Boundary effects on dynamic centrifuge testing of onshore wind turbines on liquefiable soils

Abstract

Centrifuge modelling is an effective tool to assess the response of reduced-scale structures subjected to earthquakes under increased gravity. Space limitations, however, force the model to be contained within relatively small boxes, whose boundaries may affect the seismic performance of the structure under consideration. In this paper, the influence of the proximity of the boundaries of an Equivalent Shear Beam (ESB) container during dynamic centrifuge tests of an onshore wind turbine resting on liquefiable soils is evaluated. To this end, numerical modelling of the ESB box was implemented in the Finite Element framework OpenSees, to replicate the results observed in the experiment. The hydraulic and mechanical soil parameters were calibrated against far-field centrifuge results only. From this calibration, the seismic performance of the raft foundation turned out to be in a good agreement with the experimental results for a seismic input capable of triggering liquefaction. A larger numerical model, where boundaries do not play any role, was then built, to compare its outcomes with those of the small model, thus allowing the effect of ESB boundaries to be assessed.

A Hybrid Convolutional and Recurrent Neural Network for Multi-Sensor Pile Damage Detection with Time Series

“…To achieve the installation of multiple sensors at desired depths and make use of existing test techniques, some implementation ideas are proposed for onshore and offshore piles [37][38][39]. For example, as depicted in Figure 1a, if a reinforced concrete (RC) pile is qualified for the cross-hole sonic logging (CSL) test, a series of hydrophones (commonly used in the PS method) can be plugged into one of the water-filled sonic logging tubes located below the known defect (e.g., an enlarged pile top or a detected defect); Figure 1b demonstrates a series of transducers installed along the outer surface of an offshore pile to conduct the MSPDD test, where the sensors below the superstructure can remove the effects of the above structure after signal post-processing (as will be introduced in the ensuing section).…”

Numerical Back-Analysis of Dynamic Centrifuge Tests on the Seismic Behaviour of Caisson Foundations Supporting Bridge Piers

“…The clay was consolidated at a stress level so that to obtain a soft clay ('vc = 512 kPa), together with suction applied at the bottom, u = -90 kPa. The model was placed into an Equivalent Shear Beam container (ESB) [10], whose dynamic boundary effects have been recently assessed [11]. In addition, the model was equipped with miniaturized instruments, such as those shown in Figure 2.…”