PSI - Issue 44

Gaspar Auad et al. / Procedia Structural Integrity 44 (2023) 1474–1481 Gaspar Auad et al. / Structural Integrity Procedia 00 (2022) 000–000

1479

6

3.1. Static analysis A static analysis was conducted to validate the pendular and frictional behavior of the studied frictional bearing. The static analysis consisted of a controlled horizontal displacement of the articulated slider of 0.39 m in the x direction. A comparison of the results obtained with the FEM and the physical model is presented in Fig. 3(c). Both models provide similar results. Note that once the hardening behavior of the variable curvature device is exhibited at large lateral displacements, the results of both models are almost identical. 3.2. Dynamic analysis In this subsection, a comparison between the dynamic response of the FEM and the physical model is presented aiming to validate the three-dimensional motion of the inner slider and the internal lateral impact behavior of the studied variable curvature frictional isolator. Both models were subjected to the horizontal components of the Sylmar – Olive View MED FF record (Northridge-01 Earthquake) scaled by a factor of 85%. In Fig. 4(a), a comparison of the time-history displacement response of the slider is presented. The trajectory of the slider is well represented by the physical model, even if the internal lateral impact is observed. Note that one impact occurred mainly in the x-direction. A comparison of the lateral force response in both horizontal directions is presented in Fig. 4((b), (c), (d), and (c)). The direction of the impact (i.e., the relative value of the impact force in the x and y direction) is represented accurately by the suggested numerical model.

0

0

0.4

physical model FEM

-500

-500

0.2

-1000

-1000

-0.4

-0.2

0

0.2

0.4

0

5

10

15

time (sec)

force x-direction (kN)

force x-direction (kN)

0

slider x-direction displ. (m)

(b)

(d)

-0.2

0

0

slider y-direction displ. (m)

-200

-200

-0.4

-0.4 -0.2

0

0.2 0.4

-0.3 -0.2 -0.1 0 0.1 0.2 0.3 slider y-direction displ. (m) -400 force y-direction (kN)

-400

slider x-direction displ. (m)

0

5

10

15

time (sec)

(a)

force y-direction (kN)

(c)

(e)

Fig. 4. Comparative time-history response. (a) Trajectory of the slider; (b) Lateral force in the x-direction; (c) Lateral force in the y-direction; (d) Hysteretic loops in the x-direction; (e) Hysteretic loops in the y-direction.

4. Comparative three-dimensional dynamic analysis of a structure equipped with frictional isolators This section presents an example of a reinforced concrete moment-frame structure equipped with spherical and variable curvature frictional isolators. The structure has three stories, two bays in the x-direction and one bay in the y-direction. While the beams were modeled with rectangular frame elements with an area of 40 × 70 cm 2 , the columns were represented with a square section with an area of 70 × 70 cm 2 . A total seismic weight of J = 5,120 kN was equally distributed in all the slabs. In Fig. 5, an illustration of the base-isolated building is shown. Two isolation systems were considered to perform a comparison of the dynamic response. The first one is composed of spherical isolators (i.e., classical FPS bearings) with a radius of = 2.25 m. Elliptical-shaped isolators with the following geometric parameters = 0.56 m, = 0.14 m, and - = 0.40 m form the second isolation system