Supporting device for bridge upper structure

Abstract

To reduce a moment acting on a base plate in a direction perpendicular to the bridge axis when a displacement limiting device receiving an end of an upper structure in the bridge axis direction is supported by a part projecting from the side face of the lower structure.SOLUTION: A support device 1 includes a base plate 2 that overlaps the side surface 51 of a lower structure 5, a plurality of anchor bolts 3 that join the base plate 2 to the lower structure 5, and an overhanging member 4 that overhangs from the surface of the base plate 2 toward the opposing lower structure 5, and the upper surface of an upper flange 43 on which a displacement limiting device 7 that receives the end part of an upper structure 6 is placed, is positioned below all anchor bolts 3 arranged in the uppermost stage among the plurality of anchor bolts 3 arranged in a plurality of stages.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a support device for a bridge superstructure that supports a displacement limiting device that receives an end portion of the superstructure in the bridge axis direction from a portion protruding from the side surface of the substructure.

Background Art

[0002] When supporting an end portion of a superstructure such as a bridge girder of a bridge on a portion protruding from a side surface of a substructure such as a pier facing the opposite substructure side, the end portion of the superstructure is supported on the upper surface of a bracket (protruding member) protruding from the side surface of the substructure (see Patent Documents 1 to 3 and 6).

[0003] Since the vertical load of the superstructure is mainly borne by a bearing installed on the upper surface of the substructure, the horizontal load (horizontal force) of the superstructure is mainly transmitted to the bracket on the side surface of the substructure (Patent Documents 1, 3, and 6). As shown in FIGS. 1 and 2 of Patent Document 1, the superstructure is placed on the bracket via a displacement limiting device (horizontal force sharing structure) that mainly transmits horizontal loads in two directions (hereinafter, horizontal forces) to the substructure (Patent Documents 1, 3 to 6).

[0004] Among the horizontal forces acting on the superstructure, the horizontal force in the bridge axis direction is transmitted to the substructure as a bearing pressure or a tensile force from the base plate of the bracket that is in contact with the side surface of the substructure, while the horizontal force perpendicular to the bridge axis is transmitted to the substructure through a plurality of anchor bolts fixed to the substructure through the base plate. The bearing pressure in the bridge axis direction from the base plate is borne by the substructure as a compressive force, and the tensile force is borne by the anchor bolts as a tensile force.

[0005] As shown in Fig. 4-(a), the horizontal force H in the direction perpendicular to the bridge axis not only causes the shear force S1 to be borne by the bracket 12 and the base plate 2, but also generates a moment M1 (M1 = H·h1) with the center (horizontal axis) at the position of the centroid O of all the anchor bolts 3 and the distance h1 from the acting position f of the horizontal force H as the arm length. The shear force S1 and the moment M1 acting on the bracket 12 and the base plate 2 are borne by all the anchor bolts 3 that fix the bracket 12 to the substructure 5 via the base plate 2.

[0006] Regarding the moment M1, if the distance from the centroid O of all the anchor bolts 3 to the center of each anchor bolt 3 is L1 and it is assumed that the four anchor bolts 3 shown in Fig. 4-(a) bear the load, the anchor bolts 3 bear the shear force S2 that satisfies the relationship M1 = 4·L1·S2. The shear force S2 becomes smaller as the distance L1 is larger.

[0007] In addition, as shown in Fig. 4-(b), when looking at the horizontal force H in the direction perpendicular to the bridge axis in a plan view, it acts on the bracket 12 protruding from the base plate 2 and generates a moment M2 with the horizontal distance L2 from the acting position f of the horizontal force H as the arm length around the center (vertical axis) of the base plate 2. Therefore, a withdrawal force (tensile force) acts on the anchor bolts 3. The anchor bolts 3 also need to resist this withdrawal force.

[0008] Here, when looking at the side of the substructure from the front as in Patent Documents 1 to 3 and 6, when a plurality of anchor bolts are arranged at equal intervals in the vertical direction and in multiple stages, and the centroid of all the anchor bolts is located at the center of the base plate 2, when the horizontal force H in the direction perpendicular to the bridge axis acting on the bracket 12 is constant, the moment M1 generated in the base plate 2 is determined by the magnitude of the distance h3 from the centroid (horizontal axis) O to the acting position f of the horizontal force H as shown in Fig. 2-(b) (M1 = H·h3).

[0009] When supporting the displacement limiting device on a bracket fixed to the side of the lower structure as in Patent Documents 1, 3, and 6, due to the convenience of inserting and fixing the anchor bolts for fixing the base plate to the lower structure into the lower structure, the displacement limiting device has to be placed on the support plate integrated with the uppermost part of the bracket (Patent Document 1, paragraph 0026, Figures 1 and 2; Patent Document 3, paragraphs 0040 to 0041, Figures 9 and 10; Patent Document 6, paragraph 0028, Figures 1 and 2).

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0011] In this regard, since the horizontal force H in the direction perpendicular to the bridge axis transmitted from the displacement limiting device 7 to the bracket 12 acts on the support plate (upper flange 43) at the uppermost part of the bracket 12, as shown in Figure 2, the distance h3 from the centroid (horizontal axis) O of all the anchor bolts 3 to the position where the horizontal force H acts must be at least about half of the total height of the base plate 2.

[0012] Therefore, as long as the base plate 2 is fixed to the lower structure 5 using the anchor bolts 3 arranged in multiple stages, it is difficult to shorten this distance h3. As long as the displacement limiting device 7 is supported on the support plate at the uppermost part of the bracket 12, it is difficult to reduce the moment M1 acting on the base plate 2.

[0013] As described above, the anchor bolts 3 bear the shear force S1 due to the horizontal force H in the direction perpendicular to the bridge axis and the shear force S2 due to the moment M1 caused by the horizontal force H. Therefore, if there is a limit to reducing the moment M1, there is also a limit to reducing the number of the anchor bolts 3 to be used or reducing the diameter of each anchor bolt 3.

[0014] The distance between the bottom surface of the upper structure 6 and the upper surface of the lower structure 5 is mainly determined according to the height dimension of the above-mentioned bearing, etc. Here, when the displacement limiting device 7 is fixed to the bottom surface of the upper structure 6 as in Patent Documents 1, 3, and 6, if the height dimension of the displacement limiting device 7 is smaller than the height dimension of the bearing, as shown in FIG. 2, it is necessary to bring the upper flange 43 closer to the bottom surface of the upper structure 6. Therefore, the distance h3 becomes larger than that in the case of FIG. 1 of Patent Document 1.

[0015] Based on the above background, the present invention proposes a support device for a bridge upper structure that enables reduction of the moment M1 acting on the base plate in the direction perpendicular to the bridge axis from the displacement limiting device.

Means for Solving the Problems

[0016] The support device for a bridge upper structure according to the invention described in claim 1 is a support device that projects from the side surface of the lower structure of the bridge facing the opposite lower structure side in the bridge axis direction and supports the end portion of the upper structure in the bridge axis direction. A base plate overlapping the side surface of the lower structure, A plurality of anchor bolts that penetrate through this base plate and are fixed in the lower structure to join the base plate to the lower structure, And a projecting member that projects from the surface of the base plate toward the opposite lower structure side and supports the upper structure. The plurality of anchor bolts are arranged in a plurality of vertical stages, On the upper part of the overhanging member, there is an upper flange on which a displacement limiting device for supporting the end of the upper structure in the bridge axis direction on the overhanging member and transmitting the horizontal force from the upper structure to the lower structure is placed. It is a constituent requirement that the upper surface of the upper flange is located below all the anchor bolts arranged in the uppermost stage among the plurality of anchor bolts arranged in the plurality of stages.

[0017] "The side surface of the lower structure facing the opposite lower structure side" refers to the side surface 51 of the lower structure 5 shown in FIG. 1 that faces the lower structure 5 side that is opposite (adjacent) in the bridge axis direction. The lower structure 5 includes piers and abutments. The side surface 51 of the lower structure 5 may form a vertical surface or may be inclined with respect to the vertical surface. The upper structure 6 is mainly a bridge girder, but the form (type) of the upper structure 6 is not limited as long as the end of the upper structure 6 in the bridge axis direction is supported by the overhanging member 4 that protrudes from the side surface 51 of the lower structure 5.

[0018] "The base plate overlapping the side surface of the lower structure" means that the base plate 2 directly or indirectly overlaps the side surface 51 of the lower structure 5. "The plurality of anchor bolts fixed in the lower structure through the base plate" means that the plurality of anchor bolts 3 penetrate the base plate 2 and are embedded and fixed in the lower structure 5 so as to be able to resist the assumed shear force and pulling-out force.

[0019] The term "the projecting member protruding from the surface of the base plate and projecting toward the opposing lower structure" means that the projecting member 4 projects from the surface of the base plate 2 toward the opposing (adjacent) lower structure 5 to such an extent that it can support the end portion of the upper structure 6 in the bridge axis direction. Although it is effective in ensuring stability against torsional moments about the axis in the axial direction that the entire axial length of the projecting member 4 has a closed cross-sectional shape (Patent Document 6), this is not necessarily required in the present invention. The axial direction of the projecting member 4 is basically the bridge axis direction. The projecting member 4 is mainly composed of a vertical plate 41 facing the vertical direction and a horizontal plate 42 facing the horizontal direction, but this is not necessarily required.

[0020] When the entire length of the projecting member 4 has a closed cross-sectional shape (Patent Document 6), since the torsional rigidity about the axis in the bridge axis direction is greater than that in the case of an open cross-sectional shape such as an H-shaped cross-section, it is easy to ensure resistance against torsional moments about the axis in the bridge axis direction caused by horizontal forces in the direction perpendicular to the bridge axis. In particular, if the tip side of the projecting member 4 is closed, the resistance is further improved.

[0021] The term "the projecting member that supports the upper structure" means that the projecting member 4 indirectly supports the upper structure 6 via the displacement limiting device 7. However, as described above, since the vertical load of the upper structure 6 is mainly borne by the bearing 9 installed on the upper surface of the lower structure 5, the projecting member 4 mainly bears the horizontal load (horizontal force) in the direction perpendicular to the bridge axis from the upper structure 6 and supports the upper structure 6 in a state of transmitting it to the lower structure 5.

[0022] The term "a plurality of anchor bolts are arranged in a plurality of vertical stages" means that a plurality of anchor bolts 3 are divided into two or more stages, and for each stage, a plurality of anchor bolts 3 are spaced apart from each other in the horizontal direction, for example, arranged in the horizontal direction. The anchor bolts 3, 3 spaced apart in the horizontal direction may be arranged in a staggered pattern.

[0023] The "displacement limiting device that supports the end of the superstructure in the bridge axis direction by a cantilever member" means that the displacement limiting device (horizontal force sharing structure) 7 that transmits the two-way horizontal force from the superstructure 6 to the substructure 5 supports the end of the superstructure 6 in the bridge axis direction while being supported by the cantilever member 4. "Having an upper flange on which the displacement limiting device is placed on the upper part of the cantilever member" means that the upper flange 43 is integrated as a part of the cantilever member 4 on the part of the cantilever member 4 that faces the lower surface of the superstructure 6.

[0024] "The upper surface of the upper flange is located below all the anchor bolts arranged in the uppermost row" means that, as shown in FIGS. 1-(a) and (b), the upper flange 43 is arranged so that the entire set of all the anchor bolts 3 arranged in the uppermost row among the anchor bolts 3 arranged in multiple rows on the base plate 2 is exposed on the upper surface. Assuming that the axes of the multiple anchor bolts 3 in the same row are arranged on the same horizontal line, the upper surface of the upper flange 43 will be located at least below the lower ends (lower surfaces) of all the anchor bolts 3.

[0025] "The upper surface of the upper flange is located at the lower ends of all the anchor bolts" means that the lower ends of all the anchor bolts 3 are in contact with the upper surface of the upper flange 43. Since it is "below all the anchor bolts arranged in the uppermost row", the upper surface of the upper flange 43 may also be below all the anchor bolts 3 arranged in the second row from the top.

[0026] By the upper surface of the upper flange 43 being located below all the anchor bolts 3 arranged in the uppermost row, at least all the anchor bolts 3 in the uppermost row can be positioned above the upper surface of the upper flange 43. As a result, compared with the conventional case where the upper flange 43 was arranged above the row of the uppermost anchor bolts 3, the upper flange 43 can be positioned downward by at least the distance between the axes of the adjacent anchor bolts 3, 3 above and below.

[0027] The distance h1 between the acting position f of the horizontal force H in the direction perpendicular to the bridge axis, which applies the moment M1 from the superstructure 6 (displacement limiting device 7 (horizontal force sharing structure)) to the upper flange 43, and the centroid O of all the anchor bolts 3, is reduced as the axial center distance between the adjacent anchor bolts 3, 3 above and below this is equal to or greater than a certain value. As a result, the moment M1 caused by the horizontal force H can be reduced accordingly.

[0028] Since the moment M1 caused by the horizontal force H is reduced, the shear force S2 that each anchor bolt 3 should bear to resist the moment M1 is reduced. Therefore, it becomes possible to reduce the number of anchor bolts 3 required to fix the base plate 2 to the substructure 5 or to reduce the diameter of each anchor bolt 3.

[0029] In the example of FIG. 2 showing a conventional example under the same conditions as FIG. 1 showing an example of the present invention, anchor bolts 3 arranged in 4 columns in each of 6 stages are used to fix the base plate 2 to the substructure 5. In this case, the distance h4 from the centroid O of the anchor bolt group to the upper surface of the upper flange 43 is approximately 3.5a, where a is the axial center distance between the vertically adjacent anchor bolts 3, 3. If the acting position f of the horizontal force from the superstructure 6 to the substructure 5 is at the engagement position of the upper member 71 and the lower member 72 of the displacement limiting device 7 as shown in FIG. 2-(a), then in the example of FIG. 2, the distance from the axial center of the topmost row of anchor bolts to the acting position f of the horizontal force H is about 0.5a. Therefore, the distance h3 from the centroid O to the horizontal force acting position f is about 4a.

[0030] FIG. 1 and FIG. 2 are compared under the condition that the distance between the lower surface of the superstructure 6 and the upper surface of the substructure 5 is the same, and the position (level) of the topmost row of anchor bolts for fixing the base plate 2 to the substructure 5 is the same. The reason why the topmost row of anchor bolts is located a certain distance below the upper surface (top end) of the substructure 5 is that, in FIGS. 1-(a) and 2-(a), the reinforcing bars indicated by circles are densely arranged or to be arranged in the substructure 5, and it is necessary to determine the position of the anchor bolts 3 so as to avoid the reinforcing bars in the substructure 5.

[0031] In the example shown in FIG. 2, in the example shown in FIG. 1, the base plate 2 is fixed to the substructure 5 with anchor bolts 3 arranged in 4 rows in the vertical direction and 5 columns in each row. Here, it is expected that the moment M1 due to the horizontal force H is reduced as described above, and the arrangement of the anchor bolts 3 required for fixing the base plate 2 is such that the number of anchor bolts 3 is 4 less than that in the example shown in FIG. 2.

[0032] In the example shown in FIG. 1, the axial center distance between adjacent anchor bolts 3, 3 in the vertical direction is set to the same a as in the example of FIG. 2, and assuming that the upper surface of the upper flange 43 is in the middle between the axial centers of the adjacent anchor bolts 3, 3 in the vertical direction, the distance h2 from the centroid O to the upper surface of the upper flange 43 is about a.

[0033] In FIG. 1, the distance from the centroid O to the axial center of the uppermost row of anchor bolts is about 2a, and the distance h1 from the centroid O to the acting position f of the horizontal force H is about 2.5a. In comparison with FIG. 2, h1 is about 5 / 8 h3. This means that the moment M1 acting on the base plate 2 due to the horizontal force H in the direction perpendicular to the bridge axis transmitted from the superstructure 6 to the substructure 5 is about 5 / 8 of the magnitude in the example shown in FIG. 2. The reduction in this moment M1 and the number of used anchor bolts 3 are reduced.

[0034] In FIG. 4, if the shear force that should be borne by one anchor bolt 3 due to the horizontal force H directly is S1, and the shear force that should be borne by one anchor bolt 3 due to the moment M1 is S2, and the angle formed by the acting directions of S1 and S2 is α, then the resultant force S0 of the shear forces S1 and S2 is S0 2 =(S1 + S2cosα) 2 +(S2sinα) 2 is obtained from. In FIG. 4, for the sake of simplification, the number of anchor bolts is set to 4. Therefore, if the distance from the centroid O to the axial center of the anchor bolt 3 is L1, then as described above, M1 = 4·L1·S2, so S2 = M1 / 4·L1. Here, since M1 in the example of FIG. 1 is about 5 / 8 of that in the example of FIG. 2, the shear stress that one anchor bolt 3 should bear is smaller than that in the example of FIG. 2.

[0035] Let's calculate the shear stress τ that should be borne by one anchor bolt 3 in the case of the conventional example shown in Fig. 2. Here, an example is shown where 24 anchor bolts 3 are used in 6 rows and 4 columns each on the base plate 2. Assuming that the assumed horizontal force H is 1600 kN, the horizontal force (shearing force S1) that each anchor bolt 3 should bear is S1 = 1600 / 24 = 66.7 kN. The moment M1 caused by the horizontal force H acting around the centroid O of all the anchor bolts 3 is M = 1600×1.4 = 2240 kN·m, taking the distance from the centroid O to the acting position of the horizontal force H as 1400 mm (1.4 m).

[0036] Here, assuming that the axial tensile forces P1 to P6 generated in the anchor bolts 3 arranged in 6 rows as shown in Fig. 2 are triangularly distributed (the relationship P1 / y1 = P2 / y2 = P3 / y3 = Pn / yn holds), then P2 = P1·(y2 / y1), P3 = P1·(y3 / y1), and Pn = P1·(yn / y1). Since the moment around the horizontal axis perpendicular to the bridge axis at the position where each tensile force Pn acts from the centroid O is Pn·yn, for 6 bolts, the moment M = P1·y1 + P2·y2 + P3·y3 + …… = P1·y1 + P1·(y2 / y1)·y2 + P1·(y3 / y1)·y3…… = P1 / y1·(y1 2 +y2 2 +y3 2 +……)=P1 / y1·Σyn 2 That is.

[0037] The shear force S2 acting on the anchor bolt 3 at the position farthest from the centroid O under this moment M is S2 = M×Lmax / Σyn, taking the distance from the centroid O as Lmax and the distance from the centroid O to each anchor bolt 3 as yn. 2 It is shown by. Calculating, S2 = 183 kN. When calculating S0 from the above formula, S0 = 236 kN. The shear stress τ of each anchor bolt 3 is τ = S0 / As = 160 N / mm, taking the effective cross-sectional area of the threaded part of the anchor bolt as As. 2 That is.

[0038] On the other hand, in the case of the example of the present invention shown in Fig. 1, assuming that the horizontal force H is 2280 kN, the horizontal force (shearing force S1) that each anchor bolt 3 should bear is S1 = 2280 / 20 = 114 kN. The moment M1 caused by the horizontal force H acting around the centroid O of all the anchor bolts 3 is M1 = 2280×0.525 = 1197 kN·m, where the distance from the centroid O to the acting position of the horizontal force H is 525 mm (0.525 m).

[0039] The shearing force S2 acting on the anchor bolt 3 at the position farthest from the centroid O in response to this moment M1 is calculated as S2 = 116 kN, where the distance from the centroid O is Lmax and the distance from the centroid O to each anchor bolt 3 is yn. S0 is S0 = 236 kN, and the shearing stress τ of each anchor bolt 3 is τ = S0 / As = 161 N / mm 2 becomes.

[0040] This means that although the shearing stress is at the same level, in the present invention, 20 anchor bolts 3 can bear a horizontal force H (2280 kN), which is 1.425 times the horizontal force H1600 kN borne by 24 conventional anchor bolts 3. The number of anchor bolts used is reduced by 17% (20 / 24).

[0041] Thus, in the present invention, when a plurality of anchor bolts 3 are arranged in multiple rows, the larger the number of anchor bolts 3 arranged in one row, the smaller the distance h1 between the acting position f of the horizontal force H in the direction perpendicular to the bridge axis and the centroid O of all the anchor bolts 3 can be. That is, when the number of anchor bolts 3 used is constant, h1 can be made smaller when the number of rows of the anchor bolts 3 is smaller than when the number of rows is larger as in Patent Documents 1 to 3 and 6.

[0042] In other words, it can be said that it is advantageous for the base plate 2 that fixes the cantilever member 4 to the substructure 5 to have a horizontally long shape in the joined state to the substructure 5 in reducing h1 and reducing the moment M1 (Claim 2). In this case, the base plate 2 basically has a horizontally long rectangular shape, but the shape of the base plate 2 in the usage state is not limited.

[0043] Also, when considering the case where the number of steps of the anchor bolts 3 is the same, if all the anchor bolts 3 can be arranged such that the number of arrangements of each step gradually decreases from the upper side to the lower side, the centroid of all the anchor bolts 3 can be made closer to the upper flange 43. Therefore, the distance h1 (arm length) between the centroid O and the horizontal force acting position f can be reduced, and the moment M1 acting on the cantilever member 4 can be reduced.

[0044] As a result, since the shear force that each anchor bolt 3 should bear is reduced, it becomes possible to further reduce the number of anchor bolts 3 required for fixing the base plate 2 or reduce the diameter. "The number of arrangements of each step gradually decreases as a whole" means, for example, setting the number of arrangements of the upper 1st and 2nd steps to 6, the 3rd and 4th steps to 5, and the 5th and 6th steps to 4.

[0045] In addition, since the horizontal force H in the direction perpendicular to the bridge axis from the superstructure 6 is transmitted from the displacement limiting device 7 installed between the lower surface of the superstructure 6 and the upper surface of the upper flange 43 of the cantilever member 4 to the substructure 5, if the displacement limiting device 7 is directly placed on the upper flange 43 (Claim 3), the distance h1 from the centroid O position of all the anchor bolts 3 to the horizontal force acting position f can be reduced, which is effective in reducing the number of anchor bolts 3 used.

[0046] Since the displacement limiting device 7 is divided into an upper member 71 fixed to the upper structure 6 and a lower member 72 fixed to the lower structure 5 (upper flange 43) as shown in FIGS. 1 and 2, when the upper member 71 moves relative to the lower member 72, the horizontal force H acts on the lower structure 5 from the position where the upper member 71 engages with the lower member 72. The "horizontal force from the upper structure" in claim 3 refers to the horizontal force in the direction perpendicular to the bridge axis.

[0047] In this case, when the displacement limiting device 7 is placed on the upper flange 43 of the cantilever member 4 and a space is generated between the upper surface of the displacement limiting device 7 and the lower surface of the upper structure 6, a pedestal 8 for filling the space is installed as shown in FIGS. 1 and 3 and fixed to the lower surface of the upper structure 6 and the upper surface of the displacement limiting device 7.

[0048] Incidentally, in the example shown in FIG. 2, the upper surface of the upper flange 43 was aligned with the upper surface of the lower structure 5. However, within the range where interference with the reinforcing bars in the lower structure 5 can be avoided, the upper flange 43 can be lowered as shown in FIG. 3, and the position of the displacement limiting device 7 placed on the upper flange 43 can be lowered. Theoretically, it is considered possible to make the distance h3 between the centroid O and the horizontal force acting position f smaller than that in the example of FIG. 2.

[0049] However, even in FIG. 3, since it is necessary to secure a working space below the upper flange 43 that is sufficient to tighten the nut 31 for joining the head of the uppermost anchor bolt 3 to the base plate 2, there is a limit to shortening the distance h3. In addition, it is essential to install a pedestal 8 for filling the space formed between the displacement limiting device 7 joined to the lower surface of the upper structure 6 and the upper flange 43.

Advantages of the Invention

[0050] In a support device including a base plate overlapping the side surface of the lower structure, a plurality of anchor bolts joining the base plate to the lower structure, and a cantilever member protruding from the base plate and projecting toward the opposing lower structure side, in order to position the upper surface of the upper flange below all the anchor bolts arranged in the uppermost row, at least all the anchor bolts in the uppermost row can be positioned above the upper surface of the upper flange.

[0051] As a result, the upper flange can be positioned lower by at least the distance between the axial centers of the anchor bolts adjacent vertically than when the upper flange is disposed above the row of the uppermost anchor bolts.

[0052] Therefore, the distance between the acting position of the horizontal force in the direction perpendicular to the bridge axis that acts on the upper flange and the centroid of all the anchor bolts can be reduced, and accordingly, the moment due to the horizontal force can be reduced. As a result, the shear force that each anchor bolt should bear to resist the moment is reduced, so that the number of anchor bolts required to fix the base plate to the substructure can be reduced or the diameter of each anchor bolt can be reduced.

Brief Description of the Drawings

[0053]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0054] FIG. 1-(a) shows a configuration example of the support device 1 that projects in the bridge axis direction from the side surface 51 facing the opposing lower structure 5 side of the lower structure 5 such as the pier of the bridge and supports the end of the upper structure 6 in the bridge axis direction. FIG. 1-(a) shows a longitudinal section of the lower structure 5 and the upper structure 6 viewed in a direction perpendicular to the bridge axis passing through a part of the base plate 2. FIG. 1-(b) shows the arrangement state of all the anchor bolts 3 for fixing the base plate 2 to the side surface 51 of the lower structure 5.

[0055] The support device 1 includes a base plate 2 that is fixed overlapping the side surface 51 of the lower structure 5, a plurality of anchor bolts 3 that penetrate the base plate 2 and are fixed (embedded) in the lower structure 5 to join (fix) the base plate 2 to the lower structure 5, and a projecting member 4 that is projected on the surface of the base plate 2 by welding or the like and projects toward the opposing lower structure 5 side. The projecting member 4 indirectly supports the upper structure 6 via a displacement limiting device (horizontal force sharing structure) 7 and mainly transmits the horizontal force in the direction perpendicular to the bridge axis from the upper structure 6 to the lower structure 5 via the base plate 2 and the anchor bolts 3.

[0056] A plurality of anchor bolts 3 are arranged in multiple vertical stages. An upper flange 43 is integrally formed at the upper part of the cantilever member 4, on which a displacement limiting device 7 for supporting the end of the upper structure 6 in the bridge axis direction on the cantilever member 4 is placed. The displacement limiting device 7 may be placed directly on the upper flange 43 or indirectly via a pedestal 8 as shown in Fig. 3. Since the vertical load of the upper structure 6 is transmitted to the lower structure 5 through a support 9 installed on the upper surface of the lower structure 5 as shown in Fig. 5, mainly horizontal forces are transmitted from the displacement limiting device 7 to the cantilever member 4 as the load of the upper structure 6.

[0057] The horizontal force in the bridge axis direction from the upper structure 6 is transmitted from the upper flange 43 to the lower structure 5 as a bearing pressure (compressive force) through the base plate 2 to which the cantilever member 4 is joined, or as a tensile force to the anchor bolts 3. The horizontal force in the direction perpendicular to the bridge axis from the upper structure 6 is transmitted as a shear force to a plurality of anchor bolts 3 through the upper flange 43, the cantilever member 4, and the base plate 2. By the anchor bolts 3 bearing the shear force, resistance is provided against the horizontal force in the direction perpendicular to the bridge axis.

[0058] The upper surface of the upper flange 43 is located below all the anchor bolts 3 arranged in the uppermost stage among the plurality of anchor bolts 3 arranged in multiple vertical stages as shown in Fig. 1. Fig. 1 shows an example where the anchor bolts 3 are arranged in 4 stages, with 5 bolts in each stage, but the number of vertical arrangement stages and the number of horizontal arrangements of the anchor bolts 3 are arbitrary, and the number of anchor bolts 3 arranged in each stage does not necessarily have to be the same.

[0059] The fact that the upper surface of the upper flange 43 is located below all the anchor bolts 3 arranged in the uppermost stage means that the distance h1 between the action position f of the horizontal force H in the direction perpendicular to the bridge axis acting on the lower structure 5 from the displacement limiting device 7 installed between the upper structure 6 and the lower structure 5 as shown in Fig. 4-(a) and the centroid O of all the anchor bolts 3 is reduced. In Fig. 4, the bracket 12 corresponds to the upper flange 43 of the present invention.

[0060] FIG. 1 shows an example in which the horizontal center line on the longitudinal section of the upper flange 43 is located in the middle of the two rows of anchor bolts 3, 3 on the upper stage side. In addition to the case where the upper surface of the upper flange 43 is arranged to contact the lower surface of the uppermost anchor bolt 3, it may also be arranged below the second row of anchor bolts 3 from the upper stage.

[0061] The drawings also show an example in which the upper structure 6 is a bridge girder. However, as long as the end of the upper structure 6 in the bridge axis direction is supported by the overhanging member 4 protruding from the side surface 51 of the lower structure 5, the form of the bridge (upper structure 6) is not limited, and the bridge may be a water pipe bridge. In addition, the lower structure 5 and the upper structure 6 may be newly constructed or existing. In the case of existing, the existing overhanging member fixed to the side surface 51 of the lower structure 5 is removed, and a new overhanging member 4 is installed.

[0062] When the base plate 2 has a planar area sufficient to at least close the end of the overhanging member 4 when the end of the overhanging member 4 on the lower structure 5 side is butted and joined to the surface. The base plate 2 is fixed to the lower structure 5 by fixing the anchor bolts 3 arranged at positions where there is no interference with the cross section of the vertical plate 41 and the horizontal plate 42 constituting the overhanging member 4 in the state where the overhanging member 4 is joined as shown in FIG. 1-(b) to the lower structure 5.

[0063] When the lower structure 5 is existing, the anchor bolts 3 are inserted into newly formed drilled holes except when the existing anchors can be used at the locations where the existing anchors were inserted, and are fixed to the lower structure 5 by a filling material such as an adhesive or mortar. As shown in FIGS. 5, 6-(b), (c), and 7-(c), rib plates 21 for ensuring out-of-plane rigidity are protruded at necessary locations on the surface side of the base plate 2.

[0064] In order to ensure the bending rigidity and torsional rigidity, it is desirable that the cantilever member 4 has a closed cross-sectional shape over the entire axial length. However, the cross-sectional shape of the cross-section orthogonal to the axis is not limited, and it is not necessary to have a uniform cross-section over the entire axial length. In the drawings, since it is easy to support the upper structure 6 in the state where the cantilever member 4 projects from the side surface 51 of the lower structure 5, the cantilever member 4 is formed in a box-shaped cross-sectional shape.

[0065] In this case, as shown in FIGS. 5 and 7-(a), the cantilever members 4 are basically oriented in the vertical direction and arranged at a distance in the horizontal direction so that the width and height can be freely determined. A plurality of vertical plates 41 that are integrated with the base plate 2 at the end on the lower structure 5 side, and at least arranged on the upper and lower portions of the vertical plates 41, and are assembled into a closed cross-sectional shape such as a box from the horizontal plates 42 integrated with the vertical plates 41.

[0066] The uppermost horizontal plate 42 becomes the upper flange 43, and the lowermost horizontal plate 42 becomes the lower flange 44 that acts in the vertical direction on the cantilever member 4 in opposition to the upper flange 43 and resists the bending moment. Rib plates 45 also project at necessary positions on the vertical plates 41 and the horizontal plates 42 as shown in FIGS. 5 and 6-(c).

[0067] When the vertical plate 41 and the horizontal plate 42 intersect as shown in FIG. 7-(c), either one is partially arranged between adjacent vertical plates 41, 41 or between horizontal plates 42, 42. The vertical plate 41 and the horizontal plate 42 do not necessarily have to be oriented in the vertical and horizontal directions.

[0068] An intermediate plate may be additionally arranged in parallel to either one between the opposing vertical plates 41, 41 or between the horizontal plates 42, 42. When the cantilever member 4 has a box-shaped cross-sectional shape, a square steel pipe may be used for the cantilever member 4. When the cross-sectional shape is other than a box, a (circular) steel pipe or the like, or a steel material combined with a plurality of shaped steels may be used for the cantilever member 4.

[0069] As described above, for the upper surface of the upper flange 43 to be positioned below the uppermost all-anchor bolts 3, it makes sense to reduce the distance h1 between the acting position f of the horizontal force H in the direction perpendicular to the bridge axis acting from the displacement limiting device 7 on the lower structure 5 and the centroid O of all the anchor bolts 3. For this reason, when using the same number of anchor bolts 3, it is reasonable to reduce the number of vertical arrangements (number of tiers). In this context, although it is desirable for the base plate 2 to have a horizontally long shape with a width larger than its height, for arranging the anchor bolts 3 regularly, a rectangle as shown in the figure is appropriate for the base plate 2.

[0070] The horizontal force H from the upper structure 6 is borne by the upper flange 43 on which the displacement limiting device 7 is mounted, and the vertical plate 41 bears the horizontal bending moment due to the horizontal force H. The vertical plates 41, 41 and the horizontal plates 42, 42 resist the torsional moment generated around the axis of the overhanging member 4. The end faces on the base plate 2 side of the vertical plates 41, 41 and the horizontal plates 42, 42 are both joined to the surface of the base plate 2 by welding or the like, and the vertical plates 41, 41 and the horizontal plates 42, 42 that are orthogonal or intersect with each other are also joined to each other by welding or the like.

[0071] If the end portions on the opposing lower structure 5 side, which are the tip sides of the overhanging member 4, remain open, when the overhanging member 4 receives a torsional moment, there is a possibility of torsional deformation due to the lack of restraint on the open tip side. For this reason, for the purpose of making it difficult for torsional deformation to occur in the open tip portion, as shown in FIGS. 1 and 2, a closing plate 46 is overlapped in the axial direction of the overhanging member 4 on the end face of the tip side of the overhanging member 4, or arranged so as to be in close contact (inscribed) with the inner peripheral surface of the end portion on the tip side, and by joining, the end face or the end portion of the overhanging member 4 is closed.

[0072] When the closing plate 46 closes the end face or the end of the protruding member 4 when it is open, it restrains the ends of the vertical plate 41 and the horizontal plate 42 against deformation, and functions to increase the torsional rigidity of the tip portion of the protruding member 4. However, if the closing plate 46 completely closes the end of the tip side of the protruding member 4, it becomes difficult to fasten the nut 31 to the head of the anchor bolt 3. Therefore, as shown in Fig. 7-(b), an opening 46A through which an operator can enter and exit is formed in a part of the closing plate 46.

[0073] The horizontal force from the superstructure 6 constitutes a displacement limiting device 7 placed on the upper flange 43 of the protruding member 4, and is transmitted from the upper member 71 fixed to the bottom surface of the superstructure 6 to the lower member 72 fixed to the upper flange 43. Since the position where the upper member 71 and the lower member 72 engage in the horizontal direction becomes the acting position f of the horizontal force H shown in Fig. 4-(a), in order to reduce the distance h1 between the acting position f of the horizontal force H and the centroid O of all the anchor bolts 3, it is reasonable to directly place and fix the displacement limiting device 7 on the upper flange 43. In this case, the lower member 72 of the displacement limiting device 7 is directly placed on and joined (fixed) to the upper flange 43.

[0074] When the lower member 72 of the displacement limiting device 7 is directly placed on the upper flange 43 and joined to the upper flange 43, and a space is formed between the upper member 71 of the displacement limiting device 7 and the lower surface of the superstructure 6 as shown in Figs. 1 and 5, a pedestal 8 for filling the space is interposed between the lower surface of the superstructure 6 and the upper member 71 of the displacement limiting device 7 as shown in Fig. 1-(a). The upper member 71 of the displacement limiting device 7 is joined to an upper plate 73 joined (fixed) to the superstructure 6 or the pedestal 8 as shown in Fig. 8, and the lower member 72 is joined to a lower plate 74 joined (fixed) to the upper flange 43 of the protruding member 4.

[0075] The pedestal 8 is basically assembled three-dimensionally from a vertical plate 81 and a horizontal plate 82, similar to the cantilever member 4. An upper member 71 of the displacement limiting device 7 and a lower flange 83 and an upper flange 84 for joining to the lower surface of the superstructure 6 are integrated at the lower end and the upper end, respectively. The lower flange 83 and the upper flange 84 resist the bending moment when a horizontal force is transmitted from the superstructure 6 to the substructure 5, and the vertical plate 81 resists the shear force. The lower flange 83 may also serve as the lowermost horizontal plate 82, and the upper flange 84 may also serve as the uppermost horizontal plate 82.

[0076] As described above, in the present invention, for the purpose of reducing the distance h1 between the acting position f of the horizontal force H and the centroid O of all the anchor bolts 3, it is desirable to directly fix the lower member 72 of the displacement limiting device 7 on the upper flange 43. However, when the space between the displacement limiting device 7 placed on the upper flange 43 and the lower surface of the superstructure 6 does not increase, or when the displacement limiting device 7 has to be joined to the lower surface of the superstructure 6, the pedestal 8 may be fixed on the upper flange 43.

[0077] As shown in Fig. 8, a gap that can be displaced relative to each other in the bridge axis direction and the direction perpendicular to the bridge axis (two horizontal directions) is secured between the upper member 71 and the lower member 72 during normal times. After a relative displacement occurs between the superstructure 6 and the substructure 5 such that the gap disappears, the upper member 71 engages with the lower member 72 in the horizontal direction and transmits the horizontal force in the direction perpendicular to the bridge axis to the upper flange 43 of the cantilever member 4. The horizontal force in the direction perpendicular to the bridge axis is transmitted from the upper flange 43 through the cantilever member 4 to the base plate 2, and then from the base plate 2 to each anchor bolt 3. The horizontal force in the bridge axis direction is transmitted to the substructure 5 through the cantilever member 4 and the base plate 2.

[0078] A gap is also provided in the vertical direction between the upper member 71 and the lower member 72 by a gap-holding member. When a relative displacement in the vertical direction that eliminates this gap occurs between the upper structure 6 and the lower structure 5, that is, when the upper structure 6 floats upward relative to the lower structure 5, the upper member 71 engages with the lower member 72 in the vertical direction, and the lower structure 5 prevents the upper structure 6 from floating upward beyond the gap.

[0079] Figs. 5 to 7 show specific examples of the support device 1 shown in Fig. 1. Here, an example is shown in which the upper structure 6 has a hollow cross-section and the pedestal 8 is joined to the lower surface of the upper structure 6. Fig. 6-(a) shows a cross-section of the pedestal 8 portion in Fig. 5, (b) shows a cross-section of the upper flange 43 portion, and (c) shows a cross-section of the opening 46A portion of the closing plate 46. In this example, as shown in Figs. 5 and 7-(c), the anchor bolts 3 are arranged in 6 rows and 12 columns with respect to the base plate 2.

[0080] In Figs. 5 to 7, as shown in Fig. 7-(a), since the upper structure 6 has a form in which the hollow portion on the lower floor slab 61 is partitioned by the webs 62 in the width direction, two displacement limiting devices 7, 7 are arranged in parallel in the width direction of the overhanging member 4, but the upper structure 6 may also be supported by one displacement limiting device 7.

[0081] In the case of the example in Fig. 5, the pedestal 8 overlaps directly or indirectly with the lower surface of the upper structure 6 at the upper flange 84, and is joined, for example, by anchor bolts 10 fixed (embedded) in the upper structure 6 as shown in Fig. 1-(a). When the upper structure 6 has a hollow cross-section as shown in Fig. 5, it is joined by bolts 11 passing through the lower floor slab 61 of the upper structure 6. The lower flange 83 of the pedestal 8 is joined to the upper plate 73 of the displacement limiting device 7. The upper structure 6 is not necessarily made of reinforced concrete.

[0082] In FIG. 5, as shown in FIGS. 6-(b) and 7-(b), an upper plate 47 having an area where the lower plate 74 of the displacement limiting device 7 can overlap is superposed and joined on the upper flange 43 of the overhanging member 4, and the lower plate 74 of the displacement limiting device 7 is joined to this upper plate 47. However, the lower plate 74 may also be directly joined to the upper flange 43 of the overhanging member 4.

[0083] In FIG. 5, also, in order to compensate for the decrease in torsional rigidity due to the fact that the tip (opposing lower structure 5) side of the overhanging member 4 is open as shown in FIG. 1, a closing plate 46 is joined to the tip side of the overhanging member 4.

[0084] Here, as shown in FIGS. 5 and 6-(c), for the purpose of compensating for the decrease in rigidity of the overhanging member 4 due to the formation of the opening 46A in the closing plate 46, two closing plates 46, 46 are arranged at intervals in the axial direction of the overhanging member 4. FIGS. 5 to 7 show an example in which vertical plates 41 are arranged at three locations on both sides and at the center in the width direction of the overhanging member 4, and horizontal plates 42 are arranged at two locations on both sides in the height direction of the overhanging member 4.

[0085] As shown in FIG. 7-(b), an opening 46A having an area through which an operator can enter and exit for the operation of fastening the nut 31 to the anchor bolt 3 for fixing the base plate 2 to the lower structure 5 is formed in the closing plate 46. The decrease in bending rigidity and torsional rigidity associated with the formation of the opening 46A is compensated by the protrusion of the rib plate 46b facing the out-of-plane direction of the closing plate 46 as shown in FIGS. 6-(c) and 7-(b).

Explanation of Reference Numerals

[0086] 1... support device, 2... base plate, 21... rib plate, 3... anchor bolt, 31... nut, 4... overhanging member, 41... vertical plate, 42... horizontal plate, 43... upper flange, 44... lower flange, 45... rib plate, 46... closing plate, 46A... opening, 46b... rib plate, 47... upper plate, 5... lower structure, 51... side surface, 6... Upper structure, 61... Lower floor slab, 62... Web, 7... Displacement limiting device (horizontal force sharing structure), 71... Upper member, 72... Lower member, 73... Upper plate, 74... Lower plate, 8... Pedestal, 81... Vertical plate, 82... Horizontal plate, 83... Lower flange, 84... Upper flange, 9... Support, 10... Anchor bolt (for pedestal), 11... Bolt (for pedestal), 12... Bracket, O... Centroid of all anchor bolts, f... Horizontal force acting position, h1... Distance from the centroid O of the present invention (Fig. 1) to the horizontal force H acting position f, h2... Distance from the centroid O of the present invention to the upper surface of the upper flange, h3... Distance from the centroid O of the prior art (Fig. 2) to the horizontal force H acting position f, h4... Distance from the centroid O of the prior art to the upper surface of the upper flange.

Claims

1. A support device that protrudes in the bridge axis direction from the side of the bridge substructure facing the opposing substructure and supports the end of the superstructure in the bridge axis direction. a base plate overlying the side of the substructure; a plurality of anchor bolts that penetrate the base plate and are fixed into the substructure to join the base plate to the substructure; a protruding member provided on a surface of the base plate, protruding toward the opposing lower structure, and supporting the upper structure; The plurality of anchor bolts are divided into a plurality of stages and arranged in the vertical direction, An upper portion of the overhanging member has an upper flange on which a displacement limiting device is mounted, the displacement limiting device supporting an end portion of the superstructure in the bridge axis direction on the overhanging member and transmitting a horizontal force from the superstructure to the substructure, a top surface of the upper flange being located below all of the anchor bolts arranged in the uppermost tier among the plurality of anchor bolts arranged in the plurality of tiers;

2. 2. The support device for a bridge superstructure according to claim 1, wherein the base plate has a width greater than its height.

3. 3. A support device for a bridge superstructure as described in claim 1 or 2, characterized in that the displacement limiting device, which transmits horizontal forces from the superstructure to the substructure, is mounted directly on the upper flange.

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