KR102565144B1 - Steel girder structure having restoring force - Google Patents

Abstract

A steel girder structure is disclosed, wherein the steel girder structure includes a first support portion on one side in the longitudinal direction, a second support portion on the other side in the longitudinal direction, and a middle portion connecting the first support portion and the second support portion. wealth; A saddle part extending in the longitudinal direction from the inside or outside of the steel girder part, one end in the longitudinal direction and the other end in the longitudinal direction being fixed to the first support part and the second support part, and a middle part provided in the middle part. Including a steel wire disposed to pass through, wherein the steel wire is elastically tensioned in response to a load applied thereto in a state in which the rest except for the longitudinal end, the other longitudinal end, and the middle portion are not constrained to the steel girder part Alternatively, it is provided to be elastically restored, and the steel girder part is provided so that the middle part of the steel wire is fixed to a saddle part located at a height equal to or less than the fixed height of one end in the longitudinal direction and the other end in the longitudinal direction.

Description

Steel girder structure with restoring force {STEEL GIRDER STRUCTURE HAVING RESTORING FORCE}

The present invention relates to a steel girder structure having restoring force.

In the existing steel bridge, the steel girder bears the load of the slab and the weight of the steel, and when the slabs are connected, the composite cross section resists the live load.

In PSC concrete bridges, the steel wire acts integrally with the concrete girder to resist dead weight and live load.

However, compared to existing structures in which the steel wire acts integrally with the concrete girder, the girder structure can more effectively resist the load applied during the construction process or during common use, thereby reducing the amount of steel required for the girder. The need for improvement has been increasing in recent years.

The background technology of the present application is published in Korean Patent Publication No. 10-2016-0068107.

The present invention is to solve the problems of the prior art described above, and an object of the present invention is to provide a steel girder structure having restoring force so as to be able to resist loads more efficiently than the prior art.

However, the technical problem to be achieved by the embodiments of the present application is not limited to the above technical problems, and other technical problems may exist.

As a technical means for achieving the above technical problem, the steel girder structure according to the first aspect of the present application, the first support portion on one side in the longitudinal direction, the second support portion on the other side in the longitudinal direction, and the first support portion and the first support portion A steel girder part including an intermediate part connecting two support parts; A saddle part extending in the longitudinal direction from the inside or outside of the steel girder part, one end in the longitudinal direction and the other end in the longitudinal direction being fixed to the first support part and the second support part, and a middle part provided in the middle part. Including a steel wire disposed to pass through, wherein the steel wire is elastically tensioned in response to a load applied thereto in a state in which the rest except for the longitudinal end, the other longitudinal end, and the middle portion are not constrained to the steel girder part Alternatively, it is provided to be elastically restored, and the steel girder part may be provided so that the middle part of the steel wire is fixed to a saddle part located at a height equal to or less than a fixed height of one end in the longitudinal direction and the other end in the longitudinal direction.

The above-described problem solving means are merely exemplary and should not be construed as intended to limit the present disclosure. In addition to the exemplary embodiments described above, additional embodiments may exist in the drawings and detailed description of the invention.

According to the above-mentioned problem solving means of the present application, one end in the longitudinal direction of the steel wire, the other end in the longitudinal direction and the middle portion are restrained, and the unconstrained part of the steel wire can move freely, so that the steel wire elastically stretches in response to the load acting thereon. Alternatively, it can be elastically restored, so it can serve as a reinforcing member, and thus, the amount of steel in the steel girder structure can be reduced.

1 is a schematic longitudinal cross-sectional view of a steel girder structure according to an embodiment of the present invention.
2 is a schematic longitudinal conceptual cross-sectional view of a steel girder structure according to an embodiment of the present application in which a slab is formed.
3 is a schematic longitudinal conceptual cross-sectional view of a steel girder structure according to an embodiment of the present application in which a slab to which a live load is applied is formed.
4 is a conceptual diagram illustrating the positive moment due to the self-weight and external force of the steel girder structure according to an embodiment of the present invention.
5 is a conceptual diagram illustrating a negative moment by a steel wire of a steel girder structure according to an embodiment of the present invention.
6 is a schematic longitudinal conceptual cross-sectional view of a steel girder structure according to an embodiment of the present application in which two middle portions of steel wires are formed.
7 is a schematic conceptual side view of a saddle unit of a steel girder structure according to an embodiment of the present disclosure.
8 is a cross-sectional view AA of FIG. 7 .

Hereinafter, embodiments of the present application will be described in detail so that those skilled in the art can easily practice with reference to the accompanying drawings. However, the present disclosure may be implemented in many different forms and is not limited to the embodiments described herein. And in order to clearly describe the present application in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout this specification, when a part is said to be "connected" to another part, this includes not only the case of being "directly connected" but also the case of being "electrically connected" with another element in between. do.

Throughout the present specification, when a member is referred to as being “on,” “above,” “on top of,” “below,” “below,” or “below” another member, this means that a member is located in relation to another member. This includes not only the case of contact but also the case of another member between the two members.

Throughout the present specification, when a part "includes" a certain component, it means that it may further include other components without excluding other components unless otherwise stated.

For reference, terms related to direction or position (upper side, upper side, lower side, lower side, longitudinal direction, horizontal direction, etc.) in the description of the embodiments of the present application are set based on the arrangement state of each component shown in the drawings. For example, when looking at Figure 1, the 12 o'clock direction is generally the upper side, the generally 12 o'clock direction is the upper part, the 6 o'clock direction is generally the lower side, the 6 o'clock direction is the lower part, and the 9 o'clock- The 3 o'clock direction can be the transverse direction, etc. Also, referring to FIG. 3 , the 9 o'clock - 3 o'clock direction may be a longitudinal direction.

The present invention relates to a steel girder structure having restoring force.

Hereinafter, a steel girder structure (hereinafter referred to as 'this steel girder structure') having restoring force according to an embodiment of the present application will be described.

1 is a schematic longitudinal cross-sectional view of a steel girder structure according to an embodiment of the present invention.

Referring to FIG. 1, the present steel girder structure includes a steel girder portion 1. The steel girder part 1 may be a steel girder type. For example, the steel girder part 1 may be a box-type girder having a hollow part or an I-shaped girder having no hollow part, but is not limited thereto, and various girder shapes may be applied to the steel girder part 1 of the present application. there is.

The steel girder part 1 includes a first support part 11 on one side in the longitudinal direction, a second support part 12 on the other side in the longitudinal direction, and an intermediate part 13 connecting the first support part and the second support part. . The first support portion may be one side of the steel girder portion 1 in the longitudinal direction, and the second support portion 12 may be the other side portion of the steel girder portion 2 in the longitudinal direction. Also, for example, each of the first support portion 11 and the second support portion 12 may be a portion supported by the support portion. Since the branch portion is obvious to those skilled in the art, a detailed description thereof will be omitted.

In addition, referring to FIG. 1, the present steel girder structure includes a steel wire (2). The steel wire 2 is disposed extending in the longitudinal direction from the inside or outside of the steel girder part 1. For example, when the steel girder part 1 is a bar-type girder, the steel wire 2 may extend in the longitudinal direction in the hollow of the steel girder part 1. In addition, when the steel girder part 1 is I-shaped, it may extend from the outside of the steel girder part 1 along the longitudinal direction.

In addition, one end of the steel wire 2 in the longitudinal direction and the other end in the longitudinal direction are fixed to the first support portion and the second support portion, respectively, and the middle portion is disposed so as to pass through the saddle portion 3 provided in the middle portion 13. . In addition, the steel girder part 1 is provided so that the middle part of the steel wire 2 is fixed to the saddle part located at a height below the fixed height of one longitudinal end and the other longitudinal end. In other words, each of the longitudinal end and the other longitudinal end of the steel wire 2 may be fixed to the steel girder part 2 at a height higher than the middle portion.

In addition, referring to FIG. 1, the steel wire 2 has one end in the longitudinal direction, the other end in the longitudinal direction, and the rest of the portion except for the middle portion in a state in which it is not constrained to the steel girder portion 1, and in response to the load applied thereto, elastic tension or It may be provided to be elastically restored. In other words, the steel wire 2 resists the load with the free movement of the unconstrained part, and when the load is removed, it can be restored with elastic restoration (the stage before the load is applied), and this steel wire 2 serves as a reinforcing member. can do.

The behavior of the steel wire 2 for each load application stage (circumstance) may be described as follows.

First, referring to FIG. 1, when manufacturing this steel girder structure, a steel wire 2 is arranged, and the steel wire 2 can be tensioned through structural analysis at the time of design. For example, the steel wire 2 can be tensioned to a minimum except for the tension required for the load-bearing situation described below. According to this tension, the steel wire 2 has an initial tensile force ( ) can have. That is, the initial tensile force of the steel wire 2 may be set to a level at which tension is applied so that the steel wire 2 can maintain tension without loosening.

2 is a schematic longitudinal conceptual cross-sectional view of a steel girder structure according to an embodiment of the present application in which a slab is formed, and FIG. 3 is a schematic longitudinal direction of a steel girder structure according to an embodiment of the present application in which a slab to which a live load is applied is formed A conceptual cross-sectional view, Figure 4 is a conceptual diagram illustrating the positive moment due to the self-weight and external force of the steel girder structure according to an embodiment of the present application, Figure 5 is a negative moment due to the steel wire of the steel girder structure according to an embodiment of the present application A conceptual diagram illustrating this

Referring to FIG. 2, the steel wire 2 is elastically stretched in response to the load before slab synthesis generated in the process of constructing the slab 4 on the steel girder part 1, and the load before slab synthesis Tension resisting with the first elastic restoring force may be possibly provided for at least a portion. For example, in the process of constructing the slab 4, a load may be applied to the steel girder part 1 by concrete being poured. can be Since the load before slab synthesis occurs during the construction of the slab 4, the steel wire 2 can be elastically stretched in response to the load before slab synthesis, and the upward force (first elastic restoring force) due to the tensile force of the steel wire 2 is As a result, the bending moment may be reduced.

Referring to the steel girder part (1) in which displacement occurs shown by the dotted line in FIG. 2, displacement may occur in the steel girder part (1) according to the action of the bending moment. By serving as a member, the displacement of the steel girder part 1 can be reduced compared to the case where there is no steel wire 2.

To this end, the steel wire 2 has an initial tensile force smaller than the first elastic restoring force (before the load before the slab composition is applied) ) can be provided in a tensed state by That is, as described above, the steel wire 2 may be tensioned after being placed in the manufacture of the present steel girder structure. At this time, the steel wire 2 has an initial tensile force ( ) can be tensioned so that it is smaller than the first elastic restoring force.

In addition, referring to FIGS. 2 and 3 together, when the slab 4 is synthesized, the load acting on the steel girder portion 1 is greater than before the construction of the slab 4, but can be reduced compared to the load before the slab 4 is synthesized. Correspondingly, the steel wire 2 is elastically restored compared to the construction process of the slab 4, but may have a state in which it is elastically tensioned compared to before the construction of the slab 4, and accordingly, a small restoring force compared to the first elastic restoring force ( ) can be resisted. That is, the elastic restoring force after synthesizing the slab may be equal to or less than the aforementioned first elastic restoring force.

In addition, referring to FIG. 3, the steel wire 2 is elastically stretched in response to the live load applied after the slab 4 is synthesized on the steel girder portion 1, and the second elastic restoring force ( ), the resistive tension can possibly be provided. After the slab 4 is synthesized, when a live load is applied, the steel wire 2 can be additionally elastically stretched in response to the live load, and the upward force due to the tensile force of the steel wire 2 ( ) (second elastic restoring force) may be generated to reduce the bending moment. At this time, when the live load does not act after the slab 4 is synthesized, the steel wire 2 has the aforementioned initial tensile force ( ), the resilience corresponding to ( ) and resilience after slab synthesis ( ), and when a live load acts, the steel wire 2 has the aforementioned initial tensile force ( ), the resilience corresponding to ( ) and resilience after slab synthesis ( ) In addition to the second elastic restoring force ( ) can be resisted. In this way, by the steel wire (2) serving as a reinforcing member to reduce the bending moment, the displacement of the steel girder portion (1) can be reduced compared to the case without the steel wire (2). In addition, when the live load is removed, the tensile force is restored and the steel wire 2 is in a state where the live load is removed (initial tensile force ( ), the resilience corresponding to ( ) and resilience after slab synthesis ( ) can have a resistive state).

In summary, referring to FIG. 4, a positive moment can be applied to this girder structure by its own weight and an external force. Referring to FIG. 5, the elastic restoring force acted by the steel wire 2 generates a negative moment, The bending moment of the structure can be reduced. For example, a load before slab synthesis may act on the girder structure seen in the construction process of the slab (4). In contrast, the steel wire (2) may act as a first elastic restoring force while being elastically stretched in response to the load before slab synthesis, , After the slab 4 is synthesized, the restoring force after synthesizing the slab ( ), the bending moment of the girder structure is reduced by additional elastic resistance to the load by the slab (4) synthesized, and the second elastic restoring force ( ), it is possible to reduce the bending moment of this girder structure at each stage of construction and use by additional elastic resistance to live load.

At this time, the steel wire 2 is in tension with respect to the load before slab synthesis and the load applied after slab synthesis (load of slab 4, live load, etc.) are applied (that is, the maximum load applied during construction or during use). It is preferable to be provided with a material and standard that can maintain elasticity even when it is worn.

Conventionally, the steel wire is integrated into the girder by arranging the steel wire in the sheath pipe and tensing and grouting the steel wire, but as described above, in the present steel girder structure, the steel wire 2 can act as a reinforcing member that behaves. At this time, since the steel wire 2 is not disposed in the sheath pipe unlike the prior art, it may be referred to as a steel wire protruding outside.

Specifically, the present steel girder structure includes a structure in which externally protruding steel wires installed inside the girder are placed on the steel girder part (1) to resist the load with the free movement of the steel wire (2) and restore to the previous step when the load is removed. can do. In this way, the steel wire 2 protruding outside behaves separately from the steel girder part 1 in each load case (step), so the present steel girder structure considers the efficiency for each load case. can reduce the bending moment of

In this way, since the steel wire 2 serves as a reinforcing member, other reinforcing members can be reduced. Specifically, due to the effect of the steel wire 2 being restored, the amount of steel of the present steel girder structure may be reduced compared to the prior art. In addition, safety can be excellent because the steel wire 2 is restored to a previous state out of a temporary stress state when an overloaded vehicle passes.

6 is a schematic longitudinal conceptual cross-sectional view of a steel girder structure according to an embodiment of the present application in which two middle portions of steel wires are formed.

Referring to FIG. 1 , the saddle unit 3 may include one saddle unit 31 or, referring to FIG. 6 , may include a plurality of saddle units 31 disposed at intervals along the longitudinal direction. . Accordingly, one or more middle portions of the steel wire 2 may be formed corresponding to one saddle unit 31 or a plurality of saddle units 31 .

For example, the saddle unit 31 may be formed such that the steel wire 2 is extended and disposed in a symmetrical form based on an intermediate point in the longitudinal direction of the steel wire 2 (eg, a central point or a predetermined specific point). . For example, when the number of saddle units 31 is odd, one saddle unit 31 is provided at an intermediate point in the longitudinal direction, and the other saddle units 31 are symmetrically arranged in pairs based on the one saddle unit 31. can In addition, when the number of saddle units 31 is even, the even number of saddle units 31 may be symmetrically arranged in pairs with respect to an intermediate point in the longitudinal direction.

The saddle unit 31 may be provided in the form of anchoring saddles to limit the longitudinal movement of the steel wire 2 of the middle portion of the steel wire 2 corresponding thereto. If the saddle unit 31 does not restrict the longitudinal movement of the steel wire 2 in the middle of the steel wire 2, the restoring force of the steel wire 2 is due to the nature of the free movement of parts other than the fixed part of the steel wire 2 this may be smaller. Considering this point, in the present steel girder structure, the saddle unit 31 may be provided in the form of anchoring saddles.

7 is a schematic conceptual side view of a saddle unit of a steel girder structure according to an embodiment of the present disclosure, and FIG. 8 is an A-A cross-sectional view of FIG.

Referring to FIGS. 7 and 8 , the saddle unit 31 may include a fixing unit 311 . The fixing unit 311 includes a lower unit 3112 surrounding the lower circumference of the middle portion, an upper unit 3111 wrapping the upper circumference of the middle portion, and a coupling unit combining the lower unit 3112 and the upper unit 3111 ( 3113) may be included. The fixing part 311 has a structure that firmly binds the steel wires 2, and the upper unit 3111 and the lower unit 3112 coupled by the coupling unit 3113 can grip the middle portion. Also, the coupling unit 3113 may be a bolt. Accordingly, each of the upper unit 3111 and the lower unit 3112 may be bolted to the coupling unit 3113.

In addition, the saddle unit 31 may include a first movement limiting support member 312 . The first movement limiting support member 312 is provided with a first hole to allow the passage of the steel wire 2 extending from the middle portion to one side in the longitudinal direction, but restricting the movement of the fixing unit 311 to one side in the longitudinal direction. It can be. The first movement limiting support member 312 may protrude upward from the lower surface of the steel girder part 1. In addition, the first movement limiting support member 312 may be fixed to the steel girder part 1 by welding.

Also, the settlement birds may include a second movement limiting support member 313 . The second movement limiting support member 312 is formed with a second hole to allow the passage of the steel wire 2 extending from the middle portion to the other side in the longitudinal direction, but is provided to limit the movement of the fixing unit 311 to the other side in the longitudinal direction. It can be. The second movement limiting support member 313 may protrude upward from the lower surface of the steel girder part 1. In addition, the second movement limiting support member 313 may be fixed to the steel girder part 1 by welding.

Also, the fixing unit 311 may be fixed to at least one of the first movement limiting support member 312 and the second movement limiting support member 313 . Accordingly, the middle portion of the steel wire 2 can be fixed in position.

In addition, each of the upper unit 3111 and the lower unit 3112 has extension members 31111 and 31121 extending outward in the circumferential direction to increase the opposing area to the circumference of the first hole and the circumference of the second hole, respectively, on both sides in the longitudinal direction. can be formed in Accordingly, the contact area of the upper unit 3111 and the lower unit 3112 with respect to the first movement limiting support member 312 and the second movement limiting support member 313, respectively, can be improved, and the upper unit 3111 ) And the lower unit 3112, each of the extension members 31111 and 31121 and the first movement limiting support member 312 and the second movement limiting support member 313 welded to the steel girder portion 1, respectively. The contact surface (support surface) of the movement limiting support member 312 and the second movement limiting support member 313 may resist.

In addition, in a state where the coupling unit 3113 is not installed, a gap may be formed between the lower unit 3112 and the upper unit 3111 disposed corresponding to the middle portion. Also, the coupling unit 3113 may mutually pull-couple the lower unit 3112 and the upper unit 3111 so that a final gap s narrower than the gap is formed. In addition, the fixing part 311 can be fixed to the middle part by the gripping force applied to the middle part by the pulling connection within the range of the applied load considering the pre-composite load and the live load of the slab 4 . If the lower unit 3112 and the upper unit 3111 are bonded to each other without forming a gap, the gripping force of the fixing unit 311 on the steel wire 2 may be weakened according to the behavior of the steel wire 2. . Considering this point, in the present steel girder structure, the lower unit 3112 and the upper unit 3111 can be mutually pulled together so that the final gap s is formed, and the unfixed part of the steel wire 2 The middle part of the steel wire 2 can maintain a state of being gripped by the fixing part 311 despite the behavior of the remaining parts except for it. That is, the fixing part 311 can have a final gap s so that the steel wire 2 can be securely fixed to the fixing part 311 when the bolt (coupling unit 3113) is fastened.

In addition, referring to FIG. 7, in the middle portion of the steel wire 2, a steel wire protection tube 29 is provided between the fixing part 311 so that the upper unit 3111 and the lower unit 3112 are in direct contact with respect to the outer circumference thereof. Unplaced, the steel wire protection tube 29 may be provided to surround the outer circumference of the steel wire 2 at least in some sections of the remaining parts except for the middle part. If the steel wire protection tube 29 is also disposed in the middle portion, the upper unit 3111 and the lower unit 3112 do not directly contact the middle portion of the steel wire 2, but are in contact with the steel wire protection tube 29, The middle part of the steel wire 2 may be moved (slipping, etc.) in the length direction of the steel wire 2 in the steel wire protection tube 29. Considering this point, in this steel girder structure, the steel wire protection tube 29 is not disposed in the middle part of the steel wire 2, so that the upper unit 3111 and the lower unit 3112 are in the middle part of the steel wire 2 The steel wire 2 can be securely fixed to the fixing part 311 by being in direct contact with.

In addition, according to the foregoing, the fixing unit 311 can be dismantled by disengaging the coupling unit 3113, and the steel wire 2 is not fixed in a manner in which conventional steel wires are fixed to the sheath pipe by grouting, etc. Since it is provided in a protruding form, replacement of the steel wire 2 is easily possible. Accordingly, in the present steel girder structure, the steel wire 2 may have the advantage of easy maintenance compared to other reinforcing members while serving as a reinforcing member.

When sliding occurs with respect to the saddle unit 31 while the steel wire 2 moves freely, the restoring force of the steel wire 2 may be reduced. According to the saddle unit 31 described above, slipping of the steel wire 2 relative to the saddle unit 31 can be prevented, and the restoring force can be increased by about 10%. That is, according to the saddle unit 31 described above, the restoring force of the steel wire 2 can be increased.

Meanwhile, according to the present disclosure, a bridge superstructure or bridge including the present steel girder structure may be provided. Such a bridge superstructure or bridge may be provided in various forms including configurations known to those skilled in the art or configurations developed in the future. For example, a bridge superstructure according to an embodiment of the present application may include a present steel girder structure and a slab portion disposed on the present steel girder structure. In addition, it goes without saying that the bridge superstructure may include various auxiliary facilities required for the bridge superstructure, a pavement layer, an expansion joint structure, a drainage structure, and the like, as necessary.

In addition, according to the present application, a method of constructing an upper part of a bridge applying (using) the present steel girder structure may also be provided. For example, in the bridge upper construction method according to an embodiment of the present application, the first step of arranging the present steel girder structure on the lower bridge structure (at this time, the steel wire 2 is in a tense state in response to the initial tensile force) and the present A second step of constructing a slab on the steel girder structure (at this time, the steel wire 2 is additionally tensioned by the first elastic restoring force before slab synthesis, and additionally tensioned by the corresponding elastic restoring force after slab synthesis after slab synthesis). can do. Since such a bridge construction method (process) is obvious to those skilled in the art, a detailed description thereof will be omitted.

The above description of the present application is for illustrative purposes, and those skilled in the art will understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present application. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present application is indicated by the following claims rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts thereof should be construed as being included in the scope of the present application.

1: steel girder
11: first support part
12: second support part
13: middle part
2: liner
29: steel wire protection tube
3: saddle part
31: saddle unit
311: fixing unit
3111: upper unit
3112: lower unit
3113: combined unit
312: first movement limiting support member
313: second movement limiting support member

Claims (8)

In the steel girder structure,
A steel girder portion including a first support portion on one side in the longitudinal direction, a second support portion on the other side in the longitudinal direction, and an intermediate portion connecting the first support portion and the second support portion;
A saddle part extending in the longitudinal direction from the inside or outside of the steel girder part, one end in the longitudinal direction and the other end in the longitudinal direction being fixed to the first support part and the second support part, and a middle part provided in the middle part. Including a steel wire disposed to pass through,
In the steel wire, one end in the longitudinal direction, the other end in the longitudinal direction, and the remainder except for the middle portion are elastically stretched or elastically restored in response to a load applied to the steel girder in a state in which they are not constrained to the steel girder portion,
The steel girder part is provided so that the middle part of the steel wire is fixed to the saddle part located at a height equal to or less than the fixed height of one end in the longitudinal direction and the other end in the longitudinal direction,
The steel wire,
It is provided in a tense state by the initial tensile force before the load before the slab synthesis that occurs in the process of constructing the slab on the steel girder is applied,
When the load before the slab synthesis is applied, it is tensed to resist at least a part of the load before the slab synthesis with the first elastic restoring force, and when the slab is synthesized on the steel girder part and the load is applied after the slab synthesis, the load after the slab synthesis is applied. For at least a portion of the first elastic restoring force, instead of the first elastic restoring force, it is provided with tension to resist with a restoring force after synthesizing a small slab compared to the first elastic restoring force,
After the slab is synthesized, when a live load is applied, tension resisting with a second elastic restoring force is provided to at least a part of the live load,
The initial tensile force is set smaller than the first elastic restoring force,
With the steel wire, the steel girder structure resists with a restoring force corresponding to the initial tensile force and a restoring force after the slab composite when the live load is not acting, based on after the slab synthesis, and the initial tensile force when the live load is applied. It is reinforced to resist the corresponding restoring force, the restoring force after the slab synthesis and the second elastic restoring force,
The saddle part includes one saddle unit or a plurality of saddle units disposed at intervals along the longitudinal direction,
One or more middle portions of the steel wire are formed corresponding to the one saddle unit or the plurality of saddle units,
The steel girder structure, wherein the saddle unit is provided in the form of anchoring saddles to limit movement of the steel wire in the longitudinal direction of the middle portion of the steel wire corresponding thereto. delete delete delete delete According to claim 1,
The saddle unit,
a fixing unit including a lower unit surrounding the lower circumference of the middle portion, an upper unit surrounding the upper circumference of the middle portion, and a coupling unit coupling the lower unit and the upper unit to each other;
a first movement-restricting support member having a first hole formed to allow passage of a steel wire extending from the middle portion in one longitudinal direction and limiting movement of the fixing unit in one longitudinal direction; and
A second hole is formed to allow passage of the steel wire extending from the middle portion to the other side in the longitudinal direction and includes a second movement limiting support member provided to limit the movement of the fixing unit to the other side in the longitudinal direction. struct. According to claim 6,
Each of the upper unit and the lower unit,
The steel girder structure, wherein expansion members extending outward to the circumference are formed on both sides in the longitudinal direction so as to increase the opposing area to the circumference of the first hole and the circumference of the second hole. According to claim 6,
In a state where the coupling unit is not installed, a gap is formed between the lower unit and the upper unit disposed corresponding to the middle portion,
The coupling unit mutually pulls the lower unit and the upper unit so that a final gap narrower than the gap is formed,
The steel girder structure, wherein the fixing part is fixed to the middle part by the gripping force applied to the middle part by the pulling coupling within the applied load range considering the slab composite pre-load and live load.

Images