JP2005068711A - Bearing side block - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing side block less deforming horizontally until it is broken, enabling the easy estimation of a breaking load, and having excellent restorability. <P>SOLUTION: This rubber bearing side block installed at a connection part between an upper structure and a lower structure. A slit-like groove is formed from a side compressed by the actio of a bending moment by a horizontal force in earthquake toward a side tensed by the action of the bending moment. The tip of the slit-like groove is extended at least to near a neutral axis when the bearing side block in which the slit-like groove is not formed receives the bending moment. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a bearing side block mainly used as a joint protector for a bridge.

  The rubber bearing distributes the horizontal force during the earthquake in the direction of the bridge axis up to level 1 ground motion shown in the road bridge specifications, while the displacement of the rubber bearing in the direction perpendicular to the bridge axis is regulated by the bearing side block to bridge the road between the bridge girders. This prevents damage to the telescopic device.

  However, even if the horizontal force at the time of large-scale ground motion (level 2 ground motion at the level 2 ground motion shown in the road bridge specifications) is applied, if the protection function of the support side block is not released, the superstructure of the bridge etc. The inertia force during an earthquake is transmitted to the lower structure as it is, and the lower structure is destroyed.

  Therefore, the protection function is provided by the horizontal force at the time of earthquake that exceeds the horizontal force at the time of earthquake in the case of small and medium-sized earthquakes (the horizontal force at the time of earthquake of level 1 ground motion shown in the same book) and does not exceed the retained horizontal strength of the substructure such as bridge piers. Support side block is required to be released.

  Therefore, a support side block as shown in FIGS. 9 to 12 has been proposed. FIG. 9 shows a bearing side block 101 in which bending strength design is performed without performing special processing, and FIG. 10 shows a bending strength design notched bearing side block 102 in which a cross-sectional reduced portion is formed by a notch 102a. Is a through-hole type support side block 103 of bending strength design in which a cross-sectional reduced portion is provided by the through-hole 103a. FIG. 12 shows a support side block 104 of shear strength design that shears and breaks a set bolt 104a on which the support side block is installed. It is.

  However, since the bearing side block based on the bending strength design as shown in FIGS. 9 to 11 has a large horizontal displacement until the time of breakage and it is difficult to assume a breakage load, there is a possibility that the horizontal force at the time of the earthquake will not cause breakage. Yes, especially when the range of the horizontal force at the time of the assumed earthquake is narrow, the setting of the breaking load becomes extremely difficult. In this way, these bearing side blocks are focused on the protection function of the road expansion and contraction device, and there is little consideration of the upper limit strength (breaking strength), so that the force exceeding the retained horizontal strength acts on the lower structure. There was a problem.

  The support side block shown in FIG. 12 has a problem that the work for removing the broken bolt remaining in the bolt hole of the support side block after the set bolt is sheared and broken is troublesome.

  The present invention has been made in view of the above points, and provides a bearing side block that has a small horizontal displacement until breakage, facilitates the assumption of a break load, and is excellent in recoverability. It is in.

  The bearing side block of the present invention is a side block of a rubber bearing that is installed at the joint between the upper structure and the lower structure, and from the side compressed by the action of the bending moment due to the horizontal force during an earthquake, A slit-like groove was formed toward the side pulled by the action, and the tip of the slit-like groove was extended to at least near the neutral axis when the support side block that does not form the slit-like groove receives the bending moment. It is characterized by that.

  Moreover, it is desirable to extend the front-end | tip of the said slit-shaped groove | channel to the said tension | pulling side exceeding the said neutral axis | shaft.

  Moreover, it is desirable to arrange a compressive force transmitting material in the slit-like groove.

  Furthermore, it is desirable that the compressive force transmitting material is made of a material having a small friction coefficient.

  According to the support side block of the present invention, the slit-shaped groove is formed from the side compressed by the action of the bending moment caused by the horizontal force at the time of the earthquake toward the side pulled by the action of the bending moment. Since at least the support side block that does not form the slit groove is extended to the vicinity of the neutral axis when the bending moment is received, the tensile stress is reduced after the opening of the slit groove is blocked by a horizontal force during an earthquake. The shear stress of the action part can be locally increased, and can be broken without a large displacement, and can be reliably broken by the assumed earthquake horizontal force that does not exceed the horizontal strength of the lower structure.

  In addition, by setting the breaking load of the support side block to be smaller than the breaking load of the set bolt for fixing the support side block, the support side block can be broken before the set bolt breaks. Recovery is easy because it eliminates the need for removal. Moreover, as described above, it can be reliably broken by the assumed horizontal force during an earthquake, so there is no need to increase the strength of set bolts more than necessary, and the number of set bolts used can be reduced and the installation work of the support side block can be made more efficient. I can plan. In addition, it is advantageous in terms of maintenance and cost, such as making it possible to reuse set bolts.

  In addition, the fracture characteristics can be easily controlled by adjusting the depth of the slit-shaped grooves. Therefore, when designing for the expectation of dispersion and seismic isolation effect in all horizontal directions, it is possible to reliably break with the assumed horizontal force. Therefore, it is not necessary to apply an excessive earthquake inertia force to the lower structure, and an optimum design for the lower structure becomes possible.

  Further, if a compressive force transmitting material is provided in the slit-like groove, the displacement amount of the support side block until the breakage can be further reduced, and the setting of the breakage load is further facilitated.

  Further, if the compressive force transmitting material is made of a material having a small friction coefficient, an increase in friction between the inner wall surface of the slit-like groove and the compressive force transmitting material can be suppressed, and the assumption of the breaking load is further facilitated. Become.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

  2 is a partial cross-sectional view of the support side block 1 in the bridge axis direction, and FIG. 3 is a partial cross-sectional view of the support side block 1 in the direction perpendicular to the bridge axis.

  The bearing side blocks 1 are disposed on both sides of a laminated rubber bearing 2 (an example of a rubber bearing), and normally restrict the movement of the superstructure A in the direction perpendicular to the bridge axis when the laminated rubber bearing 2 is deformed in the direction perpendicular to the bridge axis. In addition, the protect function is canceled by the above-described horizontal force at the time of the assumed earthquake.

  The laminated rubber bearing 2 includes a rubber bearing body 7 in which rubber layers 5 and intermediate steel plates 6 are alternately laminated between an upper steel plate 3 and a lower steel plate 4, and an upper flange fixed to the upper and lower portions thereof by bolts 8. 9 and lower arm 10. When the bridge girder A is a steel girder, the sole plate 13 is fixed to the lower flange A1 of the road expansion / contraction device, and the lower pier 10 is fixed to the pier (lower structure) B by bolts or welding. Further, shear keys 14 and 15 for transmitting a horizontal force between the rubber bearing body 7 and the upper and lower collars 9 and 10 are provided. When the bridge girder A is an RC girder, a PC girder or the like, the laminated rubber support 2 is fixed to the bridge girder A by means corresponding to them.

  The support side block 1 is formed of a general structural rolled steel or the like, and includes a block main body 1a and a mounting portion 1b extending laterally from the lower portion of the block main body 1a as shown in FIG.

  In the block main body 1a, the slit-like groove 1c is cut into a portion below the line of action of the assumed earthquake horizontal force, and a portion where the slit-like groove 1c is not cut is defined as a remaining portion 1d. The slit-like groove 1c is cut horizontally from the side compressed by the action of the bending moment due to the horizontal force during the earthquake, to the side pulled by the action of the bending moment and beyond the neutral axis N to the tension side. ing.

  An insertion hole 1e for the set bolt 1f is provided in the mounting portion 1b of the support side block 1, and a bolt hole is provided in the lower collar 10 of the laminated rubber support 2, and the set bolt 1f is inserted into the insertion hole to provide a bolt. By fitting into the holes, the support side block 1 is fixed to both sides of the laminated rubber support 2 and the block body 1a is erected.

  2 and 3 is a chain for preventing the broken support side block 1 from scattering, and one end of the chain is fixed to the block main body 1a above the slit-like groove 1c, and the other end Is fixed to the support side block 1 or the lower collar 10 below the slit-like groove 1c.

  When an earthquake horizontal force H is applied to the above-mentioned support side block 1 as shown in FIGS. 4A and 4B, the block body 1a above the slit-like groove 1c is inclined to open the opening 1h of the slit-like groove 1c. As shown in FIGS. 2C and 2D, the block body 1a of the supporting side block 1 is supported by the bending moment generated by the horizontal force H during the earthquake in the state where the opening 1h of the slit groove 1c is closed. A compressive stress acts on the outside and a tensile stress acts on the inside.

  When the horizontal force at the time of the earthquake is further increased, the plastic body is concentrated on the remaining portion 1d and its peripheral portion, so that the block body 1a is broken at a stretch as shown in FIG. This is presumably because the provision of the slit-like groove 1c locally increases only the horizontal shear stress acting on the tensile stress acting portion.

  As described above, according to the support side block 1 of the present embodiment, the opening 1h of the slit-shaped groove 1c is blocked, so that the bending rigidity can be secured and the shear fracture can be performed with a small amount of displacement. Can be easily set, and can be reliably broken by a horizontal force during an assumed earthquake.

  Note that the cutting tip 1j of the slit-like groove 1c may be kept on the neutral axis N or the compression side before the neutral axis N. About the position of the front-end | tip 1j of the slit-shaped groove | channel 1c, when the block main body 1a is a rectangular cross-sectional shape or a cross-sectional shape close | similar to it, it is desirable to exist in the following ranges. That is, with respect to the longitudinal dimension A shown in FIG. 1 (distance between the compression-side outer surface and the tension-side outer surface of the block body 1a), the neutral axis N is 10% from the compression side and the neutral axis N is the tension side. It is desirable to be within the range of up to 40%, more preferably within the range of 30% from the neutral axis N to the tension side and 40% from the neutral axis N to the tension side.

  FIG. 5 shows another embodiment of the present invention, in which a plate-like compressive force transmitting material 1i is inserted into the slit-like groove 1c. As a material of the compressive force transmitting material 1i, a material having a large bearing strength such as a steel plate is used.

  In this way, if the compressive force transmitting material 1i is used, bending resistance can be exhibited without blocking the slit-like groove 1c, so that the displacement amount of the support side block 1 until it breaks can be further reduced.

  As a material of the compressive force transmitting material 1i, for example, a material having a certain bearing strength and a small friction coefficient such as Teflon (R), polyamide resin or the like can be used. An increase in frictional force with the compressive force transmitting material 1i can be suppressed, and the assumption of a breaking load is further facilitated. The compressive force transmitting material 1i is fixed by a sealing material such as an epoxy resin.

  Next, an example of the design method of the support side block 1 with the slit-shaped groove 1c using the compressive force transmitting material 1i is shown. As described above, the shear stress of the tensile stress acting portion can be locally increased by the slit-like groove 1c, and the stress level and the side block size at the fracture surface are expressed by the following formula (1) by the symbols in FIG. , (2).

  Also, when the shear stress reaches the breaking stress, the design is made under the condition that the bending stress is in the elastic region, and the equation is shown in (3).

  Further, an equation for obtaining the cut depth D of the slit-like groove 1c is shown in (4).

  Here, σc: compressive stress at break, σt: tensile stress at break, τ: shear stress at break, μ: static friction coefficient of compression part, τu: shear strength of steel, σu: tensile strength of steel, σy: Yield point or proof stress of steel material, h: distance between action line of horizontal load and slit-like groove 1c, A: vertical dimension of block body 1a, B: lateral dimension of block body 1a, C: width dimension of remaining portion 1d, D: Depth of slit groove, H: Horizontal force during earthquake.

  In addition, in order to confirm the effectiveness of the support side block 1 with the slit-like groove 1c for the purpose of controlling the breaking characteristics, two specimens (actual dimension levels) having different slit depths D of the slit-like groove 1c are used. A loading experiment was conducted. Moreover, the compression force transmission material 1i made from a steel plate was used for both bodies. As a result, even when the shear rupture stress was reached (τ = τu), when the bending stress was designed to be in the elastic region, shear failure occurred under an almost assumed load (see Table 1). As a result, it was confirmed that the rupture load can be roughly calculated by the equation (2), and the validity of the proposed design method could be verified.

  Thus, according to the support side block of this embodiment, the mechanical characteristics are clear, such as controlling the fracture characteristics by shear stress, the design formula is simple, the design is easy, and the joint It became clear that the function as a protector can be demonstrated reliably.

  Specimens I and II have an A dimension of 130 mm, a B dimension of 120 mm, and a C dimension of 18 mm and 33 mm.

  The slit depth 1c of the slit groove 1c of the specimen I is 112 mm, the slit depth D of the slit groove 1c of the specimen II is 97 mm, and the gap dimension S of the slit groove 1c is 3 mm.

  Next, using the beam-type specimens III to V shown in Table 2, three types of filler plates (compressive force transmitting material 1i) having different static friction coefficients shown in Table 3 are used as slit-like grooves 1c of the beam-type specimens III to V. The beam type specimens III to V were supported in a simple beam form as shown in FIG. 8, and concentrated load was applied as shown by the arrows. The beam-type specimens III to V are reduced models (reduction ratio 0.4) in which bending and shear stresses at the time of fracture in the slit-shaped groove 1c coincide with the actual size model specimens I and II.

  In FIG. 6, dimension A is 52 mm, dimension B is 18 mm, slit groove depth C is 45 mm, span length D is 128 mm, distance E from the fulcrum to the slit groove is 49 mm, and loading from the slit groove is performed. The distance F to the point is 15 mm, and the gap between the slit grooves is 3 mm.

  The experimental results are shown in Table 4. As is clear from this table, it was found that the calculated breaking load and the experimental breaking load were in good agreement.

  7 and 8 show another embodiment. FIG. 7 shows a form in which a ductile fracture portion of the remaining portion 1d is excised, and the displacement until the fracture is further reduced by the presence of the excised portion 1k. FIG. 8A shows a form in which a narrow remaining part 1m is provided from the compression side to the tension side, and FIG. 8B shows a form in which the remaining part 1d is protruded toward the tension side.

  The bearing side block of the present invention can be applied to applications other than bridge support.

(A) is a front view which shows the support side block of embodiment of this invention, (b) is a side view of the support side block, (c) is XX sectional drawing of (b). It is the front view which fractured | ruptured and shows the state which installed the support side block in the side of the rubber support. It is the side view which fractured | ruptured and shows the state which installed the same bearing side block in the side of the rubber bearing. It is a figure which shows the state which made the horizontal force act on the support side block. It is a perspective view which shows the support side block of other embodiment of this invention. (A) is a front view which shows an experimental method, (b) is the sectional side view. It is sectional drawing which shows the support side block of the other form of this invention. It is sectional drawing which shows the support side block of the other form of this invention. (A) is a front view which shows the conventional support side block, (b) is a side view of the support side block. (A) is a front view which shows the conventional support side block, (b) is a side view of the support side block. (A) is a front view which shows the conventional support side block, (b) is a side view of the support side block. (A) is a front view which shows the conventional support side block, (b) is a side view of the support side block.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support side block 1a Block main body 1b Mounting part 1c Slit-like groove 1d Remaining part 2 Laminated rubber support (rubber support)
H Earthquake horizontal force

The bearing side block of the present invention is a side block of a rubber bearing installed at the joint between the upper structure and the lower structure. The upper end side is a free end and the lower end side is fixed. A slit-like groove is formed from the side compressed by the action of the moment toward the side pulled by the action of the bending moment, and the tip of the slit-like groove is at least a supporting side block that does not form the slit-like groove. Is set so as to extend to near the neutral axis when receiving the bending moment, and when the horizontal force acts during the earthquake above the slit-like groove, the upper part falls slightly and the slit-like groove The side block of the bearing is constructed so as to close the entrance .

The bearing side block of the present invention is a side block of a rubber bearing installed at a joint between the upper structure and the lower structure, and is bent from the side compressed by the action of a bending moment caused by a horizontal force during an earthquake. A slit-shaped groove is formed toward the side pulled by the action of the moment, and the tip of the slit-shaped groove is at least near the neutral axis when the supporting side block that does not form the slit-shaped groove receives the bending moment. It is extended and the compression force transmission material is arrange | positioned in the said slit-shaped groove | channel, It is characterized by the above-mentioned .

Further , it is desirable that the compressive force transmitting material is made of a material having a small friction coefficient. Furthermore, you may extend the front-end | tip of the said slit-shaped groove | channel to the said tension | pulling side exceeding the said neutral axis | shaft.

According to the support side block of the present invention, the upper end side is a free end and the lower end side is fixed, and from the side compressed by the action of the bending moment due to the horizontal force during an earthquake, to the side pulled by the action of the bending moment. A slit-shaped groove is formed, and the tip of the slit-shaped groove is set to extend at least near the neutral axis when the supporting side block that does not form the slit-shaped groove receives the bending moment. Since the horizontal force at the time of the earthquake acts on the upper side of the groove, the upper part is slightly tilted and the entrance of the slit groove is blocked . After the opening is closed, the shear stress at the portion where the tensile stress acts is locally increased and can be broken without a large displacement. It can be reliably destroyed by the assumed seismic horizontal force that does not exceed the horizontal strength.

Claims (3)

In a concrete damming jig that is formed in a tooth shape by arranging vertically long legs for damming concrete along the support,
The support is formed by fixing a plurality of guide bars extending in the vertical direction in parallel to the horizontal direction to the support frame,
A guided body having a vertical through hole is provided outside the upper portion of the leg,
A concrete dampening jig characterized in that the leg is movable up and down by inserting a longitudinal through hole of the guided body into the guide body of the support.   2. The concrete damming jig according to claim 1, wherein the leg is swingable back and forth and from side to side by forming the vertical through hole in a funnel shape widened downward. 3. The concrete damming jig according to claim 1, wherein the guide rod and the support frame of the support are formed of iron bars, and the guide rod and the support frame are connected by welding.

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