JP2003201703A - Method for confirming abnormality of expansion joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To discover the abnormality of a reinforcing plate or the like at a preceding stage up to a critical damage in a load supporting type expansion joint. <P>SOLUTION: In the expansion joint 1 installed between a joint for bridge girders H1 and H2, at least composed of an upper section 3 covered with an elastic body 5, the lower reinforcing plates 2a and 2b and combining sections 7a and 7b interposed among these mutual reinforcing plates 3, 2a and 2b and constituted so as to be able to support a car travelling on the expansion joint, vibrations are generated in the expansion joint 1 by a vibration from the surface side of the expansion joint, and the response vibrations are measured and abnormality generated in the expansion joint 1 is confirmed. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for confirming an abnormality in a load-supporting type expansion joint for a bridge girder. 2. Description of the Related Art Generally, a load-supporting type expansion joint provided between joints of a bridge girder includes a pair of lower reinforcing plates fixed to a step-down portion at an end of the bridge girder, and a pair of lower reinforcing plates. And an upper reinforcing plate provided so that the height position is substantially the same as the height of the bridge girder and the height of the bridge girder, and a pair of joints having shear deformation and connecting the upper reinforcing plate and each lower reinforcing plate. The reinforcing plate, the joints, and the like are configured to support the amount of vehicles traveling on the expansion joint. In particular, the upper reinforcing plate and the lower reinforcing plate are each covered with an elastic body such as a rubber material. Then, in addition to the role of absorbing the expansion and contraction of the bridge girder due to temperature change and the like, the expansion joint plays a role of making it difficult to apply a strong shock to the vehicle passing therethrough. As described above, a compressive force or a tensile force acts on the expansion joint every time a vehicle runs on it or the bridge girder expands and contracts due to a temperature change or the like. Naturally, stress such as bending stress acts on the upper and lower reinforcing plates.
Such long-term fatigue due to repeated compression, repeated bending, and the like causes abnormalities such as peeling of the elastic body from the reinforcing plate and cracking of the reinforcing plate. These abnormalities are
This is a cause of exposing the reinforcing plate, rusting, breaking, and scattering of the broken portion. Therefore, in order to discover such abnormalities of expansion joints, we will conduct periodic visual inspections,
When the expansion joint is hit, abnormal sounds that may be generated due to an abnormality of the expansion joint are detected by ears. [0004] However, because the reinforcing plate is covered with an elastic body or the like, in the inspection by visual inspection or hearing, abnormalities in the reinforcing plate that occur inside the elastic body and It cannot be absolutely determined that the expansion joint has been damaged on the back side. The only thing that can be found by visual inspection is fatal damage that could lead to a serious accident, such as the reinforcing plate being exposed from the front side of the elastic body. [0005] Therefore, there is a need for a useful means by which an abnormality in a reinforcing plate or the like can be discovered before a catastrophic damage is caused and an expansion joint can be replaced. [0006] The present invention is a method for confirming an abnormality of an expansion joint which has been devised to solve the above-mentioned problems. That is, the present invention comprises at least upper and lower reinforcing plates provided between seams of a bridge girder and covered with an elastic body, and a connecting portion interposed between the reinforcing plates, and runs on the upper and lower reinforcing plates. In the expansion joint that is configured to support the amount of vehicle to be driven, vibration is generated in the expansion joint by vibrating from the front surface side, and abnormality occurring in the expansion joint is How to confirm. In such a case, if there is an abnormality in the expansion joint, the abnormality cannot be confirmed by visual inspection etc. Abnormality of the upper and lower reinforcing plates occurring inside the elastic body or damage of the expansion joint occurring on the back side However, the response vibration will appear as a change in the natural frequency or an abnormal waveform, so that an abnormality in the expansion joint can be found at a stage before the catastrophic damage is caused, and the expansion joint can be detected from the front side. Since the vibration is shaken, it is possible to check the abnormality while the expansion joint is installed between the joints. In addition, since it is not necessary to adopt a separate configuration for abnormality checking means in the manufacture and construction of the expansion joint, it is possible to check the presence or absence of an abnormality in the expansion joint currently used. By the way, at first glance, it seems that the method for confirming abnormality of an expansion joint of the present invention requires predetermined appropriateness for applied vibration intensity. However, since the present invention is to check for abnormal waveforms and changes in the natural frequency, it is not always necessary that the intensity of vibration applied to the expansion joint is constant. Of course, there is no problem even if the intensity of the applied vibration is constant. Therefore, various modes can be considered as specific modes of the vibration. Therefore, paying attention to the fact that the abnormality confirmation target in the present invention is an expansion joint for a bridge girder, it is said that applying vibration by using the load of a vehicle traveling on the expansion joint does not require traffic regulation in the abnormality confirmation work. It is preferable in this respect. Further, as a specific mode for measuring the vibration of the expansion joint, there can be mentioned one using a vibration measuring device such as an acceleration pickup. Next, an embodiment of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, an expansion joint 1 provided between the joints of one bridge girder H1 and another bridge girder H2 has step-down portions D1, D2 at the ends of the respective bridge girder H1, H2. , Lower reinforcing steel plates 2a, 2b, an upper reinforcing plate 3 provided substantially at the center of the lower reinforcing steel plates 2a, 2b, and a pair of connections connecting the upper reinforcing steel plate 3 and the lower reinforcing steel plates 2a, 2b. Parts 7a and 7b. Each lower reinforcing steel plate 2
Reference numerals a and 2b each have an L-shaped cross section extending in the bridge girder width direction, and are attached by fixing members 4 including anchor bolts and the like. And these lower reinforcing steel plates 2a, 2b
Is almost completely covered with an elastic body 5 such as a rubber material.
The upper reinforcing steel plate 3 extends in the bridge girder width direction similarly to the lower reinforcing steel plates 2a and 2b, and is completely covered with an elastic body 6 such as a rubber material. The upper reinforcing steel plate 3 is for supporting a vehicle load whose height position is approximately equal to the bridge girder road surface height. The joints 7a and 7b are made of an elastic material such as a rubber material having a shearing property. That is, the expansion joint 1 applies the load of the vehicle traveling on the expansion joint 1 to the coupling portions 7a, 7
b and the lower reinforcing steel plates 2a, 2b, etc., in addition to absorbing the expansion and contraction of the bridge girders H1, H2 due to temperature changes, etc., and making it difficult to apply a strong shock to vehicles passing thereover. Play a role. The expansion joint 1 is provided with expansion grooves 8 at positions between the paired connecting portions 7a and 7b and at both sides of the upper reinforcing steel plate 3, respectively. Thus, an arbitrary position (for example, a position indicated by a symbol P in FIGS. 2 and 3) on the front surfaces 51 and 61 of the elastic members 5 and 6 corresponding to the front surface side of the above-described expansion joint 1 is determined. When hit with a hammer or the like, vibration occurs in the entire expansion joint 1 and the fixed member 4. If a vibration measuring instrument such as an acceleration pickup is installed at an arbitrary position (for example, a position indicated by a reference symbol Q in FIGS. 2 and 3) on the front surfaces 51 and 61 of the elastic bodies 5 and 6, The response vibration can be detected, and this can be analyzed. Therefore, if there is an abnormality in the expansion joint 1 or the like, the abnormality is an abnormality of the lower reinforcing plates 2a, 2b or the upper reinforcing steel plate 3 occurring inside the elastic members 5, 6 which cannot be visually confirmed, Even if the fixing member 4 is abnormal such as a loose anchor bolt, or if the expansion joint 1 is damaged on the back side, it appears in the detected response vibration as an abnormal waveform or a change in the natural frequency. Therefore, the abnormality of the expansion joint 1 and the like can be found at a stage before the catastrophic damage is caused, and since the vibration is applied from the front surfaces 51 and 61, the expansion joint 1 is installed between the joints. In this state, it is possible to check the abnormality. By the way, there is a slight difference in the response vibration detected due to the difference in the excitation position and the vibration measurement position, but this difference does not have a great effect when observing a change in the natural frequency or an abnormal waveform. Needless to say. It is also possible to specify the best point of the excitation position or the vibration measurement position by experience. The present invention is not limited to the illustrated example. For example, the base station may receive the response vibration due to the excitation, and analyze the response vibration at the base station. As a specific mode, as shown by a two-dot chain line in FIG. 2, for example, a vibration measuring instrument R having a function of converting the response vibration into a data format that can be transmitted to the base station in addition to the function of detecting the response vibration is used. One installed on the back side of the expansion joint so that the base station can receive response vibration detected by the vibration measuring device R in a wired format or a wireless format using FM waves or the like. Then, in this case, if the vibration means uses the load of the vehicle running on the expansion joint instead of hitting with a hammer or the like, the abnormality checking work can be performed without requiring traffic regulation. At the same time, the detected response vibration can be analyzed and managed centrally.
This effect is useful in view of the fact that the number of expansion joints is equal to the number of seams of the bridge girder. The base station may be provided on a bridge girder as long as it is located away from the expansion joint,
It may be provided at a position away from the bridge girder itself. It goes without saying that a dedicated machine may be used as the means for exciting. Furthermore, in the present embodiment, a so-called single type expansion joint having one upper reinforcing steel plate has been described as an object to be checked for abnormality. However, as shown in FIG. The so-called double-type expansion joint 101 including the central reinforcing steel plate 104 provided between the lower reinforcing steel plates 102a and 102b so as to extend between the step-down portions d1 and d2 can be set as an abnormality confirmation target. Needless to say. In this case, it goes without saying that an abnormality such as a crack in the central reinforcing steel plate 104 can be confirmed. As described above in detail, the method for confirming an abnormality of an expansion joint according to the present invention enables an abnormality of an expansion joint to be detected at a stage before fatal damage. Therefore, the expansion joint can be replaced before an accident occurs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a state in which an expansion joint according to an embodiment of the present invention is installed between seams of a bridge girder. FIG. 2 is a schematic sectional view showing a state in which the expansion joint according to the embodiment is installed between seams of a bridge girder. FIG. 3 is a plan view showing the expansion joint according to the embodiment. FIG. 4 is a schematic sectional view showing a double type expansion joint. [Description of Signs] 1 Expansion joints 2a, 2b Lower reinforcing steel plate (lower reinforcing plate) 3 Upper reinforcing steel plate (upper reinforcing plate) 5, 6 Elastic bodies 7a, 7b Joints H1, H2 Bridge girders

Claims (1)

Claims: 1. An upper and lower reinforcing plate provided between seams of a bridge girder and covered with an elastic body, and at least a connecting portion interposed between these reinforcing plates, and at least a portion above the reinforcing plate. In an expansion joint that is configured to support the amount of vehicle traveling, vibration is generated in the expansion joint by vibrating from the front side of the expansion joint. How to check.