JP2002513877A - Fixing method and device of tip support type for external prestress reinforcement method - Google Patents

Abstract

(57) [Summary] Tip support for external prestressing reinforcement method to repair and reinforce concrete structures that have been severely damaged such as cracks caused by bending or sagging of concrete structures such as bridges or piers The fixing method and apparatus of the system are started. In the present invention, the extension of the end plate is provided with a tension so that the tension of the external steel wire is received by the concrete in contact with the end plate located at the end of the girder by the tip support method. The strength of the weak end welds of the tip support type is increased by extending the welding length of the end support to increase the supporting force. As a result, damage to the original structure can be avoided because a small number of short anchor bolts can be used, and if the welding length at the end is secured, the supporting force increases, so that the angle between the fixing plate and the end plate is increased. The possibility of damage due to stress concentration in the part is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

【Technical field】

The present invention relates to a fixing method of a tip support type for an external pre-stress reinforcement method for repairing and reinforcing a seriously damaged concrete structure such as a bridge or a pier which is cracked due to bending or sagging of the concrete structure. More specifically, a tension is applied to the extension line of the end plate so that the concrete in contact with the end plate located at the end of the girder receives the tension of the external steel wire by the tip support method in more detail. The present invention relates to a fixing method and an apparatus of a tip support system in which a welding length between a strut and an end plate is extended to increase a supporting force and a strength of a weak end weld portion of the tip support system is increased.

[0002]

[Background Art]

Over time, all structures have reduced bearing capacity and reduced life. Also, with the development of industry, the damage phenomenon of bridges has become more serious. Many bridges currently have a total weight of 32
Where tonnes of second-grade bridges occupy, these bridges are being damaged more rapidly by the passage of vehicles than the bridges can support. To prevent this,
The development of an efficient and economical repair and reinforcement method to increase the supporting capacity of existing bridges and reinforce them to bridges having the supporting capacity of first class bridges that can withstand a total weight of 43 tons is urgent.

[0005] Construction methods for solving such problems include a floor plate reconstruction method, a steel plate reinforcement method, and an external steel wire reinforcement method.

The floor slab rebuilding method is a method using high-strength concrete after completely removing the floor slab of an existing bridge, and is partially used. However, the enormous construction cost, manpower, and long time required for rebuilding the floor slab are required. It takes a long period of construction, and there is a problem that the vehicle must be completely controlled during the construction period.

[0005] The steel plate reinforcement method has been the main type of reinforcement work for most bridges and piers. However, recently, examples of use have been gradually increased due to problems in materials used, construction quality assurance and maintenance and management. Shrinking. The use of reinforcing methods using high-strength, high-elastic materials such as carbon fibers has been increasingly used, but there are still few applications to bridges.

[0006] On the other hand, a method of reinforcing an existing structure using an external steel wire has high adaptability to the structure and a high reinforcing efficiency, and is actively used for reinforcing various structures. Such a construction method using an external steel wire is roughly divided into four depending on the installation of a fixing device, and is used a lot in reinforcing a structure in practice. However, such various fixing methods have many problems. There is. That is, it is insecure or a relatively large compressive force should be applied, or the load transmitting structure is complicated and the fixing tool cannot be designed.

The types of the existing fixing tools are briefly summarized and introduced below. In reinforcing existing bridges using an external prestress reinforcement method, various types of fixing devices are used in a method of transmitting the tension of an external steel wire to a structure.

These fixing devices can be typically classified into four types, such as a shear support type, a tip support type, a friction support type, and a composite support type. In these fixing types, the concept of load transmission depends on the structure and installation position of the fixing device. The differences are shown, and the construction features and advantages and disadvantages for this are as follows.

[0009] First, as the shear support type shown in FIG. 1, a method for supporting the tension P of the PS steel wire 17 with a shear force V _an, the anchor bolt 13, the anchor bolt if tension is increased Thirteen should be increased.

If the order of construction is checked, first, the fixing plate 11 is manufactured and perforated in the original concrete PS concrete girder 18, and then the anchor bolt 13 is attached to fix the fixing plate 11.
Thereafter, the space between the fixing plate 11 and the concrete is filled with epoxy, and finally, the fixing device 14 is filled.
, 15 to tension the steel wire 17.

In the load transmission process, if the steel wire 17 in the steel wire tube 16 is tightened, the tension P is fixed to the fixing device 1.
Joined the 10 Brace the fixing plate 12 through 4, 15, the force is supported by the shear force V _an, of the anchor bolt 13 reaches the anchor bolt 13 which transmitted the fixing plate 11 is provided in the concrete.

This method has an advantage that materials can be easily purchased and construction is simple, but has many disadvantages.

First, during the drilling work for installing the anchor bolts, there is a high possibility of damaging the steel wire 17 and the fixing device of the existing concrete structure, thereby lowering the supporting force of the original structure. In addition, there is a possibility that the end portion may be broken due to a cross-sectional defect due to perforation at a stress concentration portion at an end portion of the PS concrete girder, and when the strength of the concrete structure is weak, an anchor bolt may be pulled out. This poses a problem that quality control and design are difficult because the magnitude of the shear supporting force of the anchor bolt depends on the strength of the concrete. In particular, there is no appropriate method for estimating the strength of concrete in existing structures, so the reliability of strength measurement is greatly reduced.

[0014] The second and first disadvantages limit the amount of tension that can be introduced according to the limitations of anchor bolt installation. In the shear support method, most of the tension is supported by the anchor bolt. However, if the existing concrete girder is damaged or the quality of the concrete is not accurately determined, the installation of the anchor bolt is limited only. Therefore, there is a limit to the introduction of tension.

Third, the number of anchor bolts applied to the tension increases and the size of the fixing device increases. The anchor bolt can obtain the shearing force applied when a certain distance or more is secured. If the spacing of the bolts is small, a corresponding reduction factor should be introduced to recalculate the shear forces of the bolts. Therefore, as the tension increases, more anchor bolts are required, and the spacing between them must be ensured, so that the fixing plate must be larger. Therefore, this method cannot be used when the area of the girder is small.

Fourth, the supporting force of the bolt is proportional to the diameter of the bolt, but the supporting force per bolt is within 2 to 3 tons, and in order to secure the supporting force necessary for external prestress, A sufficient number of bolts should be used at appropriate intervals or more. This is the same reason that the above-mentioned fixing plate becomes large.

In the friction support method, as shown in FIG. 2, a large compressive force is applied to the fixing plate using bolts for fixing the PS steel rod 29, and the adhesive force between the fixing plate 21 and the original structure due to the compressive force is applied. In this method, the tension P of the PS steel wire 27 is supported by the frictional force. Generally steel bar 2
No. 9 tensions the fixing tool and the PS concrete girder with an average tension of about 40 tons.

The working order is as follows. First, the fixing plate 21 is manufactured, and the steel plate 2 is formed by piercing the PS concrete girder.
After inserting the fixing plate 9, the fixing plate 21 is provided. The space between the fixing plate 21 and the concrete is filled with epoxy. Then, finally, the fixing device 25 is provided and tensioned.

In the load transmitting process, when the steel wire 27 in the steel wire tube 26 is tightened, the tension P is fixed to the fixing plate immediately fixing the fixing device because there is no fixing plate and no tension as in other systems. In addition, this force is supported by the frictional force generated by the steel bar.

The feature of this construction method is that the construction is possible when the gap between the girders, which cannot be constructed by the tip support method, is narrow, and the appearance is good and the size is small.

On the other hand, the first disadvantage is that the cost of PS steel rods is high and requires specialized skills to construct them. In order for the fixing device to withstand the tension, a compressive force of several tens tons corresponding to its size should be applied to the fixing plate, but special production of steel rods and bolts and nuts is inevitable, Tightening work and special equipment are required to provide a tensile force of up to 40 tons. Further, there is a disadvantage in that an accurate compression force with respect to the tension cannot be calculated because the measurement based on the torque when tightening the nut and the compression force due to the tightening do not increase in a fixed proportional relationship.

Second, since the final anchoring position of the tendon does not extend to the pier, it is necessary to study the stress distribution and safety between the anchor and the support point. This is because the generation of tensile stress and the stress distortion phenomenon can occur around the hole of the tensile bar even when the whole is under a compressive force.

Next, according to the tip support method, an end plate 39 and a fixing plate 31 are provided in a zigzag form at the end of the PS concrete girder, and the concrete surface in contact with the end plate 39 reduces the tension of the external steel wire 37. It is a method to support. As can be seen from FIG. 3, unlike the above-described shearing support method, the fixing plate 31 was small, the number of anchor bolts was small, and the length was short. This is because tension is applied at the ends.

The fixing sequence is as follows. First, the fixing plate 31 is manufactured, the anchor bolt 33 is provided by piercing the concrete, and then the fixing plate 31 is provided. At this time, since the anchor bolts are only used to fix the fixing plate 31 to the original position during the work, it is not necessary to drill holes deeply unlike the shear support method. Thereafter, the end plate 39 is welded to the fixing plate 31, and the gap between the fixing plate 31 and the end plate 39 is filled with epoxy. Finally, fixing devices 34 and 35 may be provided to tension the steel wire 37 in the steel wire tube 36.

In the load transmission process, when the steel wire 37 is tensioned, the tension P is applied to the fixing plate 32 (cross anchoring plate) in the same manner as in the shearing support system, and the force is sheared by the tension plate 30 and the fixing plate 31. You. However, the subsequent load transfer process is different from the shear support method. The force applied to the fixing plate 31 reaches the end plate 39 beyond the fixing plate 31, and this force is supported by the concrete girder fc that has finally contacted the end plate. As shown in FIG. 4, in this process, as shown in FIG. 4, in the process in which the tension reaches the end plate 39 via the fixing plate 31, the tension is applied to the corner between the fixing plate 31 and the end plate 39. There is always the danger that the weld will fall off due to high stresses. That is, if a tension is applied to the fixing plate, the end plate 39 is deformed, and a tensile crack is generated on the inner surface of the joint portion of these plates, thereby causing a problem that the welded portion is damaged.

This construction method has an advantage that the purchase and construction of materials are easy, and the effect of the external steel wire can be given evenly to all the spans.

On the other hand, the disadvantage is that there is a high possibility that the weld at the corner at the end of the first PS concrete girder is broken. The end of the PS concrete girder is where the existing steel wires are dense and where the stress is quite concentrated and a lot of reinforcing bars are arranged, but a considerable compressive force is introduced to the end side In such a case, a local destruction phenomenon is likely to occur. Also,
There is a recess block at the end of the PS concrete girder to hide the projection of the tension mounting device, but this is filled with general cement mortar after completion of the tensioning work, but the condition is often poor When a considerable compression force acts on the external steel wire, it can be said that cracks are likely to occur. In order to solve the problem of crack initiation, the space between the concrete structure and the end plates and the fixing plate should be filled with epoxy.

Second, there is a problem that there may be restrictions on construction. This fixing method can be applied only when there is a minimum gap of 3 cm or more at the end of the PS concrete girder.
When the concrete girder is continuous or at a narrow interval, there is a problem that it is difficult to secure a sufficient end plate thickness.

Third, the behavior of the bridge is restricted. This is because the above-mentioned restrictions were examined in other aspects.The spacing between the PS concrete girder and the PS concrete girder is designed to absorb the expansion and contraction of the bridge due to the effect of temperature, but during this period When the hardware is inserted, the space for the expansion and contraction of the PS concrete girder is reduced. Therefore, this method can be applied only when the girder interval is at least 3 cm or more.

Finally, a composite support system in which the shear support system and the tip support system are mixed will be described.
The composite support method is a method devised because it is difficult to compensate for the disadvantages described above. Rather than a method that presents a certain logical solution, the mutual complementation effect is achieved by appropriately combining the various methods described above. It's just a way to expect something.

The work order is as follows. First, the fixing plate 51 is manufactured, and a hole for providing the anchor bolt 53 is formed. In the case of the steel bar 53 ′ to be provided on the center side, only when the existing girder has a hole for providing the same. Since installation is possible and it is almost impossible to make a new hole, it can be said that this is not often applicable in practice. After the anchor bolts are provided, the fixing plate 51 and the end plate 59 are welded.
4 and 55 are provided to tighten the steel wire 57 in the steel wire tube 56.

Since the load transmitting process is a case where the shear supporting method and the tip supporting method are mixed, the load transmitting process is similar to the load transmitting process of the above two types. That is, the load is transmitted to the end plate 59 and the fixing plate 51 via the strut 50 and the fixing device 52. At the end of the load transmitting process, the composite support method uses the anchor bolt 53 and the concrete at the end. The only difference is that they all receive tension P.

An advantage of this method is that various fixing methods are used in combination, so that an increase in the overall supporting force can be expected. However, there are the following disadvantages.

Disadvantages are that, first, the various support methods do not work at the same time. Instead, if the fixing plate 51 moves forward after the end plate 59 serving as the tip support function is sufficiently deformed, the anchor bolt 53 Shear force begins to act on the steel bar 53 '. This is because the bolt holes in the fixing plate should be larger than the bolts for installation of the anchor bolts in the construction, so no shearing force acts on the bolts before deformation of about 1-2 mm or less occurs, so the shear support effect Is very difficult to expect to occur simultaneously with the tip support effect. Therefore, since the composite support system does not have the support force corresponding to the sum of the respective support forces, but the support force of each fixing device is generated sequentially, the actual support force of the method is the same as that of each method. It is much smaller than the sum of the supporting forces. Therefore, when the fixing force of this method is calculated, simply adding the supporting forces of the respective methods has a great possibility that the fixing device is destroyed due to excessive calculation of the supporting force. In addition, since it is difficult to calculate the load distribution ratio of each fixing method, it can be said that the design of the fixing device is almost impossible.

Second, since the holes used when moving the PS concrete girder cannot be inserted with steel rods, that is, most are located at the lower end or upper end of the girder, it is impossible to install steel rods. The case can be said to be the majority.

Third, there is a problem that the same original structure as that of the shear support method may be damaged due to the installation of the anchor bolt. That is, in order to expect the shearing force of the anchor bolt, the landfill depth of the bolt should be deep, and it can be said that damage to the original structure, especially the internal steel wire and the fixing device is inevitable.

As described above, the fixing technique using the conventional external stressed steel wire may have a problem that stress concentration occurs at an end corner or a crack occurs, and thus the installation work of the anchor bolt is not easy. In addition, there is a disadvantage that the major members of the bridge are likely to be seriously damaged during the installation work. In addition, there is a problem that it is very difficult to calculate the load distribution ratio of each part, so that it is very difficult to design a fixing device.

[0038]

DISCLOSURE OF THE INVENTION

The technical problem to be solved by the present invention is to solve the above-mentioned problems of the conventional fixing device by improving the tip support method so that when the steel wire is tightened, the vicinity of the corner at the end of the fixing device is improved. Provided is a fixing method and apparatus of a front end supporting type for an external prestress reinforcement method for preventing damage to an end of a fixing device by a method in which an end plate and a fixing plate are stretched so as to reduce a generated stress concentration phenomenon. That is.

Another technical problem to be solved by the present invention is to facilitate the work of installing the fixing device,
An object of the present invention is to provide a fixing method and apparatus of a tip support type for an external prestress reinforcement method which can be installed in a small space and minimize damage to an existing bridge during construction.

In order to achieve the above object, the present invention provides a fixing method and an apparatus of a tip support type for an external prestress reinforcement method, wherein a fixing plate is attached to a PS concrete girder with a small number of anchor bolts, and an end of the PS concrete girder is provided. A tip support for an external prestress reinforcement method in which an end plate is welded to and adhered to the fixing plate, a fixing plate is provided on the fixing plate, and an external steel wire is tensioned through a fixing tool supported by the fixing plate. In the fixing method and apparatus of the type, at least one or more square struts are provided on an extension of the end plate, and the struts are welded to the end plate and the fixing plate. As a result, it is possible to increase the support force by additionally welding and attaching a strut to the weak end of the existing tip support method.

[0041]

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of a fixing method and an apparatus of a tip support type for an external prestress reinforcement method according to the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 6 is a plan view for explaining a fixing method of a tip support method for an external prestress reinforcement method of the present invention, and FIG. 7 is a front view of FIG. As shown in FIGS. 6 and 7, the fixing method of the tip support method for the external prestress reinforcement method according to the present invention is based on the tension of the external steel wire 67 in the steel wire tube 66 by the existing tip support method. P is received by the concrete in contact with the end plate 69 located at the end of the girder.
9, the length of the weld between the tension plate 60 and the end plate 69 is increased by increasing the tension of the tension plate 60, the supporting force is increased, and the strength of the weak end weld portion of the tip support system is increased. To improve. At this time, as shown in FIG.
May be provided on the fixing plate 61 at at least one right-angled portion.

The fixing device of the tip support type for the external prestress reinforcement method according to the present invention is provided with an end plate 69 and a fixing plate 61 at the end of a PS concrete girder 68 in a zigzag manner. The contacting concrete surface is designed to support the tension of the external steel wire 67. As can be seen from FIG. 6, unlike the above-mentioned existing tip support method, the tension 60 is welded to the fixing plate 61 and the end plate 69, so that the welding length capable of receiving a load can be greatly extended.

The fixing sequence is as follows. First, the fixing plate 61 is manufactured, the PS concrete girder 68 is pierced to provide the short anchor bolt 63, and then the fixing plate 61 is provided. Then, the end plate 69 is positioned at the end of the girder 68, and the end plate 69 and the fixing plate 61 are welded.
At this time, the tension 60 welded to the fixing plate 61 is simultaneously welded to the end plate 69 to complete the assembly. Next, the space between the fixing plate 61 and the concrete and the space between the end plate 69 and the concrete are filled with epoxy. Here epoxy injection is very important. The reason for this is that even if a small gap is formed during the action of tension, the concrete may be deformed in that space and a crack may be generated. Finally, the fixing devices 64 and 65 and the fixing plate 62 are provided, and the steel wire 67 in the steel wire tube 66 is tensioned to complete the operation. In the present invention, the role of the anchor bolt 63 is to merely take the fixing plate 61 before the fixing plate 61 is hardened by epoxy, and to prevent the inner steel wire 67 from being damaged, the length of the anchor bolt 63 is 10 mm.
It is also a great advantage that you can use short bolts within cm. The reason that the steel rod is not used in the present invention is that when the steel rod is provided at the end of the fixing device as in the existing composite fixing method, only when the transport hole of the PS concrete girder is located at the center of the girder. Although it can be applied, in most cases, the carrying hole is actually located at the lower end of the girder, and in many cases there is no such hole at all, and in this case, it is impossible to install a steel rod at all.

In the load transmitting process of this method, when the steel wire 67 is tensioned, the tension P is applied to the fixing plate 62 similarly to the shearing support system, and the force is applied to the tension plate 60, the fixing plate 61 and the end plate 6.
Sheared to zero. That is, the force applied to the fixing plate 61 reaches the end plate 69 through the fixing plate 61 and the strut 60, and this force is supported by the concrete girder fc that has finally contacted the end plate 69. According to the present invention, as can be seen in the load transmission process, as shown in FIG. 8, when the tension reaches the end plate 69 via the fixing plate 61, as shown in FIG. The tensile stress generated at the corner between the component plate and the fixing plate is reduced. Such a decrease in the tensile stress reduces the possibility of the occurrence of a tensile crack, so that it is possible to prevent the fixing device from being destroyed as the crack advances.

According to FIG. 8, in the existing tip support method, the shape of the rearward strut is triangular and the welded portion in contact with the end plate is straight, but in the present invention, the shape of the strut 60 is square. The length of the end plate 69 is further increased, so that the welding length of this portion is increased, and the supporting force of the fixing device is increased accordingly. In the present invention, the stress concentration at the corner of the abutting portion between the fixing plate and the end plate in the existing tip support method can be reduced by welding the end plate 69 and the fixing plate 61 while the end plate 69 becomes longer together with the tension 60. By receiving the parts separately, the tensile stress at the corners is reduced.

As described above, the fixing method and apparatus of the tip support type for the external pre-stress reinforcement method of the present invention can use the short anchor bolts 63, so that the steel wires and the fixing device of the original structure can be used. The advantage is that it can avoid damage, secure the welding length at the end and exert the anchoring force, so it can be designed, and it can make the fixing tool of the existing tip support type compact. There is an advantage that damage to the fixing device due to concentration of stress at the corner between the fixing plate and the end plate, which is a disadvantage of the existing tip support method, can be reduced. Also, since the shape of the weld is not planar, even if damage occurs at the boundary with the fixing plate, these cracks will be greatly deformed while advancing to the strut weld, so maintenance of appearance is important. Has the advantage of making observation easier. Further, since the increased fixing force means that a large tension is applied, there is an advantage that the tension can be increased by re-tensioning when necessary. In addition, this method has an advantage that the purchase and construction of the material are easy, and the effect of the external steel wire can be given equally to all the spans.

[0048]

[Industrial applicability]

INDUSTRIAL APPLICABILITY The fixing method and apparatus of the tip support method according to the present invention are used for reinforcing a bridge or a pier by adopting an improved tip support method for an external prestress reinforcement method. In particular, it is easy to install, minimizes damage to existing bridges and piers, and can be reinforced in narrow spaces.

[Brief description of the drawings]

FIG. 1 is a plan view for explaining a fixing method of a shear support method for a conventional external prestress reinforcement method.

FIG. 2 is a front view for explaining a fixing method of a friction support method for a conventional external prestress reinforcement method.

FIG. 3 is a plan view for explaining a fixing method of a tip support method for a conventional external prestress reinforcement method.

FIG. 4 is a detailed view of a portion where an end plate and a fixing plate of FIG. 3 are in contact with each other.

FIG. 5 is a plan view for explaining a fixing method of a composite support method employing both a shear support method and a tip support method for a conventional external prestress reinforcement method.

FIG. 6 is a plan view for explaining a fixing method of a front end supporting method using the external prestress reinforcement method of the present invention.

FIG. 7 is a front view of FIG. 6;

FIG. 8 is a detailed view of a welded portion according to the tip support method of FIG.

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY , CA, CH, CN, CU, CZ, DE, DK, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP , KE, KG, KP, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, VN, YU, ZWF Term (reference) 2D059 BB39 CC02 GG40 2E163 DA02 FA12 FD03 FD12 FD25 FD43 FF12 2E164 AA02 AA13 AA31 BA12 DA01 DA03 DA12 DA22

Claims (2)

[Claims] 1. A fixing plate is attached to a PS concrete girder with an anchor bolt, and the PS
A tip for an external prestress reinforcement method in which an end plate is welded to an end of a concrete girder and the fixing plate, and a fixing plate is provided on the fixing plate and an external steel wire is tensioned through a fixing device supported by the fixing plate. In the supporting method and the fixing method, at least one square strut is provided on an extension of the end plate, and the strut and the end plate and the fixing plate are welded and adhered. Fixing method of tip support method for external prestress reinforcement method. 2. Fixing plate is attached to PS concrete girder with anchor bolts
A tip for an external prestress reinforcement method in which an end plate is welded to an end of a concrete girder and the fixing plate, and a fixing plate is provided on the fixing plate and an external steel wire is tensioned through a fixing device supported by the fixing plate. An external prestress, wherein at least one or more square struts are provided on an extension of the end plate, and the strut is welded between the end plate and the fixing plate. Fixing device of tip support type for reinforcement method.