KR20000050435A - Shear strain control device for lrb(lead rubber bearing) compensating thermal movement of super structure for bridge - Google Patents

Abstract

PURPOSE: An adjuster is provided to deliver dynamic load to a bridge by being installed between the bridge and a pier, to absorb elasticity of the upper plate of the bridge caused by temperature change and to distribute earthquake force to each pier. CONSTITUTION: A strain preventing strut for a bridge adjusts the transforming value of a head end whenever temperature is changed. The strut is constructed by pushing the upper structure by a bridge strut on a pier. Also, load applied to the bridge is frequently checked to be adjusted so that the bridge and the pier are prevented from being damaged by excessive impulse.

Description

Shear STRAIN CONTROL DEVICE FOR LRB (LEAD RUBBER BEARING) COMPENSATING THERMAL MOVEMENT OF SUPER STRUCTURE FOR BRIDGE}

Recently, mandatory seismic design is required for bridges under construction and construction in Korea. This is because the structural damage caused by the earthquake or external vibration causes a great deal of human and physical damage.

It is an object of the present invention to increase the frequency of earthquakes in Korea in recent years, and is an invention for a device for proper installation different from the operating temperature of the LRB is installed to minimize the damage of the bridge when an earthquake occurs. Large bridges use LRB, a shock absorber and absorber, such as 1st and 2nd jersey. This device is installed between the bridge and the bridge deck to absorb the contraction and expansion of the bridge deck caused by seasonal temperature changes and to reduce the seismic and vibration transmitted from the outside to an appropriate level. At this time, the LRB is pierted as shown in FIGS. 7, 8, and 9 in the state where the initial deformation is fixed by using the deformation amount adjusting device of ① of FIG. 2 in consideration of the deformation amount according to the main surface temperature at the time of installation as shown in FIG. Install between and the top plate of the bridge. As the shear deformation adjusting device, a turn buckle can be used as in Fig. 2 ①, and a hydraulic device can be used according to the action shear force.

There are many methods for the construction of the bridge, but the method of placing the large top plate on the pier and if it cannot be installed other than the conditions of the installation site, the method of continuously building and curing the top plate at one end of the bridge (ILM Public method).

When constructing bridge using lLM method, minimize frictional force between top plate and pier by using sliding plate as ① of FIG.

However, in the process of pushing out the upper plate, if excessive force is applied to the installed LRB in the main shear direction as shown in Figs. 7 and 8, the initial deformation value (Fig. 3) of the LRB is changed or the deformation value is adjusted. It can happen that the turn buckle can be broken.

This cause occurs when the frictional force of the sliding plate of FIG. 1 when the top plate is installed increases or the top plate does not push in a predetermined direction.

A further problem is that excessive force is applied to the bolts that fasten the pier to the LRB of FIG. In order to solve this problem, it is a device to measure the stress using the strain gauge from the initial deformation amount setting stage of the LRB so that an appropriate force is applied. In the initial setting, it is attached to ① of FIG. 2 to measure the shear force according to the deformation amount, and after the LRB is installed, monitoring is performed in the same manner to confirm the occurrence of excessive shear force, and accordingly, the shear of the bolt due to the increase of the frictional force of the sliding plate And strain gauges and real-time measuring devices to prevent breakage and cracking of bridge piers such as ⑥ of FIGS. 4 and 5 due to shear force acting on the piers due to excessive force being applied to the piers. It is extensive in scope and essential to the ILM process.

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As shown in Figure 1, the lead seismic isolator used as a seismic isolator for large structures including bridges should be capable of permitting shear deformation including the amount of expansion due to the temperature change of the upper structure as well as the amount of shear deformation caused by seismic forces. In particular, when applied to bridges exposed to the outside due to the installation conditions, the height of the bridge upper structure is increased according to the ambient temperature, so the height of the LRB is increased to secure the required shear deformation and the installation area of the sufficient piers. Should be secured. In other words, when installing LRB in the summer, the expansion of the upper structure of the bridge should be considered in the shear deformation caused by the seismic force. Therefore, when the deformation amount is calculated in accordance with the temperature at the time of installation and the LRB is installed in a shear deformation state, the installation area is reduced by that amount.

To give the initial deformation at the construction site, a large load must be applied in the transverse direction, and by measuring the amount of deformation and the transverse force according to the characteristics of the product accurately, there should be no problem in installation and use.

To this end, the shear displacement is calculated according to the operating temperature, and in order to generate the calculated shear displacement, a separate reaction force structure is installed on the piers, and the shear load is applied to the LRB, which is very cumbersome to install. In addition, in the case of using the ILM method, which uses a sliding plate on the upper part of the pedestal installed on the pier to install the bridge support (ILM method), a uniform load is applied to the pedestals installed on the left and right sides of the bridge structure. It is practically difficult to do, and a very large force acts so that excessive shear force can act on the piers and cause breakage of the piers. Therefore, it is necessary to accurately measure and manage the shear load acting on the product when generating the initial deformation due to the shear force action before the product is shipped out of the factory, and in real time the load acting on the bridge support during the construction of the superstructure on the pier. By measuring the torsional load on the bridge piers and minimizing the damage of the product due to the uneven loading of the bridge supports on the left and right.

The present invention was able to adjust the shear deformation value required for the installation of the seismic support for the bridge in the field according to the temperature at the time of installation and when pushing the upper structure through the bridge pedestal on the pier at the factory shipment of the product (ILM method) The present invention relates to a device for preventing damage to the LRB and piers caused by excessive propulsion by constantly checking and adjusting the load acting on the LRB.

2. Brief description of the drawings

Figure 1 shows the shape of the LLB (stereogram)

2 is the shape (LR) of the LLB

3 is the shear deformation direction of the LLB and the shape after the shear

4 is an example of the installation of LRB on a large bridge (cross section)

5 is an example of mounting the LRB on a large bridge.

6 is: frequency analysis system

Figure 7: Example of LRB Field Installation

8 is: Bridge construction example by ILM

9 is: temperature deformation of the top plate and the LRB installation site

Figure 10: Field Installation Status of the LLB

* Description of the main sections of the drawing

<Figure 1>

① LRB top plate ② LRB bottom plate

③ ILM upper and lower plate fixing block ④ LRB

⑤ Pierce and LRB tightening bolt ⑥ Lead lead

⑦ Sliding Plate ⑧ Base Plate

⑨ anchor bolt

<Figure 2>

① Shear strain control device of LRB

<Figure 3>

전단 Shear deformation direction set at initial installation of LRB

<Figure 4, 5>

① Bridge deck ② Pier

③ LRB top plate ④ LRB bottom plate

⑤ Pier and plate fastening bolt ⑥ Pierce crack

<Figure 6>

⑦ Signal Cable ⑧ Frequency Analysis System

<Figure 7> LRB site installation state

① Bridge deck ② LRB installed on the bridge

③ Pier

<Figure 8>

① Change direction according to the temperature and load of the bridge deck (main shear deformation direction)

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Claims (3)

ILM LRB device with upper and lower plate fixing blocks to resist propulsion during ILM construction. It is a device that can reduce the installation space of seismic isolator by giving shear deformation to the seismic isolator in order to correct the amount of expansion and contraction of the bridge according to the product installation temperature. By paragraph 2 Device that adjusts the propulsion force so that the bridge deck moves constantly by measuring the horizontal thrust force applied to the base isolation support when the bridge top plate is pushed and installed