Keywords: velocity and displacement dependent hydraulic damper, modified Maxwell theory, discrete solution, passive energy-dissipating device.

The structural control system using a hydraulic damper can be divided into three categories including: the active control system, the semi-active control system and the passive control system. The development of these kinds of dampers uses oil viscosity to dissipate the dynamic energy. The characteristics of these hydraulic dampers are: it can simultaneously reduce the structural displacement and the acceleration reaction can provide effective results depending on the requirement of the structure and there is less problem during the life cycle. The current devices, such as the Taylor device [1], an Electrorheological damper [2] and a Magnetroheologrical damper [3], an semi-active hydraulic damper developed by Kobori [4,5,6] and Shih and Sung [7,8,9]. These dampers basically function by either shifting the size of the orifice to promptly adjust the shear stress of oil or by means of using specific valves to produce the proper hydraulic performance [7,8,9].

The design concept of Velocity and Displacement Dependent Hydraulic Damper, VDHD is passive energy dissipation control system that conducts control through the damping force generated by the flow going through the small orifice by fluid. This new hydraulic damper, is composed of hydraulic jack, check valve, relief valve and throttle valve, is installed with an additional relief valve parallel to the throttle valve to change its orifice size.

The component tests show that the energy dissipation behaviours of this damper are similar to purely a viscous dashpot model and the classical elastic-perfectly plastic model by low and high velocity respectively. Therefore, a friction model is added in series to Maxwell model so as to simulate its energy dissipation behaviour, and the discrete solution is presented to simulate the mechanical phenomenon of the varied throttle orifice diameters when this damper is in an expansion and contraction direction. In addition, when the relief and throttle phenomenon occur simultaneously, the elasticity of the relief valve and throttle valve of the VDHD will be adjusted under displacement control. The verification shows that this mathematical analysis model can accurately simulate the relation of force and displacement and the relation of the force and velocity during the process of energy dissipation. Therefore, the proposed mathematical model can adequately simulate the actual energy dissipation behaviour of the VDHD added to the structure in various energy dissipation situations.

1

Lee, D. and Taylor, D.P., 2001. Viscous damper development and future trends. The Structural design of Tall Buildings, 10: 311-320. doi:10.1002/tal.188

2

Xu, Y.X., Qu, W.L. and Ko, J.M., 2000. Seismic Response Control of Frame Structures Using Magnetorheological/Electrorheological Dampers. Earthquake Engineering and Structural Dynamics, 29: 557-575. doi:10.1002/(SICI)1096-9845(200005)29:5<557::AID-EQE922>3.0.CO;2-X

3

Dyke, S.J., Spencer, B.F. Jr, Sain, M.K. and Carlson, J.D., 1998. An experimental study of MR dampers for seismic protection. Smart Master. Struct., 7: 693-703. doi:10.1088/0964-1726/7/5/012

4

Kurata, N., Kobori, T., Takahashi, M., Niwa, N., Midoridawa, H., 1999. Actual Seismic Response Controlled Building with Semi-Active Damper System. Earthquake Engineering and Structural Dynamics, 28: 1427-1447. doi:10.1002/(SICI)1096-9845(199911)28:11<1427::AID-EQE876>3.0.CO;2-#

5

Kurata, K., Kobori, T., Takahashi, M., Ishibashi, T., Niwa, N., Tagami, J., and Midorikawa, H. 2000. Forced Vibration Test of a Building with Semi-Active Damper System. Earthquake Engineering and Structural Dynamics, 29: 629-645. doi:10.1002/(SICI)1096-9845(200005)29:5<629::AID-EQE928>3.0.CO;2-9

6

Kobori, T. Takahashi, M., Ishibashi, T., Niwa, N., Tagami, J., and Midorikawa, H., 1999. Development of Active Variable Damping (AVD) System for structural response control in large earthquakes (in Japanese). Annual Report, Kajima Technical Research Institute, Kajima Corporation, 47: 167-172. doi:10.2208/jsceseee.21.121s

7

Shih, M.H., Sung, W.P. and Go, C.G., 2003. A Design Concept with a Displacement Dependent Semi-Active Hydraulic Damper for Energy Dissipation. Experimental Techniques, 27(6): 53-56. doi:10.1111/j.1747-1567.2003.tb00139.x

8

Shih, M.H., Sung, W.P., 2004. The Energy Dissipation Behavior of Displacement Dependent Semi-Active Hydraulic Damper. Journal of Structural Mechanics and Earthquake Engineering, Japan Society of Civil Engineering, 21(2): 121s-129s.

9

Shih, M.H., Sung, W.P. and Go, C.G., 2002. Development of Accumulated Semi-Active Hydraulic Damper, Experimental Techniques, 26(5): 29-32. doi:10.1111/j.1747-1567.2002.tb00081.x

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