WO2006109901A1

WO2006109901A1 - Concrete composite column and composite pier

Info

Publication number: WO2006109901A1
Application number: PCT/KR2005/001219
Authority: WO
Inventors: Ki Hong Lee
Original assignee: B.B.M. Korea Co., Ltd.
Priority date: 2005-04-11
Filing date: 2005-04-27
Publication date: 2006-10-19
Also published as: KR100666703B1; KR20060107710A

Abstract

Provided are a concrete-filled steel tube (CFT) column and a concrete composite pier using the same, capable of eliminating a work required to arrange reinforcements as well as remarkably improving a adhesive strength between the concrete and the steel tube, thereby maximizing a combined action of the concrete and the steel tube and improving outer appearance. The CFT column includes a steel tube; at least one armature attached to an inner surface and in a lengthwise direction of the steel tube and having a coupling plate, a web and at least one concrete-gripping hole; and concrete poured into a space defined by the steel tube and the armature.

Description

Description CONCRETE COMPOSITE COLUMN AND COMPOSITE PIER

Technical Field

[1] The present invention relates to a concrete-filled steel tube (CFT) column which is filled with concrete to form a column, and a concrete composite pier using the same. The present invention is capable of eliminating arrangement work for reinforcement as well as remarkably improving adhesive strength between the concrete and the steel tube, thereby maximizing the combined action of the concrete and the steel tube and creating a nice outer appearance. The CFT column comprises a steel tube; at least one armature having a coupling plate coupled to an inner surface of the steel tube in a lengthwise direction, a web, and at least one concrete-gripping hole; and concrete poured into a space defined by the steel tube and the armature. Background Art

[2] Columns are constructs subjected to an axial load and a bending moment at the same time, and are generally classified into reinforced concrete columns and composite columns.

[3] Reinforced concrete columns are designed with an arrangement of longitudinal and transverse bars enclosed in concrete, thereby integrating the bars and concrete to resist axial load and bending moment. According to the type of the transverse bars, reinforced concrete columns are further classified into tie bar columns and spiral bar columns.

[4] Meanwhile, composite columns are further classified into steel columns and concrete- filled steel tube (CFT) columns. Steel columns are made by burying a steel beam such as an H-beam or a cross-shaped beam in a concrete column together with reinforcing bars and hoops, and CFT columns are made by filling a steel tube with concrete, wherein the steel tube serves as a mold and provides reinforcement.

[5] Reinforced concrete structures, such as the above-described reinforced concrete columns, are composite structures where the concrete and bars are used as compression and tension materials, respectively. Reinforced concrete structures are mainly used for civil engineering and building construction. Reinforced concrete structures are manufactured by providing a mold for the concrete, arranging reinforcing bars in the mold, pouring concrete into the mold, and removing the mold after the concrete has completely hardened.

[6] However, in building reinforced concrete structures, it is often difficult to remove the mold from the hardened concrete because they easily stick together. And, when the mold is separated from the concrete, the concrete surface tends to be rough and uneven, requiring finishing.

[7] CFT columns are steel tube columns filled with fresh, unhardened concrete, wherein the steel tube provides sufficient stiffness to act as a mold and provide reinforcement. CFT columns have many structural and practical advantages and therefore are widely used nowadays.

[8] With CFT columns, there is no framework or mold to install and dismantle and thus construction requires less time and cost. Further, the concrete core acts to prevent local buckling of the steel tube, thereby resisting inward strain and increasing structural stiffness. In addition, because the concrete is confined by the steel tube, it is capable of withstanding more stress and strain, and thus the strength of the CFT column is greater than the mere sum of the strengths of the concrete and the steel tube. Consequently, a significantly stronger column exhibiting excellent energy absorbency can be made at relatively low cost.

[9] However, concrete is a brittle material, and a structure made of concrete is particularly brittle when it has defects such as local corner fracture. Thus, when the concrete is locally damaged, the steel tube is subjected to a full load.

[10] In this case, when the concrete is not firmly adhered to the steel tube, which is relatively susceptible to compression, the steel tube may be deformed leading to buckling of the column.

[11] In general, concrete is quite resistant to compression but not tension. Thus, concrete is generally disregarded in the design of columns to which a bending moment is applied. In the case of a steel tube column, the entire cross-section of the concrete can be designed to be effective because the steel tube encloses the concrete. However, since the concrete is not firmly adhered to the steel tube, the strength and ductility of the entire column are reduced.

[12] On the other hand, in the case of a hollow concrete column, there is an advantage of light weight but a disadvantage of brittleness because an inner surface of the column is not restrained. For this reason, a method of inserting a steel tube into a hollow space has been used. Here, like general steel tube columns, the concrete and the steel tube reinforce each other most effectively when there is sufficient adhesion between them. Without sufficient adhesion, the strength of a composite column cannot be maximized.

[13] Therefore, there is strong demand for a steel tube-reinforced concrete column in which there is sufficient adhesion between the concrete and the steel tube that they behave integrally without relative displacement and thus maximize the strength and ductility of the composite column. Disclosure of Invention Technical Problem [14] It is an objective of the present invention to provide a concrete composite column in which at least one armature is attached to the inner or outer surface of a steel tube to provide firm adhesion between the steel tube and hardened concrete, thereby optimizing characteristics of the composite column by causing the concrete and steel tube to behave as one without any separation.

[15] It is another objective of the present invention to provide a concrete composite pier in which an upper steel tube having at least one armature is connected at a right angle to an upper portion of a steel tube so that a column and an abutment are integrally formed to increase adhesive strength and structural stiffness. Technical Solution

[16] In accordance with an aspect of the present invention, the above and other objectives can be accomplished by providing a concrete composite column comprising: a steel tube; at least one armature attached to an inner surface of the steel tube in a lengthwise direction of the steel tube; and concrete poured into a space defined by the steel tube and the armature.

[17] In accordance with another aspect of the present invention, there is provided a concrete composite column comprising: a steel tube; at least one armature attached to an inner surface of the steel tube circumferentially; and concrete poured into a space defined by the steel tube and the armature.

[18] In accordance with still another aspect of the present invention, there is provided a concrete composite column comprising: a steel tube; at least one armature attached to an outer surface of the steel tube in a lengthwise direction of the steel tube; and concrete poured into a space defined by the outer surface of the steel tube and the armature.

[19] In accordance with yet another aspect of the present invention, there is provided a concrete composite column comprising: a steel tube; at least one armature attached to an outer surface of the steel tube circumferentially; and concrete poured into a space defined by the outer surface of the steel tube and the armature. In accordance with still yet another aspect of the present invention, there is provided a concrete composite pier comprising: a steel tube; at least one armature attached to an inner surface of the steel tube in a lengthwise direction of the steel tube; an upper steel tube bonded to an upper portion of the steel tube and extending in a direction perpendicular to the steel tube, having the armature attached to an inner surface thereof and filled with concrete integrally; and a joint at which the steel tube and the upper steel tube are bonded.

[20] In accordance with a further aspect of the present invention, there is provided a concrete composite pier comprising: a steel tube; at least one armature attached to an inner surface of the steel tube circumferentially; an upper steel tube bonded to an upper portion of the steel tube and extending in a direction perpendicular to the steel tube, having the armature attached to an inner surface thereof and filled with concrete integrally; and a joint at which the steel tube and the upper steel tube are bonded. Advantageous Effects

[21] The present invention causes the hardened concrete and the steel tube to firmly adhere to one another using at least one armature attached to the inner or outer surface of the steel tube, thereby allowing the concrete and steel tube to behave as one without any separation to maximize their combined action in the composite column.

[22] Further, the present invention is capable of eliminating work required to arrange at least one reinforcement, as well as increasing the overall stiffness of the column, thereby advantageously reducing the size of the structure so that it takes up less space, and providing a nice outer appearance.

[23] While exemplary embodiments of the present invention have been described, it will be apparent to those skilled in the art that various modifications, additions, and substitutions are possible without departing from the spirit and scope of the invention as defined in the accompanying claims. Brief Description of the Drawings

[24] The above and other objects, features, and advantages of the present invention will be more clearly understood from the following detailed description when considered in conjunction with the accompanying drawings, in which:

[25] Fig. 1 is a partially cut-away perspective view of a concrete composite column according to a first exemplary embodiment of the present invention;

[26] Fig. 2 is a perspective view of an armature according to a first exemplary embodiment of the present invention;

[27] Fig. 3 is a perspective view of an armature according to a second exemplary embodiment of the present invention;

[28] Fig. 4 is a perspective view of an armature according to a third exemplary embodiment of the present invention;

[29] Fig. 5 is a partially cut-away perspective view of a concrete composite column according to a second exemplary embodiment of the present invention;

[30] Fig. 6 is a partially cut-away perspective view of a concrete composite column according to a third exemplary embodiment of the present invention;

[31] Fig. 7 is a cross- sectional view of a concrete composite column according to the third exemplary embodiment of the present invention;

[32] Fig. 8 is a partially cut-away perspective view of a concrete composite column according to a fourth exemplary embodiment of the present invention; and

[33] Fig. 9is a partially cut-away perspective view of a concrete composite pier according to an exemplary embodiment of the present invention; Best Mode for Carrying Out the Invention

[34] The present invention provides a concrete composite column comprising: a steel tube; at least one armature attached to an inner surface of the steel tube in a lengthwise direction of the steel tube; and concrete poured into a space defined by the steel tube and the armature.

[35] Here, the armature includes: a coupling plate formed with at least one coupling part; a web formed perpendicular to the coupling plate in the middle of the coupling plate and having at least one concrete- gripping hole; and at least one concrete-gripping protrusion formed on an upper end of the web by cutting the upper end into wings and alternately bending the wings in opposite directions. Mode for the Invention

[36] Further, the present invention provides a concrete composite column comprising: a steel tube; at least one armature attached to an inner surface of the steel tube circum- ferentially; and concrete poured into a space defined by the steel tube and the armature.

[37] Furthermore, the present invention provides a concrete composite column comprising: a steel tube; at least one armature attached to an outer surface of the steel tube in a lengthwise direction of the steel tube; and concrete poured into a space defined by the outer surface of the steel tube and the armature.

[38] In addition, the present invention provides a concrete composite column comprising: a steel tube; at least one armature attached to an outer surface of the steel tube circumferentially; and concrete poured into a space defined by the outer surface of the steel tube and the armature.

[39] Meanwhile, the present invention provides a concrete composite pier comprising: a steel tube; at least one armature attached to an inner surface of the steel tube in a lengthwise direction of the steel tube; an upper steel tube bonded to an upper portion of the steel tube, extending in a direction perpendicular to the steel tube, and having the armature attached to an inner surface thereof; a joint at which the steel tube and the upper steel tube are bonded; and concrete filling the steel tube and the upper steel tube.

[40] Further, the present invention provides a concrete composite pier comprising: a steel tube; at least one armature attached to an inner surface of the steel tube circumferentially; an upper steel tube bonded to an upper portion of the steel tube, extending in a direction perpendicular to the steel tube, and having the armature attached to an inner surface thereof; a joint at which the steel tube and the upper steel tube are bonded; and concrete filling the steel tube and the upper steel tube.

[41] Hereinafter, concrete composite columns and piers according to exemplary embodiments of the present invention will be described with reference to the attached drawings.

[42] However, the following embodiments are provided to assist those of ordinary skill in the art to understand the present invention. The following embodiments can be modified in various ways and should not be construed as limiting the scope of the present invention.

[43] Fig. 1 is a partially cut-away perspective view of a concrete composite column according to a first exemplary embodiment of the present invention.

[44] As shown in Fig. 1, armatures 41 are each composed of a coupling plate 45, a web

44, concrete-gripping holes 42, and concrete- gripping protrusions 43, and formed along the length of a steel tube 10 to be closely attached to an inner circumferential surface of the steel tube 10. When concrete 11 poured in the steel tube 10 is hardened to exert strength, the armature 41 is engaged with the concrete 11. As a result, the concrete 11 and the steel tube 10 are mechanically combined in one member to resist a load without relative sliding.

[45] It is shown in Fig. 1 that the armatures 41 attached inside the steel tube 10 are four in number. However, this is simply to show one example of the concrete-filled composite according to the present invention. Thus, such a number of the armatures can be varied within a range capable of exerting actions and effects of the invention as many as needed. In view of both structure and economy, it is preferable to have three to five armatures 41.

[46] The coupling plate 45 is closely coupled with the inner circumferential surface of the steel tube 10 by coupling parts 46 that are formed at a constant interval in the lengthwise direction thereof. Thereby, the armatures 41 are firmly attached to the steel tube 10.

[47] The coupling parts 46 are formed on both sides of the coupling plate 45 in the lengthwise direction of the steel tube 10, and subjected to spot welding at a constant interval on the coupling plate 45. Although not shown in Fig. 1 at hand, all possible means used generally as a coupling means of steel sheets in the art of interest can be employed for the coupling parts 46. Thus, except the spot welding, stud welding or riveting may be used.

[48] The interval between the coupling parts 46 may be varied according to a specifically applied structure, and preferably has a range from 30 to 50 cm on the coupling plate 45.

[49] The web 44 starts at the middle of the coupling plate 45 to radially inwardly extend with respect to the steel tube 10, and is integrally formed with the concrete-gripping protrusions 43 on the end thereof. As seen from Fig. 1, the web 44 linearly extends along the lengthwise direction of the steel tube 10, thereby taking a charge of a function similar to a longitudinal reinforcement in a reinforced concrete column. Therefore, the web 44 bears a vertical load and resists flexural tension together with steel materials when the column is subjected either to a bending moment by a direct lateral load such as an earthquake, a wind load etc. or a secondary moment by a vertical load, thereby acting to induce ductile deformation.

[50] The concrete-gripping holes 42 are formed in a row along the web 44 in the lengthwise direction of the steel tube 10 at an interval between 10 and 20 cm, and have a circular shape. When pouring the concrete 11, fresh concrete 11 poured in the steel tube 10 passes through and fills the concrete-gripping holes 42. Then, when the concrete 11 is completely hardened, the web 44 is engaged with the concrete 11.

[51] Unlike being shown in Fig. 1, the concrete-gripping holes 42 may be varied in number as well as in shape. For example, the concrete-gripping holes 42 may have a triangular shape, a quadrangular shape, an oval shape, a slot-like shape and so on. These modifications all have substantially same purposes, actions, and effects as the concrete-gripping holes 42 of the present invention, and can be easily predicted from the concrete-gripping holes 42 of the present invention by those skilled in the art, thus being considered to be within the scope of the present invention.

[52] The concrete-gripping protrusions 43 are alternately formed to the left and right of the web 44 by cutting an upper portion of the web 44 to bend the cut upper segments of the web 44 left and right. In this case, the concrete-gripping protrusions 43 are formed by starting at an end of the web 44 to bend the web 44 in a direction perpendicular to a diameter direction of the steel tube 10 and have a quadrangular shape. In other words, the concrete-gripping protrusions 43 are formed by bending the web 44 in the opposite directions to be parallel to the coupling plate, as shown in Fig. 1.

[53] The concrete-gripping protrusions 43 maximize a combined action between the steel tube 10 and the concrete 11 together with the web 44 due to frictional and mechanical actions with the concrete 11, and act just like a tie bar (hoop) in the reinforced concrete column. When the column is subjected to compression, the concrete-gripping protrusions 43 restrain the concrete 11 of the middle portion of the column, thereby increasing compressive and yield strength of the core concrete 11 as well as the flexural strength of the column.

[54] In Fig. 1, the concrete-gripping protrusions 43 are shown only in the rectangular shape. However, it will be apparent to those skilled in the art that the concrete-gripping protrusions 43 may be formed in the various shapes such as a semi-circular shape, a trapezoidal shape, a triangular shape and so on.

[55] The steel tube 10 has the four armatures 41 attached to the inner circumferential surface in the lengthwise direction. Fresh concrete 11 is filled and hardened in the steel tube 10. The steel tube 10 prevents a dry creep phenomenon that occurs under the conditions of dry contracting and drying of the concrete 11 by keeping the inner concrete 11 from being exposed to external air, thereby greatly reducing a long-term strain of the member. Meanwhile, as the steel tube column, there are a circular column and an angular column. In the case of the angular column, a quadrangular column is widely used. While not directly shown in Fig. 1, the steel tube column according to the present invention may be sufficiently applied to angular steel tubes of, for example, quadrangle, trapezoid and so on.

[56] The concrete 11 is filled in the steel tube 10 in an unhardened state and then hardened. For the purpose of providing firmly adhesion to the armatures 41, the fresh concrete 11 has to flow well up to the corners of the armatures 41 to fill the corners or concrete-gripping holes 42 without any air gap. To this end, the concrete 11 must secure workability as well as good fluidity and fillability. Thus, it is preferable to make use of high fluidity concrete capable of securing the workability without increasing a water-to-cement ratio or uncompacted concrete having self-compactability.

[57] In general, in the case of the conventional concrete-filled composite column, a shear connector or diaphragm is installed so that a load which is applied to a steel tube in order to enhance efficiency of the member as the composite column is sufficient transmitted to the concrete 11 in the steel tube. However, in the case of the concrete- filled composite column according to the present invention, the steel tube 10 and the concrete 11 are adapted to behave as one by means of the armatures 41, and thus such a shear connector or diaphragm are not required.

[58] Fig. 2 is a perspective view of an armature according to a first exemplary embodiment of the present invention. As shown in Fig. 2, an armature 41 of the invention has concrete-gripping protrusions 43 formed alternately on the upper portion of a web 44.

[59] The web 44 has concrete-gripping holes 42 formed at the intermediate portion in the lengthwise direction in order to strengthen adhesion to concrete 11, and a coupling plate 45 coupled with a steel tube or panel 10 at the lower portion, which is as already described with reference to Fig. 1.

[60] The concrete-gripping protrusions 43 are alternately formed to the left and right of the web 44 by cutting an upper portion of the web 44 to bend the cut upper segments of the web 44 left and right.

[61] By forming the concrete-gripping protrusions 43 in this manner, it is possible to secure sufficient adhesion due to frictional and mechanical actions between the armature 41 and the concrete 11. Thus, the concrete-gripping protrusions 43 act to maximize effects as a composite column of the steel tube 10 and the concrete 11, which is as already described as well.

[62] Of course, when it is required to increase strength, it is possible to go side by side with, for example, arrangement of transverse and longitudinal bars as in the prior art. This configuration is apparent to those skilled in the art from the description of the present invention, thus being construed as falling within the technical scope of the present invention.

[63] While it is shown in Fig. 2 that the concrete-gripping protrusions 43 are horizontally formed to the left and right of the web 44 alternating with each other, an angle between each concrete-gripping protrusion 43 and the web may be configured of an acute or obtuse angle as long as within a range capable of securing a predetermined adhesive strength.

[64] The concrete-gripping holes 42 has a circular shape, and are formed at the web 44 in the lengthwise direction of the armature 41, thus acting to promote the adhesive strength between the steel tube 10 and the concrete 11.

[65] The coupling plate 45 is vertically coupled to the web 44 by welding. Thereafter, the coupling plate 45 has its bottom closed contacted with an inner surface of the steel tube 10, thereby acting to couple the armature 41 to the steel tube 10, which is as described with reference to Fig. 1.

[66] Fig. 3 is a perspective view of an armature according to a second exemplary embodiment of the present invention. A web 44 is formed perpendicular to and in the middle of a coupling plate 45 and provided with concrete-gripping holes 42 at a constant interval. This configuration is similar to that shown in Fig. 2.

[67] Unlike the first embodiment of the armature shown in Fig. 2, the second embodiment of the armature shown in Fig. 3 is not formed with concrete-gripping protrusions 43.

[68] Instead of the concrete-gripping protrusions 43, a rectangular steel sheet is attached to the web 44 so as to act as an upper flange 43a. Thus, the armature 41 of the invention has a cross section of an H shape on the whole, wherein the upper flange 43a has a width narrower than the coupling plate 45.

[69] It is shown in Fig. 3 that the upper flange 43a has the width narrower than the coupling plate 45. In connection with the widths of the upper flange 43 a and coupling plate 45, their relative size can be appropriately adjusted on the basis of construction environment and desired strength of each structure. This is no more than mere design variation of the present invention, thus being considered to fall with the scope of the present invention.

[70] Fig. 4 is a perspective view of an armature according to a third exemplary embodiment of the present invention. A web 44 is formed perpendicular to and in the middle of a coupling plate 45 and provided with concrete-gripping holes 42 at a constant interval. This configuration is similar to that shown in Fig. 2.

[71] Unlike the first and second embodiments, the third embodiment of the armature 41 shown in Fig. 4 is neither provided with concrete-gripping protrusions 43 nor upper flange 43a. When an adhesive strength of a structure can be sufficiently secured without the concrete-gripping protrusions 43 or upper flange 43a, the armature 41 shown in Fig. 4 is used, thereby allowing of improvement of economical efficiency and workability.

[72] Fig. 5 is a partially cut-away perspective view of a concrete composite column according to a second exemplary embodiment of the present invention.

[73] Each armature 41 includes a coupling plate 45, a web 44, concrete-gripping holes

42, and concrete- gripping protrusions 43. When concrete 11 poured in a steel tube 10 is hardened to exert strength, the armature is engaged with the concrete 11. As a result, the concrete 11 and the steel tube 10 are mechanically combined in one member to resist a load without relative sliding. This configuration is similar to that as described with reference to Fig. 1.

[74] In the concrete composite column according to the second exemplary embodiment of the present invention, the armatures 41 are each attached to an inner circumferential surface of the steel tube 10 circumferentially rather than in a lengthwise direction. An interval between the two neighboring armatures 41 can be appropriately adjusted on the basis of a desired strength of a structure, and preferably has a range from 1.5 to 2.0 m.

[75] The coupling plate 45 is closely coupled with the inner surface of the steel tube 10 by coupling parts 46 that are formed at a constant interval in the lengthwise direction thereof, thereby firmly attaching each of the armatures 41 to the steel tube 10. This function is as described with reference to Fig. 1.

[76] As in Fig. 1, the coupling parts 46 are formed on both sides of the coupling plate

45 at a constant interval by spot welding, riveting, stud welding or the like.

[77] The web 44 starts at the middle of the coupling plate 45 to radially inwardly extend with respect to the steel tube 10, and is cut and bent on one end thereof to form the concrete- gripping protrusions 43. This configuration is as described with reference to Fig. 1. However, the web 44 according to the second embodiment of the present invention is characterized in that it is annularly formed on the inner circumferential surface of the steel tube 10.

[78] As shown in Fig. 5, the web 44 is formed in a radial direction of the steel tube 10.

Therefore, the web 44 directly bears a load which the concrete 11 supports. The load which the web 44 bears is transmitted to the steel tube 10 through the coupling plate 45 and coupling parts. Consequently, the web 44 allows the concrete 11 and the steel tube 10, which are combined in one member, to firmly resist a load that is applied to the column.

[79] The concrete-gripping holes 42 have a circular shape, are formed on the web 44 at a constant interval and act to strengthen adhesion to the concrete 11 , which is as described with reference to Fig. 1. Further, the concrete-gripping holes 42 may be modified into various shapes such as a triangular shape, a quadrangular shape, an oval shape, a slot-like shape etc. inclusive of the circular shape shown in Fig. 2, which is as described with reference to Fig. 1.

[80] The concrete-gripping protrusions 43 are formed perpendicular to the diameter direction of the steel tube 10 by bending the end of the web 44 in alternate directions and have a quadrangular shape, which is as described with reference to Fig. 1. The concrete-gripping protrusions 43 act like a tie bar in the reinforced concrete column and increase a compressive force of the concrete 11. This function is similar to the first embodiment of the composite column according to the present invention.

[81] In Fig. 5, the concrete-gripping protrusions 43 are shown to have only the rectangular shape. However, the concrete-gripping protrusions 43 may be formed in various shapes such as a semi-circular shape, a trapezoidal shape, a triangular shape and so on.

[82] Description of configuration and action of the steel tube 10 and description of the concrete 11 are as described with reference to Fig. 1 , and thus will be omitted below.

[83] Fig. 6 is a partially cut-away perspective view of a concrete composite column according to a third exemplary embodiment of the present invention, and Fig. 7 is a cross-sectional view of a concrete composite column according to a third exemplary embodiment of the present invention.

[84] In the case of ordinary hollow concrete columns, there is an advantage of material and weight saving, but there is a disadvantage of showing a brittleness behavior caused by crushing in an inner surface of the column because the inside of the column is not restrained. For this reason, a method of inserting the steel tube 10 into a hollow space is in use.

[85] As shown in Fig. 7, four armatures 41 are attached to an outer surface and in a lengthwise direction of a steel tube 10 with each other facing in the opposite direction. Concrete 11 is poured in a space defined by the steel tube, armatures 41 and a formwork 50.

[86] As discussed with reference to Fig. 1, the armatures 41 are each composed of a coupling plate 45, a web 44, concrete-gripping holes 42, and concrete -gripping protrusions 43. However, in the composite column according to the third embodiment of the present invention, the armatures 41 are attached to the outer surface and in the lengthwise direction of the steel tube 10, as shown in Fig. 6.

[87] Since the armatures 41 are firmly attached to the outer surface of the steel tube, adhesion between the concrete poured on the outer surface of the steel tube and the steel tube is secured. Thereby, it is possible to greatly improve supporting capability as a steel tube reinforced hollow concrete column. [88] Meanwhile, the coupling plate 45, web 44, concrete-gripping holes 42, and concrete- gripping protrusions 43 are same as already described with reference to FIGS. 1 and 2, and thus their description will be omitted.

[89] Further, while only the first embodiment of the armature 41 according to the present invention is applied to the armature 41 shown in Fig. 6, the armature 41 shown in Fig. 6 may be replaced by the second embodiment of the armature 41 shown in Fig. 3 or the third embodiment of the armature 41 shown in Fig. 4 at any time. This modification can be construed as not departing from the spirit of the present invention because any person skilled in the art can easily predict the modification from the present invention.

[90] In the meantime, while it is shown in FIGS. 6 and 7 that the armatures 41 attached to the steel tube 10 are 4 in number, the number of armatures 41 can be varied within a range capable of exerting actions and effects of the present invention at any time, which is as already described above.

[91] Fig. 8 is a partially cut-away perspective view of a concrete composite column according to a fourth exemplary embodiment of the present invention.

[92] In the concrete composite column according to the fourth embodiment of the present invention, armatures 41 are each attached to an outer circumferential surface of a steel tube 10 circumferentially rather than in a lengthwise direction, and at an interval from 1.5 to 2.0 m in the lengthwise direction of the steel tube 10.

[93] A coupling plate 45 is closely coupled with the outer surface of the steel tube 10 by coupling parts 46 that are formed at a constant interval in the lengthwise direction thereof, thereby firmly attaching each of the armatures 41 to the steel tube 10. The coupling parts 46 are formed on both sides of the coupling plate 45 at a constant interval by spot welding, riveting, stud welding or the like, which is as already described above.

[94] As shown in Fig. 8, a web 44 is formed in a diameter direction of the steel tube 10.

Therefore, the web 44 directly bears a load which concrete 11 supports. The load which the web 44 bears is transmitted to the steel tube 10 through the coupling plate 45 and coupling parts 46. Thus, the web 44 allows the concrete 11 and the steel tube 10, which are combined in one member, to firmly resist a load that is applied to the column.

[95] The concrete-gripping holes 42 have a circular shape and are formed on the web 44 at a constant interval. The concrete-gripping holes 42 act to strengthen adhesion to the concrete 11. Further, the concrete-gripping holes 42 may be modified into various shapes such as a triangular shape, a quadrangular shape, an oval shape, a slot- like shape etc. inclusive of the circular shape shown in Fig. 8.

[96] Meanwhile, the concrete 11 is poured in a space defined by the steel tube 10, armatures 41 and a formwork 50 to form a steel tube reinforced hollow concrete column, and thereby the steel tube 10 restrains an inner surface of the concrete 11, which is same as described with reference to FIGS. 6 and 7.

[97] Fig. 9is a partially cut-away perspective view of a concrete composite pier according to an exemplary embodiment of the present invention.

[98] An upper steel tube 12 is bonded to the upper portion, and in a diameter direction, of a steel tube 10. The upper steel tube 12 acts to transmit a load of a bridge s upper deck to a composite column.

[99] Armatures 41 acts not only to strengthen adhesion between the upper steel tube 12 and concrete 11 but also to increase flexural and shear strength of the upper steel tube 12 when a bending moment is applied to the upper steel tube 12.

[100] Referring to Fig. 9, the upper steel tube 12 has a circular cross section, but may be modified into various cross sections such as an oval cross section, a slot-like cross section, a trapezoidal cross section, a quadrangular cross section and so on, inclusive of the circular cross section. These modifications are no more than mere design variation of the present invention, thus falling within the spirit of the present invention.

[101] The armatures 41 each correspond to any one of those shown in FIGS. 2 to 4. Thus, its components, namely concrete-gripping holes 42, concrete-gripping protrusions 43, upper flange 43 a, web 44, coupling plate 43 and coupling parts 46 will be no longer described.

[102] A joint 13 refers to a portion where the steel tube 10 and the upper steel tube 12 are bonded, and is formed by cutting out a portion of the upper steel tube 12 which comes into contact with a top surface of the steel tube 10.

[103] Since the joint 13 passes through the upper steel tube 12 in part, the steel tube 10 is connected with the inside of the upper steel tube 12. Thus, the concrete 11 can be integrally poured in the steel tube 10 and upper steel tube 12. The concrete 11 poured integrally acts to remarkably increase stiffness of the concrete composite pier according to the present invention.

[104] The steel tube 10 is bonded with the upper steel tube 12 and has the armatures 41 attached. The steel tube 10 and the upper steel tube 12 attached to the steel tube 10 have the same configuration as described above, and thus their description will be omitted.

[105] According to the foregoing, the composite column has only the circular cross section, but may be modified into various cross sections such as an oval cross section, a slot-like cross section, a quadrangular cross section, a trapezoidal cross section, and so on, inclusive of the circular cross section. These modifications are apparent to those skilled in the art, and thus being construed as falling within the scope of the present invention. Industrial Applicability According to the composite column and pier used in bridges etc., work required to arrange reinforcements can be eliminated, and an adhesive strength between the filled concrete and the steel tube can be considerably improved. Thereby, combined action of the concrete and the steel tube can be maximized and an outer appearance can be improved.

Claims

[1] A concrete composite column comprising: a steel tube; at least one armature attached to an inner surface of the steel tube in a lengthwise direction of the steel tube; and concrete poured into a space defined by the steel tube and the armature. [2] A concrete composite column comprising: a steel tube; at least one armature attached to an inner surface of the steel tube circum- ferentially; and concrete poured into a space defined by the steel tube and the armature. [3] The concrete composite column as set forth in claim 1 or 2, wherein the armature includes: a coupling plate formed with at least one coupling part; a web formed perpendicular to the coupling plate in the middle of the coupling plate and having at least one concrete- gripping hole; and at least one concrete-gripping protrusion formed on an upper end of the web by cutting the upper end into wings and alternately bending the wings in opposite directions. [4] The concrete composite column as set forth in claim 1 or 2, wherein the armature includes: a coupling plate formed with at least one coupling part; a web formed perpendicular to the coupling plate in the middle of the coupling plate and having at least one concrete- gripping hole; and an upper flange formed perpendicular to the web. [5] The concrete composite column as set forth in claim 1 or 2, wherein the armature includes: a coupling plate formed with at least one coupling part; and a web formed perpendicular to the coupling plate and having at least one concrete-gripping hole. [6] A concrete composite pier comprising: a steel tube; at least one armature attached to an inner surface of the steel tube in a lengthwise direction of the steel tube; an upper steel tube bonded to an upper portion of the steel tube and extending in a direction perpendicular to the steel tube, having the armature attached to an inner surface thereof and filled with concrete integrally; and a joint at which the steel tube and the upper steel tube are bonded. [7] A concrete composite pier comprising: a steel tube; at least one armature attached to an inner surface of the steel tube circum- ferentially; an upper steel tube bonded to an upper portion of the steel tube and extending in a direction perpendicular to the steel tube, having the armature attached to an inner surface thereof and filled with concrete integrally; and a joint at which the steel tube and the upper steel tube are bonded. [8] The concrete composite pier as set forth in claim 6 or 7, wherein the armature includes: a coupling plate formed with at least one coupling part; a web formed perpendicular to the coupling plate in the middle of the coupling plate and having at least one concrete- gripping hole; and at least one concrete-gripping protrusion formed on an upper end of the web by cutting the upper end into wings and alternately bending the wings in opposite directions. [9] The concrete composite pier as set forth in claim 6 or 7, wherein the armature includes: a coupling plate formed with at least one coupling part; a web formed perpendicular to the coupling plate in the middle of the coupling plate and having at least one concrete- gripping hole; and an upper flange formed perpendicular to the web. [10] The concrete composite pier as set forth in claim 6 or 7, wherein the armature includes: a coupling plate formed with at least one coupling part; and a web formed perpendicular to the coupling plate and having at least one concrete-gripping hole. [11] The concrete composite pier as set forth in claim 6 or 7, wherein the upper steel tube has a circular, ovular, slot-like, trapezoidal, or quadrangular cross-section. [12] A concrete composite column comprising: a steel tube; at least one armature attached to an outer surface of the steel tube in a lengthwise direction of the steel tube; and concrete poured into a space defined by the outer surface of the steel tube and the armature. [13] Aconcrete composite column comprising: a steel tube; at least one armature attached to an outer surface of the steel tube circum- ferentially; and concrete poured into a space defined by the outer surface of the steel tube and the armature. [14] The concrete composite column as set forth in claim 12 or 13, wherein the armature includes: a coupling plate formed with at least one coupling part; a web formed perpendicular to the coupling plate in the middle of the coupling plate and having at least one concrete- gripping hole; and at least one concrete-gripping protrusion formed on an upper end of the web by cutting the upper end into wings and alternately bending the wings in opposite directions. [15] The concrete composite column as set forth in claim 12 or 13, wherein the armature includes: a coupling plate formed with at least one coupling part; a web formed perpendicular to the coupling plate in the middle of the coupling plate and having at least one concrete- gripping hole; and an upper flange formed perpendicular to the web. [16] The concrete composite column as set forth in claim 12 or 13, wherein the armature includes: a coupling plate formed with at least one coupling part; and a web formed perpendicular to the coupling plate and having at least one concrete-gripping hole.