Finite element modeling of free‐standing cylindrical columns under seismic excitation

Abstract

Rocking motion is notoriously sensitive to the parameters that define it, with experimental tests oftentimes being non-repeatable. Therefore, validating numerical models using a deterministic approach is impossible, since the consistency of any benchmark experimental test is dubious. Three-dimensional rocking is even harder to predict than planar rocking. This paper presents a threedimensional finite element model to predict the statistics of the rocking/sliding response of free-standing cylindrical columns. The response parameters of interest were the maximum displacement at the top of the columns and the residual displacement. Three different columns with varying slenderness and size were examined. The columns were able to slide, rock, and wobble in all directions, with this behavior being representative of building components and monumental structures. The numerical results were statistically compared to a large database of experimental tests, proving the accuracy of the proposed model. The influence of all modeling and physical parameters was elucidated, employing a large number of non-linear time-history analyses. It is shown that, when the numerical parameters are varied within a reasonable range, they do not influence the statistics of the response, even though they influence each individual oscillation. The friction coefficient between the interfaces (physical parameter) can influence the statistics of the response and should be carefully selected. Energy dissipation should be modeled explicitly, following the physics of the problem.

Seismic response of slender MDOF structures with self‐centering base shear and moment mechanisms

“…Following the motion‐by‐motion comparison, the numerical and experimental results of the shaking table dataset were revisited with a focus on the statistical comparison of the Cumulative Distribution Function (CDF) of key response parameters that were discussed previously. The concept of statistical validation using the CDF plots has been applied to modelling of rocking structures that showed predictable rocking responses in the statistical sense 30–32 , 35–38 . Figure 5 presents the CDF plots used for the statistical comparison in this section.…”

“…The concept of statistical validation using the CDF plots has been applied to modelling of rocking structures that showed predictable rocking responses in the statistical sense. [30][31][32][35][36][37][38] Figure 5 presents the CDF plots used for the statistical comparison in this section. The numerical and experimental CDF plots were compared based on the Kolmogorov-Smirnov (K-S) distance 39,40 (i.e., the maximum vertical distance between the experimental and numerical CDF plots) and the relative errors (𝜀, defined as the absolute error between the experimental and numerical values divided by the experimental value) at the maximum horizontal distance, as well as at median and 90 th percentile of the experimental CDF plots, as listed in Table 1, and within each plot of Figure 5.…”

Experimental study on rocking blocks subjected to bidirectional ground and floor motions via shaking table tests

“…[17][18] Bidirectional shaking table tests on an aluminum slab supported on four wobbling circular structural steel columns and on six freestanding rocking specimens with square and round bases were carried out, respectively. [19][20][21][22][23] For a better understanding of the seismic rocking performance of freestanding blocks under different ground motion records, the problem was also studied using probabilistic methods. [24][25][26][27] In particular, the overturning fragility estimates of the freestanding blocks were obtained from the outcomes of the shaking table tests.…”

“…Regarding the experimental work, the seismic rocking and overturning performance of a typical museum display case and two hospital cabinets was investigated via unidirectional and bidirectional shaking table tests, respectively 17–18 . Bidirectional shaking table tests on an aluminum slab supported on four wobbling circular structural steel columns and on six freestanding rocking specimens with square and round bases were carried out, respectively 19–23 …”

Material Testing of Micro-Concrete and 3d-Printed Reinforcement for Use in Small-Scale Seismic Testing of Rc Structures

“…This is a weaker model validation test that requires that the structural model only be unbiased and introduce less uncertainty than the uncertainty introduced by the excitation itself. In other words, models that can be designated "good", in the scope of earthquake engineering, should introduce less uncertainty than the already-existing motion-to-motion variability [15,16]. Such statistical procedure is possible at a material or component level, but it is currently impossible at a system level due to the prohibitive cost of performing multiple shake table tests with virgin identical specimens.…”