Engineering Structures 30 (2008) 2739–2751 Contents lists available at ScienceDirect Engineering Structures journal homepage: www.elsevier.com/locate/engstruct An innovative earthquake isolation system using fibre reinforced rubber bearings Andrea Mordini a,∗,1 , Alfred Strauss b a VCE – Vienna Consulting Engineers, Hadikgasse 60, 1140 Vienna, Austria b University of Natural Resources and Applied Life Sciences, Department of Civil Engineering + Natural Hazards, Institute for Structural Engineering, Peter Jordan Strasse 82, 1090 Vienna, Austria article info Article history: Received 8 March 2007 Received in revised form 26 February 2008 Accepted 17 March 2008 Available online 28 April 2008 Keywords: Fibre reinforced rubber bearings Isolated structures Liquid storage tanks Seismic protection Petrochemical facilities abstract In this contribution, a new innovative isolation system for structures in earthquake regions is presented. The system consists of high damping rubber bearings strengthened with glass fibre fabrics. A wide parametric numerical investigation through Finite Element Analysis is carried out in order to develop and verify analytical models for these new isolation devices. Experimental investigations provided useful information for numerical modelling and derivation of analytical approaches. Comparisons with simplified formulations are reported as well. In order to demonstrate the effectiveness of the proposed solution and to verify the reliability of the numerical simulations, the new devices are applied to the seismic analysis of a liquid storage tank, a strategic structure for civil protection. © 2008 Elsevier Ltd. All rights reserved. 1. Introduction Rubber bearings, in different versions with interposed steel plates, have been used extensively in bridge superstructures as they are able to carry large vertical loads and provide only small resistance to lateral displacements. More recently, their use has been extended to seismic isolation of buildings and structures [1, 2]. During the last decades new models of isolators have been investigated and developed, these contain interposed fibre layers, e.g. glass or carbon fibres, instead of classical steel plates [3– 11]. This contribution focuses on such bearings strengthened with fibres instead of steel plates. The first part of this study describes the numerical investigation of the bearing in order to find out its mechanical behaviour both in static and dynamic simulations. For this reason, a parametric analysis is performed varying specimen size, vertical load, glass fibre layer number, boundary conditions and material constitutive models. The results of three experimental campaigns are briefly presented. The experimental tests provided the authors with important information about material properties, damping capabilities, boundary conditions and connection between rubber and fabric layers. The computational demand for analyzing a full three-dimensio- nal bearing model is very high because of the huge number ∗ Corresponding author. E-mail address: andrea@andreamordini.com (A. Mordini). 1 When the work was done: University of Parma, Department of Civil Engineering, Via P.G. Usberti 181/A, 43100 Parma, Italy. of elements required, the material and geometric non-linearity, and the iterations in the non-linear time history simulation with direct integration. Consequently, including bearings in the analysis of engineering structures seems to be impossible with the current computational resources. Therefore, an alternative way is proposed in order to include the bearings in the full-scale analysis of structures. 2. Modelling techniques The investigated Fibre Reinforced Rubber Bearings are made of a rubber body with embedded glass fibre layers. An extensive parametric numerical program is performed with the commercial Finite Element (FE) code ABAQUS [12]. The simulated bearings differ in size, number of layers and material properties: the 150 × 150 × 50 small-scale bearing (with 12 fibre layers and shear modulus 0.45 MPa), the 245 × 245 × 80 mock-up bearings (with 7 or 13 fibre layers and shear modulus 0.45 or 1.02 MPa) and the 490 × 490 × 150 full-scale bearing (with 12, 18 or 24 fibre layers and shear modulus 0.45 or 1.02 MPa). Modelling characteristics and assumptions of the specimen 490 ×490 ×150 are illustrated in Fig. 1. The number of analyses for each case depends on the vertical load, how this is done is explained in the following paragraph. The proposed simulation method provides an all-around knowledge of the parameters influencing the bearings. 2.1. Materials: Rubber and fabric The material model describing the rubber has to fulfill a nearly incompressible behaviour. Therefore, the hyperelastic Neo Hooke 0141-0296/$ – see front matter © 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.engstruct.2008.03.010