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Friction type retrofitting device for steel tower structures

1. Field of the Invention

The present invention relates generally to a friction type retrofitting device for steel tower structures. More particularly, the present invention relates to a friction type retrofitting device for a steel tower, such as a power-transmission tower that transmits high voltage to a distant place, in which a slot and a friction plate are provided on a coupling part between columns constituting a post of the steel tower, thus attenuating vibrations generated by wind force acting on the steel tower.

2. Description of the Related Art

FIG. 1 is a front view showing a general steel tower, FIG. 2 is a side view showing the steel tower of FIG. 1, when wind acts on the front of the steel tower, FIG. 3 is a detailed view showing part of a post of the steel tower, and FIG. 4 is a view showing the structural change of the conventional post under the condition of FIG. 2.

As shown in FIG. 1, a general steel tower, especially a power-transmission tower 10 for transmitting high voltage, includes a frame 70 which is set up vertically, arms 20 which are horizontally provided on the upper portion of the frame 70, insulators 30 which hang downwards from ends of the arms 20, and electric wires 40 which are connected to the lower ends of the corresponding insulators 30.

The frame 70 includes four vertical posts 50, and cross members 60 which are crossed between the vertical posts 50 to be coupled to the vertical posts 50.

As shown in FIG. 2, when wind 80 blows in all directions, the power-transmission tower 10 is shaken. The part of the power-transmission tower 10 that is moved by the wind 80 is restored to its original position within a predetermined elastic range after the wind 80 dies down.

As shown in FIG. 3, each post 50 of the power-transmission tower 10 has a cruciform section. The cruciform section is formed by contacting edges of L-shaped columns 52 and 54 with each other and positioning the remaining parts of the columns 52 and 54 to be opposite to each other. Among the two columns 52 and 54, the inner column 52 faces the interior of the power-transmission tower 10, while the outer column 54 faces the exterior of the power-transmission tower 10 and has on predetermined portions thereof coupling parts 90.

Each coupling part 90 of the conventional power-transmission tower includes first holes 92 and second holes 93 which are formed in the inner column 52 and the outer column 54, respectively, an angle bracket 94 which has an “L”-shaped section and is provided with third holes 96 and fourth holes 99, first bolts 98 which pass through the first holes 92 and the third holes 96, second bolts 100 which pass through the second holes 93 and the fourth holes 99, first nuts 97 which are fastened to the first bolts 98, second nuts 102 which are fastened to the second bolts 100, and washers 88 which are provided in front of the first nuts 97.

However, the outer column 54 is provided at an outer position relative to the inner column 52. Thus, when the power-transmission tower 10 is moved by the wind, as shown in FIG. 4, the outer column 54 provided at a position facing the wind 80 is extended further than the inner column 52. The outer column 54 provided at the opposite side is compressed more than the inner column 52.

Thereby, the force applied to the power-transmission tower 10 by the wind is transmitted to each coupling part 90 of FIG. 3, so that a large amount of energy acts on the second bolts 100, the second holes 93, and the fourth holes 99. Thus, the wind repeatedly acting on the power-transmission tower 10 greatly reduces the durability of the coupling part 90.

Further, in the case where the interval between the coupling parts 90 mounted to each post 50 is large, so that the length of the post is larger than the cross-section thereof, the post is apt to buckle, that is, bend suddenly, when the compressive load acting on both ends of the post reaches a predetermined level.

Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a steel tower structure, in which coupling parts are mounted to posts of a steel tower at proper intervals, thus preventing the posts from buckling, a slot is formed in a coupling part of an outer column, and a friction plate is coupled to the coupling part of the outer column, thus absorbing wind energy using friction energy, therefore enhancing durability.

In order to accomplish the above object, the present invention provides a friction type retrofitting device for steel tower structures, including a coupling part coupling an outer column and an inner column of a post of a steel tower to each other using an angle bracket and a bolt, a slot formed in a portion of the outer column to which the coupling part is coupled, and a friction plate provided to contact an outer circumferential surface of the slot. In this case, wind energy transmitted to the steel tower is attenuated by friction between the slot and the friction plate of the coupling part.

Further, a horizontal section of the post has a cross shape, and a horizontal section of each of the outer column and the inner column has an L shape. Further, a plurality of coupling parts having the slot in the outer column may be provided on the post, and the friction plate may be provided on one of the coupling parts. A reinforcing plate may be provided on a portion of the outer column to which the coupling part is coupled.

The present invention provides a friction type retrofitting device for steel tower structures, including an outer column which is arranged to be parallel to an inner column, thus providing a post of a steel tower, and is divided at a predetermined position into two portions, a slot which is formed in one of the divided portions, and a friction plate which is provided to contact an outer circumferential surface of the slot. In this case, wind energy transmitted to the steel tower is attenuated by friction between the slot and the friction plate.

Further, a horizontal section of the post has a cross shape, and a horizontal section of each of the outer column and the inner column has an L shape. Further, a plurality of coupling parts is provided to couple the outer column to the inner column using an angle bracket and a bolt, with a slot formed in a portion of the outer column to which the coupling part is coupled.

The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a front view showing a general steel tower;