A3.2 and A3.3 relating to DUCTILITY, establishes the criteria for applying its regulations, to steels other than carbon steels, within which 302 CR Stainless Steel fits. COMPATIBILITY OF DEFORMATIONS: For ios ASTM A572 and Stainless 302 galvanized CR steels and Concrete with the design specifications of mixtures defined above, the equivalence of the maximum unit deformations within the elastic range is maintained: 0.2%. Fundamental hypothesis in the behavior of the composite system. MINIMUM THICKNESS OF COLLABORATING PEARLS: The standard applies: AISI B.1 .1: "CONSIDERATIONS ON THE RELATIONSHIP BETWEEN THE FLAT WIDTH AND THEIR THICKNESS: w / í", aimed at ensuring that the section reaches creep, before of presenting local deformations. Additionally, the collaborating perlin sheet is severely impeded to deform the interior, since that space is occupied by the concrete core. The above is analytically corroborated using the FINITE ELEMENTS method, in the STAAD.Pro V8i program, to simulate the behavior of one of the faces of a COLLABORATING PERLIN, internally restricted by the concrete core.

In the analysis example shown below, a thin sheet of ASTM A36 steel, creep limit: 250MP or 2549kgf / cm ² , with a thickness of 0.6mm, 2G0mm wide, by 2480mm long, corresponding to a typical side of a collaborating perlin. The boundary conditions for the lateral edge nodes (10) are: freedom of movement along the Z axis, which corresponds to the vertical displacement of the column body, due to the effect of the compression load. But unable to travel along the X axis, by virtue of the presence of the concrete core and without considering the Poisson effect, which will occur in the final phase of the concrete core failure, see Figure 9, icons in red-green, that correspond to the support, see right box: Supports-Whoie Sfructure. The table in Figure 10 shows the degrees of freedom defined for these lateral nodes. The lower supports of the blue model, See Figure 9, are assimilated to joints, with freedom of rotation, but which prevent the vertical displacement of these nodes and correspond to the lower end of the column. The model will be subjected to the load necessary to bring the section of the sheet to the creep limit and distributed over the lateral nodes of the model, as follows: upper half of lateral nodes (10) with the loads oriented in the -Z direction . Lower half of lateral nodes (0) with loads oriented in the + Z direction. Load condition that would be given by the transfer between concrete core and collaborating perlin, to apply the indicated load, on the upper face of concrete core. See Figure 1 1. A Once the model has been run under the conditions indicated above, the displacement in the Y (wrinkle) direction of the most demanded node is determined: the central nodes in the directions: X, Y, Z. The results are shown in the table in Figure 12. The displacement perpendicular to the plane of the sheet, direction Y, or wrinkling is null.

. According to the results obtained:

(C _F ^" ) Creep load ------ 2549 * 20 cm * Q

.G6cm ------ 3058.8kg f

Number of side nodes: 250

3058.8 /

(F) Absolute load value applied per node = ^ T "—— 12, 2352 /

250

* 12.24

The previous data, using the mathematical model of finite elements, reveal the non-generation of "wrinkling" in the thin sheet of the tubular or collaborating jacket, working with the restrictions imposed by the concrete core and allowing the use of thin sheet, as a material for the tubular of the present invention, which the current NSR-10 or AC! norm does not allow.

VOLTAGE TRANSFER BETWEEN COLLABORATING PERLINES AND THE NUCLEUS CONCRETE: This transfer, together with the hypothesis defined in the subtitle: 4.2 .: COMPATIBILITY OF DEFORMATIONS, allows joint or solidarity work between the two components of the composite system: COLLABORATING PERLINES and core of concrete, preventing the sliding of one in relation to the other, as defined above. The stress transfer model between the two components was previously defined in the following terms: "The transfer of stresses between the concrete core and the COLLABORATING perlines will be given by the shear resistance of the concrete bridges (5), that would go through the perforations (3) 25mm in diameter made on the skates (2) of the collaborating perlines, which would be embedded in the concrete core. "To take full advantage of the resistant capacity of both components, it must be ensured that the interns of concrete, contained within a section of reasonably short length; that we will love anchor length (La) (1 1), ensure that none of the components of the collaborating profiles slide before it reaches the creep point. As an example, the anchoring length (1 1) of a collaborating perlin will be determined: L125mmx1 mm in stainless steel, which has a higher yield limit than the ASTM A572 CR galvanized steel sheets See Figure 14.

Section perimeter L125xl: p = 2 (125mm + 75mm) = 400mm

Cross section diameter in concrete: I) = 25mm

Concrete pass-through area: A _c = nr ² = n \ 2 ² mm ^L = 490.86mm ²

Anchor Length: L _a

Number of sections that work the shear for each intern: 2

Anchor Length: L _a ------ 76mm - 25 (n— 1)

Effective section area 1125x1: A _is = (400rnm— 2x25mm) xl ----- 350mm ²

Creep limit Stainless Steel CR 302: l, 3G8 p

Maximum tension of the steel section when it reaches the creep point: T _s

T _s = 350mm x 1.308Afp = 457.800N

Shear strength of concrete: v _c = 15.46 p

Maximum shear of intern sections in concrete: T _c

T _c = 2n490.86mm ² xl5.46Mp = nl5.177.4N

457,800.0N

So, n = - «30

15,177.4N

L _a = 76mm + 25 (30— l) mm = 801mm

In conclusion, the collaborating shirt of the present application offers the option of forming the tubular on site, from CR sheets, or that facilitates the construction operation, from transport, through storage, to the construction process which assimilates the assembly of the tubular, formed of the form.

On the other hand, the thickness of the sheets used in the collaborating jacket of the invention ranges between 0.45mm and 3mm, which is much less than the minimum thickness required for existing systems in the state of the art, e! which must be greater than 8mm. Additionally, the location of the thicknesses of the open sections may vary according to the amount requirements required in the column section: in conventional tubulars with uniform wall thicknesses, this is not possible.

Another relevant advantage of the present invention is that by not requiring additional components that must be welded, such as projections, plates or reinforcing bars welded to the profile or structural tube before placing the concrete, it allows to reduce costs. In addition to the above, the characteristics of the concrete core guarantee the necessary shear resistance that provides the composite work of the two parts, the tubular steel and the concrete core. Additionally, the option of producing the periines in galvanized or stainless steel sheet, allows to handle two alternatives of protection against corrosive processes, depending on the aggressiveness of the environment.

Finally, the open section sheet in stainless steel 302 allows the tubular to be formed in a steel with a creep limit of: 1 138mp, compared to the 412mp of the reinforcing bars or ios 345mp of the ASTM galvanized CR sheet in ASTM steel A572, demand smaller amounts.

Claims

A collaborating perlin formed from sheets of steel, characterized in that they comprise an aima (1) and one or two skates (2) that project (n), towards the internal space of the column, coming into contact with e! concrete (4) and said skates (2) along its length comprise a series of perforations (3),

The collaborating perlin of claim 1, characterized in that the steel sheet is a Cold Rol! (CR).

The collaborating perlin of claim 2, characterized in that the perlines are produced in galvanized steel or stainless steel.

The collaborating perlin of claim 1, characterized in that the thickness of the sheet fluctuates between 0.45mm and 3mm.

The collaborating perlin of claim 1, characterized in that it has an L, C or U shape and has a pair of skates (2) at each of its ends.

The collaborating perlin of claim 1, characterized in that the width of the soul (1) of the perlines is between 1 mm to 150 mm.

The collaborating perlin of claim 1, characterized in that the width of the skates (2) is between 50mm and 75mm

The collaborating perlin of claim 7, characterized in that the skates (2) are 75mm wide.

The collaborating perlin of claim 1, characterized in that the perforations (3) are distributed equidistant along the skate (2), are centered in relation to the lateral edges of the skate (2) and have a diameter ranging between 25 mm and 38 mm

The collaborative perlin of claim 9, characterized in that the diameter of the perforations is 25mm and the distance (L) between one drilling center and another is 1 to 2 times the diameter of the perforations.

1 1. The collaborating perlin of ia claim 10, characterized in that the distance (L) between one drilling center and another is 75 mm and the distance between the center of the perforation (3) and the edges of the skate (2) is 37.5 mm

12. A collaborating jacket characterized in that it comprises a tubular formed by the profiles of claims 1 to 1 1 and a concrete core (4) confined in the internal space of the tubular.

13. The collaborating shirt of claim 12 characterized in that it comprises four L-shaped collaborating periines (1A), located in the corners, joined by means of its skates (2) to the skates (2) of four C-shaped collaborating periines ( 1 B) occupying the central part, and the perforations (3) of the adjacent skates coincide.

14. The collaborating shirt of claim 12 characterized in that it comprises four collaborating U-shaped periines (1 C), joined together through their skates (2).

15. The collaborating jacket of claim 13 or 14 characterized in that the skates (2) of the periins are provisionally joined by an epoxy resin adhesive or type 70XX welding, generating an empty space inside to form a tubular section with the dimensions of the column.

16. The collaborating shirt of claim 15 characterized in that its skates (2) are joined definitively by means of the mooring of the through sections of the concrete core that cross the perforations (3) creating a concrete bridge (5).

17. The collaborating sleeve of claim 12 characterized in that the mixture for the concrete core has a compressive strength of 40 Mp.

18. The collaborating jacket of claim 17 characterized in that the concrete mixture comprises metal fibers of circular section with anchor hooks at their ends, having a diameter of 0.75mm ± 0.03mm, a length of 60mm ± 0.03mm and minimum strength to tension: HOO p.

19. The collaborating jacket of claim 18, characterized in that the proportion of metallic fiber in the concrete mixture is 160 kg / m3.

20. The collaborating jacket of claim 18 characterized in that the concrete mixture has a water / cement ratio = 0.4, comprises a super piastifying additive, a water reducing additive based on modified polycarboxylates or the like, has a consumption of 16ml / kg of cement, and includes a thick aggregate such as fractured boulder, with a maximum size of 15mm.

21. A method for the construction of a collaborating shirt characterized in that it comprises the following steps:

to. Prepare the perlines in the form of L and C or in the form of U, depending on the type of column to be built;

b. Provisionally join the skates (2) of the perlines by means of an adhesive or weld, ensuring that the perforations (3) of the adjacent skates coincide leaving a hollow space, through which the concrete flows, and creating an empty space inside ios perlines joined to form the tubular;

C. Fill the interior space of the tubular with concrete; Y

d. Wait for the concrete to set, so that when solidifying the through sections of the concrete core that cross the perforations (3) generate bridges (5) that definitely join the periines and consolidate the column composed of collaborating periines - concrete core.