Experimental and analytical studies on the response of 1/4-scale models of freestanding laboratory equipment subjected to strong earthquake shaking

Abstract

This paper investigates the seismic response of freestanding equipment when subjected to strong earthquake motions (2% probability of being exceeded in 50 years). A two-step approach is followed because the displacement limitations of the shake table do not permit full-scale experiments. First, shake table tests are conducted on quarter-scale wooden block models of the equipment. The results are used to validate the commercially available dynamic simulation software Working Model 2D. Working Model is then used to compute the response of the full-scale freestanding equipment when subjected to strong, 2% in 50 years hazard motions. The response is dominated by sliding, with sliding displacements reaching up to 70 cm. A physically motivated dimensionless intensity measure and the associated engineering demand parameter are identified with the help of dimensional analysis, and the results of the numerical simulations are used to obtain a relationship between the two that leads to ready-to-use fragility curves.

Dynamics of planar rocking-blocks with Coulomb friction and unilateral constraints: comparisons between experimental and numerical data

“…9. The maximal acceleration of the base is known to play a significant role in the block dynamics; see, e.g., [26] where this is denoted as PTA (for Peak Table Acceleration) and used to study the so-called engineering demand parameter in purely sliding motions. It is also noteworthy that our results are not based on some model approximations as done sometimes [1], but keep the full nonlinearity of the dynamics in addition to the nonsmooth features.…”

“…Let us consider that the base has the pulse-type motion (called one-sine type-A pulse in [26,37,61]) with an acceleration equal tȯ…”

“…If it has not overturned before it starts to lose its energy, it will never overturn. This has been used in [26,61], where one can find numerical results about the safe and unsafe areas depending on the amplitude and frequency of the base excitation (see, for instance, Fig. 6 in [26]).…”

Seismic Reliability Assessment of Rocking Behaviour Under Near-Fault Excitations

“…Following the proposed dimensionless-orientationless products of Equation (9), we select IMs similar to that in [29] for sliding objects. According to Equation (9), there are two groups that could be considered as candidate IMs: the frequency ratio ω p /p and the dimensionless slenderness α g /(gtanα).…”

Dynamic Response of a Rigid Slab Supported by Four Rigid Cylinrical Rocking and Wobbling Columns

“…Indeed, a simple freestanding rocking block has been systematically studied for more than five decades both when the block is assumed rigid [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] and when it assumed deformable [27][28][29][30][31][32][33][34][35][36][37]. Small scale experiments have been also performed [38][39][40][41][42][43][44][45][46][47][48][49][50][51]. It has been proven that structures that rock inplane (2d rocking) have remarkable dynamic stability.…”