KR20120109807A

KR20120109807A - Structural reinforcement of chord members in truss system to enhance load-carrying capacity against flexural stress resultants at supports and fabrication method of it

Info

Publication number: KR20120109807A
Application number: KR1020110027404A
Authority: KR
Inventors: 최하정
Original assignee: 최하정
Priority date: 2011-03-28
Filing date: 2011-03-28
Publication date: 2012-10-09

Abstract

PURPOSE: A reinforcement structure of upper and lower chord members and diagonal members of a truss for improving resistance to bending moment and a manufacturing method thereof are provided to cost-efficiently construct a truss bridge. CONSTITUTION: A reinforcement structure of upper and lower chord members and diagonal members of a truss for improving resistance to bending moment is comprised as follows. I-beams are inserted into upper and lower chord members of pipes of a pipe truss bridge structure. Support plates are installed on both ends of a steel form, and the steel form is filled with concrete. The upper and lower chord members, the steel form, and the filled concrete are integrated to improve resistance to bending moment.

Description

Structural reinforcement of chord members in truss system to enhance load-carrying capacity against flexural stress resultants at supports and fabrication method of it}

The present invention relates to a truss upper and lower chord and a reinforcing structure of the yarn which have improved the load bearing capacity against the moment cross-sectional force generated in the point portion. The shaft is inserted into some sections between sections or nodes, and filled the interior of the currents such as upper chords, lower chords and sand yarns with concrete so that the present and internal filled concrete consisting of pipe sections and the rigid members inserted into the currents act integrally. The present invention relates to a cross-sectional reinforcement method that dramatically increases the rigidity and strength of moment cross-sectional force as well as directional cross-sectional force.

By reinforcing the upper and lower chords and yarns with internal rigid members as well as concrete, the upper and lower chords reduce the bending deformation against external forces, including their own weight, thereby reducing the deflection and vibration of the middle section of the bridge and improving the usability of the structure. In this regard, the stress concentration at the front end and the heel of the end is reduced, thereby improving the endothelial performance.

The truss bridge is a axial force in which the major cross-sectional force generated in the member generates the same stress throughout the cross section in a structural form in which the current is arranged in the form of a triangle to transmit the member force through the node located at the vertex of the triangle to resist external force. Therefore, structural efficiency is superior to other structural forms.

In the early truss structure, the member connection at the node adopts the hinge connection method by the fin structure so that the bending moment does not occur in the current truss structure, but the pin structure is found to be very vulnerable to fatigue, Node connection method adopts steel structure by bolt connection or welding connection.

As such, the moment cross-sectional force is generated in the truss members by various causes by rigidly connecting the members at the nodes. The causes of moment cross-sectional force can be classified into three main reasons.

First, as shown in Figure 1, the cross-sectional moment due to external force and self-weight acting on the truss current other than the node,

Second, as shown in Fig. 2, the center line of the member does not act on the center of the node, so that the eccentricity (e) occurs due to the sectional moment,

Third, as shown in Fig. 3, it can be roughly classified into a cross-sectional moment generated by the force moment due to the axial cross-sectional force of the up-and-down chord not coinciding with the resistance moment due to the external force.

The cross-sectional moment due to the eccentricity (e) between the cross-sectional moment due to the external force acting on the truss current and the cross-sectional force at the node is not significant in size and great attention is given to the cross-sectional design of the truss current if the designer pays close attention to minimize the influence. It is possible to limit so as not to affect.

However, since the size of the section moment caused by the third reason is remarkably generated at the point, the design of the cross section is negligible when neglecting the cross section and it may cause problems such as lack of cross section load capacity during common use.

Fig. 3a shows the axial force cross-sectional force generated in the upper and lower chords due to dead load in a two span continuous truss structure having two end points and one internal point, and Fig. 3b is equivalent to the truss structure. As shown in the truss girder, the equivalent moment force of the truss girder generated by the axial sectional force generated by the upper chord and the lower chord is shown in FIG. 3c of the actual girder having the same span configuration and the same dead weight as the truss structure. The resistance moments are shown respectively.

3b and 3c overlap with each other, as shown in FIG. 3d, a portion where the moments do not coincide is generated, and this shaded portion is generated as a bending moment in the upper chord, the lower chord, the yarn and the vertical. The size of the truss structure varies depending on the shape of the member arrangement and the interplanar configuration and the bending rigidity of each member.

Fig. 3E shows the bending moment occurring in the upper chord and the bottom chord, and Fig. 3F shows the bending moment occurring in the yarn. As shown in FIGS. 3E and 3F, the bending moment occurring in the truss current is small in the middle portion of the truss but increases in size at the point.

Even though the current constituting the actual truss is connected to the steel structure, the cross section stress due to the bending moment is small enough for the center part of the trunk to be designed considering the axial cross-sectional force in consideration of the axial section force when designing the truss structure. The stress due to the bending moment generated in the member by the moment corresponds to the stress due to the axial cross-sectional force or exceeds the bending stress, so the moment cross-sectional force becomes the main cross-sectional force of the design along with the axial cross-sectional force.

In particular, the bending moment generated at the present point is significantly increased in size as the length of the ground increases, resulting in an uneconomical design due to the increase of steel required for the cross section.

In addition, the rotational displacement generated by the moment moment force of the point portion increases the deflection of the center portion of the ground and impairs usability, which is a major cause of the long span of the pipe truss bridge.

Figure 4a shows the deflection due to dead weight in a two-span continuous truss structure, as shown in Figure 4b which enlarges the inner point portion of Figure 4a, the rotational displacement due to the bending moment in the upper and lower chords It can be seen that it is the main factor that increases the deflection of the center part.

There is an attempt to increase the stiffness and strength by filling concrete inside the pipe section, but by filling concrete inside the cross section of the lower chord or upper chord section between the bridges, the self weight of the middle section is increased excessively and the bending moment is In the case of large occurrence of the tensile stress due to the bending moment in the member as shown in Figure 5 due to the lack of bending strength of the current cross-section.

In this case, due to the characteristics of concrete materials that have little resistance to tensile stress, cracks are generated in the concrete filling section inside the pipe section, and the flexural tensile stress generated at the present point is caused by the alternating stress caused by the moving load and wind load caused by the vehicle. When the tensile stress changes, the cracks in the concrete filling section gradually increase, making it difficult to achieve the intended purpose of reinforcing the stiffness and strength of the concrete.

Another technical problem that arises in the construction of pipe truss bridges is the stress concentration at the front end and the heel of the end of the sand at the weld joint where the sand and the upper or lower chords meet, and the stress concentration at the end of the sand decreases the fatigue resistance and reduces the reliability of the structure as a whole. In addition, it is pointed out that the variable stress due to the moving load and the wind load of the bridge is the main cause of shortening the service life.

Fig. 6 shows the change in size from the front to the heel of the yarn end for the stress caused by the axial cross-sectional force and the bending moment at the node adjacent to the inner point. In general, even if the thickness of the material is increased so that the stress of the material except the end is within the allowable stress, the front and heel of the end often exceed the allowable stress, and stress concentration of the front and heel is difficult to avoid even if the thickness of the material is increased. .

Figure 7a illustrates the stress distribution in the sand and lower chords or between the sand and the top chords through numerical analysis program, and Figure 7b shows the stress and the stress at the end of the sand in the pipe truss structure. This is an example of an overseas case where fatigue failure was observed.

Thus, as described above, the present invention has been made to solve various problems in the related art. The first object of the present invention is to provide rigidity and strength in the point load chord and inside of the truss structure where the bending moment is largely generated in the member. By inserting additional members and filling the inside of the members with concrete, all the cross-sectional forces generated in the members such as bending moments, bending moments, etc. To provide a method to increase the cross-sectional stiffness and cross-sectional strength economically and efficiently without increasing the size of the upper and lower chords and materials throughout the entire section of the structure,

The second object of the present invention is to reduce the deflection and vibration of the middle section of the trunk by reducing the point rotational displacement caused by the point bending moment in the upper chord and the lower chord through reinforcement of section stiffness, thereby increasing the usability of the long span truss bridge. To make it happen,

The third object of the present invention is to distribute the stress at the end of the sand through the steel and the filling concrete which is additionally installed inside the sand, thereby reducing the stress concentration occurring at the front and heel of the end of the sand by the axial cross-sectional force and bending moment. It is greatly reduced to improve the structural reliability of the pipe truss structure and to improve the fatigue resistance to extend the service life.

The reinforcement of the truss structure upper chord and lower chord which has improved resistance to the bending moment of the point of the present invention is divided into the case where the axial cross-sectional force of tension occurs and the axial cross-sectional force of compression occurs.

The up and down current section in which the axial cross-sectional force of compression occurs is the inner point lower current section and the up and down current section in the end point. The load current section is applicable.

The reinforcement structure of the section where compressive section force is generated is filled with concrete by reinforcing section inside the reinforcement section by inserting the rigid members in the inner point lower current reinforcement section and the upper part of the upper section. The upper and lower chords inside the reinforcement section are fitted together, and support ribs are installed on the inner diameter surface of the outer side of the support plate at both ends of the reinforcement section.

The supporting ribs transmit the axial force of the steel pipe section generated in the upper and lower reinforcement sections to the filled concrete and the steel member and distribute the axial force of the steel pipe section to the filled concrete and the steel member of the reinforcement section.

The inner diameter members of the pipes of the upper and lower reinforcement sections and the internal rigid members inserted into the pipes of the upper and lower reinforcement sections are provided with shear connectors in the form of perforated steel plates or stud bolts before inserting the members into the pipes. It is to ensure complete unity behavior. When concrete is tightly filled inside the pipe of the reinforcement section, it is possible to integrate the structure between the upper and lower current reinforcement section pipe and the filled concrete through the shear connection material. Integral behavior by synthesis becomes possible.

Instead of attaching the shear connector to the inserted rigid member, a hole may be drilled in the rigid member to obtain the same effect as the shear connector of the perforated steel sheet.

Through this, the up-and-down chord of the up-and-down chord reinforcement section and the rigid member inserted into it are not directly connected, but through the concrete filled inside the reinforcement section, the behavior of moment cross-sectional force as well as the axial cross-sectional force in the up-and-down chord reinforcement section Integrated behavior is also possible.

The filling of the concrete inside the lower chord of the pipe in the upper and lower current reinforcement section is made through the inlet and discharge port (not shown) provided at both ends of the reinforcement section. Make sure the concrete in the reinforcement section is filled tightly.

In the up-and-down current section in which the axial cross-sectional force of tension occurs, cracking occurs in the concrete filled therein due to the tensile cross-sectional force, making it difficult to fully exert the reinforcing effect of the cross section. Therefore, the reinforcement effect can be maximized by introducing prestressing so that cracks do not occur in the concrete.

In the vertical direction section where the axial cross-sectional force of tension occurs, an additional hole for installing steel rods or steel wires is provided in the supporting plates at both ends of the upper and lower current reinforcement sections, and the steel rod or steel wire is installed through this hole to tension By offsetting the cross-sectional force, the load capacity of the upper and lower current reinforcement sections can be increased, and the cracking of the filled concrete can be suppressed.

The reinforcing structure of the up-and-down chord section in which the axial cross-sectional force of tension | tension generate | occur | produces is provided with the support member in the both ends of the up-and-down chord reinforcement section, and inserting a rigid member in the up-and-down reinforcement section of the inner point part. Drill holes in the supporting plates at both ends to install sheath pipes for inserting steel rods or steel wires in the reinforcement section, and then fill concrete inside the reinforcement section so that the top and bottom currents of the reinforcement section fit together. The installation of the support ribs on the inner diameter surface of the outer side of the support plate and the installation of the shear connector on the inner diameter surface of the upper and lower current reinforcement section and the rigid member inserted therein, and their structural characteristics. Same as current reinforcement.

The steel reinforcement structure at the point of truss structure with improved resistance to bending moments is a steel with a length of 0.2 to 0.3 times the length of the material at the internal position of the steel connector before installing it at the lower and upper chords. Welded connection to the lower and upper chords. The reason for the length of the steel to be 0.2 to 0.3 times the length of the sand is that the moment cross section force generated at the point sand is reversed at the opposite ends of the sand, so that the moment cross section force at the center of the sand becomes 0. This is because the section where the cross-sectional force has a great influence is a section 0.2 to 0.3 times the length of the yarn from the yarn edge.

If the steel insert to be inserted into the sand is installed on the outer side of the lower chord and the upper chord, the sander connector is installed on the outer side of the lower chord and the upper chord. Produce and install a little longer to prevent spatial interference between the middle part and the steel when installing the middle part connecting the sand connector.

When the sand connector is welded and installed on the lower chord and the upper chord outer surface, both ends of the middle sand between the sand connector are welded to the sand connector. Both ends of the sand bars are equipped with an inlet for filling concrete on one side, and the filling of the sand material reinforcement structure is completed by filling concrete. Perforated steel plates or studs are formed on the inner diameters of the steel and sand connections and the middle part of the sand material. The bolt-type shear connector is welded in advance so that the sand, steel, and filled concrete are fully integrated in the same way as the point load current reinforcement structure.

In addition, the concrete filled at the end of the sand and the steel insert inserted into the sand not only reduce the stress at the end of the sand but also reduce the stress concentration at the front and the heel of the sand at the end of the sand, and also reduce the fluctuation stress caused by the moving load. It will play a role will greatly improve the fatigue performance of the front and heel.

According to the present invention, by inserting a rigid member into the upper and lower chords and sand of the truss bridge causing a very large bending stress and filling with concrete, it is possible to reinforce the cross section in an economically and aesthetically superior way by dramatically increasing the cross-sectional load capacity and rigidity. Can be.

In particular, avoiding cross-sectional reinforcement using only expensive steel and suggesting a method of increasing load capacity not only for axial cross-sectional force but also for moment cross-sectional force by synthesizing inexpensive concrete and steel material, It can be constructed.

In addition, according to the present invention, by reducing the point rotational displacement caused by the point bending moment in the upper chord and the lower chord through the reinforcement of the section stiffness, the deflection and vibration in the center of the ground are reduced, thereby increasing the usability of the long span truss bridge. Can be obtained.

And by dispersing the stress at the end of the sand through the additional steel and filling concrete installed inside the sand, the stress concentration in the front and the heel of the end of the point sand by the axial cross-sectional force and the bending moment is greatly reduced. The structural reliability of the structure can be improved and fatigue resistance can be improved to prolong the service life.

1 is an external force acting on the current other than the node
Fig. 2 shows eccentricity occurring at the load action point at the node
Figure 3 is a cross-sectional force diagram of the truss
4 is the deflection shape of the truss
5 is a problem of conventional concrete filling
6 is stress concentration occurring in the heeled heel at the end of the sand
Fig. 7 shows fatigue failure at the end of yarn
8 is the scope of the present invention reinforcement range
9 to 12 is a top and bottom current reinforcement process diagram of the present invention
Figure 13 is a cross-sectional view of the present invention compression section force up and down reinforcement
14 is a perspective view of the present invention tensile section force up and down reinforcement
15 to 18 is a process of the present invention reinforcement

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention. 3e, 3f and 8 illustrate the reinforcement range of the point truss member in the present invention.

First, the reinforcement plan of the up and down current at the point where the compressive cross section force and the moment cross section force are generated will be described. The reinforcement section corresponds to the inner branch lower current section and the end point upper current section. As shown in Figs. 9 and 10, the reinforcing structure of this section inserts the rigid member 187 into the upper and lower current pipes of the inner point lower chord reinforcement section and the end point upper chord section.

In this case, a shear connector for synthesizing the pipe member and the concrete to be filled is installed. As a specific method, a perforated steel sheet in which holes 186 are perforated in the pipe cross section of the inner branch lower chord and the end branch upper chord ( 185) or stud bolts are installed radially on the inner diameter of the pipe.

Then, the hole 188 is formed in the steel member 187 as a shear connecting material for the synthesis of the concrete to be filled with the inserted steel member 187, or a perforated steel sheet is additionally welded to the steel mold. In addition, a stud bolt may be installed on the rigid member.

And the shear connector for the synthesis with concrete is installed on the inner diameter surface of the upper and lower chords and the steel member 187 to measure the synthesis of the concrete and the upper and lower chords and the concrete and the steel filled in the upper and lower chords inside the reinforcement section.

Thus, the pipes constituting the up-and-down chords and the rigid members inserted therein through the internally filled concrete act integrally with respect to the axial cross-sectional force and the moment cross-sectional force.

As such, the rigid member 187 inserted into the upper and lower chords of the reinforcement section in which the compressive section force is generated has a cross-sectional strength for the moment cross-sectional force as well as the cross-sectional strength for the axial cross-sectional force of the upper and lower chords of the reinforcement section when the inside of the cross section is filled with concrete. It is greatly improved and the stiffness of the cross section is also very large.

The support plate 180 is installed at both ends of the reinforcement section after inserting the rigid member 187 at both ends of the reinforcement section where the compressive section force acts, that is, the inner current section of the lower chord and the upper current end point. The interior of the reinforcement section is to be closed when the concrete is filled in the interior, and support ribs 182 are installed on the inner diameter surface of the outer side of the support plate at both ends of the reinforcement section. This support rib serves to transmit and distribute the axial force of the up and down current pipe cross section generated in the reinforcement section to the filled concrete and the rigid member 187 inserted therein.

Concrete inlet (not shown) and discharge port (not shown) are provided at both ends of the compressed section force reinforcement section, and concrete is sealed in the reinforcement section by confirming that concrete is discharged through the discharge port at high pressure through the injection port. To be filled. After the concrete filling and curing is completed, the upper and lower chords with reinforced sections are welded to the sand.

The upper and lower reinforcement sections at the point where the tensile section force and the moment section force are generated are the upper section of the inner section and the section at the end point.

In the section in which the axial cross-sectional force of tension occurs, cracking occurs in the inner-filled concrete due to the tensile stress occurring in the cross-section according to the tensile cross-sectional force, which makes it difficult to fully exert the effects of the inner steel and the concrete filling. By introducing the tension cracks to maximize the reinforcement effect.

In the up and down current reinforcement method of the section in which the tensile cross-sectional force is generated, the process of inserting the steel (177) and the shear connector 175, 178 in the interior and the process of installing the support plate 170 on both ends of the reinforcement section and The manufacturing method is the same.

However, a hole 171 ′ for penetrating one or more steel bars or sheath pipes is drilled in the circular plate 171 of the support plate 170 to introduce prestressing.

The shear connector 175 is installed in the up and down chords of the reinforcement section in which the tensile section force is generated, and the steel mold 177 is inserted in the up and down chords. The steel bar or sheath tube 173 is installed inside the sheath tube 173 for inserting the steel rod 173 or the steel wire and through a through hole 171 ′ provided in the circular plate 171 of the support plate 170 at both ends of the reinforcement section. To settle.

After that, the concrete inlet section (not shown) and the discharge port (not shown) are provided at both ends of the tensile cross-section reinforcement section, and the concrete is injected at high pressure through the inlet and the concrete in the reinforcement section is discharged through the outlet. Fill and cure tightly. After curing is completed, prestressing is introduced by straining the pre-installed steel bar or inserting the strand into the sheath pipe installed.

In this way, pre-stressing is used to connect the upper and lower chords, which have been reinforced, with welding material.

In addition to the axial section force, the section section reinforcement structure with improved section strength and stiffness for moment section force is 0.2 ~ 0.3 of the length of the yarn at the internal position of the yarn connector before installing the yarn connectors 112 and 142 on the outer circumferential surface of the lower chord and the upper chord. Steels 115, 117, 145, and 147 having a length of about twice are welded to the outer circumferential surface of the lower chord and the upper chord.

The cross section of the steel inserted into the sand can be selected from the I-shaped cross section (115,145) or the circular cross section (117,147), and the shear connecting material such as welded shear connector such as perforated steel plate or stud bolt on the outer circumferential surface of the steel or by drilling holes in the steel It can also replace

When the steel reinforcing steel molds 115, 117, 145, and 147 are welded to the lower chord and the upper chord outer circumferential surface, the sand joints 112 and 142 are welded to the outer circumferential surface of the lower chord and the top chord so that the sand reinforcing steel mold is included therein. And the length of the sand connector is slightly larger than the length of the reinforcing steel is inserted into the interior so that the spatial interference between the middle section and the steel when installing the intermediate section 50 connecting the four ends of the four sections.

At this time, the shear connector such as perforated steel plate or stud bolt is radially placed on the inner surface of the sand connector so that the concrete and sand can be synthesized when the concrete is filled.

After welding the intermediate part yarns 50 and the yarn connector, one side of the yarn connector at both ends of the yarn is provided with an inlet (not shown) for filling the concrete, filling the concrete tightly and curing the branch yarn reinforcement is completed.

50: private
112: yarn connector
115,117,145,147: Steel reinforcement part steel
120: Height current
150: present
173: Steel rods or sheathed pipes of up and down reinforcement parts subjected to tensile section force
177: Rigid steel for vertical beam reinforcement subjected to compressive section force
187: Rigid steel for reinforcement of up and down current under tensile section force
175, 185: shear connector
170: upper and lower current reinforcement support plate subjected to tensile cross-sectional force
180: upper and lower current reinforcement support plate subjected to compressive force

Claims

In pipe truss bridge structures with end points or internal points
The I-shaped steel is inserted into the up-and-down current section in the up-and-down current section that receives the compression section force and the moment cross-sectional force of the inner point pipe lower chord or the end point pipe top chord, and the support plates are installed at both ends of the pipe to fill and cure concrete. The upper and lower current reinforcement structure of the section of the compressed section force section of the truss bridge which improves the strength and stiffness not only of the compressive section force but also the moment section force by allowing the current and the internal steel and the filled concrete to be integrated.

In pipe truss bridge structures with end points or internal points
In the upper and lower current sections receiving the tensile section force and the moment cross section force of the inner branch pipe upper chord or end point pipe lower chord, I-shaped steel is inserted into the upper and lower chords at all times, and support plates are installed at both ends of the steel pipes or steel wires in the upper and lower chords. A sheath pipe for insertion and filling curing is then used to tension the installed steel rod or to insert and wire a steel wire into the sheath pipe so that the upper and lower chords and the internal steel and the filled concrete behave integrally so that not only the tensile cross-sectional force but also the moment cross-sectional force Up and down current reinforcement structure at the point of tensile section force section of truss bridge with improved strength and rigidity

The method according to claim 1 or 2,
Reinforcing structure of the upper and lower points of the point portion, characterized in that the perforated steel sheet or stud bolt is installed on the inner diameter of the upper and lower chords as a shear connecting material for the synthesis of the concrete filled in the upper and lower chords of the reinforcement section

The method according to claim 1 or 2,
The upper and lower current reinforcement structure of the point portion, characterized in that the perforated steel plate or stud bolts are installed as a shear connector for the synthesis of the filled concrete on the outer peripheral surface of the I-type steel inserted into the pipe upper and lower chords of the reinforcement section

In pipe truss bridge structures with end points or internal points
The hollow point or I-shaped steel is welded to the outer circumferential surface of the upper and lower chords so as to be 0.2 to 0.3 times the length of the yarn, and then the yarn connector is welded to the outer circumferential surface of the upper and lower chords. Branch reinforcement structure of the branch part, characterized in that the curing of the concrete filled inside by welding the secondary material and the joints on both sides

The method according to claim 5,
Branch reinforcement structure of the point portion, characterized in that for installing the perforated steel sheet or stud bolts on the inner diameter surface of the material as a shear connection material for the synthesis of the filled concrete in the pipe material of the reinforcement section

The method according to claim 5,
Branch hollow reinforcement structure, characterized in that for installing the hollow steel sheet or stud bolt as a shear connector for the synthesis of filled concrete on the outer circumferential surface of the hollow cone-shaped or I-type steel is inserted into the pipe sand of the reinforcement section

In pipe truss bridge structures with end points or internal points
The I-shaped steel is inserted into the up-and-down current section in the up-and-down current section that receives the compression section force and the moment cross-sectional force of the inner point pipe lower chord or the end point pipe top chord, and the support plates are installed at both ends of the pipe to fill and cure concrete. Method of constructing reinforcement structure of upper and lower currents at the point of compression section force section of truss bridge which improves strength and stiffness not only for compression section force but also for moment section force by allowing current and internal steel and filled concrete to be integrated

In pipe truss bridge structures with end points or internal points
In the upper and lower current sections receiving the tensile section force and the moment cross section force of the inner branch pipe upper chord or end point pipe lower chord, I-shaped steel is inserted into the upper and lower chords at all times, and support plates are installed at both ends of the steel pipes or steel wires in the upper and lower chords. A sheath pipe for insertion and filling curing is then used to tension the installed steel rod or to insert and wire a steel wire into the sheath pipe so that the upper and lower chords and the internal steel and the filled concrete behave integrally so that not only the tensile cross-sectional force but also the moment cross-sectional force Construction method of upper and lower current reinforcement structure of tension section of truss bridge with improved strength and rigidity

In pipe truss bridge structures with end points or internal points
The hollow point or I-shaped steel is welded to the outer circumferential surface of the upper and lower chords so as to be 0.2 to 0.3 times the length of the yarn, and then the yarn connector is welded to the outer circumferential surface of the upper and lower chords. Construction method of reinforcement structure of branch part, characterized in that curing the concrete filling inside by welding the sub-materials with the connector of both sides