JPH04323403A - Cable stayed bridge erection method - Google Patents

Abstract

PURPOSE:To economically erect a cable stayed bridge with a temporary supporting point utilized as an adjusting mechanism by adjusting the height of the temporary supporting point set at the time of erection so that the stress and the displacement of the various parts of a cable stayed bridge structure can come into a favorable condition in view of strength or construction. CONSTITUTION:The height (h) of a temporary supporting point 4, set at the time of erecting a cable stayed bridge, is adjusted so that the stress and the displacement of the various parts of an obliquely hanging bridge structure can come into a favorable condition in view of strength or construction. Then the temporary supporting point 4 is not only used as merely staging for erecting a girder but also is fully utilized as an adjusting mechanism for the stress and the displacement of structure.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing a cable-stayed bridge.

0002

2. Description of the Related Art FIG. 8 shows the construction of a conventional cable-stayed bridge. In the figure, 1 is the main girder, 2 is the main tower, 3 is the cable, 4 is the temporary support, and 5 is the main structural support. The temporary supports 4 provided during the erection of a cable-stayed bridge are used only as staging for girder erection, and are not used to adjust the stress or deformation of each part of the structure.

0003

[Problem to be Solved by the Invention] The above-mentioned prior art includes:
There are the following problems. Conventionally, temporary supports installed when constructing cable-stayed bridges have been used simply as staging for girder erection, and when considering construction methods, their height has been determined based on the stress and deformation state of each part of the structure during erection. Rather, the height of the temporary support was determined appropriately, and then the stress and deformation of each part of the structure were examined.

[0004] As a result, cable tension and stress in certain parts of the structure exceed allowable values, requiring reinforcement for erection, or the displacement of the main girder at the tip of the overhang is large and a large force is required to close the main girder. There were many situations where this was necessary. The present invention solves the above-mentioned problems in the conventional technology, and uses temporary supports provided during cable-stayed bridge construction not only as staging for girder erection, but also to reduce stress and displacement of each part of the structure, which increases the structural strength. Alternatively, it is an object of the present invention to propose a cable-stayed bridge construction method that utilizes temporary supports as a mechanism for adjusting stress or displacement of various parts of the structure, so as to be advantageous in construction work.

[0005]

[Means for solving the problem] Temporary supports provided during the erection of cable-stayed bridges are not only used as staging for girder erection, but also because stress and deformation in each part of the structure are advantageous in terms of structural strength and construction work. The height of the temporary support is determined so that the temporary support is used as a mechanism for adjusting stress or displacement of the structure.

[0006]

[Operation] By using the temporary support as a mechanism for adjusting the stress or deformation of each part of the structure, the girder of the cable-stayed bridge can be constructed in a manner that is preferable in terms of structural strength or construction work.

[0007]

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 to 7. In the figure, 1 is the main girder, 2 is the main tower, 3 is the cable, 4 is the temporary support, and 5 is the main structural support. FIG. 1 shows a deformed state when the displacement adjustment of the main girder 1 by the height of the temporary support 4 of the present invention is not performed. In this example, the height of the temporary support 4 is set to the height of the main girder 1 when it is completed. A downward displacement δ0 occurs at the overhanging tip of the main girder 1, and in order to install this point on the fulcrum of this structure, a lifting force to eliminate this displacement, and therefore equipment for that purpose, is required. Next, FIGS. 2 to 7 show deformed states when the displacement of the main girder 1 is adjusted according to the height of the temporary support 4 of the present invention. By lowering the height of the temporary support 4 from h0 to h in Figure 8, the displacement of the overhanging tip of the main girder 1 can be reduced to zero, and no special equipment is required to install this point on the support of the main structure. Become.

FIGS. 2 and 3 show the general structure of the temporary support 4, in which the main girder 1 is supported by a pedestal 13 or a jack 14 on a temporary gantry 12. A method of adjusting the height at the temporary support as described above is shown in FIGS. 4 to 7. FIG. 4 shows a normal state in which the main girder 1 is supported by the frame 13. When increasing the height Δh from this state, first jack up the main girder 1 as shown in FIG.
3 by a required height Δh, and finally jacked down as shown in FIG. 7, and the main girder 1 is supported by the frame 13. This procedure is also similar when reducing the height.

Next, the principle of the present invention will be explained. Generally, a cable-stayed bridge is a high-order, statically undetermined structure even when it is erected, so the reaction force changes depending on the height of the temporary support, and therefore the stress and displacement of each part of the structure also change. That is, if the stress or displacement that becomes a problem in construction is X, then this becomes a function X(h) of the height h of the temporary support. This X(h
), restrictions are imposed on structural strength or construction work. That is, if the upper limit is XU and the lower limit is XL, then XL
≦X(h)≦XU ......(1).

Basically, h that satisfies inequality (1) provides a temporary support height that is advantageous in terms of structural strength or construction work when constructing a cable-stayed bridge. Generally, the amount of attention X(h) changes depending on the construction stage, and the amount of attention itself requires several items. Let the number of such X(h) be n. Furthermore, it is conceivable that there may be a plurality of temporary supports. Let the number be m. In such a general case, the expression (
1) becomes the following simultaneous inequalities. XLi≦Xi (h1,...,hm)≦XUi
(i=1,...,n)......(2) h1,...,hm that satisfy this simultaneous inequality determines the temporary support height that realizes the adjustment of stress or displacement in the cable-stayed bridge construction system according to the present invention. support. Simultaneous inequalities can be solved by mathematical programming, such as goal programming.

Next, a method for measuring stress and displacement will be explained. First, stress is not directly measured using strain gauges, etc., but based on the idea that if the required cable tension (as calculated) is introduced, the stress in the main girder should be in the normal state. This can be replaced by measuring cable tension. Cable tension can be determined, for example, by the vibration method (
Cable tension is determined indirectly from frequency by utilizing the fact that there is a functional relationship between frequency and tension. In addition, displacement is often measured using surveying equipment such as a level, or by measuring the water level using a water communication pipe. Cable tension affects the stress and displacement of the main girder. Therefore, the cable tension is to be controlled as one item of stress in each part of the structure. That is, the height of the temporary support is determined so that the cable tension does not exceed the strength constraints. At the same time, the cable tension is also indirectly affected by the stress and displacement of the main girder.

0012

[Effects of the Invention] The cable-stayed bridge construction method according to the present invention uses temporary supports that are installed when constructing a cable-stayed bridge so that the stress and displacement of each part of the cable-stayed bridge structure are in a state that is advantageous in terms of structural strength or construction work. By adjusting the height, the following effects can be obtained. Cross-sectional reinforcement for erection and equipment for closing are reduced or unnecessary, making it possible to construct cable-stayed bridges economically.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a deformed state during construction of a cable-stayed bridge according to the present invention.

FIG. 2 is a front view of the main girder and temporary support.

FIG. 3 is a view taken along the line AA in FIG. 2;

FIG. 4 is a diagram showing a first stage of height adjustment of a temporary fulcrum.

FIG. 5 is a diagram showing the second stage of height adjustment of the temporary support.

FIG. 6 is a diagram showing the third stage of height adjustment of the temporary fulcrum.

FIG. 7 is a diagram showing the fourth stage of height adjustment of the temporary fulcrum.

FIG. 8 is a diagram showing a deformed state when a cable-stayed bridge is constructed according to the prior art.

[Explanation of symbols]

1 Main girder 2 Main tower 3 Cable 4 Temporary fulcrum

Claims (1)

[Claims] Claim 1: When constructing a cable-stayed bridge, the height of temporary supports to be installed when constructing a cable-stayed bridge is determined so that the stress and displacement of each part of the cable-stayed bridge structure is in a state that is advantageous in terms of structural strength or construction work. A cable-stayed bridge construction method characterized by adjusting.