Simulating a conical tuned liquid damper Fabio Casciati a, * , Alessandro De Stefano b , Emiliano Matta b a Department of Structural Mechanics, University of Pavia, Via Ferrata 1, 27100 Pavia, Italy b Department of Structural Engineering and Geotechnics, Polytechnic of Turin, Corso Duca degli Abruzzi 34, 10100 Torino, Italy Received 14 May 2002; received in revised form 7 April 2003; accepted 12 April 2003 Abstract In recent years, tuned liquid dampers (TLD) have proved a successful control strategy for reducing structural vibrations. The present study focuses on the frustum-conical TLD as an alternative to the traditional cylindrical tank. If compared to the cylindrical reservoir, the cone-shaped TLD allows calibrating its natural frequency through varying liquid depth, which makes it suitable for a semi-active implementation, and attains the same level of performance with a fewer mass, at least for small fluid oscillations. A linear model is presented which can interpret TLDÕs behaviour for small excitations. For larger amplitudes, strong nonlinearities occur and the linear model is no longer predictive. Consequently, for a frustum-cone TLD subjected to harmonic excitations, a tuned mass damper (TMD) analogy is established where TMD parameters vary with the excitation amplitude. Ó 2003 Elsevier B.V. All rights reserved. Keywords: Conical tank; Energy dissipation; Nonlinearities; Passive control; Tuned liquid damper 1. Introduction TLDs have been mainly applied in Japan. The TLD devices installed in the 77.6 m high structure of the Tokyo Airport Tower (1993), for instance, consist of 1400 tanks filled with water and floating particles. The containers, low cylinders of diameters 0.6 and 0.125 m, are stored in six layers on steel consoles. The total mass of the TLDs is approximately 3.5% of the first modal mass of the tower and its frequency is opti- mised to 0.74 Hz. Floating polyethylene particles were added in order to enhance * Corresponding author. E-mail addresses: fabio@dipmec.unipv.it (F. Casciati), alessandro.destefano@polito.it (A. De Stefano), emiliano.matta@polito.it (E. Matta). 1569-190X/03/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved. doi:10.1016/S1569-190X(03)00051-0 www.elsevier.com/locate/simpat Simulation Modelling Practice and Theory 11 (2003) 353–370