JP3395630B2 - Method for suppressing stress and deformation of stiffening girder, stiffening girder and suspension bridge - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention particularly relates to stress / deformation of stiffening girders for suppressing horizontal stress / deformation of stiffening girders.
Belongs to deformation suppression method and stiffening girders and suspension bridges.

[0002]

2. Description of the Related Art Wind resistance is a problem in long suspension bridges. First, it is necessary to design the members so as to resist the static deformation sectional force of the stiffening girder due to strong wind. In a long suspension bridge with a center span of 2000 m, such as the Akashi Kaikyo Bridge, the design wind load becomes dominant, and according to trial calculations when the stiffening girder is a truss girder, the main structure of the stiffening truss is determined by the wind load ( Reference: Yamashita, Nitta et al. "Trial design of ultra-long suspension bridge by structural wind stability improvement measures" Proceedings of JSCE No.453 / VI-17, pp.59-68, 1992.
9).

In the prior art, the structural member cross section is determined so as to be able to resist the static deformation sectional force, and when the design wind load is large, it is dealt with by increasing the structural member cross section.

[0004]

However, the prior art has the following problems. As the span length of the suspension bridge increases, the wind load acting on the stiffening girder increases, so the deformation of the stiffening girder increases. In suspension bridges, the wind load is borne by the cable and girder, but in order to ensure wind stability, it is necessary to secure the required torsional rigidity of the girder. In order to secure a required torsional rigidity, the horizontal flexural rigidity of the girder also inevitably increases. Therefore, due to the increase in horizontal flexural rigidity, the load on the girder against the wind load increases, and the cross-sectional force increases. In order to suppress the generated stress to be less than the allowable value, it is necessary to increase the cross section of the constituent member, and as a result, the weight of the girder is increased.

Further, as the weight of the girder increases, the cross section of the main cable supporting the girder increases, the rigidity of the cross section of the main tower supporting the cable increases, and the scale of the base part (fixing part) also increases. It was uneconomical.

The present invention has been made in view of the above problems, and an object of the present invention is to suppress the stress / deformation occurring in the stiffening girder without forming the cross-section of the structural member of the stiffening girder. It is possible to provide a stiffening girder stress / deformation suppressing method, a stiffening girder, and a suspension bridge.

[0007]

[Means for Solving the Problems] The present invention has the following constitution in order to solve the above problems. The gist of the invention according to claim 1 is that a plurality of stiffening girder blocks are connected in the bridge axis direction, and further, between the stiffening girder blocks, there is a live load or a wind load in a low wind speed range. Under normal load conditions, the blocks behave as one without separating from each other,
A joint member is provided to urge the blocks away from each other in a windstorm, and the joint member is used to stiffen each of the stiffeners.
A set of brackets at the end of the girder block and adjacent
To the two brackets provided on the stiffening girders that contact
A connecting member in which each end is fixed separately, and an end of the connecting member
And a biasing means interposed between the bracket and the bracket.
It resides in HoTsuyoshiketa which is characterized in that. The gist of the invention according to claim 2 is that, of the pair of the brackets, one of the brackets has a protrusion protruding in the bridge axis direction from the end face of the stiffening girder block, and the other bracket has the one of the one of the brackets. The stiffening girder according to claim 1, wherein the bracket is concave so that the bracket can be fitted therein.

In the present invention, the "biasing means" means
An object that prevents adjacent stiffening girder blocks from separating,
For example, coil springs, viscoelastic members (high damping rubber, Viscous
Elastic material), laminated rubber, a member having a viscous function, and the like, which are suitable for carrying out the present invention.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. As shown in FIG. 1, the suspension bridge S according to the present embodiment is similar to an existing suspension bridge in that a main tower (not shown in FIG. 1) that is erected upright in a erection section with a required interval is provided between these main towers. A main cable 1 stretched between cable anchors (not shown) via a tower and a stiffening girder 3 suspended from the main cable 1 via a hanger cable 2 are provided.

The stiffening girder 3 comprises a plurality of stiffening girder blocks 3a,
3b, 3c, ... Are connected in the bridge axis direction.

Adjacent stiffening girder blocks 3a, 3b, 3c
Between the stiffener girder blocks 3 as shown in FIGS. 2 and 3.
A joint member 10 is provided that biases a, 3b, and 3c so that they do not separate from each other. 2 to 4 and 8
And in FIG. 9, only between the stiffening girder blocks 3a and 3b is shown.

As shown in FIG. 4, the joint member 10 includes brackets 11a and 11b provided on the end portions of the respective stiffening girder blocks 3a, 3b and 3c, and two brackets provided on the adjacent stiffening girders 3. Each end is fixed separately to P
It has a C cable 12 (connecting material) and a spring 13 (biasing means) interposed between the end of the PC cable 12 and the bracket.

The bracket has a male (convex bracket 11a) and a female (concave bracket 11b) which are fitted with each other. As shown in FIG. 5, the convex bracket 11a forms a truncated cone with an outer contour that projects in the bridge axis direction and outside the stiffening girder blocks 3a, 3b, 3c. As shown in FIG. 6, the concave bracket 11b is a convex bracket 11b.
The stiffening girder blocks 3a, 3b, so that a can be fitted.
It forms a bottomless truncated cone that is recessed inside 3c. The height of the convex bracket 11b and the depth of the concave bracket 11b are set such that the stiffening girder 3 does not come off even during normal traveling (in other words, except during windstorm).

The spring 13 is interposed between the cushioning material 14 that contacts the brackets 11a and 11b and the fixing nut 15 that is located at the end of the PC cable 12 by being biased.
As a result, the stiffening girder blocks 3a, 3b, 3c attract each other. The spring rigidity is the stiffening girder block 3
The bending rigidity is less than or equal to a, 3b, 3c, and a gap is created due to relative displacement between the stiffening girder blocks 3a, 3b, 3c, so that a pedestrian's traffic is not hindered. As the cushioning material 14, hard rubber, laminated rubber or the like suitable for carrying out the present invention is used. The fixing nut 15 may be a single piece or a double nut.

Next, the operation of the suspension bridge S will be described. When the wind is generated, the stiffening girder 3 is deformed as shown in FIG. In the figure, the stiffening girders 3 shown by dotted lines are when there is no wind, and the stiffening girders 3 that are shown by solid lines are when there is wind. Joint member 10
In the case of wind, the spring 13 is urged (contracted) as the stiffening girder blocks 3a, 3b, 3c move from the state of no wind shown in FIG. 8 as shown in FIG. Due to the deformation of the spring 13, the entire stiffening girder 3 has a structure that resists wind load. When the windless state is restored, the relative displacement of the stiffening girder blocks 3a, 3b, 3c disappears due to the restoring force of the spring member, and the windless state shown in FIG. 8 is restored.

Furthermore, when the vehicle is stopped by a windstorm, the joint member 10 is largely deformed,
The stiffening girder 3 has a structure of a windsock. Deformation is suppressed by inserting the joint member 10, and each stiffening girder block 3a, 3
The deformation of b, 3c, ...
Since the deformation is limited to the wind load acting on a, 3b, 3c, ..., Each stiffening girder block 3a, 3b, 3c,
Large stress does not act on…. Joint member 10
By making the strength of the stiffener girder blocks 3a, 3b, 3c, ..., smaller, the horizontal deflection amount of the entire stiffener girder block suspension bridge S becomes larger than that of the conventional technique, but the suspension bridge S has a flexible structure. The impact is not large.

Since the displacement suppressing method according to the embodiment, the stiffening girder 3 and the suspension bridge S are configured as described above, the following effects can be obtained.

Simply, the stiffening girder blocks 3a, 3b, 3c,
Since only the springs 13 are installed between the stiffeners 3, it is possible to make the structure capable of withstanding the deformation of the stiffeners 3 without increasing the cross section of the constituent members of the stiffeners 3. In other words, the stiffening girder 3 having a smaller weight than the conventional technique can be obtained. Certainly, the brackets 11a, 1 for mounting the spring 13
Although the weight of 1b increases, the weight increase is much smaller than that of the case where the cross section of the stiffener girder 3 is increased. As a result, according to the present embodiment, it is possible to construct the suspension bridge S that is much more economical than the conventional technique.

Further, even if the stiffening girder 3 is damaged by an excessive static wind load, it is suppressed by the damage of the joint member 10, and the repair at the time of storm passage can be completed by replacing the joint member 10. It is convenient from the top.

Since the joint member 10 has the convex bracket 11a and the concave bracket 11b,
It can bear the shearing force acting horizontally and diagonally.

A viscoelastic member may be used instead of the spring 13. If a viscoelastic member is used, the stiffening girder 3
In addition to the above spring function, the suspension bridge damping is increased due to the deformation between the blocks caused by the vibration.

Further, the shape of the bracket according to the present invention is not limited to the truncated cone shape having an outer contour, and may be a shape suitable for carrying out the present invention, such as a cylinder or a prism.

Further, although the number of the joint members 10 was two, four or the like may be suitable for carrying out the present invention.

Further, it is possible to provide an elastic member or the like so that no gap is generated between the stiffening girder blocks 3a, 3b, 3c when the stiffening girder 3 is deformed.

Further, the coil spring can be directly fixed to the stiffening girder.

Further, the number, position, shape, etc. of the above-mentioned constituent members are not limited to those in the above-mentioned embodiment, and the number, position, shape, etc. suitable for carrying out the present invention can be adopted.

In each figure, the same components are designated by the same reference numerals.

[0028]

Since the present invention is configured as described above, it has the following effects. Since the joint member is simply installed between the plurality of stiffening girder blocks divided in the bridge axis direction, the stiffening girder can have a structure capable of withstanding deformation without increasing the cross section of the girder component members. As a result, it is possible to construct an economical suspension bridge.

[Brief description of drawings]

FIG. 1 is a partial side view showing a suspension bridge according to an embodiment of the present invention.

FIG. 2 is a side view showing an installation position of the joint member shown in FIG.

FIG. 3 is a front view showing an installation position of the joint member shown in FIG.

4 is a side view of the joint member shown in FIGS. 2 and 3. FIG.

5 is a perspective view showing a convex bracket provided on an end surface of a stiffening girder block according to the joint member shown in FIGS. 2 and 3. FIG.

FIG. 6 is a perspective view showing a concave bracket provided on the end surface of the stiffening girder block according to the joint member shown in FIGS. 2 and 3;

7 is a conceptual plan view showing a deformed state of the stiffening girder of the suspension bridge shown in FIG.

FIG. 8 is a side view showing a state of the joint member shown in FIG. 1 when there is no wind.

9 is a side view showing a state of the joint member shown in FIG. 1 when there is wind.

FIG. 10 is a side view showing an installation position of a joint member according to another embodiment.

[Explanation of symbols]

S suspension bridge P main tower 1 main cable 2 hanger cable 3 stiffening girders 3a, 3b, 3c Stiffening girder block 10 Joint member 11a Convex bracket 11b concave bracket 12 PC cable (connecting material) 13 Spring (biasing means) 14 cushioning material 15 Fixing nut

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Go Sato Marunouchi 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Inside Nippon Kokan Co., Ltd. (56) Reference JP-A-60-84412 (JP, A) JP-B 28 -535 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) E01D 11/00-11/04 E01D 1/00

Claims (2)

(57) [Claims] 1. A plurality of stiffening girder blocks are connected in the bridge axis direction, and between the stiffening girder blocks, there is a normal load condition such as a live load or a wind load in a low wind speed region. in it behaves together without blocking each other apart, the joint member is provided for biasing as between blocks away during storm, the joint member, the at the end of each HoTsuyoshiketa block
A pair of brackets provided and adjacent stiffeners
Each end is fixed separately to the two brackets provided
Interlocking member, and is interposed between the end of the connecting member and the bracket.
A stiffening girder having a biasing means . 2. A set of the brackets, one of the brackets has a protrusion protruding in the bridge axis direction from an end face of the stiffening girder block, and the other bracket can be fitted with one of the brackets. The stiffening girder according to claim 1, wherein the stiffening girder is concave.