KR100951670B1 - Segmental precast prestressed concrete girder and method for constructing the same - Google Patents

Abstract

PURPOSE: A segmental precast prestressed concrete girder and a construction method thereof are provided to obtain clearance between a river cask and a bridge and increase the stability of a unified girder terminal and a segmental girder joint part. CONSTITUTION: A construction method of a segmental precast prestressed concrete girder comprises following steps. A left and a right segment(1,2) and a center segment(3) are manufactured. The left and the right segment are transported to the field. The segments are coupled with each other and are assembled at fixed intervals to spread epoxy. Compression stress is applied on a segment junction surface.

Description

Segmented precast prestressed concrete girder and method for constructing the same}

The present invention relates to a girder for bridges, and more particularly, to increase the stability of the joint between the girder and the integrated girder anchoring end, to secure the clearance in the stream passage and bridge, and to increase the common life of the girder. The present invention relates to a segmented precast prestressed concrete girder and its construction method.

Generally, segmented precast prestressed concrete girder (hereinafter referred to as 'segmental girder') is a single girder divided into several segments and manufactured in a factory or workshop, and then used Prestressed concrete girder is made by joining segments together and installing tension in one longitudinal direction.

Such segmental girder is easy to quality control by factory manufacturing of each segment, and the manufacturing process is all done in the factory except the connection of beam and the introduction of tension force, which can greatly reduce the work air in the field, and short-term instead of the large production site on site Applicability is very good because only a small assembly site is required. However, there are not many cases of application due to vague rejection and lack of reliability of joints.

On the other hand, in the method of joining the joints of segments for the production of segmental girder, in situ segments are placed at regular intervals to connect reinforcing bars and then cast by concrete or mortar, and adhesives such as epoxy on the joining surfaces. There is a contact bonding method of applying a thin and then contact by bonding by introducing a tension force.

Among the above-mentioned methods, in the field casting method, since the concrete or mortar is cast on the joint, the shape of the joint surface of the segment joint does not need to match, but the work of reinforcing the rebar between the segments to be joined and the casting of the concrete And since curing is required, there is a problem that the operation is complicated and the air is long.

On the other hand, the contact bonding method is a method of joining a segment with a pre-fabricated shear key by simply attaching it together without the process of pouring and curing concrete in the field, thereby making the girder significantly shorter than the field casting method. This is economical in terms of cost. In addition, there is a problem that the cross-sectional shape of the joint surface must match each other, but there is no difficulty in manufacturing because it can have a high precision in the characteristics of factory manufacturing. However, because the reinforcing bars are not connected at the joints, the concrete joint surface should be closely adhered to secure the joint surface. Therefore, it takes a separate temporary fixing stage and the tension material for close contact with the joint surface, thereby reducing the above advantages because the tension work is added accordingly.

Hereinafter, the existing prestressed concrete girder related technologies using a contact bonding method will be described.

First, Korean Patent Registration No. 10-0510254 (hereinafter referred to as "prior art 1") is a method of manufacturing a prestressed concrete girder by applying a contact bonding method, each other between the segments to produce a precise joint surface A pair of joint blocks installed to be connected are applied in a matchcasting method, that is, a method of manufacturing one joint block first and then using the pre-fabricated joint block as part of a mold when manufacturing another joint block.

That is, after manufacturing the junction block 100 having a shear key corresponding to one end of the segment at the factory, and using the pre-fabricated junction block as a form part to manufacture the other end junction block 200, the junction block is girder Segment girder segments (10a) (10b) (10c) are manufactured by placing them in the position to be segmented, and transported the fabricated segments to the site, and then assembling between segments in the site, inserting tension material, applying epoxy on the joint surface, introducing tension force, The grouting operation is carried out sequentially, the segment girder 10 is mounted on the alternating and pier, and the bottom plate is placed, cured, and paved to complete the bridge (see Fig. 1 (a) to (bar)). .

On the other hand, Figure 2 is a detailed cross-sectional view of the girder according to the prior art 1, Figure 3 is a view showing the tension member arrangement of the girder according to the prior art 1, Figure 4 is a stress distribution diagram of the lower edge of the girder, prior art 1 By applying match casting method, precise joint surface construction is possible, and the joint block has higher strength than the segment girder body, so the safety of the joint is increased.

However, the above-described prior art 1 has various problems as follows.

That is, in the prior art 1, since the joining block is used as part of the formwork of the other joining block and the formwork end of the segmental girder, since the segmental girder 10 cannot be manufactured without prior construction of the joining block, air is increased, and epoxy is bonded to the joining surface. After application, there is no temporary tension member and anchorage stage to introduce the compressive stress of 0.3MPa at least as suggested in the Concrete Structural Design Standard (Korea Concrete Institute). Since the eccentricity in the transverse direction or in the height direction is very large, the compressive stress is not evenly transmitted to the joint or some tensile stress is likely to be introduced at the joint. In the long run, shear and torsion can cause serious damage to the stability of the bridge.

Looking at the stress acting on the joint surface of the joint for the girder of the prior art 1 as follows.

Here, Yt represents the distance from the neutral axis to the upper edge of the girder, Yb : represents the distance from the neutral axis to the lower edge of the girder, (+) value means compression, and (-) value means tension.

Therefore, in the case of the prior art 1, there is no problem in the case of the lower edge of the girder, but it can be seen that in the case of the upper edge of the girder, tensile stress may occur due to an increase in the amount of eccentricity. In addition, by applying concrete with strength higher than that of the segment girder body, the material is not the same, so it is inevitable to supply additional materials.The concrete joint is subject to tension and shear, so concrete that is very vulnerable to tensile strength is made of high strength. It is skeptical of use. In addition, it is invented only for precision fabrication of joints, and therefore has the disadvantages of general prestressed concrete girders. This is because all anchors are placed at the end and excessive compressive stress is introduced. There is no choice but to be vulnerable to cracking.

In addition, in the case of the prior art 1, the junction block is used as a part of the rejection of the other junction block, or used as a rejection end of the segment girder segment, so that it is impossible to manufacture the segmental girder without prior construction of the junction block. There is a disadvantage that the air is increased.

In addition, after the epoxy is applied to the joint surface, there is no temporary tension member and anchoring stage for introducing a compressive stress of at least 0.3 MPa as presented in the Concrete Structural Design Standard (Korea Concrete Institute). However, this is because the amount of eccentricity in the transverse direction or in the height direction is very large, so that the compressive stress is not evenly transmitted to the joint or some tensile stress is likely to be introduced at the joint, so that the entire cross section of the joint surface is not joined. The stability of the cross section is very poor.

And the lack of reliability of the concrete joint surface can cause serious damage to the stability of the bridge by shear and torsion in the long run.

In addition, the prior art 1 by applying the concrete of the strength higher than the strength of the segment girder body in the manufacture of the junction block, the material of the segment girder body and the junction block is not the same, there is an inevitable separate supply of materials, especially concrete joints Departments are subject to tension and shear, and the use of concrete as a high strength material, which is very susceptible to tensile forces at these joints, is technically insignificant and uneconomical.

In addition, since all the fixing stages are disposed at the end of the girder and excessive compressive stress is introduced, there is a problem in that it is vulnerable to cracking due to acupressure fracture or local tensile stress at the end.

Next, a technique disclosed in Korean Patent Registration No. 10-0334635 (hereinafter referred to as "Prior Art 2") will be described with reference to FIGS. 5 to 8.

5 is a construction sequence diagram of the girder according to the prior art 2, Figure 6 is a detailed cross-sectional view of the joint of the girder according to the prior art 2, Figure 7 is a view showing the tension member arrangement state of the girder according to the prior art 2, Figure 8 Is the stress distribution of the lower edge of the girder.

The technique of the prior art 2 is also a method of manufacturing the prestressed concrete girder 20 by applying a contact bonding method, and transports each segment girder segment 20a, 20b, 20c manufactured in the factory to the site, Connect several segments in the field, but install temporary fixing stage and tension member to introduce the compressive stress of 0.3MPa minimum suggested in the Concrete Structural Design Standard (Korea Concrete Institute), and then apply epoxy to the joint surface to apply tension to the installed tension member. It is brought into close contact with each other (see Fig. 5 (a) to Fig. 5 (c)), which is very effective in ensuring the reliability of the concrete joint surface.

However, it requires a separate temporary settling stage and temporary tensioning material to closely contact the joint surface, and thus the addition and dismantling work of the tension work must be performed in parallel, which is cumbersome in construction and increases the construction cost and air.

In addition, the prior art 2 inherent in the disadvantages of ordinary prestressed concrete girder because it is a technology that is only concerned in the joint of the joint, this is because all the anchoring end is disposed at the end, so that excessive compressive stress is introduced, so that the pressure breakage or localization of the end There is a problem inevitably vulnerable to cracking due to tensile stress.

The present invention is to solve the problems as described above, to increase the stability of the segment girder joint and integrated girder fixing end, and can be produced in the form of the end section lower than the central section to allow the clearance in the stream passage and bridge It is advantageous to provide a segmented precast prestressed concrete girder and its construction method, and precast concrete segments applied to it, which is advantageous for high security, and which can increase the common life of the girder by arranging maintenance tension members. have.

In order to achieve the above object, the present invention, the jack receiving space is accommodated in the jack for the tension force introduction, the first duct for receiving the inner fixing end tension material in communication with the jack receiving space, and for receiving the external fixing end tension material A left segment provided with a shear key for joining a second duct to a joint end of another segment;

A right segment facing the left segment and formed to have the same structure;

A first connection duct and a second connection respectively connected to key grooves provided at both ends of the joint to insert the shear keys of the left segment and the right segment, and the first duct and the second duct for accommodating the tension member for the internal fixing end and the tension member for the external fixing end. A segmented precast prestressed concrete girder is provided, comprising a central segment provided with a duct, wherein each segment is precast.

At this time, the girder of the present invention, to apply the tension to the joint surface of the center segment and the left and right segments, the inner fixing end tension member is installed in the first duct to be equally bonded and the first to apply the tension force to the bonded girder as a whole It is characterized in that it further comprises a tension member for external mounting stage is installed in the two ducts.

And, each end of the left segment and the right segment forms a lower shape than the central cross-section, characterized in that the lower side of the lower end is further provided with a preliminary duct for accommodating the maintenance tension material.

And, the bottom surface of the jack accommodation space provided in the left segment and the right segment is characterized in that the structure inclined downward from the outside toward the inside.

And, the inner fixing end of the left segment and the right segment is characterized in that it is located near the center of the cross section of the segment.

On the other hand, according to another aspect of the present invention for achieving the above object, it is provided with a jack receiving space for the tension force introduction and the left and right segments having an internal shear key in the joint and a key groove corresponding to the front and rear keys of the left and right segments are installed therein. Factory manufacturing a central segment;

Transporting the left and right segments and the central segment to the site;

Assembling the left and right segments and the central segment to each other in the field, but at intervals for applying epoxy to the joint surface;

Introducing a compressive stress to the mating surfaces of the left and right segments and the center segment;

Segmental precast prestressed concrete girder construction, comprising the step of introducing a compressive stress for the segment girder integrated to overcome the deflection of the girder and cracks that may occur during the main load under the integrated girder A method is provided.

The construction method further comprises the steps of mounting the segment girder in which the compression force is introduced to the alternating and piers, performing the bottom plate placing and curing, and performing a packaging operation.

The step of introducing a compressive stress to the joint surface of the left and right segments and the center segment, the step of inserting the inner fixing end tension member in the first duct for accommodating the inner fixing end tension member, and the step of tensioning the inner fixing end tension member; It is characterized by including.

The tension of the inner fixing end tension member is characterized in that it is made by a jack installed in the jack receiving space respectively formed in the left and right segments.

The step of introducing the compressive stress to the segment girder, characterized in that it comprises the step of inserting the external fixing end tension member in the second duct for accommodating the external fixing end tension member, and the step of tensioning the external fixing end tension member. .

According to the present invention, after applying epoxy to the joint surface, the temporary tension member and the fixing end for introducing a compressive stress of at least 0.3 MPa presented in the Concrete Structural Design Standard (Korea Concrete Institute) are excluded, Initial tension by using a short tension member in the installed internal fixation stage distributes the compressive stress evenly to the joint, thus realizing uniform joint.

Next, according to the present invention, it is possible to introduce a stepped tension corresponding to the moment shape by arranging the fixing unit inside and outside, so that excessive compressive stress is not introduced into the fixing stage, thereby ensuring safety against cracking due to acupressure or local tensile stress. It can be increased.

Further, according to the present invention, since all the fixing stages are not disposed at the end, the number of end-side fixing apparatus can be reduced, so that the utility of the cross section is increased, so that the height of the cross-section is lower than that of the central cross-section, and thus the lower fixing cross section is provided. Since additional tension members can be placed, it is possible to increase the common life of the girders by installing maintenance tension members.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

9 is a construction flowchart of a segmented precast prestressed concrete girder according to the present invention, Figure 10 is a detailed view of the cross-section partial cutaway of the left or right segment according to the present invention, Figure 11 is a view of the center segment according to the present invention 12 is a partial cross-sectional cutaway view of the joint, and FIG. 12 is a view showing a tension member arrangement state of the girder according to the present invention, and FIG. 13 is a stress distribution diagram of the lower edge of the girder according to the present invention.

Referring to these figures, the segmental girder of the present invention comprises a left segment 1, a right segment 2 and a center segment 3, wherein each segment is precast, i.e. factory manufactured. .

Here, the left segment (1) is a jack receiving space (10) for receiving the jack for tension force introduction, and the first duct (11) for accommodating the inner fixing end tension member (4) in communication with the jack receiving space (10) ), A second duct 12 for accommodating the tension member 5 for the external fixing end, and a shear key 13 for joining the joint ends of the other segments.

The right segment 2 is formed to face the left segment 1 but to form the same structure. That is, the right segment 2 also has a jack accommodation space 20 in which a jack for introducing a tension force is accommodated, and a first duct 21 for accommodating the internal fixing end tension member 4 communicating with the jack accommodation space 20. And a second duct 22 for accommodating the tension member 5 for the external fixing end, and a shear key 23 for joining the joint ends of the other segments.

The jack accommodation spaces 10 and 20 of the left segment 1 and the right segment 2 are formed in the upper surface of each segment.

On the other hand, the center segment (3) is a key groove 33 is provided on both ends of the joint so that the front end key 13, 23 of the left segment (1) and the right segment (2), and the internal fixing end tension member (4) And a first connection duct 31 and a second connection duct 32 communicating with the first duct 11 and the second duct 22 for accommodating the external tension fixing member 5, respectively.

In addition, the first ducts 11, 21 and 31, which are connected to each other to be equally bonded by applying a tension force to the joint surface of the center segment 3 and the left and right segments, are provided with an internal fixing end tension member 4, In order to apply tension to the bonded girders as a whole, the interconnected second ducts 12, 22 and 32 are provided with external tensioning tension members 5.

At this time, the inner fixing end 7 of the left segment 1 and the right segment 2 is located near the center of the cross section of the segment. Reference numeral 9 denotes an external mounting stage.

On the other hand, each end of the left segment (1) and the right segment (2) forms a lower shape than the central cross-section, the cut end is provided with a preliminary duct (8) for receiving the maintenance tension member (6) do.

In addition, the bottom surface of the jack accommodation space (10) 20 provided in the left segment (1) and the right segment (2) forms a structure inclined downward from the outside to the inside.

The construction process of the present invention segmented girder is configured as follows.

First, the center segment (3) having left and right segments (1) and (2) having inner shear keys (13) and (23) at the joint portion and key grooves (33) corresponding to the shear keys (13) and (23) respectively installed therein. Manufacture factory. At this time, on the upper surface of the left and right segments (1) and (2), jack accommodation spaces 10 and 20 for jack accommodation are respectively formed.

Next, when the factory manufacturing is completed, the precast left and right segments (1) and (2) and the center segment (3) are carried to the site.

In the field, the left and right segments (1) and (2) and the center segment (3) are assembled to each other but spaced apart for the epoxy coating on the joint surface.

Then, the inner fixing end tension member 4 is inserted through the first ducts 11, 21, 31 of the assembled girder and connected to the joining surfaces of the left and right segments 1, 2 and the center segment 3, respectively. Epoxy (not shown) is applied.

Subsequently, the jacks are installed in the jack accommodation spaces 10 and 20 of the left segment 1 and the right segment, respectively, and the inner fixing end tension member 4 is tensioned through the jacking action of the jack (not shown). Compression stress is introduced to the joint surfaces of the segments (1) (2) and the center segment (3).

At this time, according to the present invention, since the tension member 4 for internal fixation ends passes through the center of the joint surface between the segments, the compressive stress is introduced evenly against the joint surface initially.

After joining and integrating each segment (1) (2) (3) as described above, compressive stress for preventing cracks that may occur during deflection and main load load of the girder as a whole for the integrated girder is obtained. Will be introduced.

To this end, the external traction end tension member 5 is inserted into the second duct 12, 22 and 32 for accommodating the external tension end tension member 5, and then the jacks are installed at the left and right sides of the integrated segment girder. Using the jacking action to tension the external fixation end tension material (5).

As described above, after the compressive force is introduced to the entire segment girder, the segment girder with the compressive force is introduced into the alternating and piers, and the bottom plate is placed and cured, followed by pavement to complete the construction. do.

According to the present invention configured and constructed as described above will exhibit various advantages as follows.

First, according to the present invention, the quality control is well made through the factory production of each segment constituting the segment girder, there is an advantage to escape from the constraints on the production site.

That is, the present invention uses a variety of construction equipment at the temporary site after precisely manufacturing the bridge superstructure (segmental precast prestressed concrete girder) segmented to a certain length by precisely producing a uniform quality through the factory production of the segment constituting it By completing the upper structure by sequentially connecting the pre-stress by post-tension, quality control is made easily, and can be freed from the constraints of on-site production.

Next, the present invention distributes the compressive stress evenly to the joint by initial tension using a short tension material at the inner fixing end installed in the center of the cross section while being located near the joint when connecting each segment constituting the segment girder. There is an advantage that can be realized evenly.

That is, since the initial tension is carried out by the tension member for internal fixation stage (4) there is no tension force of the external anchorage stage. In this case, the stress acting on the joint surface of the joint is as follows.

Here, Yt represents the distance from the neutral axis to the upper edge of the girder, Yb : represents the distance from the neutral axis to the lower edge of the girder, (+) value means compression, and (-) value means tension.

Since the internal fixation end subjected to the initial tension in the above equation is close to the neutral axis of the cross section, the amount of eccentricity has a value close to "0" (refer to the joint drawing along the section B-B in FIG. 12).

Therefore, the above equation can be modified as follows by assuming that the amount of eccentricity is "0".

Therefore, evenly distributed compressive stress can be achieved on the joint surface, so that even bonding can be realized.

In addition, since the present invention enables the introduction of a stepped tension force corresponding to the moment shape by disposing the fixing part inside and outside (see FIG. 13), excessive compressive stress is not introduced into the fixing end, so that it is not cracked due to acupressure or local tensile stress. There is an advantage that the safety is increased.

In addition, the present invention has a structure in which not all the fixing end is arranged on the end side of the segment girder, so that the number of end-side fixing device can be reduced, thereby increasing the usability of the cross-section, so that it can be manufactured in a lower shape than the central cross section. Therefore, the additional tension member can be placed on the lower side of the lower side of the lower edge, so that the maintenance tension member can be installed to increase the common life of the girder. Also advantageous.

Meanwhile, the present invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the scope of the technical idea of the present invention.

Accordingly, the rights of the present invention are not limited to the embodiments described above, but are defined by what is stated in the claims, and those skilled in the art can make various modifications and adaptations within the scope of the claims. It is self evident.

According to the present invention, it is possible to increase the stability of the segmental girder joint and the integrated girder fixing end, and to produce the end section in a shape lower than that of the central section, so that it is advantageous to secure the clearance in the stream passages and bridges, and for maintenance. The possibility of industrial use is very high because the tension can be arranged to increase the service life of the girder.

1 is a construction flowchart of the girder according to the prior art 1

Figure 2 is a partial cross-sectional view of the joint of the girder according to the prior art 1

Figure 3 is a view showing a tension member arrangement state of the girder according to the prior art 1

4 is a stress distribution diagram of the lower edge of the girder according to the prior art 1

5 is a construction sequence diagram of the girder according to the prior art 2

6 is a partial cross-sectional view of the joint of the girder according to the prior art 2

Figure 7 is a view showing a tension member arrangement state of the girder according to the prior art 2

8 is a stress distribution diagram of the lower edge of the girder according to the prior art 2

9 (a) to (e) is a construction flowchart of the segmented precast prestressed concrete girder according to the present invention

10 is a detailed view of the partial cross-section of the joint of the left or right segment according to the present invention.

11 is a detailed view of the partial cross-section of the joint of the central segment according to the present invention

12 is a view showing a tension member arrangement state of the girder according to the present invention.

13 is a stress distribution diagram of the lower edge of the girder according to the present invention

Explanation of symbols on the main parts of the drawings

1: left segment 2: right segment

3: central segment 10, 20: jack accommodation space

11, 21, 31: 1st duct 12, 22, 32: 2nd duct

13, 23: shear key 33: key groove

4: tension member for internal fixation 5: tension member for external fixation

6: Maintenance tension material 8: Spare duct

Claims (11)

A jack accommodation space accommodating the jack for tension force reception, a first duct for accommodating the tension member for the internal fixation stage communicating with the jack accommodation space, a second duct for accommodating the tension member for the external anchorage end, and a joint end of another segment A left segment provided with a shear key for bonding; A right segment facing the left segment and formed to have the same structure; A first connection duct and a second connection respectively connected to key grooves provided at both ends of the joint to insert the shear keys of the left segment and the right segment, and the first duct and the second duct for accommodating the tension member for the internal fixing end and the tension member for the external fixing end. Segmental precast prestressed concrete girder, comprising a central segment provided with a duct, wherein each segment is precast. The method of claim 1, A tension member for the internal fixing end installed in the first duct to apply an even force to the joint surface of the center segment and the left and right segments so as to be equally bonded; Segmental precast prestressed concrete girder, characterized in that it further comprises a tensioning material for the external mounting stage is installed in the second duct to apply the tension to the bonded girders as a whole. The method of claim 1, Segmental precast prestressed concrete girder, characterized in that each end of the left segment and the right segment form a lower shape than the central cross-section. The method of claim 1, Segmental precast prestressed concrete girder, characterized in that the preliminary duct for accommodating the maintenance tension material is provided in the lower end surface of the left segment and the right segment. The method of claim 1, Segmental type precast prestressed concrete girder, characterized in that the bottom surface of the jack accommodation space provided in the left segment and the right segment has a structure inclined downward from the outside to the inside. The method of claim 1, Segmental precast prestressed concrete girder, characterized in that the inner fixing end of the left segment and the right segment is located near the center of the cross section of the segment. Manufacturing a center segment including a left and right segment having an internal shear key in the jack receiving space and a joint for introducing a tension force, and a central segment having a key groove corresponding to the shear key of the left and right segments; Transporting the left and right segments and the central segment to the site; Assembling the left and right segments and the central segment to each other in the field, but at intervals for applying epoxy to the joint surface; Introducing a compressive stress to the mating surfaces of the left and right segments and the center segment; Segmental precast prestressed concrete girder construction, comprising the step of introducing a compressive stress for the segment girder integrated to overcome the deflection of the girder and cracks that may occur during the main load under the integrated girder Way. The method of claim 7, wherein The construction method, Mounting the girder with compression force on the alternating and piers, Performing the bottom plate pouring and curing, Segmental precast prestressed concrete girder construction method further comprising the step of performing a paving operation. The method of claim 7, wherein Introducing compressive stress to the joint surface of the left and right segments and the center segment, Inserting the internal fixation end tension material into the first duct for accommodating the internal fixation end tension material, Segmental type precast prestressed concrete girder construction method comprising the step of tensioning the tension member for internal fixation. The method of claim 9, The tension of the internal fixing end tension member is a segment type precast prestressed concrete girder construction method characterized in that the jack is installed in the jack receiving space respectively formed in the left and right segments. The method of claim 7, wherein Introducing a compressive stress as a whole for the segment girder, Inserting the external anchoring tension member into the second duct for accommodating the external anchorage tension member; Segmental type precast prestressed concrete girder construction method comprising the step of tensioning the tension member for external fixing stage.

Images