JP2012117364A - Vibration control bridge pier structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration control bridge pier structure capable of improving a restoration property, reducing earthquake responses, reducing residual deformations and improving workability or the like by basically evading formation of a plastic hinge at column upper and lower end parts and capable of efficiently absorbing energy by the entire frame by disposing a brace to the column upper and lower end parts as well, in a vibration control bridge pier of an RC rigid frame structure.SOLUTION: Strength is increased by using a precast form of UFC (Ultra-strength Fiber-reinforced Concrete) or the like at the upper and lower end parts of a column 3 of an RC frame 5 to prevent the formation of plastic hinges H at the total of four parts at the column upper and lower end parts by an earthquake motion (level 2 earthquake motion) at or higher than an assumed level. A brace 6 having a damper function for connecting a pair of left and right columns 3 is disposed at the column upper and lower end parts as well, one end of the braces 6 at the upper and lower end parts of the column 3 is respectively joined to haunches respectively formed at the upper and lower ends of the column 3 or joined to a lower surface of a beam 4 and an upper surface of a footing 2.

Description

  The present invention relates to a seismic control pier structure, and by installing an energy absorbing device such as a damper in a frame structure composed of RC members such as a pier with an RC rigid frame structure, the cross-section of the column is reduced, and the horizontal at the time of an earthquake It is applied to seismic control piers intended to improve damping performance while extending the natural period of directional vibration.

  An increase in natural period at the pier is effective in reducing the inertial force acting on the pier during an earthquake, but it leads to an increase in response displacement. On the other hand, the improvement of the damping performance is effective in reducing the response displacement without increasing the inertial force during an earthquake. The seismic control pier can reduce the shearing force that acts during an earthquake by increasing the period and reduce the response displacement by improving the damping performance. In addition, conventional RC piers have been designed to cope with large-scale Level 2 earthquakes by enlarging the cross section, so that the structural weight of the entire pier tends to increase. On the other hand, the seismic control pier is small in scale and composed of a flexible RC member and a damper, so that the structural weight of the entire pier is small. Therefore, the inertial force acting on the foundation during an earthquake is reduced, and the scale of the foundation can be reduced. Downsizing the foundation is effective in reducing the construction cost of the entire pier including the foundation.

  Seismic control piers can be applied to general bridges such as urban viaducts, but especially for high piers with high pier height (for example, about 30m or more) and RC main towers of suspension bridges, etc. This is preferable because the effect of improving earthquake resistance is increased.

  As a conventional structure for reducing an earthquake response by a damper in an RC viaduct or an RC pier with a frame structure, for example, as described in Patent Document 1, a plastic hinge is formed at the upper and lower ends of a column. This includes an RC rigid frame structure composed of a pair of columns erected at a predetermined interval and a beam spanned on the top of the column, and a damper brace mechanism disposed in the structural surface of the rigid frame structure. The damper brace mechanism is composed of a vertical displacement damper and a pair of horizontal V-shaped braces joined at the apexes on both sides of the vertical displacement damper so as to sandwich the vertical displacement damper. The two other ends of the braces are joined at positions spaced apart from each other in the vicinity of the middle position of each column, and the aspect ratio B / H of the RC frame frame (B: length of the beam, H: height of the column) Is less than 1. There are the following actions and effects.

(A) The rigidity of the whole frame is lowered, and a large displacement can be obtained. As a result, the natural period increases compared to before the plastic hinge is formed, which is effective in reducing the seismic response.
(B) When a plurality of X brace dampers are arranged in the vertical direction in the frame, it is possible to cause a substantially uniform relative displacement in each damper. As a result, the same damper may be disposed, and the design and production are simple.
(C) It is not necessary to install braces near the plastic hinges at the upper and lower ends of the column.

  The applicant has applied for a seismic pier (Patent Document 2). As an example, this seismic pier is composed of a truss structure by connecting multiple columns with trusses, separating the trusses to the left and right at the central truss rating point between the columns, and relative to the truss rating A damping device such as a honeycomb damper that absorbs energy by displacement is arranged so that the relative displacement is in the vertical direction, and the horizontal displacement of the column during the earthquake is converted into the vertical displacement of the truss rating point position. The seismic energy is absorbed by the relative displacement of the vibration control device in the vertical direction, and the seismic force is reliably reduced with a relatively simple pier structure.

Japanese Patent No. 3712178 JP-A-2005-207111

  In the case of the conventional earthquake-resistant frame structure in which the plastic hinges are formed at the upper and lower ends of the conventional columns, there are the following problems.

 (1) In contrast to the above (a), in some important structures, it may not be allowed to allow plasticization. If four plastic hinges are formed in one frame, the load-bearing mechanism becomes unstable, and the P-Δ effect cannot be ignored especially on piers with high pier heights, and the deformation tends to increase in one direction. Appears and is very dangerous. In addition, in the case of a structure that greatly allows plasticization, there is a problem that residual deformation after an earthquake becomes large. The bottom of the pier column is mostly in the ground, and it takes time and labor to check for earthquake damage, such as excavation for inspection, making it difficult to start operation immediately after the earthquake. Inspection work is not easy because the top of the column is also work at high places.

 (2) There is no practical problem with respect to (b) above, but if the plastic hinge is not formed, the damper displacement will not be uniform, so it will be as small as normal wind vibration or level 1 earthquake motion. In the displacement region, the damping performance is not necessarily ideal.

 (3) In contrast to the above (c), as shown in FIG. 15, when a plurality of X braces are installed, if two braces 6 from above and below are joined at one point and fixed to the pillar 3, the braces 6 Since the compressive force and tensile force of the cylinder 3 act on the column 3 as a displacement force in the axial direction of the column 3 (see FIG. 15 (b)), fixing this is relatively difficult in the general part of the column 3. It was easy. However, in order to fix the uppermost and lowermost braces 6 to the pillars 3 obliquely, a shearing force acts on the pillars 3 (see FIG. 15C). In seismic control piers, it is advantageous to reduce the cross-sectional dimensions in order to make the pier rigidity as small as possible, but such concentrated loads are a major structural problem. For example, if a damper having a large yield load is installed only in the middle part of the column, an axial force of the brace 6 corresponding to the yield load of the damper is generated, and the brace 6 and the column 3 are used to cope with such a relatively large axial force. The structure of the joint part of this was complicated, and the cost and workability were inferior. As for the column 3 itself, a lateral force (that is, a force in a direction orthogonal to the member axis generates a shearing force on the column) acts on the intermediate portion, so that reinforcement in the vicinity of the joint portion of the column 3 is necessary. .

 (4) On the other hand, the upper and lower ends of the columns where the plastic hinges are formed are also positions where they are joined to the beams and footings of the column heads. Since it is relatively easy, it is rather advantageous to attach braces positively there. However, it is necessary to securely fix the reaction force of the brace at a position where a large plasticization (that is, damage) such as a plastic hinge occurs or in the vicinity thereof.

 (5) It is desirable to arrange a large number of braces and dampers in the height direction when the height is large with respect to the span of the frame structure such as a high pier or RC main tower.

  The present invention has been made to solve the problem in the case of positively forming a plastic hinge at the upper and lower ends of a conventional column in an RC rigid frame structure damping pier. By avoiding the formation, it is possible to improve the recoverability, reduce the seismic response, reduce the residual deformation, improve the workability, etc. It provides a seismic control pier structure that enables efficient energy absorption as a whole.

  Claim 1 of the present invention is an RC frame structure comprising two or more RC member columns standing on a foundation (footing) at intervals and a RC member beam spanned on the top of the columns. And a brace frame having a vibration control function arranged in the surface of the RC frame frame, wherein the RC frame frame has a plastic hinge formed by a greater than expected earthquake motion. Braces that connect a pair of left and right columns are also arranged at the upper and lower ends of each column, and one end of each brace at the upper and lower ends of this column is joined to a haunch formed on the upper and lower ends of each column, or It is a seismic control pier structure that is joined to the lower surface and the upper surface of the foundation, and designed so that no plastic hinge is formed at the upper and lower ends of the column. The present invention can be applied to a planar frame having two or three columns (see FIG. 13) and a column having two or more columns in the bridge axis direction and the bridge axis direction.

  In the present invention, the design does not allow the plastic hinge to be formed at the upper and lower ends of the column, but includes both the case where the plastic hinge is not formed and the case where the plastic hinge is formed. In order to avoid the formation of plastic hinges at the upper and lower ends of pillars during level 2 earthquakes in important structures, etc., a precast formwork made of high-strength fiber reinforced concrete or mortar as will be described later (FIGS. 2 and 3). Etc.) to increase the toughness of the pillar.

  Moreover, in this invention, a brace is actively arrange | positioned also in the plastic hinge area in a column upper-lower end part. In the conventional seismic frame structure in which plastic hinges are formed at the upper and lower ends of a column, a single brace is joined in the middle of the column and shear force is generated in the column (see FIG. 15). The braces arranged at the upper and lower ends of the column of the present invention can cause a reaction force to be applied to the beam at the top of the column and the foundation at the bottom of the column. The upper and lower ends of the column are positions where large plasticization (damage) called a plastic hinge occurs, and the reaction force of the brace is reliably fixed. As the fixing method of the uppermost lower brace, for example, any of the following methods can be used.

 (1) For example, as shown in FIG. 2 and FIG. 3, a haunch is provided at the upper and lower end positions of the column, and the end of the brace is joined to the haunch. The fixing hardware attached to the end of the brace is fixed with a PC steel rod and an anchor plate, a perforated steel plate gibber, a stud gibber or the like. The tensile force is transmitted by the tensile force of the PC steel material penetrating the haunch, and is borne on the anchor plate in the foundation or the beam, or is borne by a diver or the like. The compressive force is directly taken by the haunch and / or transmitted by the compressive force of the PC steel material penetrating the haunch and is borne by the anchor plate. These fixing methods can also be applied to a haunch provided in the middle of a pillar.

  Alternatively, as shown in FIG. 4, an anchor made of a plate material or a single round steel is embedded and fixed so as to be substantially pin-joined, and a steel pipe surrounding the outer periphery of the column is installed. It is borne by the anchor embedded in the beam. This is a case in which braces are attached to the range of the precast formwork at the upper and lower ends of the column, and is a fixing method that does not hinder the effect of the method using the precast formwork composed of a plurality of blocks divided vertically.

 (2) For example, as shown in FIG. 5 and FIG. 6, it is fixed obliquely in the vicinity of the column on the upper surface of the foundation or the lower surface of the beam. The vicinity means a degree in which a relative triangle is formed by the deformation of the pillar by forming a substantially triangular shape by the two upper and lower braces and the pillar. In FIG. 5, a fixing hardware having a perforated steel plate gibber, a stud gibber, or the like is disposed adjacent to the inside of the column precast formwork. As shown in FIG. 6, it may be installed in two places before and after the pillar in the direction of the bridge axis.

 (3) For example, as shown in FIG. 7, a brace is installed across the upper and lower ends of the column, and is fixed to the upper surface of the foundation or the lower surface of the beam. Attaching the left and right braces separately, or combining the left and right brace tips and adding a mechanism to restrain the displacement in the vertical direction, and then fixing to the upper surface of the foundation or beam so that horizontal relative displacement occurs. There are methods.

  The form of the brace (made of steel, RC, etc.) is preferably an X-shaped brace double warren truss in front view. The Warren truss is included in the present invention although the structural characteristics of the frame are asymmetrical. As the damper, a steel honeycomb damper can be cited as an example. However, any damper may be used as long as it acts on relative shear displacement. High damping rubber, laminated rubber with lead plug (LRB), friction type, viscous sandwich type Etc. can be used. Further, a damper brace capable of absorbing energy in accordance with expansion / contraction displacement in the direction of the brace axis, such as a buckling restraint brace or an expansion / contraction damper, can be used for the brace itself.

  The seismic pier structure according to claim 1, wherein the plastic hinge sections at the upper and lower ends of the column are composed of a precast form made of high-strength fiber reinforced concrete or mortar and concrete cast in the precast form. The precast formwork has a vibration-damping pier structure in which a plurality of crack-inducing joints are formed at intervals in the vertical direction. For example, the precast formwork may be divided into a plurality of blocks in the vertical direction, a crack-inducing joint having a low tensile strength may be formed at the joint of each block, and the cracks may be dispersed and induced.

This is a case where a precast FRC formwork made of high-strength fiber reinforced concrete or the like is used in order to avoid the formation of plastic hinges at the upper and lower ends of the column during a level 2 earthquake. Prevent compression damage of concrete in the part. High-strength fiber reinforced concrete or the like is a material in which steel fiber, carbon fiber, glass fiber, or the like is mixed in concrete or the like having high compressive strength. The compressive strength is 100 to 250 N / mm ² and the bending tensile strength is 10 to 40. N / mm ^2, ultra high strength fiber reinforced concrete tensile strength cracking is 5~15 N / mm ² (UFC) is preferred. By using a material with high compressive strength and tensile strength for the precast formwork in the plastic hinge section and constraining the inside, it is possible to suppress the collapse of the core concrete and the buckling of the main rebar and achieve high deformation performance it can. If necessary, the high-strength reinforcing bar is used as the axial steel material. The application range of the UFC formwork is at least 1D or more, preferably 2D or more, and is a range that prevents compressive damage of concrete according to the moment gradient of the column and the concrete strength other than the UFC formwork.

  Precast formwork is divided into multiple layers of high-strength fiber reinforced concrete or mortar in the production form of precast formwork to form joints where fibers do not continue vertically on the joint surface. You may make it form the crack induction joint by the said joint integrally in a mold.

  High-strength fiber reinforced concrete or the like is continuously introduced in the circumferential direction of the manufacturing formwork during the production of the precast formwork, and the fibers are continuously arranged in the circumferential direction by being divided and placed in multiple layers. However, a crack-inducing joint in which fibers are not continuous is formed on the joining surface of each layer, and a plurality of crack-inducing joints are formed in one precast mold form at intervals in the vertical direction. Cracks are easily generated by this crack-induced joint. In the state where the bridge pier is not bent during an earthquake or the like, cracks do not occur and the cracks close after a small and medium-scale earthquake, so that long-term durability can be ensured while no joint treatment is required.

  A haunch may be formed at each end portion at the boundary between the FRC formwork structure portion by the precast formwork and the RC structure portion at the middle of the column, and the brace may be joined to the haunch.

  For example, as shown in FIG. 8, it is desirable to form a haunch or the like at the boundary between the FRC (UFC) formwork structure and the RC structure in order to alleviate the stress concentration on the RC structure due to the difference in elastic modulus. .

  The brace fixing method in the middle of the pillar, particularly at the boundary between the FRC (UFC) formwork structure part and the RC structure part, as shown in FIG. 9, for example, is similar to the fixing method of the lowermost brace described above. A fixing method provided with a stud gibber, a perforated steel plate gibble, a PC steel bar, an anchor plate, or the like can be used. Further, in the fixing method using the PC steel rod and the anchor plate, as shown in FIG. 10C, the boundary between the FRC (UFC) formwork structure portion and the RC structure portion is formed by a pair of fixing plate steel plates and their restraining force. Because it is reinforced, the aforementioned haunch can be eliminated.

  Claim 2 of the present invention is the seismic control pier structure according to claim 1, wherein the braces in the middle part excluding the upper and lower ends of the column are assembled into a column by gathering the ends of the two upper and lower braces in one place. It is a seismic control pier structure characterized by being established.

  For example, as shown in FIG. 10, a brace in the middle of a pillar is not fixed to the pillar, but two upper and lower braces that cause compression and tension are attached to the pillar as a pair, so that Only the displacement force is applied (see FIGS. 14 and 15), and the structure of the mounting portion is simplified. In other words, a simple and easy fixing method such as a stud diver or a perforated steel plate diver is possible.

  According to a third aspect of the present invention, in the vibration control pier structure according to the first or second aspect, an X-shaped brace is disposed between the pair of left and right columns in a front view, and is divided into left and right at the intersection of the X-shaped brace. The damping pier structure is characterized in that a damper that absorbs energy in accordance with the relative displacement in the vertical direction is disposed at the intersection.

  For example, as shown in FIG. 1, the brace form is a double warren truss structure. Compared with the case where the plastic hinge of FIG. 1A is formed and deformed in a parallelogram, in the present invention in which the plastic hinge of FIG. 1B is not formed, the relative displacement of the damper at the center in the frame frame height direction However, the ratio of the dampers at each mounting position in such a structure is substantially constant during the earthquake response process, that is, regardless of the magnitude of deformation of the frame. Therefore, it is possible to cause energy absorption in the entire frame structure by changing the capacity of a damper such as a honeycomb damper depending on the arrangement position.

  According to a fourth aspect of the present invention, in the vibration-damping pier structure according to the first or second aspect, a damper that absorbs energy according to a relative displacement in the vertical direction is disposed between the column and the brace. It is a seismic control pier structure.

  For example, as shown in FIG. 11, this is applied to a double warren truss structure. A damper such as a honeycomb damper is installed at the junction between the pillar and the brace. For example, every other damper is arranged, and plastic hinges are not formed at the upper and lower ends of the column, and seismic energy is absorbed by the relative displacement in the vertical direction of many dampers.

  According to a fifth aspect of the present invention, there is provided a vibration control pier structure according to the first or second aspect, wherein the brace is a damper brace that absorbs energy in accordance with an axial expansion / contraction displacement. is there.

  For example, as shown in FIG. 12, the brace itself is a damper brace (such as an expansion / contraction damper or a buckling restrained brace) in a double warren truss structure. All the damper braces are joined to the pillars at both ends, and plastic hinges are not formed at the upper and lower ends of the pillars. Seismic energy is absorbed by the expansion and contraction of a large number of damper braces themselves.

  In the present invention as described above, (1) by applying a precast formwork such as UFC to a portion where the bending moment of the upper and lower ends of the column is increased, the strength of the cover portion at the same location can be increased. It is possible to delay the collapse of the concrete of the column member. In the seismic control pier to be realized by the present invention, the inertial force during an earthquake is reduced by reducing the cross section as much as possible and lengthening the natural period. Also, it is assumed that the column member does not become plastic even during a level 2 earthquake due to the reasons described above (see (1) in the column of the problem to be solved by the invention). For this reason, in conventional seismic control piers, many reinforcing bars are placed in a small cross section that receives a high axial compressive force, and the compressive force of the concrete during bending deformation increases. There is a possibility that the concrete will be plasticized by crushing before it is done. In general, failure modes preceded by concrete crushing are brittle and should be avoided in the design of RC members. Even in such a case, for example, by applying a technique using a precast formwork such as UFC, the concrete can be crushed after the main bar yields.

 (2) Since the deformed shape of the frame frame depends on the rigidity of the column member, when forming a plastic hinge (see Fig. 1 (a)), it differs greatly before and after the formation, and the optimal damper arrangement throughout the formation It was impossible to do. If the structure does not allow plastic deformation as in the present invention, the change in the stiffness of the column is only due to the presence or absence of cracks in the concrete. The crack generation range changes with deformation, and the crack region progresses from the upper and lower ends of the column toward the middle of the column, but the seismic control pier has a larger reinforcing bar ratio than the normal pier, and the difference in cross-sectional rigidity before and after the crack is The deformation shape of the frame frame is not so large, and is almost equal to the deformation assuming crack rigidity (so-called RC rigidity) in the entire length of the column. For this reason, since the ratio of displacement of the plurality of dampers arranged can be made constant by increasing the deformation of the frame structure, it is possible to cause energy absorption in the entire frame structure.

  For example, if a honeycomb damper is used, it is easy to change the capacity of the damper according to the arrangement position by appropriately combining the number of sheets and the number and size of comb teeth. Particularly, in the case of a vibration control pier, the required reaction force of the damper is large, so that a plurality of honeycomb dampers are originally required, so there is no problem in practical use.

 (3) By installing multiple dampers, energy absorption distributed throughout the vertical direction of the RC frame frame occurs, so braces are placed only in the middle part of the column, and energy is concentrated on the large damper. As compared with the case of absorbing the column, the dimensions of the column are not changed, the axial force of the brace is reduced, and the brace-column bonding structure per place is simplified. Thereby, workability is also improved.

 (4) In the seismic control pier according to the present invention, since it is assumed that a plurality of braces having a damper function are installed, it is necessary to provide a brace fixing portion in the middle of the column. In the method using the stud gibber and perforated steel plate gibber proposed as the fixing method, it is necessary to install the fixing part at the time of placing the pillar, but this is a method that has a proven record in composite structures, etc. Since it is small, it has excellent reliability and simplicity in the fixing structure. On the other hand, in the method of tensioning with a PC steel bar penetrating the inside of the column, although the evaluation of the fixing force varies depending on the setting of the friction coefficient, in fixing at the boundary between the precast formwork such as UFC and the RC structure, Since the restraint force by the fixing plate and PC steel bar installed on the column surface acts on the boundary part, the same part is reinforced, so there is no need for a haunch that should be installed for the purpose of reducing stress concentration. Become. In addition, by providing a PC steel rod through-hole in the column in advance with a sheath tube, etc., it is possible to perform the installation work of the damper including the fixing part after placing / demolding the column member, improving workability To do.

 (5) When a damper is attached to the uppermost / lowermost part or a hunch part such as a boundary between a precast formwork such as UFC and an RC structure part, a fixing method in which a fixing part is provided in the hunch part can be applied. As described above, the brace fixing hardware can be installed in the haunch portion by a stud diver, a perforated steel plate gibel, a PC steel bar or the like. These methods are particularly effective for the haunch part of precast formwork such as UFC. In this case, by installing and embedding the fixing part in the precast formwork in advance, the workability during construction of the pier is improved. Can be made.

 (6) In fixing braces at the upper and lower ends of foundation and beam columns, anchor points can be provided on rigid foundations and beams compared to column members. In this case as well, a fixing method such as a stud diver or a perforated steel plate can be used. However, since the cross section of the installation location is large, the installation method can be given flexibility, which is advantageous in terms of workability.

  The seismic control piers according to the present invention as described above can be applied to general bridges such as urban viaducts, but in particular, high piers with high pier heights (for example, about 30 m or more) and RC mains of suspension bridges. It is suitable for towers and the like because the effect of reducing the structural weight and improving the seismic performance is increased.

  Since the present invention is configured as described above, the following effects can be obtained.

 (1) Inspection of the upper and lower ends of the column after an earthquake (work at high places and ground) is not permitted by applying precast formwork such as UFC at the upper and lower ends of the column. Central work) is no longer necessary, and recoverability, that is, serviceability after an earthquake is improved.

  In addition, the natural period is stable and the seismic response can be predicted more easily than when yielding is allowed and the period is increased by deformation. In recent years, the evaluation technology of seismic motion has improved, and it has become possible to predict the dominant period band of seismic motion determined from fault source information, crustal structure, characteristics of the ground at the bridge point, etc. It is possible to reliably separate the vibration period of the structure, suppress the resonance as much as possible, and further reduce the seismic response.

  In addition, since the plastic deformation does not occur in the column, the residual deformation is extremely small. In addition, when the formation of plastic hinges is allowed, it is generally necessary to closely arrange the strip reinforcing bars near the rating points, but by reducing the yield of the axial steel material, the required amount of strip reinforcing bars can be reduced. And workability is improved.

 (2) The relative displacement of the damper at the center of the pier height direction is larger than that of the damper near the upper and lower ends of the frame structure, compared with the case where plastic hinges are formed and deformed in parallelograms. The ratio of the deformation of the damper at each mounting position is substantially constant during the earthquake response process (that is, regardless of the magnitude of the deformation of the frame frame). For this reason, it is possible to efficiently arrange the dampers throughout the response at the time of the earthquake.

 (3) By installing a haunch on a precast formwork such as UFC and attaching the brace to the haunch, it becomes possible to attach the brace to the upper and lower ends of the pillar, and to operate the damper over the entire frame structure. .

 (4) By attaching the braces at the upper and lower ends of the pillar across the plastic hinge, it is not necessary to attach to the damaged part.

  In addition, one brace is not fixed to the pillar, and all the braces that cause compression and tension are attached to the pillar as a set, so that the frame frame is attached in the direction of the member axis. Only the displacement force acts, and the structure of the mounting portion can be simplified. For example, the structure is simplified compared to pulling, such as applying a compression force with a PC steel rod and fixing it with friction.

  Also, by changing the capacity of the damper according to the deformation of the frame structure and making the compression and tension transmitted from the two dampers approximately equal, it is possible to apply only the displacement force, so the stud gibber An easy fixing method such as a perforated steel plate gibber can be applied.

  If two braces are not used as one set, one brace is fixed to the upper surface of the foundation or the lower surface of the beam alone. However, in such a part, it is fixed to massive concrete. Absent.

It is the schematic which compared the deformation | transformation state of the frame frame by the conventional and this invention in the damping bridge pier. It is a vertical sectional view which shows an example of the joining structure of the brace in the UFC formwork of the column lower end part of this invention. FIG. 1 shows an example of a brace joining structure in a UFC formwork at the upper end of a column according to the present invention, where (a) is a vertical sectional view and (b) is an exploded perspective view. It is a vertical sectional view showing another example of the joining structure of braces in the UFC formwork at the lower end of the column of the present invention. It is a vertical sectional view showing another example of the joining structure of braces in the UFC formwork at the lower end of the column of the present invention. It is a perspective view which shows the other example of the joining structure of the brace in the pillar lower end part of this invention. It is another example of the joining structure of the brace in the column upper-lower end part of this invention, (a) is a front view, (b) And (c) is a vertical sectional view. It is a front view which shows the example of the joining state of the brace in the boundary part of the UFC formwork and RC structure part of the pillar of this invention. It is a vertical sectional view showing an example of a brace fixing structure in a boundary portion between the UFC formwork and the RC structure portion of the present invention. It is a vertical sectional view showing an example of a fixing structure of a brace in the middle of a boundary part and a column between a UFC formwork and an RC structure part of the present invention. It is the example applied to the bridge pier of RC frame structure of the double warren truss structure of this invention, and is the schematic before and behind a deformation | transformation. It is the example which made the brace itself the damper brace in the double warren truss structure of FIG. 11, and is the schematic after deformation | transformation. It is a front view which shows the example of the pier of the conventional structure and the pier of the RC rigid frame structure to which this invention is applied. It is a front view which shows the force which acts on a pillar from a brace in the pier of this invention in FIG. It is an example of the frame frame in which a plastic hinge is formed in the conventional column upper-lower end part, (a) is a general view, (b) and (c) are partial views.

  Hereinafter, the present invention will be described based on the illustrated embodiments. This embodiment is an example applied to a pier having an RC rigid frame structure. FIG. 1 is a schematic diagram comparing the deformation state of a frame frame according to the prior art and the present invention. In FIG. 1, a bridge pier 1 having an RC rigid frame structure is composed of a pair of RC members 3 standing on a foundation (footing) 2 at intervals, and an RC member suspended over the top of the columns 3. A braced frame including a RC frame frame 5 composed of a beam or a main beam column girder 4 and a brace 6 arranged in the surface of the RC frame frame 5 with a vibration control device (damper, damper brace, etc.). 7.

  In the present invention, the braces 6 that connect the pair of left and right columns 3 are also arranged at the upper and lower ends of the columns 3 of the RC frame 5 where the plastic hinges H are formed by an earthquake motion (level 2 earthquake motion) more than expected, As will be described later, one end of each brace 6 at the upper and lower ends of the pillar 3 is joined to a haunch formed on the upper and lower ends of the pillar 3, or joined to the lower surface of the beam 4 and the upper surface of the footing 2, The strength is increased by using a precast formwork, which will be described later, at the upper and lower ends of the column 3 so that the plastic hinges H are not formed at a total of four locations at the upper and lower ends of the column 3.

  In the conventional structure of FIG. 1 (a), plastic hinges H are formed at the upper and lower ends of the columns, the frame frame 5 is deformed into a parallelogram, and the relative positions of the dampers installed at the truss rating points in the center between the columns The displacement is equal. On the other hand, in the structure of the present invention shown in FIG. 1B, the column 3 is deformed as an upper and lower fixed beam, and the relative displacement of the damper is small at the upper and lower portions of the column and large at the middle portion.

  As shown in FIGS. 2-5, in this invention, in order to avoid formation of the plastic hinge H at the time of a level 2 earthquake, super high strength fiber reinforcement is carried out in the four plastic hinge area L of the upper and lower ends of the pillar 3. As shown in FIG. Precast formwork (hereinafter referred to as UFC formwork) 10 made of concrete or mortar is used to prevent compressive damage of concrete at the upper and lower ends of the column with a narrowed cross section. The axial steel material 11 (see FIG. 3) is a high-strength reinforcing bar. The application range of the UFC formwork 10 is at least 1D or more, preferably 2D or more, and is a range that prevents compressive damage of concrete according to the moment gradient of the column 3 and the concrete strength other than the UFC formwork.

In addition, ultra high strength fiber reinforced concrete or mortar is a material in which steel fiber, carbon fiber or glass fiber is mixed in concrete or mortar with high compressive strength, compressive strength is 100 to 250 N / mm ² , bending tensile It has a strength of 10-40 N / mm ² and a tensile strength of 5-15 N / mm ² when cracking occurs.

  As the crack inducing structure of the UFC mold 10, the structure described in Japanese Patent Application No. 2006-200272 can be used. For example, high-strength fiber reinforced concrete or mortar is continuously introduced in the circumferential direction of the production formwork during the production of the precast formwork, and the fibers are continuously provided in the circumferential direction by placing in multiple layers. A crack-inducing joint in which fibers are not continuous is formed on the joining surface of each layer, but a plurality of crack-inducing joints are formed in one precast formwork at intervals in the vertical direction. . Cracks are easily generated by this crack-induced joint. In the state where the bridge pier is not bent during an earthquake or the like, cracks do not occur and the cracks close after a small and medium-scale earthquake, so that long-term durability can be ensured while no joint treatment is required. Further, the present invention is not limited to this, and a crack-inducing joint having a low tensile strength may be used at a joint portion between a plurality of precast formwork blocks.

  By applying the UFC formwork 10 to the part where the bending moment of the upper and lower ends of the column 3 is increased, it is possible to increase the strength of the cover part of the same part and delay the collapse of the concrete of the column 3. it can. Even in a level 2 earthquake, the column 3 does not become plastic, and the concrete can be collapsed after the main bar yields. For the pillars 3 other than the UFC formwork, a precast formwork made of ordinary concrete is used, or cast-in-place concrete is used in the same manner as a conventional RC member construction method.

  In the present invention, the braces 6 are also attached to the upper and lower ends of the columns in the plastic hinge section, and as described later, it is desirable to distribute the braces with a damper with as small a yield load as possible over the entire range of the ramen height. .

  Compared with the case where the plastic hinge of FIG. 1A is formed and deformed in a parallelogram, in the present invention in which the plastic hinge of FIG. 1B is not formed, the relative position of the damper at the center in the height direction of the frame 5 Although the displacement is larger than the dampers near the upper and lower ends of the frame 5, the ratio of the dampers at each mounting position is substantially constant during the earthquake response process (that is, regardless of the magnitude of deformation of the frame). Therefore, it is possible to cause energy absorption in the entire frame structure 5 by changing the capacity of a damper such as a honeycomb damper depending on the arrangement position. Any of the following methods can be used as a fixing method for the uppermost and lowermost braces 6.

 (1) FIG. 2 and FIG. 3 show an example of a brace joining structure in a UFC formwork at the lower end of a column. A haunch 12 is provided at the lower or upper corner of the UFC formwork 10, and the end of the brace 6 is joined to the haunch 12.

  In the embodiment of FIG. 2, a haunch 12 is provided at the fixing portion at the lower end of the pillar 3, and the fixing hardware 20 attached to the end of the brace 6 is fixed by the PC steel rod 21 and the anchor plate 22. The tensile force is transmitted by the PC steel rod 21 penetrating the haunch 12 and is borne by the anchor plate 22 in the footing 2. The compressive force is directly applied to the haunch 12 via the fixing hardware 20.

  In the embodiment of FIG. 3, a haunch 12 is provided at the fixing portion at the upper end of the column 3, a perforated steel plate gibbel 23 is attached to the end of the brace 6, and an oblique slit 24 is formed at the joint of the UFC formwork 10 divided vertically. The perforated steel plate diver 23 is fixed in the column 3 from the slit 24, and both the compressive force and the tensile force are borne by the perforated steel plate divel 23. A hole 25 through which the axial rebar 11 passes is formed in the perforated steel plate gibber 23. In addition, a fixing plate provided with a stud gibber or the like can be used (see FIG. 9).

  FIG. 4 is an example of a brace joint structure that does not hinder the effect of using a UFC formwork divided into a plurality of blocks. In FIG. 4A, an anchor 26 made of a plate material orthogonal to the plane constituting the brace 6 is embedded in the footing 2 (or the beam 4), or an anchor 26 made of a single round steel so as to be substantially pin-joined. Embed. In FIG. 4 (b), a steel pipe 27 surrounding the outer periphery of the column 3 is installed, and fixing in the vertical direction is borne by an anchor of a perforated steel plate gibber 27a embedded in the footing 2 (or beam 4).

 (2) FIGS. 5 and 6 are other examples of the brace joint structure in the UFC formwork at the upper and lower ends of the pillar, and the brace 6 is in the vicinity of the pillar 3 at the top end of the footing 2 (or the lower surface of the beam 4). In this case, the image is fixed obliquely. In either case, a T-shaped fixing tool 30 is disposed adjacent to the UFC mold 10, and the brace 6 is joined to the steel plate 30a by welding or the like. Here, the vicinity of the pillar 3 means a degree in which a substantially triangular shape is formed by the two upper and lower braces 6 and the pillar 3, and relative deformation of the damper is caused by the deformation of the pillar 3.

  In FIG. 5 (a), a perforated steel plate dowel 30b is used for fixing. It is possible to insert the reinforcing bar of the footing 2 into this hole. There are many footing rebars, and the use of such a perforated steel bar gibber as a penetrating rebar is less problematic, and there are fewer restrictions on the perforated steel bar gibel for bearing the tensile force of the brace 6.

  FIG. 5B uses a headed stud 30c. In FIG. 5C, a shearing force and a pulling force are applied by the shear key 30d and the deformed stud 30e.

  FIG. 6 shows a method in which the brace 6 is installed in two places before and after the pillar 3 (in the direction of the bridge axis). In FIG. 6, the brace 6 is shown as a steel pipe. However, when the frame construction surface is deformed out of the plane, an acute angle is set as the damper position by providing a member having low bending rigidity in the out-of-plane direction. The triangle formed by the two front and rear braces 6 can follow the out-of-plane deformation of the frame structure. In addition, the two front and rear braces 6 can be temporarily joined with a U-shaped member in the vicinity of the lower end of the column 3 and then connected to the damper position with a single brace (not shown).

 (3) FIG. 7 is another example of the brace joining structure at the upper and lower ends of the pillars, in which a pair of left and right braces 6 are arranged straddling the upper and lower ends of the pillars 3 and the top end of the footing 2 (or the beam 4). This is the case where the toner image is fixed at the center of the lower surface. As shown in FIG. 7 (a), three X-shaped braces 6 are arranged in the middle part of the RC frame 5 in front view, and inverted V-shaped and V-shaped braces 6 are arranged at the upper and lower parts. A damper 8 such as a honeycomb damper is disposed at the intersection of the X-shaped braces 6, and the damper 8 is also disposed on the lower surface of the beam 4 and the upper surface of the footing 1.

  7B and 7C show a method of fixing the brace 6 to the top end of the footing 2, and FIG. 7B shows a method of attaching the left and right braces 6 separately. A recess 40 is formed at the top of the center of the footing 2, the upper part of the honeycomb damper 8 is attached to the end of the brace 6, and the lower part is attached to the inclined surface of the recess 40 to absorb the oblique relative displacement of the brace 6 in the axial direction. I can do it.

  In FIG.7 (c), the edge part of the left and right braces 6 is connected to the steel plate beam 41, and both ends of the steel plate beam 41 are supported by the steel plate columns 42. The steel plate beam 41 and the steel plate column 42 are arranged in the vertical direction. A mechanism that restricts displacement and allows movement in the horizontal direction, for example, is connected to a pin with a long long hole in the horizontal direction, the upper part of the honeycomb damper 8 is attached to the steel plate beam 41, and the lower part is anchor bolt 43 at the top of the footing 2 So that relative displacement in the horizontal direction occurs in the honeycomb damper 8. The steel plate column 42 is fixed to the footing 2 by a perforated steel plate gibber 42 a and a footing rebar 44.

  FIG. 8 shows an example of the joining state of the brace 6 at the boundary between the UFC mold 10 of the pillar 3 and the RC structure 13. It is desirable to install a haunch 12 or the like at the boundary between the UFC mold 10 and the RC structure 13 in order to relieve stress concentration on the RC structure due to a difference in elastic modulus. 8A shows the case where the brace 6 is joined to the vertical surface of the boundary portion, and FIG. 8B shows the case where the brace 6 is joined directly to the inclined surface of the haunch 12.

  FIG. 9 shows an example of the fixing structure of the brace 6 at the boundary portion between the UFC formwork 10 and the RC structure portion 13. As described above, it is desirable to provide the haunch 12, but when the brace 6 is attached to the haunch 12, the inclined surface of the haunch 12 and the brace 6 can be substantially orthogonal to each other. Can be easily transmitted to the pillar 3 or the footing 2 or the beam 4, and the fixing hardware can be embedded in the axial extension of the brace 6 with respect to the tensile force. There is an advantage that it is difficult to be restricted by the fixing depth and the size of the fixing hardware.

  FIG. 9A shows a case where the stud metal 28 is provided on the fixing hardware 20. FIG. 9B shows a case where a perforated steel plate gibbel 23 is provided in the fixing hardware 20. FIG. 9C shows a case where the fixing hardware 20 is fixed by the PC steel rod 21 and the anchor plate 22.

  FIG. 10 shows an example of the fixing structure of the brace 6 in the middle of the boundary part between the UFC mold 10 and the RC structure part 13 and the column 3. When two or more X braces are installed, if the two braces 6 from above and below are joined at one point and fixed to the column 3, the compressive force and tensile force of the brace 6 become the axial displacement force of the column 3, and the column 3 (see FIG. 13B). Therefore, since the fixing force to be borne is the yield load of the damper only by the shifting force in the column axis direction, the structure can be made relatively simple.

  FIG. 10A shows a case where the stud gibber 28 is provided in the fixing hardware 20 and is embedded when the column concrete is placed. FIG. 10B shows a case in which a perforated steel plate gibbel 23 is provided in the fixing hardware 20, which is embedded when placing column concrete.

  In FIG. 10C, a hole through which the PC steel bar 21 passes is provided in the column 3, and the PC steel bar 21 is tensioned so that the brace fixing portion is sandwiched between the fixing hardware 20 and the anchor plate 22. In this case, the fixing force of the brace 6 is ensured by the frictional force accompanying the tension force introduced by the PC steel rod 21. Further, in this method, since the boundary portion between the UFC mold 10 and the RC structure portion 13 is a fixing plate, it is a sandwich structure reinforced by a steel plate and restraining force, so it is necessary to provide a haunch or the like at the boundary portion described above. Disappear.

  FIG. 11 is an example applied to a bridge pier 1 having an RC rigid frame structure of a double warren truss structure, and shows a state before and after deformation when a damper 8 such as a honeycomb damper is installed at a joint portion between a column 3 and a brace 6. The dampers 8 are arranged every other one, and plastic hinges are not formed at the upper and lower ends of the columns 3, and the seismic energy is absorbed by the relative displacement in the vertical direction of the numerous dampers 8.

  FIG. 12 shows an example in which the brace itself is a damper brace 6 in the double warren truss structure of FIG. As the damper brace 6, an expansion / contraction damper or a buckling restraint damper (a plastic core material buckled and stiffened with a restraining material) or the like is used. All the damper braces 6 are joined to the pillars 3 at both ends, and the damper braces 6 themselves expand and contract. In the state of FIG. 12, the damper brace 6a inclined from the lower left to the upper right is extended, and the damper brace 6b inclined from the lower right to the upper left is compressed.

  FIG. 13 and FIG. 14 are examples when the number of columns is three in the vibration control pier structure of the present invention. When the column has a square cross section with one side D, the cross-sectional area is proportional to D2, and the bending rigidity is proportional to D4. Therefore, in order to support the weight of the superstructure, if the same total cross-sectional area is used, the bending rigidity will be smaller if three or more thin columns are arranged than if supported by two columns. Suitable for piers. For bridge piers that support wide superstructures with many lanes, it is necessary to make the width of the piers perpendicular to the bridge axis generally equal to the width of the superstructure (main girder). Is reasonable.

  In FIG. 13, in the case of the wall type pier of the conventional structure of (a), rigidity is very large. In the case of a vibration control pier with a two-column portal frame of (b), the rigidity is low and a long period can be achieved. In the case of a vibration control pier with a three-column, two-span frame in (c), the rigidity is even lower. Further, as shown in FIG. 14, in the middle pillar of the three pillars, the forces from the four braces on the left, right, and top and bottom cancel each other, so that the structure can be further simplified.

  Although not shown, the present invention can also be applied to a three-dimensional frame structure having two or more columns in the bridge axis direction and the bridge axis direction.

  Needless to say, the present invention is not limited to the illustrated examples.

1 …… Bridge pier 2 …… Funding
3 ... Column 4 ... Beam or main girder column head girder 5 ... Frame frame 6 ... Brace 7 ... Brace frame 8 ... Damper 10 ... Precast formwork such as ultra high strength fiber reinforced concrete (UFC type) frame)
DESCRIPTION OF SYMBOLS 11 ... Axial steel material 12 ... Haunch 13 ... RC structure part 20 ... Fixing metal 21 ... PC steel rod 22 ... Anchor plate 23 ... Perforated steel plate gibber 24 ... Slit 25 ... Insertion hole of axial rebar 26 ... Plate material and round steel Anchor 27 ... Steel pipe 27a ... Perforated steel plate gibber 28 ... Stud gibber 30 ... Fixing tool 30a ... Steel plate 30b ... Perforated steel plate gibble 30c ... Sted stud 30d ... Shear key 30e ... Deformed stud 40 ... Recess 41 42a ... Perforated steel plate gibble 43 ... Anchor bolt 44 ... Footing rebar L ... Plastic hinge section

Claims (5)

  An RC frame frame composed of two or more RC member columns erected at intervals on the foundation and an RC member beam spanned on the top of the column, and in the surface of the RC frame frame A seismic pier structure composed of a brace frame having a seismic control function, and a pair of left and right sides of the RC frame frame in which a plastic hinge is formed by an earthquake motion more than expected. Braces that connect the pillars of the pillars are arranged, and one end of the braces at the upper and lower ends of the pillars are joined to the hunches formed at the upper and lower ends of the pillars, respectively, or joined to the lower surface of the beam and the upper surface of the foundation, Seismic control pier structure designed to prevent plastic hinges from being formed at the lower end of the column.   The seismic pier structure according to claim 1, wherein the braces in the middle portion excluding the upper and lower ends of the column are fixed to the column by gathering the ends of the upper and lower braces in one place. Damping pier structure.   3. The damping pier structure according to claim 1 or 2, wherein an X-shaped brace is arranged between the pair of left and right columns in front view, and is divided into left and right at the intersection of the X-shaped brace, and relative to the intersection in the vertical direction. Seismic control pier structure with dampers that absorb energy according to displacement.   3. The damping pier structure according to claim 1, wherein a damper that absorbs energy in accordance with a relative displacement in the vertical direction is disposed between the column and the brace. 4.   3. The damping pier structure according to claim 1, wherein the brace is a damper brace that absorbs energy in accordance with an axial expansion and contraction displacement. 4.

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