JP6773279B2 - Fire resistance test method for segments - Google Patents

Description

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

In the full-scale fire resistance performance confirmation test (segment fire resistance test) of the segment used for tunnel lining, the RABT60 heating curve (road tunnel specified in the guideline of the German Ministry of Transport) is applied while giving the design cross-sectional force that acts in the actual tunnel. It is a fire curve assuming a vehicle fire inside, and the heating is stricter than the heating assuming a general building fire, in which the temperature is raised to 1200 ° C in 5 minutes after the start of heating and then slowly cooled after being held for up to 60 minutes. Perform heating based on the conditions), and confirm that the temperature of the site of interest is below the permissible 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 to a segment during a test, conventionally, an axial force is applied by tensioning a PC steel rod, and a bracket attached to the segment is pressed by a hydraulic jack. I try to give a bending moment.

Japanese Unexamined Patent Publication No. 2008-286593

On the other hand, in recent years, the tunnel cross section has become larger, and along with this, the size of the segment test piece (specimen) used for the full-scale fire resistance test has increased, and the axial force and bending moment to be introduced have also increased. In addition, there is a need for a applying method that can handle both forward bending and negative bending.

For this reason, when conducting a full-scale refractory performance confirmation test of a segment, there is a problem of the size that the refractory furnace that can burn a large test piece is limited, and the equipment (brackets, jacks) for introducing force becomes large and expensive. There is a problem of becoming.

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

To achieve the above object, the present invention provides the following means.

Fire test method segments of the present invention, the test body segments and prestressed concrete test body, and a reinforcing plate fitted with a reinforcing stud dowels embedded in the concrete is a PC steel end of the prestressed concrete test body together are placed so as to overlap with the bearing capacity plate fixing surface, split裂補strong muscles on the end side of the prestressed concrete test body is provided on each of the vertical and horizontal directions, characterized by using a specimen of said segments And.

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

It is sectional drawing which shows the test body which concerns on one Embodiment of this invention. It is the X1-X1 line arrow view of FIG. It is the X2-X2 line arrow view of FIG. It is the X3-X3 line arrow view of FIG. It is an arrow view of X4-X4 line of FIG. It is a front view which shows the end reinforcement plate. It is a side view which shows the end reinforcement plate. It is a front view which shows the side reinforcement plate. It is a side view which shows the side reinforcement plate. It is a conceptual diagram of the stress distribution (horizontal direction) of a test piece. It is a figure which shows the fixing tool performance test method of the Japan Society of Civil Engineers. It is a figure which shows the analysis model. It is a figure which shows the analysis result. It is a figure which shows the reinforcement target range. It is a figure which shows the relationship between the bead width and the throat thickness. It is a figure which shows the shape of a welded joint.

Hereinafter, the fire resistance test method of the segment according to the embodiment of the present invention will be described with reference to FIGS. 1 to 16.

Here, the present embodiment relates to a fire resistance test method for a segment used for tunnel lining. In particular, the shape of the test piece (specimen) of the segment is devised, and the desired axial force and eccentricity are obtained by the introduction tension force of the PC steel material. The present invention relates to a method of introducing a bending moment according to the above-mentioned method so as to preferably perform a fire resistance test using an inexpensive and compact segment test piece.

When the segment test piece is a prestressed concrete test piece and an inexpensive and compact test piece is used, it is necessary to design the test piece in consideration of the influence of the temperature rise during the fire resistance test and the soundness of the fixing portion. .. That is, the fixed portion of ordinary prestressed concrete cannot satisfy the sufficient 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 portion requires special reinforcement for applying a large force to a narrow area.

As described above, in order to carry out the fire resistance test using the compact test piece, it is important to set / establish the optimum arrangement of the PC steel material and the reinforcement method against the local stress.

The following three points are important points for reinforcement for using a compact test piece.

1-1) Secure the amount of eccentricity required to reproduce the cross-sectional force.
1-2) Do not interfere with the main bar of the segment and the PC steel material.
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 specimens: FIGS. 1 to 5, Support plate: see FIGS. 6 and 7, side reinforcing plate: see FIGS. 8 and 9).

2-1) Enlarge the bearing plate attached to the end of the test piece 1 to increase the area to which the bearing pressure is applied.

2-2) Partially increase the plate thickness in order to alleviate the local bearing stress caused by the deformation of the bearing plate.

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

2-4) Install the side reinforcement plate 4 + reinforcement stud gibber 3 to make up for the shortage of the side edge distance.

2-5) The split reinforcing bars 6 are D16 x 4 (φ40 mm specifications) per location in both the vertical and horizontal directions, and a fixing length equivalent to that of the grid bars is secured.

2-6) Weld the reinforcing stud gibber 3 and the split reinforcing bar 6 at the portion where the fixing length of the split reinforcing bar 6 cannot be obtained.

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

Then, the inventors of the present application worked diligently on the points of 2-1) to 2-7) and took measures of 2-1') to 2-7') 1-1) to 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 piece 1. The thickness of the reinforcing plate 2 does not necessarily have to be limited to 40 mm.

In addition to 2-2') 2-1'), a standard-sized bearing plate (some custom-made products) is placed on the fixing part of the PC steel rod.

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

2-4') The side reinforcing plate 4 has t = 12 mm, and a stud gibber 3 having a D19-150 mm is arranged. The stud gibber 3 is installed at the reinforcing bar position because the side reinforcing plate 4 is integrated and the horizontal reinforcing bar 6 is fixed.

2-5') In the vertical reinforcing bar 6, the amount of reinforcing bars equivalent to D16 × 4 is arranged in the vicinity of 200 mm from the end face where the split stress is maximized. As the horizontal reinforcing bar 6, D19 × 4 having the same diameter as the stud gibber 3 is arranged in the same manner as in the vertical direction.

2-6') Welding of the horizontal reinforcing bar 6 and the reinforcing stud gibber 3 shall be flare welding with a throat thickness of 8 mm (L = 60 mm). The flare welding length of the horizontal split reinforcing bar 6 of the axial force introduction portion is determined based on the "Reinforcing bar fixing / joint guideline (2007 version: Japan Society of Civil Engineers)".

2-7') The minimum pure cover of the reinforcing bar 6 near the end is 25 mm (maximum aggregate size 20 mm + 5 mm). Since the reinforcing bars on the hot surface side may have an adverse effect (explosion) on the concrete due to the temperature rise, heat-resistant curing is performed on the surface, and the reinforcing bars 6 and the reinforcing studs 3 arranged in the cover are affected by heat. Take no measures.

As described above, the inventors of the present application use the segment test piece as the prestressed concrete test piece, and even when an inexpensive and compact test piece is used, the target cross-sectional force can be safely and surely obtained as the segment test piece. It was confirmed that it could be introduced, and that the reinforcing part and the PC steel material were sound during both the tension introduction and the fire resistance test, and the test piece 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 carry out the fire resistance test with high accuracy using an inexpensive and compact test piece, and the cost required for the full-scale fire resistance test of the large cross-section shield segment is reduced. It becomes possible to do.

Here, the contents of the examination regarding the full-scale fire resistance performance confirmation test of the PC (prestressed concrete test piece (segment)) actually performed will be specifically described below.

In the examination of this full-scale fire resistance performance confirmation test, the test piece of the segment was heated based on the RABT60 heating curve while giving the design cross-sectional force acting in the actual tunnel, and the temperature of the part of interest was lower than the allowable temperature. It was confirmed that there was no excessive deformation or explosion.

In addition, the design cross-sectional force (axial force, bending moment) in service was reproduced by introducing prestress using a PC steel rod.

The basis for setting the introduction tension (prestressed amount) is shown below, and the results of studies on the arrangement of PC steel rods and the method of reinforcing the fixing part are shown.

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

As for the specifications of the PC steel material, it was decided to use a commercially available product and to use a general PC steel rod "Class B No. 2" having high tensile strength. Since the prestress loss due to relaxation at high temperature is large, it was decided to use type B having high tensile strength.
Table 1 shows the specifications of the PC steel rods used in this study.

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

In examining the arrangement and number of PC steel materials, the limit value of the stress degree of PC steel materials was set as follows.

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

Since the test body of this test is temporary, the limit value was set to 3-1). Further, since the effective diameter is as large as 0.9 due to the increase in relaxation due to the temperature rise, it becomes 3-2). Furthermore. The PC steel material (with grout) of the negative bending test piece placed 175 mm from the heated surface is added to 3-1) and 3-2) in consideration of the rapid expansion of the concrete surface exposed to fire in the fire resistance test. 3-3) was set as the limit value.

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

In this test, the design section force is reproduced by introducing prestressed concrete using a PC steel rod. PC steel materials placed near the heating surface or near the gripping hardware are affected by heat due to heating. The accuracy and safety of the test are ensured by grasping the thermal effect characteristics of the PC steel material and determining the arrangement in the temperature range where the physical properties of the PC steel material do not change.

Here, a general PC steel material has the following thermal characteristics.
4-1) Relaxation increases (varies depending on temperature and heating time).
4-2) The tensile strength sharply decreases when the temperature exceeds 300 ° C, 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 material reaches 300 ° C., both the strength (tensile / yield) and the elastic modulus sharply decrease. Therefore, in this test, the arrangement is set so that the temperature rise of the PC steel material is 150 ° C. or less.

Then, based on the actual product of the realization field, the thermal characteristics that are the placement policy of the PC steel material were grasped, and the test result of this realization field showed that the temperature rise of the reinforcing bar 130 mm from the heating surface was about 150 ° C. In the test, the minimum distance from the heated surface to the center of gravity of the PC steel material was set to 175 mm. Further, it was decided to carry out cement grout on the PC steel rod having a distance of 175 mm from the heating surface.

Further, in the test result of the realization site, the temperature rise of the main bar near the gripping metal fitting 250 mm from the heating surface was about 150 ° C., so it was decided to secure a space of 50 mm or more between the gripping metal fitting and the PC steel material.

[Examination of PC steel layout]
Next, a study on the arrangement of PC steel materials will be described.

First, the minimum center spacing and the minimum edge distance of the PC steel fixing portion will be described.
When designing the PC fixing part, it must be designed so that the bearing force fracture and the lateral split fracture of the concrete do not occur due to the tension force considered in the design. In each fixing method, the minimum arrangement interval of the fixing tool, the minimum edge distance, the diameter and the number arrangement of the split reinforcing bars are shown.

Since there is no officially indicated arrangement of the fixing tool for general PC steel rods (φ40) and the amount of split reinforcing bars, in “3.3) Examination of arrangement of PC steel rods (φ40 mm)”, The required minimum center spacing, minimum edge distance, and split reinforcement muscle mass were calculated by FEM analysis.

[Arrangement of PC steel materials]
The contents and results of the examination regarding the arrangement of the PC steel rod (φ40 mm) are as follows.

First, FIG. 10 shows the concept of stress distribution on the back surface of the fixing portion.
Generally, the back surface of the PC fixing part is reinforced with grid bars to prevent cracking, but for general PC steel rods (φ40), the split reinforcing bars etc. are described in the design and construction manual of the fixing part specified by each manufacturer. There are no structural details regarding. In the NEXCO design procedure, it is stipulated that the amount of reinforcement should be determined by FEM analysis or the like in the design of the anchoring projection, and in this study as well, the amount of split reinforcement on the back surface of the anchoring portion was determined by FEM analysis. As a result, four D16s were used as the reinforcing bars per one cross section of the fixing portion.

The size of the FEM model is the size of the test piece (one side is twice the minimum edge distance) according to the fixture performance test method of "Prestressed Concrete Construction Method Design and Construction Guideline (JSCE)" (see Fig. 11). The height was 4 times the minimum edge distance).

The minimum edge distance (minimum steel material spacing) with respect to general PC steel rods (φ40) is the value for φ26, φ32, and φ36 steel rods shown in the “Dyckerhoff Construction Method Design and Construction Manual” because there is no guideline to specify this. Estimated from.

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

Then, the analysis result is shown in FIG. 13 as a direct stress contour diagram in the Y direction (center cross section in the Y axis direction). The contour range is 0 to 5 N / mm ² (positive is tension).

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

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

The compressive strength of concrete during tension is F _ck '= 30 N / mm ² , and the tensile strength of concrete during tension is F _TK = 0.23 x F _ck ^2/3 (concrete standard specification, design) = 2.22 N / mm. It becomes ² .

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

[Split reinforcement muscle mass]
Since the analytical model is symmetrical in 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 reinforcement range is integrated with the element area, and the tensile force generated in the reinforcement range is calculated. Divide the tensile force by the amount of split reinforcing bar and confirm that the allowable reinforcing bar tensile stress is satisfied. The allowable reinforcing bar tensile stress was the value shown in the section of fixing part design in the NEXCO design manual.

Allowable rebar tensile stress ^{_{σ sa = 120N / mm 2 (}} SD345), the tensile force generated in the reinforcing range _{Σ (σ y · A) =} 81511N, split裂補strong muscle mass (D16,4 present) 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.

[Arrangement of PC steel materials]
From the above results, the following can be said about the arrangement of the PC steel rod (φ40 mm).

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

Then, the number and arrangement of PC steel materials may be determined according to the following policy in addition to "grounds for setting the introduction tension force (PC steel rod diameter)" and "examination of PC steel material arrangement".
Tables 6 and 7 show the PC steel material introduction axial force (the basis for determining the diameter and number).

6-1) There are four types of diameters used for PC steel: 26 mm, 32 mm, 36 mm, and 40 mm.
6-2) The generated stress of PC steel shall be less than or equal to the "limit value of PC stress".
6-3) The diameter of the PC steel rod shall be the minimum required diameter that is the closest to "0.7 times the yield stress" (larger elongation).

The decision policy for arranging PC steel materials 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 center of gravity, the eccentricity of 150 mm (negative bending), and the eccentricity of 450 mm (forward bending).
7-3) As a general rule, secure the minimum center spacing and minimum edge distance shown in the study on PC steel layout.
7-4) The distance between the centers of the negatively bent PC steel rods shall be 380 mm in consideration of the heat effect of the gripping hardware (negative bending test piece).
7-5) The distance between the centers of the axial force PC steel rods shall be 290 mm in consideration of the heat effect of the gripping hardware (negative bending test piece) and the hanging jig insert (reinforcement required).
7-6) Set the minimum physical center spacing to 115 mm from the required space for nut tightening and jack setting of the negative bending test piece (PC steel rod φ40) (reinforcement required).
7-7) Secure a side edge distance of 100 mm or more (reinforcement required).

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

As described above, the arrangement of the PC steel rods of this test piece is determined with an emphasis on 1-1), 1-2), and 1-3).

1-1) Secure the amount of eccentricity required to reproduce the cross-sectional force.
1-2) Do not interfere with the main bar of the segment and the PC steel material.
1-3) Not excessively affected by temperature rise.

For this reason, a fixing portion that does not satisfy the minimum center spacing and the minimum edge distance shown in "Study on PC Steel Arrangement" is generated.
Explaining Case-1 and Case-2 as an example, in Case-1, the upper surface edge distance of 125 mm of the forward bending PC steel rod does not satisfy the minimum edge distance of φ32 of 137.5 mm. In Case-2, the center distance of the negatively bent PC steel rod is 115 mm, the side edge distance of 100 mm, and the lower surface edge distance of 175 mm do not satisfy the minimum center distance of φ40 of 310 mm and the minimum edge distance of 200 mm.

By the way, the minimum placement dimensions of PC steel rods shown in the construction standards (catalog) were determined by a destructive test using a bearing plate with standard dimensions (prestressed concrete construction method design and construction guidelines (JSCE) Fixture Performance. Test method).

As described above, since there is a fixed portion that does not satisfy the minimum arrangement dimension, in this test (fire resistance test method for the segment of the present embodiment), the bearing stress (split stress) of concrete is referred to as the above-mentioned fracture test. As mentioned above, it was decided to carry out reinforcement based on the policies of 2-1) to 2-7) in order to keep the equivalent or less.
In addition, considering the certainty of the test and the safety of work, the amount of reinforcement is determined assuming the PC steel rod φ40 mm, which is the strictest condition, and it is applied to all places.

2-1) Enlarge the bearing plate to increase the area to which the bearing pressure is applied.
2-2) Partially increase the plate thickness to relieve local bearing stress due to plate deformation.
2-3) Install a stud gibber on the bearing plate to ease the concentration of bearing stress.
2-4) Install a side plate + reinforced stud gibber to make up for the lack of side edge distance.
2-5) The split reinforcing bars shall be D16 x 4 (φ40 mm specifications) per location in both the vertical and horizontal directions, and the anchorage length equivalent to the grid bars shall be secured.
2-6) Weld the reinforcing stud gibber and the split reinforcing bar at the part where the fixing length of the split reinforcing bar cannot be obtained.
2-7) Reinforcing bars should be placed within the design cover of the segment, giving priority to the reinforcing effect.

Then, as a specific reinforcement method, as described above, 2-1') to 2-7') are used (see FIGS. 1 to 9).

2-1') Install a 40 mm thick reinforcing plate on the fixing surface of the test piece.
In addition to 2-2') 2-1'), a standard-sized bearing plate (some custom-made products) is installed on the fixing part of the PC steel rod.
A stud gibber (D19-150 mm) is installed on the reinforcing plate of 2-3') 2-1'). Since the end face stud gibber is arranged as a precaution, the arrangement amount is determined in consideration of workability such as filling property.
2-4') The side plate has t = 12 mm, and a D19-150 mm stud gibber is placed. The stud gibber is installed at the position of the reinforcing bar in order to integrate the plate and also serve as the fixing part of the horizontal reinforcing bar.
2-5') For the vertical reinforcing bars, the amount of reinforcing bars equivalent to D16 × 4 is arranged in the vicinity of 200 mm from the end face where the split stress is maximized. As the horizontal reinforcing bars, D19 × 4 having the same diameter as the stud gibber are arranged in the same manner as in the vertical direction.
2-6') Welding of the horizontal reinforcing bar and the reinforcing stud gibber shall be flare welding with a throat thickness of 8 mm (L = 60 mm). The flare welding length of the horizontal split reinforcement of the axial force introduction part was determined based on the "Reinforcing Bar Fixing / Joint Guideline (2007 Edition) (Japan Society of Civil Engineers)".
2-7') The minimum pure cover of the reinforcing bar near the end is 25 mm (maximum aggregate size 20 mm + 5 mm). Reinforcing bars on the hot surface side may adversely affect concrete due to temperature rise (explosion), so heat-resistant curing is performed on the surface to prevent thermal effects on the reinforcing bars and reinforcing studs placed inside the cover. To take.

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

The flare welding length of the horizontal split reinforcing bar of the axial force introduction part was determined based on the "Reinforcing Bar Fixing / 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 welded portion is τ = 490 / √3 = 282.9 N / mm ² .

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

In addition, the pointer states that welding is performed leaving about 20 mm at both ends of the welded portion as a margin length. Therefore, the lap length is 100 mm (= 20 + 60 + 20) (FIG. 16).

[Examination of corbel department]
Next, the examination of the corbel section will be described.

Here, the forward bending test piece has an outer cable structure having a corbel type fixing body. In addition, the maximum required tensile force of 605 kN / piece will be examined.

The force for peeling 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 by studs. As a result, the degree of tensile stress generated in the bearing plate is 288000 / (800 × 40) = 9N / mm2.

The above stress level is very small, and deformation that causes a decrease in prestress or the like does not occur in the corbel portion. From the above, it was confirmed that the soundness of the corbel-type anchorage was sufficiently maintained.

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

Reinforce the tension of the test piece and the vicinity of the fixed end. In addition, giving priority to the reinforcing effect, a split reinforcing bar is also arranged at the cover (minimum pure cover of the reinforcing bar near the end: 25 mm (maximum aggregate size 20 mm + 5 mm)). Therefore, in order to prevent problems such as explosion due to temperature rise, heat-resistant curing (bottom 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 of heat-resistant curing conform to the side curing of this test piece.

Based on the above studies, as a result of conducting a fire resistance test using the segment fire resistance test method of the present embodiment, the target cross-sectional force could be safely and surely introduced. It was also confirmed that the reinforcing part and the PC steel material were sound both when the tension was introduced and during the fire resistance test. It was also demonstrated that the specimen can be reduced to the minimum required size and the cost required for the full-scale fire resistance test of the large cross-section shield segment can be significantly reduced.

In addition, a full-scale fire resistance performance confirmation test of RC segments other than those described in this embodiment is performed, and in particular, a test during normal bending (reinforcing bar tension state) action and negative bending (concrete compression state) action using the segment body. By performing the above, suitable test setting conditions such as test conditions could be determined.

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

That is, even when a compact test piece is used, 1) the amount of eccentricity required to reproduce the cross-sectional force should be secured, 2) the main bar of the segment should not interfere with the PC steel material, and 3) the temperature rise. It is possible to prevent the undue influence of the fire resistance test and to perform a highly reliable fire resistance test.

Although one embodiment of the segment fire resistance test method according to the present invention has been described above, the present invention is not limited to the above embodiment and can be appropriately modified without departing from the spirit of the present invention.

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

Claims (1)

The segment test piece was a prestressed concrete test piece.
And, together with the reinforcing plate fitted with a reinforcing stud dowels embedded in the concrete is placed so as to overlap with the bearing capacity plate fixing surface of the PC steel end of the prestressed concrete test specimen,
Split裂補strong muscles on the end side of the prestressed concrete test body is provided on each of the vertical and horizontal directions,
A method for a fire resistance test of a segment, which comprises using a test piece of the segment.