Experimental Validation of Numerical Model for Bi-Tilt-Isolator

Shock and Vibration, Mar 2018

Bi-Tilt Isolator (BTI) is composed of bi-tilt beveled substrate and slider. The advantages of BTI are that the maximum upload seismic force of structure can be easily controlled and displacement of isolation layer will be reduced. Sliding force, friction force, and impulse force are caused in the slanting process of BTI, nonlinear behavior. A nonlinear mathematical model is derived based on the sliding upwards, sliding downwards, and transition stages. Then, BTI element of nonlinear analysis program, GENDYN, is developed by the fourth-order Runge-Kutta method, the discretized ordinary differential equation for three movement stages of BTI. Then, test set-up of superstructure installed with BTI is tested and recorded the real displacement and acceleration responses under conditions of full lubrication, mild lubrication, and without lubrication between interface of bi-tilt beveled substrate and slider with three various initial displacements. The comparison of simulation results and test results shows the following: root mean square error is below 1.35% for WD40 sprayed, 0.47% for WD40 whipped, and 0.54% for without lubrication, respectively; the maximum root mean square error for simulating with cubic polynomial function of friction is much less than those of constant friction except conditions of full lubrication, which are not affected by kinetic friction force; application of cubic polynomial function for simulating friction of BTI with three different lubricated conditions can perform very fine simulation results, compared with the test results. This proposed mathematical model and BTI element of GENDYN program, using cubic polynomial function of friction, perform fine simulation capability to assess nonlinear isolation effect of structure installed with BTI.

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Experimental Validation of Numerical Model for Bi-Tilt-Isolator

Experimental Validation of Numerical Model for Bi-Tilt-Isolator Ming-Hsiang Shih,1 Wen-Pei Sung,2 and Chia-Yu Ho1 1Department of Civil Engineering, National Chi Nan University, Nantou 545, Taiwan 2Department of Landscape Architecture, Integrated Research Center for Green Living Technologies, National Chin-Yi University of Technology, Taichung 41170, Taiwan Correspondence should be addressed to Wen-Pei Sung; wt.ude.tucn@spw Received 8 September 2017; Accepted 7 February 2018; Published 14 March 2018 Academic Editor: Paulo B. Gonçalves Copyright © 2018 Ming-Hsiang Shih et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Bi-Tilt Isolator (BTI) is composed of bi-tilt beveled substrate and slider. The advantages of BTI are that the maximum upload seismic force of structure can be easily controlled and displacement of isolation layer will be reduced. Sliding force, friction force, and impulse force are caused in the slanting process of BTI, nonlinear behavior. A nonlinear mathematical model is derived based on the sliding upwards, sliding downwards, and transition stages. Then, BTI element of nonlinear analysis program, GENDYN, is developed by the fourth-order Runge-Kutta method, the discretized ordinary differential equation for three movement stages of BTI. Then, test set-up of superstructure installed with BTI is tested and recorded the real displacement and acceleration responses under conditions of full lubrication, mild lubrication, and without lubrication between interface of bi-tilt beveled substrate and slider with three various initial displacements. The comparison of simulation results and test results shows the following: root mean square error is below 1.35% for WD40 sprayed, 0.47% for WD40 whipped, and 0.54% for without lubrication, respectively; the maximum root mean square error for simulating with cubic polynomial function of friction is much less than those of constant friction except conditions of full lubrication, which are not affected by kinetic friction force; application of cubic polynomial function for simulating friction of BTI with three different lubricated conditions can perform very fine simulation results, compared with the test results. This proposed mathematical model and BTI element of GENDYN program, using cubic polynomial function of friction, perform fine simulation capability to assess nonlinear isolation effect of structure installed with BTI. 1. Introduction Earthquakes and strong winds are unavoidable natural disasters on the planet. Recently, the intensity of natural disasters has been enhanced according to many factors; strong earthquakes, such as 9.0 magnitude (Richter scale) earthquakes, happened on 2004 in India and 2011 in Japan and triggered severe tsunami, resulting in heavy losses of life and property. In addition, some strong earthquakes occurred in the world. For example, 7.7 magnitude (Richter scale) earthquake in Pakistan on 2013 and 7.8 and 7.3 magnitude (Richter scale) earthquakes in Nepal on 2015 caused a lot of casualties. Taiwan is located in the Circum-Pacific Seismic Zone and also at the junction of the Eurasian plate and the Philippine Sea plate, witnessing sensible earthquakes every year. In particular, Chi-Chi earthquake (7.3 magnitude on the Richter scale) happened on 1999 to result in great damage to buildings and bridges. Moreover, a 6.4 magnitude (Richter scale) earthquake happened in southern Taiwan and led to the 16-story building collapsing on the ground, causing heavy casualties in 2016, before Chinese New Year. The main reason for building collapse is the lack of earthquake resistance capability. To maintain the safety of buildings to resist seismic force and external force, structural control theorems and equipment are widely applied in Architecture and Civil Engineering. Structural control techniques [1–3] have been divided into passive control (isolation, shock absorption, and energy dissipation) [4–11], active control [12–23], and semiactive control [24–27]. In this study, a newly developed Bi-Tilt Isolator is proposed as an isolation system for building. Traditionally, soft isolation layer is used as base isolation, for example, lead rubber bearing, LRB [28–33], and rubber bearing, RB [34, 35]. The purposes of LRB and RB are applied to extent structural period and isolate seismic waves into the structures to reduce the horizontal seismic force. The defect of these kinds of isolation systems is a large displacement of isolation layer, affecting the practicality. To improve shortcomings of base isolation system, Bi-Tilt Isolator, BTI, composed of bi-tilt beveled substrate and slider, as shown in Figure 1, is proposed in this study. Although the proposed BTI and Friction Pendulum System (FPS) look quite similar, isolation efficiency and practical perf (...truncated)


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Ming-Hsiang Shih, Wen-Pei Sung, Chia-Yu Ho. Experimental Validation of Numerical Model for Bi-Tilt-Isolator, Shock and Vibration, 2018, 2018, DOI: 10.1155/2018/7163516