PSI - Issue 6

Nadezhda Ostrovskaya et al. / Procedia Structural Integrity 6 (2017) 19–26 Nadezhda Ostrovskaya, Yury Rutman / Structural Integrity Procedia 00 (2017) 000 – 000

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Based on the analytical dependences, that were developed by Rutman and Ostrovskaya (2007, 2012, 2015), a family of nonlinear force characteristics of plastic dampers has been formed. As variable design values we considered configuration, dimensions and quantity of plastic dampers. As an example Fig. 6 presents various force characteristic of rod dampers, derived in the result of varying the length of rectilinear rods, being plastic deformable elements of plastic dampers. These characteristics were approximated by bilinear power diagram with elastic unloading.

Fig. 6. Dependence of force in plastic dampers on the relative horizontal displacements of plastic deformable rod ends.

Further, as in the linear model case, a representative sample of accelerogramms was used as system input and maxima of the absolute OP accelerations were averaged. As the efficient one we considered the force characteristic of plastic dampers, which gave the mean value of maximum which was close to its optimal value, received in LDM. As a methodical example for calculation of the protected object, located on the SIB shown above had been performed. The plot of the mean values of absolute OP accelerations maxima versus dimensionless damping factor  is presented in the Fig. 7. The Fig. 7 shows that minimum of the parameter is reached for 0 25 .   . This parameter corresponds with the mean value of the absolute acceleration maximum 1.23 m/s 2 . In more detail the question of optimum damping parametrs is considered by Davidova et al. (2013). For nonlinear problem the maxima are summarized in Table 2. Based on the results received we had chosen the efficient characteristic and design values corresponding to it. In this condition operability of dampers with the chosen parameters under the conditions of cyclic load input was tested.

Fig. 7. Plot of the mean values of absolute OP accelerations maxima versus dimensionless damping factor  .

Table 2. Results for dynamic load calculation of SIB. No T f , m/s 2  , 1/s 0  , 1/s

x y u max      , m/s 2

1 2 3 4 5

0.75 0.65

8.15 6.35 2.25 1.25 5.2

1.25 1.05 0.85 0.55 0.25

1.8 1.7

0.5

1.65

0.25

1.6

0.1

1.75