# Example of accumulation damage level calculation in a sealed joint

The accumulated damage level of a sealed joint was calculated using the factor conditions shown in Table 5. The accumulated damage level at a sealed joint can be calculated using Miner’s Rule, according to Eq 3. The resulting accumulated damage level for the linear section of the sealed joint is 0.05, and is 0.28 for the intersection of the sealed joint. Both accumulated damage levels for the sealed joint sections are smaller than 1 and the fatigue resistance of the sealed joint is sufficient for a service life of about 25 years. However, the sealed joint design method proposed in our study does not consider weathering, and the accumulated damage level of sealed joints is actually greater than the value calculated in this study.

TABLE 5—Factor conditions.

 Target service life of sealed joint 25 years Sealant MS-2 Width of joint 20 mm Type of sealed joint Lineal- section of sealed joint Intersection of sealed joint (Fixed type) Rocking motion type (F/Wp=0.25) The radius of curvature l mm

Conclusions

1. The relationship between the story drift and the number of cyclic movements at the sealed joint in Japan was calculated to clarify the service life of a sealed joint. The number of cyclic movements at a sealed joint occurred several thousand times at R= 1/300, several hundreds times at R = 1 /200, and tens of times at R = 1 /100.

2. It was obvious that the fatigue resistance of sealed joints was lower for the intersectional area than for the linear sections of the joints, and was lowest when the same movement occurred in both, vertical and horizontal, joints.

3. The fatigue resistance of sealants to relative story displacement became higher in the order, PS-2, MS-2, and SR-2.

4. The fatigue resistance of sealed joints to relative story displacement movements caused by earth­quakes was studied for their linear sections and for the intersection of sealed joints, and a new joint design method providing the necessary sealed joint performance was proposed, which con­siders the service life of sealed joints. This process of method design took into consideration the relationship between the number of cyclic movements in a service life and the number of cycles to crack initiation of sealed joints obtained using a fatigue test.

5. The service life of a sealed joint was evaluated using Miner’s Rule.