Evaluation of Sealed Joint Performance Using Miner’s Rule

“This proposed sealed joint method is divided to two-stages. Namely, it is judged whether the performance of sealant is sufficient to the target service life of sealed joint to relative story displacement by expression of Miner’s rule, expressed by the number of cyclic movements occurring in service life and the number of cycles to crack initiation of the sealed joint, and expresses the accumulated damage level of the sealed joints.”

During the first stage, the targeted service life of sealed joint is decided upon and is converted into a relationship between story drift and the number of cyclic movements occurring at the sealed joint during its service life. The number of cyclic movements to relative story displacement occurring during service life for each story drift R= 1/100, 1 /200, and 1 /300, is calculated. During the second stage, the number of cycles to crack initiation of the sealed joint is evaluated for the linear joint and the intersection of sealed joints for R= 1/300, 1/200, and 1/100. However, it is difficult to obtain data for the crack initiation number because of the number of parameters. The calculation of the number of cycles to crack initiation of the sealed joint was proposed as shown in Fig. 12. This figure shows the relationship between the number of cycles to crack initiation of the sealed joint and other factors, namely, story drift; sealant types;

I a reel service life of sealed joinl lo relative story displacement

Decision of service life of sealed joint

Calculation of number of cycles to relative story displacement

during service life (і I WO. 1/200. I 100)

Wide of joint width

( nangc sealant type

•Large of the radius of curvature

FIG. J J—Flow of sealed joint method proposed in the current study.

width of joint; radius of curvature at intersection of sealed joints; and distance between the upper and lower floor fixation of curtain wall panel. The radius of curvature at the intersection of sealed joints, and the distance between the upper and lower floor fixation of a curtain wall panel was calculated and described in our previous papers [13,14]. During the third stage, the accumulated damage level at the sealed joint was calculated using Miner’s Rule [15-18]

W ПІ «1/300 «1/200 «1/КЮ

M = ~ + "

Ni Л’іШ) ^ I /200 Ni/100

= accumulation damage level at the sealed joint

(For M=l, the crack initiation occur at the sealed joint), = number of cyclic movements occurring in service life,

= number of cycles to crack initiation of the sealed joint.

To satisfy the targeted service life of the sealant, the result of Eq 3 must be lower than 1. If the accumulation damage level at the sealed joint is larger than 1, the fatigue resistance of the sealed joint must be improved by making the joint wider or by changing the type of sealant; furthermore, for the intersection of sealed joints, the radius of curvature must be increased.