JP2006336371A - Member replacement method of construction of trussed structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform the replacement of a member safely and easily without reassembling a truss by mechanically analyzing the flow of a load acted on a trussed structure and by transferring a load acted on a member which becomes a subject of the replacement of a member to a replacement tool or a fastening tool. <P>SOLUTION: In the case where a pulling force is exerted on the member which is the object of the replacement, the replacement of the member is performed by reducing the pulling force exerted on the member to the extent that the bolt of the member can be unfastened by fastening the joints on both ends of the member with the fastening tool A. Then in the case where a compression force is exerted on the member 2 which is the object of the replacement, the joints on both ends of the member 1a are fastened by the fastening tool A, and the tension member 1a is taken out. The member 1a is a pair of the member 2 which is the object of the replacement, and a pulling force is exerted on the member 1a. Furthermore, the joints taken out are fastened with the tool A, and the replacement of the member 2, which is the object of the replacement and on which the compression force is exerted, is performed by reducing the compression force of the member 2, which is the object of the replacement and on which the compression force is exerted, to the extent that the bolt of the member can be unfastened. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for replacing a member of a truss structure. In addition to an electric business (transmission tower) and a communication business (wireless tower) having a truss structure coupled with bolts, a railway / water supply business (overhead wire) In equipment such as trusses, water towers, and stadium facilities (lighting towers, advertising towers), it can be used to safely and easily replace the members when the members of the truss structure are corroded or deformed. .

  For example, a truss structure such as the above-mentioned power transmission tower is subjected to its weight or a tensile load such as an electric wire. Since these loads are also transmitted to the members constituting the truss, the loads act on the bolts connecting the members, and in many cases, the bolts cannot be removed during replacement work. In this case, the electric wires and the like are removed by a procedure reverse to that for assembling the truss and the member is removed from the top of the truss to achieve the desired member replacement. However, this method requires a large-scale construction for reassembling the truss structure to replace one member.

Therefore, in order to avoid the large-scale construction as described above, in the replacement method of the damaged member of these truss structures, the replacement member is a compression material (a member on which a force to compress the member acts), Judge whether it is a tensile material (a member on which a force to stretch the member acts), attach replacement tools corresponding to these members, and let the replacement tool bear the force that the replacement member has borne A replacement method has been developed.
JP 2001-268758 A Registered Utility Model Publication No. 3058930

  However, in the construction method in which the load is applied to these replacement tools, only the load of each replacement member is borne. For replacement of other members, a replacement tool can be attached to each replacement member each time. It must be done. Therefore, the work is extremely time-consuming.

  The present invention has been made in view of these points. The load flow acting on the truss structure is dynamically analyzed, and the load acting on the member to be replaced is replaced with a replacement tool (or tightening tool). It is an object of the present invention to provide a member replacement method for a truss structure that realizes member replacement safely and easily without reassembling the truss by transferring to an upper tool.

  Therefore, in the invention according to claim 1, in the replacement of the member of such a truss structure, when a tensile force (force for extending the member) acts on the replacement member, the joint between the nodes at both ends of the member is tightened. By tightening with the upper tool, the tensile force acting on the member is reduced to such an extent that the bolt of the member is removed, and the member is replaced. Also, the replacement member has a compressive force (a force to compress and compress the member). ) Is applied, tighten the gap between the nodes on both ends of the member that acts as a pair with the replacement member with the above tightening tool, remove the tension member, and connect the removed nodes together. A member replacement method for a truss structure that is tightened by a tool and reduces the compression force of the replacement member on which the compression force acts to such an extent that the bolt of the member is removed to replace the member on which the compression force acts. did.

  According to a second aspect of the present invention, in the first aspect of the invention, the truss structure member is obtained by further applying a lifting load by a lifting tool to the nodes immediately above and immediately below the lifting load applied by the lifting tool. The member replacement method for the truss structure was performed, in which the load was averaged to replace the member.

  The principle of the present invention will be described below. FIG. 8 shows how the load acting on the truss structure is transmitted. The tensile load (2-3, 4-5, 6-7) is transmitted to one of the X-shaped members at each height. A compression load (1-4, 3-6, 5-8) is transmitted to one member. The applied load is transmitted to the ground through two member paths. One is compression (1-4) → tensile (4-5) → compression (5-8), and the other is tension (2-3) → compression (3-6) → tensile (6- 7). Thus, the load is transmitted while alternately changing the shape of the members of the truss structure in the order of tension → compression → tensile → compression.

  FIG. 9 shows a load transmission state in a state in which a tightening load is applied to both end nodes 4 and 5 of the member and the tensile member 4-5 is removed in order to remove the member 4-5 subjected to the tensile load. . The load acting on the truss by the tightening load is mainly transmitted to the member 1-4 (compression) → the tightening tool 4-5 (tensile) → the member 5-8 (compression), and the member 2-3 (tensile) → the member 3 The load on the path of −6 (compression) → member 6-7 (tensile) decreases.

  FIG. 10 shows the load transmission state in a state where the state of FIG. 9 is further tightened and the compression member 3-6 is removed. The load is completely transferred from the member 1-4 (compression) to the lifting tool 4-5 (tensile) to the member 5-8 (compression), and the truss (tensile member 4-5, compression member 3-6) of this portion is moved. Even if it disappears, the load can be safely transmitted to the ground. In this state, the member 2-3 and the member 6-7 are not determined to be compressed or tensile (indicated by a one-dot chain line in the figure).

  FIG. 11 shows a method of reducing the load on the truss component by adding a tightening load. That is, when a tightening load is applied as shown in FIGS. 9 to 10 to remove the replacement member, the upper or lower member to which the tightening load is applied (members 1-4 in FIG. 10) before the replacement member is removed. , Member 5-8, etc.) becomes large, and the strength of the member may be exceeded. In order to prevent this, the load of the truss components can be averaged by applying an additional tightening load at the nodes immediately above and below the tightening load. In addition, the upper part of the truss structure was abbreviate | omitted for the principle description of said FIG.8, FIG.9, FIG.10 and FIG. 11, respectively.

  According to the first aspect of the present invention, when a tightening tool is attached between the nodes of a member on which a tensile force acts and tightened by this tool, not only a member on which the tensile force acts but also a member on which a compressive force acts. Can also be safely replaced. Further, even after the member is removed, the load of the truss structure is safely transmitted by the lifting tool, and there is no need to reinforce the truss structure. Therefore, the truss structure member can be easily and quickly replaced as compared with a method of replacing the replacement tool or the lifting tool for each replacement member. In addition to the effect of the invention of claim 1, the invention of claim 2 can average the load of the truss component members, does not apply a load exceeding the proof stress of the member, and can replace the member more safely. Can do.

  When replacing a member of a truss structure, if a tensile force acts on the replacement member, attach a lifting tool between the nodes on both ends of the member, and tighten the space between the nodes by using this tool. The tensile force acting is reduced to such an extent that the bolt of the member is removed, and the member is replaced. When a compressive force acts on the replacement member, the tensile force paired with the replacement member acts. The joint between both ends of the member is tightened by the tightening tool, the tensile member is removed, the joint between the removed nodes is tightened by the tool, and the compressive force of the replacement member on which the compressive force acts is This is a member replacement method for the truss structure, in which the bolts are reduced to such an extent that they are removed, and the members to which the compressive force acts are replaced.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic work process diagram showing a replacement method when a tensile force is applied to a member 1 to be replaced in the truss structure, and the upper portion of the truss structure is omitted for explanation. In this case, by attaching the lifting tool A between the nodes at both ends of the replacement target member 1 and tightening between the nodes with the tool A, the tensile force acting on the replacement target member 1 is zero or The member is reduced to such an extent that the bolt is removed, and in this state, the replacement target member 1 is removed and a new member is attached.

  FIG. 2 is a schematic work process diagram showing a replacement method when a compressive force is applied to the member 2 to be replaced of the truss structure, and the upper portion of the truss structure is omitted for explanation. In this case, the tightening tool A is attached between the nodes on both ends of the member 1a acting with the tensile force paired with the member 2 to be replaced, and the tool A is tightened between the nodes, When the member 1a on which the force acts is removed and the removed node is tightened with the tool A, the compression force of the replacement target member 2 on which the compression force acts is reduced to zero or the bolt of the member is removed. Therefore, the replacement target member 2 on which the compression force acts is removed and a new member is attached.

  FIG. 3 is an explanatory diagram of the tightening tool A. The replacement target members 1 and 2 of the truss structure 3 are fixed to the plates 8 provided on the main column members 6 and 7 at both ends thereof. Of the replacement target members 1 and 2, four fixing brackets 9 for fixing the lifting tool A to both end nodes of the replacement target member 1 that is a tension member are provided on the upper and lower main column members of the plates 8. 6 and 7 are fixed. Each of these fixing brackets 9 is easily attached to the main column members 6 and 7 of the truss structure 3 and has a structure that does not deform the main column members 6 and 7 locally. Further, the fixing brackets 9 positioned above and below the plates 8 are connected to each other by a connecting plate 10 and are used as receiving materials. Even if the lifting load is applied, it does not move upward or downward.

  Further, two sets of fixing metal fittings 9, 9 provided at both end nodes of the replacement target member 1 which is the tension member are connected by a steel rod or chain 11, respectively. When these steel rods or chains 11 are steel rods, some of them can be used in connection with the size of the truss. Each steel rod or chain 11 is connected to a lifting device (turn buckle or chain block) 12 for generating a lifting load and a load measuring device 13 for measuring the lifting load. As shown in FIG. 3, these steel rods or chains 11, the lifting device 12, and the load measuring device 13 may be used in two up and down positions with the replacement target member 1 interposed therebetween. In some cases, the member 1 is used in quadruple in the vertical and horizontal directions.

  The above-described tightening tool A is used in such a manner that four fixing brackets 9 are attached to the main column members 6 and 7, and the connecting plates 10 are fixed to the fixing brackets 9 positioned above and below, respectively, so that they are aligned. The upper and lower fixing brackets 9 are attached. Subsequently, a steel rod or chain 11, a lifting device 12, and a load measuring device 13 are set on each fixing bracket 9, and a lifting load is applied by the lifting device 12 while comparing with a load analysis result of a truss described later. Add. The tightening load is reduced until the tensile load of the replacement target member 1 disappears or until the bolt of the replacement target member 1 can be removed, and is added so as to be equal in the vertical direction while looking at the load measuring device 13. The replacement target member 1 is removed. Further, the tightening load is increased and the replacement target member 2 is removed.

  4 and 5 are a plan view and a front view showing the structure of the fixing bracket 9 when the main column members 6 and 7 to which the fixing bracket 9 is attached are steel pipe materials. In this case, the steel band 14 is wound around the outer periphery of the main column member 6 or 7, and both ends thereof are passed through the both ends of the band receiving member 15 in contact with one side of the main column member 6 or 7, and the nuts 16, 16 are passed. And fasten to the main pillar 6 or 7. The band receiving member 15 has a structure in which one end of a connecting plate 10 connected to a fixing metal 9 positioned below and a steel rod or chain 11 for applying a tightening load is connected.

  6 and 7 are a plan view and a front view showing the structure of the fixing bracket 9 when the main pillar members 6 and 7 to which the fixing bracket 9 is attached are angle-shaped members. In this case, the angle members 17 and 18 corresponding to the chevron shape of the main pillar member 6 or 7 are stacked so as to sandwich the main pillar member 6 or 7, bolts 19 are passed through both ends of these angle members 17 and 18, and the nut 20 And is fixed to the main column member 6 or 7 by tightening. Further, the inner angle member 17 is connected to one end of a steel rod or chain 11 to which a tightening load is applied, and the outer angle member 18 is fixed to one end of the connecting plate 10. .

  Next, when using the construction method of the present invention, when the lifting tool A is mounted on the tower and tightened, stress is generated in other members of the tower due to this tightening, but the load that these other members can withstand The values must be calculated in advance and sufficient care must be taken not to affect the safety of these parts or truss structures. Therefore, strength analysis is performed on the method of the present invention.

As analysis methods, (a) strength analysis is performed based on partial trusses of a total of 7 panels, including 3 panels before and after the replacement member panel. (B) The basis of strength analysis is the simple three-dimensional analysis method for the partial truss in (b), and the input load and truss formation conditions are as shown in FIG. (C) Strength analysis reveals the required tightening load and limit lifting load in the following cases, the position of the minimum safety factor member and its safety factor, and the safety factor of the lifting tool for a certain load condition To.
・ Tensile member removal (incorrect compression member side tightening)
・ Tensile member removal (Tensile member side tightening: minimum value of limit tightening load before and after removal of tension member)
・ Removal of compression member (Tension member side tightening: Minimum value of limit tightening load before and after compression member removal)

  The above-mentioned required lifting load is the theoretical tightening load at which the stress of the replacement member is zero in the analysis. The critical lifting load is a member safety factor of 1.00 or more against the allowable stress. Indicates the maximum lifting load that can be achieved. The minimum safety factor member means a member having the smallest safety factor among the members of the steel tower. In this case, the insertion state of the lifting tool A is simulated by a member having the same cross-sectional area as the tool. Assumes in case. The tightening tool safety factor is obtained by dividing the overall load rating of the tightening tool A to be used by the above limit tightening load.

The basic procedure for member replacement based on the above analysis results is shown below in the case of no wind in the steel tower.
(1) The lifting tool A is attached to the tension member side of the panel from which the member is removed.
(2) Remove the nut of the tension member while tightening to the middle of the required tightening load value, and confirm that the compression force is not acting on the tension member.
Note that if the nut is removed at the initial stage of tightening, there is a risk that the bolt joint will be twisted, so this is not performed until the tensile member stress exceeds half of the analytical value.
(3) Tighten to the tension member required tightening load value or a value close to it, and check whether the member can be removed in that state.
(4) If the member cannot be removed in the above (3), it is tightened up to the limit lifting load value, and it is confirmed whether the member cannot be removed in the process.
(5) If the tension member cannot be removed by the above (4), there is a possibility that the compression member is tightened depending on the steel tower. Therefore, the tightening tool A is attached to the member side assumed to be the compression member side. Repeat steps 2) to (4).
(6) If the member cannot be removed up to (5) above, give up replacing the member.

<If the tension member can be removed up to (4) above, the following procedure is followed. >
(7) Remove the nut of the compression member in the tightening load state when the tension member is removed, and confirm that no tensile force is acting on the compression member.
(8) The compression member is tightened to the required tightening load value or a value close thereto, and it is confirmed whether the member cannot be removed in that state.
(9) If the member cannot be removed in the above (8), it is tightened up to a limit tightening load value, and it is confirmed whether the member cannot be removed in the process.
(10) If the member cannot be removed by (9) above, give up replacing the compression member.

In the above, confirmation of member stress by applying strain gauges can only measure the amount of load increase / decrease, and it involves work such as attaching gauges the day before. The safety of the tower body is ensured by limiting it to a range that exceeds the value. If the replacement of the member is abandoned in (6) and (10) above, the possibility of detaching the member by the double tightening method or the double-sided tightening method will be examined again.
When removing the compression member, it is also considered to temporarily fix it with a small-diameter auxiliary bolt without removing the tension member in order to prevent deformation of the member.

It is a schematic work process figure which shows the replacement | exchange method of a tension member in the member replacement | exchange method of this invention. It is a schematic work process figure which shows the replacement | exchange method of a compression member in the member replacement | exchange method of this invention. It is a front view which shows the state attached to the truss structure of the lifting tool used for the method of this invention. It is a top view which shows the attachment state of the fixing bracket of a lifting tool when the main pillar material of the truss structure using the method of this invention is a steel pipe material. It is a front view which shows the attachment state of the fixing bracket of a lifting tool when the main pillar material of the truss structure using the method of this invention is a steel pipe material. It is a top view which shows the attachment state of the fixing bracket of a lifting tool when the main pillar material of the truss structure using the method of this invention is an angle material. It is a front view which shows the attachment state of the fixing bracket of a lifting tool when the main pillar material of the truss structure using the method of this invention is an angle material. The principle of this invention is shown and it is explanatory drawing which shows the load transmission method of a truss structure. The principle of this invention is shown and it is explanatory drawing which shows the removal state of the tension member by tightening between the both-ends nodes of a tension member. FIG. 4 is a diagram illustrating the principle of the present invention and is an explanatory diagram illustrating a state where a compression member is removed by tightening between both end nodes of the tension member. FIG. 9 is a diagram illustrating the principle of the present invention and is an explanatory diagram illustrating a load reducing method for a truss constituent member by a double tightening load. It is explanatory drawing which shows the input load to a partial truss, and truss formation conditions in the strength analysis of the construction method of this invention.

Explanation of symbols

A tightening tool 1 member to be replaced 2 member to be replaced 3 truss structure 6 main pillar material 7 main pillar material 8 plate 9 fixing bracket
10 Connecting plate 11 Steel rod or chain
12 Tightening device 13 Load measuring device
14 Steel band 15 Band receiving material 16 Nut 17 Angle material 18 Angle material 19 Bolt 20 Nut

Claims (2)

  In the replacement of the member of the truss structure, when a tensile force acts on the replacement member, the tensile force acting on the member is increased by tightening between the nodes on both ends of the member with a lifting tool. When the member is replaced by reducing the bolt to such an extent that the bolt is removed, and when a compressive force is applied to the replacement member, the above-mentioned tightening between the nodes on both ends of the member on which the tensile force is applied is paired with the replacement member. Tighten with the upper tool, remove the tension member, further tighten between the removed nodes with the same tool, reduce the compression force of the replacement member on which the compression force acts, to the extent that the bolt of the member is removed, A member replacement method for a truss structure, wherein the member on which the compressive force acts is replaced. It is characterized in that the load of the truss structure member is averaged by adding the lifting load to the nodes immediately above and below the lifting force applied by the lifting tool, and replacing the member. The member replacement method for the truss structure according to claim 1.