JP2018025494A - Method for testing fire-resistance of segment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for testing the fire-resistance of a segment which can desirably conduct a test of the fire-resistance.SOLUTION: A test piece of a segment is a pre-stressed concrete test piece 1. The test piece 1 is formed by setting a reinforcement plate 2 on a fixing surface of a PC steel material in an end of the test piece 1 so that the plate 2 will overlap with a pressure supporting plate, the reinforcement plate 2 having a reinforcement stud dowel 3 buried in concrete attached thereto, and by forming a cracking reinforcement steel 6 near the end in a vertical direction and a horizontal direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fire resistance test method for a segment.

  In the actual fire resistance performance verification test (segment fire resistance test) of the segment used for tunnel lining, the RABT60 heating curve (road tunnel specified by the German Ministry of Transport guidelines) while applying the design cross-sectional force acting on the actual tunnel It is a fire curve that assumes a vehicle fire inside the building. Heating is more severe than heating assuming a general building fire in which the temperature is raised to 1200 ° C in 5 minutes after the start of heating and is gradually cooled after being held for 60 minutes. Heating based on (condition), and confirming that the temperature of the site of interest is below the allowable temperature, and that there is no excessive deformation or explosion (see, for example, Patent Document 1).

  In addition, as a method of introducing a desired axial force and bending moment into a segment during a test, conventionally, axial force is applied by tensioning a PC steel rod, and a bracket attached to the segment is pressed with a hydraulic jack. A bending moment is applied.

JP 2008-286593 A

  On the other hand, in recent years, the tunnel cross-section has been increased in size, and accordingly, the size of the segment specimen (test specimen) used in the full-scale fire resistance test has increased, and the axial force and bending moment to be introduced have increased. In addition, there is a need for a force application method that can handle both positive and negative bending.

  For this reason, in conducting the actual fire resistance performance confirmation test of the segment, there is a problem that the refractory furnace that can burn large specimens is limited, and the equipment (brackets, jacks) for introducing power is large and expensive. The problem of becoming.

  In view of the above circumstances, an object of the present invention is to provide a segment fire resistance test method capable of suitably performing a fire resistance test.

  In order to achieve the above object, the present invention provides the following means.

  The segment fire resistance test method according to the present invention is such that a test piece of a segment is a prestressed concrete test piece, and the test piece is provided with a reinforcing plate to which a reinforcing stud diver embedded in concrete is attached. The steel plate is formed by being installed on the fixing surface of the steel material so as to overlap the bearing plate, and split reinforcing bars are provided on the end side in the vertical direction and the horizontal direction, respectively.

  In the segment fire resistance test method of the present invention, it is possible to conduct a fire resistance test using an inexpensive and compact test specimen.

It is sectional drawing which shows the test body which concerns on one Embodiment of this invention. It is the X1-X1 arrow view figure of FIG. FIG. 2 is an X2-X2 arrow view of FIG. 1. It is the X3-X3 line arrow directional view of FIG. It is the X4-X4 line arrow figure of FIG. It is a front view which shows an edge part reinforcement plate. It is a side view which shows an edge part reinforcement plate. It is a front view which shows a side reinforcement plate. It is a side view which shows a side reinforcement plate. It is a conceptual diagram of the stress distribution (horizontal direction) of a test body. It is a figure which shows the civil engineering society fixing tool performance test method. It is a figure which shows an analysis model. It is a figure which shows an analysis result. It is a figure which shows the reinforcement object range. It is a figure which shows the relationship between bead width and throat thickness. It is a figure which shows the shape of a welded joint.

  A segment fire resistance test method according to an embodiment of the present invention will be described below with reference to FIGS.

  Here, the present embodiment relates to a fire resistance test method for a segment used for tunnel lining, and in particular, devise the shape of a test specimen (specimen) of a segment and a desired axial force and eccentricity by introducing tension of PC steel. The present invention relates to a method for suitably performing a fire resistance test using an inexpensive and compact segment specimen.

  And when the segment specimen is a prestressed concrete specimen and an inexpensive and compact specimen is used, it is necessary to design a specimen that takes into account the effect of temperature rise during the fire resistance test and the soundness of the fixing part. . In other words, in an ordinary prestressed concrete anchoring portion, it is not possible to satisfy a marginal arrangement determined from the relationship between the specimen size and the introduction force in order to reduce the specimen size. For this reason, the fixing unit needs special reinforcement for applying a large force to a narrow area.

  As described above, in order to conduct a fire resistance test using a compact test body, it is important to set / establish an optimal arrangement of PC steel materials and a method for reinforcing local stress.

  And the following 3 points | pieces are mentioned as an important point of reinforcement for using a compact test body.

1-1) Ensuring the amount of eccentricity necessary to reproduce the cross-sectional force.
1-2) Do not allow the segment main bars to interfere with PC steel.
1-3) Not excessively affected by temperature rise.

  In order to satisfy these three conditions, the inventors of the present application have found that it is necessary to study the following 2-1) to 2-7) (test body: FIGS. 1 to 5, Supporting plate: see FIG. 6 and FIG. 7, side reinforcing plate: see FIG. 8 and FIG.

2-1) The bearing plate attached to the end of the test body 1 is enlarged to increase the area to which the bearing pressure is applied.

2-2) In order to relieve local bearing stress due to deformation of the bearing plate, the plate thickness is partially increased.

2-3) The reinforcing plate 2 is installed on the fixing surface (end portion) of the test body 1 and the stud gibel 3 is installed on the reinforcing plate 2 to alleviate the concentration of the bearing stress.

2-4) In order to compensate for the shortage of the edge distance on the side surface, the side surface reinforcing plate 4 and the reinforcing stud dowel 3 are installed.

2-5) The split reinforcing bars 6 are D16 × 4 (φ40 mm specification) per location in both the vertical and horizontal directions to secure a fixing length equivalent to the grid bars.

2-6) Where the fixing length of the split reinforcing bar 6 cannot be taken, the reinforcing stud gibber 3 and the split reinforcing bar 6 are welded.

2-7) The split reinforcing bars 6 are arranged in the design cover of the segment, giving priority to the reinforcing effect.

  And the inventors of this application work on earnest research about the point of 2-1)-2-7), and take the countermeasure of 2-1 ')-2-7'), and 1-1)-1- It was found that the three conditions of 3) can be satisfied.

2-1 ') A 40 mm thick reinforcing plate 2 is installed on the fixing surface of the test body 1. Note that the thickness of the reinforcing plate 2 is not necessarily limited to 40 mm.

2-2 ') In addition to 2-1'), a standard size bearing plate (partially custom-made) is placed on the fixing part of the PC steel bar.

2-3 ') A stud gibber (D19-150 mm) 3 is installed on the reinforcing plate 2 of 2-1'). Further, the end face stud gibel 3 is arranged as a precaution, and the arrangement amount is determined in consideration of workability such as fillability.

2-4 ') The side reinforcing plate 4 is t = 12 mm, and the stud dowel 3 of D19-150 mm is arranged. The stud gibel 3 is installed at the reinforcing bar position in order to combine the side reinforcing plate 4 and the fixing portion of the horizontal reinforcing bar 6.

2-5 ′) The vertical reinforcing bars 6 are arranged in the vicinity of 200 mm from the end face where the splitting stress is maximized with the amount of D16 × 4 reinforcing bars. The horizontal reinforcement bars 6 are arranged in the same manner as the vertical direction in the D19 × 4 pieces having the same diameter as the stud gibber 3.

2-6 ′) The horizontal reinforcing bar 6 and the reinforcing stud dowel 3 are welded to flare welding with a throat thickness of 8 mm (L = 60 mm). The flare weld length of the horizontal split reinforcement 6 at the axial force introduction portion is determined based on the “Rebar fixing / joint guideline (2007 version: Japan Society of Civil Engineers)”.

2-7 ') The minimum pure fog of the reinforcing bar 6 near the end is 25 mm (maximum aggregate size 20 mm + 5 mm). Since the hot steel bar may adversely affect (explode) the concrete due to temperature rise, heat-curing is performed on the surface, and the reinforcing bar 6 and the reinforcing stud 3 placed in the cover have a thermal effect. Take no measures.

  As described above, the inventors of the present invention use a pre-stressed concrete test specimen as a segment test specimen, and even when using an inexpensive and compact test specimen, the target cross-sectional force can be safely and reliably set to the segment test specimen. It was confirmed that the reinforcing part and the PC steel material were sound both at the time of introduction of the tension force and at the time of the fire resistance test, and the test specimen could be suppressed to the minimum necessary.

  As a result, according to the segment fire resistance test method of the present embodiment, it is possible to accurately perform a fire resistance test using an inexpensive and compact test body, and reduce the cost required for the actual large-scale shield segment fire resistance test. It becomes possible to do.

  Here, the content of the examination regarding the actual fire resistance performance confirmation test of the PC (pre-stressed concrete specimen (segment)) actually performed will be specifically described below.

  In the examination of the actual large-scale fireproof performance confirmation test, heating is performed based on the RABT60 heating curve while giving the design cross-sectional force acting in the actual tunnel to the test specimen of the segment, and the temperature of the focused part is lower than the allowable temperature. It was confirmed that there was no excessive deformation or explosion.

  Moreover, reproduction of the design cross-sectional force (axial force, bending moment) in service was performed by introducing prestress using a PC steel rod.

  Below, the grounds for setting the introduction tension (prestress amount) are shown, and the results of the examination on the arrangement of the PC steel bars and the reinforcing method of the fixing portion are shown.

[Preliminary examination of introduction tension (PC steel bar diameter) setting]
First, the preliminary examination of the introduction tension (PC steel rod diameter) setting will be described.

The specification of the PC steel material was a commercial product and a general PC steel bar “Type B No. 2” having a high tensile strength. Since the prestress loss due to relaxation at high temperature is large, class B having high tensile strength was used.
Table 1 shows the specifications of the PC steel bar used in this study.

[PC steel stress limit value]
Next, the limit value of the stress degree of the used PC steel will be described.

  In examining the arrangement and number of PC steel materials, the limit values of the PC steel material stress degree were set as follows.

3-1) Stress degree immediately after pre-stress: 0.85σ _py = 790 N / mm ²
3-2) 90% of the stress level during pre-stress (effective coefficient: see 2.4)): 0.90σ _py × 0.9 = 753 N / mm ²
3-3) 0.7 times the yield stress level: 0.70σ _py = 651 N / mm ²

  In addition, since the test body of this test is temporary, it was set as 3-1) as a limit value. Further, since the effective diameter is as large as 0.9 due to the increase in relaxation due to the temperature rise, 3-2). Furthermore. In addition to 3-1) and 3-2), the negative bending specimen PC steel (with grout) placed at 175mm from the heating surface is considered in the fire resistance test, taking into account the rapid expansion of the concrete surface exposed to fire. 3-3) was set as the limit value.

[Examination of fire resistance]
Next, examination of fire resistance will be described.

  In this test, the design cross-sectional force is reproduced by introducing prestress using a PC steel bar. The PC steel material arranged near the heating surface or the gripping hardware is affected by heat. The accuracy and safety of the test are ensured by grasping the heat-influencing characteristics of PC steel and determining the arrangement in the temperature range where the physical properties of PC steel do not change.

Here, general PC steel has the following thermal characteristics.
4-1) Relaxation increases (changes with temperature and heating time).
4-2) When the tensile strength exceeds 300 ° C., the tensile strength rapidly decreases and reaches about 50% of the normal temperature at 500 ° C.
4-3) The yield point is about 75% at 350 ° C. and about 30% at 500 ° C.

  As described above, when the PC steel reaches 300 ° C., both strength (tensile / yield) and elastic modulus rapidly decrease. Therefore, in this test, the arrangement is set so that the temperature rise of the PC steel is 150 ° C. or less.

  Then, based on the actual product of the realization field, grasp the thermal characteristics that will be the placement policy of the PC steel, and in this realization field test result, the temperature rise of the 130 mm rebar from the heating surface was about 150 ° C. In the test, the minimum distance from the heating surface to the PC steel centroid was set to 175 mm. Also, cement grout was carried out on the PC steel bar whose distance from the heating surface was 175 mm.

  Further, in the test results of the realization field, since the temperature rise of the main bars near the holding metal 250 mm from the heating surface was about 150 ° C., it was decided to secure a clearance of 50 mm or more between the holding metal and the PC steel material.

[Examination on PC steel placement]
Next, the examination about PC steel material arrangement | positioning is demonstrated.

First, the minimum center distance and the minimum edge distance of the PC steel material fixing portion will be described.
In designing the PC fixing portion, it must be designed so that the bearing load failure and the lateral splitting failure of the concrete do not occur against the tension force considered in the design. Each fixing method shows the minimum arrangement interval of fixing tools, the minimum edge distance, the diameter and the number of split reinforcing bars.

  In addition, since there is nothing publicly shown about the arrangement of the fixing tool and the amount of split reinforcement for the general PC steel bar (φ40), in “3.3) Examination on the arrangement of PC steel bar (φ40 mm)” The required minimum center distance, minimum edge distance, and split reinforcement strength were calculated by FEM analysis.

[Placement of PC steel]
And the examination content and examination result regarding arrangement | positioning of PC steel bar (phi 40mm) are as follows.

First, the concept of stress distribution on the back surface of the fixing unit is shown in FIG.
In general, the back surface of PC fixing parts is reinforced with grid bars to prevent splitting, but for general PC steel bars (φ40), split reinforcement bars, etc. in the design and construction manual for fixing parts determined by each manufacturer There is no provision for structural details. The NEXCO design guideline stipulates that the amount of reinforcement is determined by FEM analysis or the like in the design of the fixing protrusion, and the amount of split reinforcement on the back surface of the fixing portion was also obtained by FEM analysis in this study. As a result, four reinforcing bars D16 per section of the fixing portion 1 were used.

  The size of the FEM model is the size of the specimen (one side is twice the minimum edge distance) according to the fixing tool performance test method in the “Prestressed Concrete Construction Design Guidelines (Japan Society of Civil Engineers)” (see FIG. 11). The height was 4 times the minimum edge distance).

  The minimum edge distance (minimum steel interval) for general PC steel bars (φ40) is the value for φ26, φ32, and φ36 steel rods shown in the “Dividark Method Design and Construction Manual” because there is no guideline to define this. Estimated from

Table 2 shows the minimum edge distance of the PC steel bar (φ40).
The elements of the FEM model are all solid, with 5460 nodes and 4700 elements. A model outline diagram and an FEM model diagram are shown in FIG.
Table 3 shows a list of analysis conditions.

The analysis results are shown in FIG. 13 as a Y-direction direct stress contour diagram (Y-axis direction central section). The contour range is 0 to 5 N / mm ² (positive is tensile).

  Based on this, the reinforcement range and split reinforcement amount are set as follows.

[Reinforcement range]
As shown in FIG. 14 (and FIG. 13), an allowable value of the concrete tensile stress is determined, and a range where a tensile stress higher than that is generated is defined as a reinforcing range.

Concrete compressive strength during tension is F _ck ′ = 30 N / mm ² , and concrete tensile strength during tension is F _TK = 0.23 × F _ck ^2/3 (Concrete Standard Specification, Design) = 2.22 N / mm ² .

When it is desired to prevent cracking, the safety factor against cracking is n = 1.85 (Standard Specification for Concrete, Design), and the allowable value of concrete tensile stress considering safety factor n = 1.85 is σ = F _TK / n = the ^{0.22 / 1.85 = 1.20N / mm 2} .

[Amount of split reinforcement]
Since the analysis model is symmetrical in the cross section, only half (left) is considered. Table 4 shows the tensile stress σy (N / mm ² ) in the reinforcing range, and Table 5 shows the element area A (mm ² ) corresponding to the tensile stress σy.

  The tensile stress generated in the reinforcing range is calculated by integrating the tensile stress generated in the reinforcing range with the element area. Divide the tensile force by the split reinforcement amount and confirm that the allowable reinforcing bar tensile stress is satisfied. The allowable reinforcing bar tensile stress was the value shown in the fixing part design section of the NEXCO design guideline.

The allowable rebar tensile stress is σ _sa = 120 N / mm ² (SD345), the tensile force generated in the reinforcement range is Σ (σ _y · A) = 81511 N, and the split reinforcement strength (D16, 4) is A _s = 198. 6 × 4 = 794.4mm ^2, and, rebar tensile stress will be ^{_{σ s = 81511 / 794.4 = 102.6N}} / mm 2 <120N / mm 2 ··· OK.

[Placement of PC steel]
From the above results, the following can be said with respect to the arrangement of the PC steel bars (φ40 mm).

5-1) The minimum center distance may be 200 mm.
5-2) The minimum edge distance may be 310 mm.
5-3) The amount of split reinforcement is 680 m ² (about D16 × 4) or more per location.
5-4) The reinforcement range (position) is appropriately 200 mm or more from the bearing surface.

And the number and arrangement | positioning of PC steel materials should just determine according to the following policies in addition to "the grounds for setting introduction tension | tensile_strength (PC steel rod diameter)" and "examination about PC steel material arrangement | positioning".
Tables 6 and 7 show the PC steel material introduction axial force (the basis for determining the diameter and number).

6-1) Use diameters of PC steel are four types of 26 mm, 32 mm, 36 mm, and 40 mm.
6-2) The generated stress level of the PC steel material is set equal to or less than the “limit value of the PC steel material stress level”.
6-3) The diameter of the PC steel rod is set to the necessary minimum diameter that is closest to “0.7 times the yield stress degree” (the elongation amount is increased).

  The policy for determining the placement of PC steel is as follows.

7-1) Prioritize the placement of structural reinforcing bars in the segment.
7-2) The arrangement in the height direction is based on the centroid, the eccentricity 150 mm (negative bending), and the eccentricity 450 mm (positive bending).
7-3) As a rule, the minimum center distance and the minimum edge distance shown in the study on PC steel material arrangement are secured.
7-4) The distance between the centers of the negative-bending PC steel bars is set to 380 mm in consideration of the thermal effect of the gripping hardware (negative-bending specimen).
7-5) The distance between the centers of the axial force PC steel bars is 290 mm (reinforcement required) in consideration of the thermal effect of the gripping metal (negative bending specimen) and the hanging jig insert.
7-6) Based on the space required for tightening the nut and jack set of the negative bending test specimen (PC steel rod φ40), the minimum physical center distance is set to 115 mm (reinforcement required).
7-7) Ensure that the side edge distance is at least 100 mm (reinforcement required).

[Reinforcement policy and method]
Next, the reinforcement policy and the reinforcement method will be described.

  As described above, the arrangement of the PC steel bars of the test specimen is determined with emphasis on 1-1), 1-2), and 1-3).

1-1) Ensuring the amount of eccentricity necessary to reproduce the cross-sectional force.
1-2) Do not allow the segment main bars to interfere with PC steel.
1-3) Not excessively affected by temperature rise.

For this reason, the fixing | fixed part which does not satisfy the minimum center space | interval and minimum edge distance which were shown in "examination regarding PC steel-material arrangement | positioning" arises.
Case-1 and Case-2 will be described as an example. In Case-1, the upper edge distance 125 mm of the positive bent PC steel rod does not satisfy the minimum edge distance 137.5 mm of φ32. In Case-2, the center interval 115 mm, the side edge distance 100 mm, and the lower surface edge distance 175 mm of the negative bending PC steel rods do not satisfy the minimum center distance 310 mm and the minimum edge distance 200 mm of φ40.

  By the way, the minimum arrangement size of the PC steel bar indicated in the construction standard (catalog) is determined by the destructive test using the bearing plate of the standard size (Prestressed Concrete Method Design and Construction Guidelines (JSCE)) Test method).

As described above, since there is a fixing portion that cannot satisfy the minimum arrangement dimension, in this test (the fire resistance test method for the segment of the present embodiment), the bearing stress level (split stress level) of the concrete is determined as the above destructive test. In order to make it equal or less, as described above, reinforcement was carried out under the policies of 2-1) to 2-7).
In consideration of test reliability and work safety, the amount of reinforcement is determined assuming the most severe PC steel rod φ40 mm, and applied to all locations.

2-1) Enlarge the bearing plate and increase the area where the bearing pressure is applied.
2-2) Partially increase the plate thickness to relieve local bearing stress due to plate deformation.
2-3) Install stud gibels on the support plate to reduce the concentration of support stress.
2-4) In order to make up for the shortage of the edge distance on the side surface, install a side plate and a reinforcing stud dowel.
2-5) The split reinforcing bars are D16 × 4 (φ40mm specification) per location in both the vertical and horizontal directions, and a fixing length equivalent to the grid bars is secured.
2-6) At locations where the fixing length of the split reinforcing bar cannot be obtained, weld the reinforcing stud gibber and the split reinforcing bar.
2-7) Placing reinforcing bars in the design cover of the segment gives priority to the reinforcing effect.

  As a specific reinforcing method, as described above, 2-1 ') to 2-7') are performed (see FIGS. 1 to 9).

2-1 ') A 40 mm thick reinforcing plate is installed on the fixing surface of the specimen.
2-2 ') In addition to 2-1'), a standard-size bearing plate (partially custom-made) is installed on the fixing part of the PC steel bar.
2-3 ′) A stud gibber (D19-150 mm) is installed on the reinforcing plate of 2-1 ′). Since the end stud gibber is arranged as a precaution, the arrangement amount is determined in consideration of workability such as fillability.
2-4 ′) The side plate is t = 12 mm and a D19-150 mm stud gibber is arranged. The stud gibber is installed at the reinforcing bar position in order to combine the plate and the fixing part of the horizontal reinforcing bar.
2-5 ′) The vertical reinforcing bars are arranged in the vicinity of 200 mm from the end face where the splitting stress is maximized with the amount of D16 × 4 reinforcing bars. The horizontal reinforcing bars are arranged in the same manner as the vertical direction with D19 × 4 having the same diameter as the stud gibber.
2-6 ′) Flare welding with a throat thickness of 8 mm (L = 60 mm) is used for welding of the horizontal reinforcing bar and the reinforcing stud dowel. The flare weld length of the horizontal split reinforcement in the axial force introduction part was determined based on the “Rebar fixing / joint guideline (2007 version) (Japan Society of Civil Engineers)”.
2-7 ′) The minimum pure fog of the reinforcing bars near the end is 25 mm (maximum aggregate size 20 mm + 5 mm). Because the hot steel bar may adversely affect (explode) concrete due to temperature rise, heat-curing is performed on the surface, and measures to prevent the thermal effect on the reinforcing bars and studs placed in the cover Take.

[Flare welding length]
Here, the details of the examination of the flare welded joint length between the stud and the horizontal rebar in 2-6 ′) will be described.

  The flare weld length of the horizontal split reinforcement in the axial force introduction part was determined based on the “Rebar fixing and joint guideline (2007 version: Japan Society of Civil Engineers)”.

A welding material having a tensile strength of 490 N / mm ² is used.

From the relationship of shear strength τ = tensile strength σ / √3, the design shear strength of the weld is τ = 490 / √3 = 282.9 N / mm ² .

Here, the design throat thickness in strength calculation is a ≧ 0.39φ−e = 0.39 × 19−3 = 4.41. A minimum throat thickness of a = 8.0 (> 4.41) mm is secured from the bead width w = 9.5 mm (≧ φ / 2) (FIG. 15), the strength reduction due to on-site welding is 0.9, and a temporary structure Using 1.25 as the safety factor of the object, the weld length is calculated below.
Weld length = 60 mm (≧ 286.5 × 345 / (8.0 × 282.9 × 0.9 × 1.25) + 2 × 19.0 / 2)

  In addition, the guide is welded by leaving about 20 mm at both ends of the welded portion as a margin length. Therefore, the wrap length is 100 mm (= 20 + 60 + 20) (FIG. 16).

[Examination of Kobel Club]
Next, the examination of the corbel part will be described.

  Here, the positive bending test body has an outer cable structure having a corbel-type fixing body. Further, the maximum value of the necessary tensile force is considered to be 605 kN / line.

The force to peel off the protrusion is 605 × 2 × (125/525) = 288 kN.
A 40 mm reinforcing plate is fixed to the end face of the test body with studs. As a result, the tensile stress generated in the bearing plate is 288000 / (800 × 40) = 9 N / mm 2.

  The degree of stress is very small, and deformation that causes a decrease in prestress does not occur in the corbel. From the above, it was confirmed that the soundness of the corbel-type fixing member was sufficiently maintained.

[Examination of heat-resistant curing at the end]
Next, the examination of heat-resistant curing at the end will be described.

  Reinforce the specimen tension and the vicinity of the fixed end. In addition, priority is given to the reinforcing effect, and split reinforcing bars are also arranged in the cover part (minimum pure cover of the reinforcing bars near the end: 25 mm (maximum aggregate size 20 mm + 5 mm)). Therefore, in order to prevent problems such as explosions due to temperature rise, heat curing (lower surface, both sides) is applied within a range of 300 mm from the end face, and measures are taken to prevent excessive temperature rise in concrete and split reinforcement. . The specifications for heat-curing conform to the side-curing of this specimen.

  Based on the above examination, as a result of performing a fire resistance test using the segment fire resistance test method of the present embodiment, it was possible to safely and reliably introduce the target cross-sectional force. It was also confirmed that the reinforcing part and the PC steel were sound both during the introduction of tension and during the fire resistance test. It was proved that the size of the test body can be reduced to the minimum necessary size, and the cost required for the full-scale fire resistance test of the large-section shield segment can be greatly reduced.

  In addition, a full-scale fire resistance performance confirmation test of RC segments other than those described in the present embodiment is performed, and in particular, a test at the time of a positive bending (rebar tension state) action and a negative bending (concrete compression state) action using the segment main body. By performing the above, it was possible to determine suitable test setting conditions such as test conditions.

  Therefore, according to the segment fire resistance test method of the present embodiment, the test body of the segment can be formed as a prestressed concrete test body by forming the test body by providing the reinforcing plate, the reinforcing stud dowel and the split reinforcing bar. it can. And it becomes possible to perform a fireproof test using an inexpensive and compact test body by setting the optimal arrangement of the PC steel material and the method of reinforcing the local stress as described above.

  That is, even when a compact specimen is used, 1) ensure the amount of eccentricity necessary to reproduce the cross-sectional force, 2) do not allow the segment main bars and PC steel to interfere, and 3) increase the temperature. Therefore, it is possible to perform a reliable fire resistance test.

  As mentioned above, although one Embodiment of the fire-resistance test method of the segment which concerns on this invention was described, this invention is not limited to said embodiment, In the range which does not deviate from the meaning, it can change suitably.

1 Specimen 2 Reinforcement plate 3 Stud gibber 4 Side reinforcement plate 6 Split reinforcement

Claims (1)

The segment specimen is a prestressed concrete specimen,
In addition, the test body is formed by installing a reinforcing plate attached with a reinforcing stud dowel embedded in concrete so that it overlaps the supporting plate on the fixing surface of the PC steel material at the end of the test body. A segment fire resistance test method, comprising split reinforcing bars provided on the side in the vertical direction and the horizontal direction, respectively.