Experimental Manufacturing of a Small Shaking Table in Uzbekistan

Abstract eng:
Tashkent, Capital of Uzbekistan, experienced the earthquake damage in April 1966, just 50 years ago. In 1988 of The Soviet Era, devastating Armenia Spitak Earthquake occurred. Therefore, in order to research the seismic stability of structures, the reaction walls for seismic tests were constructed in Tashkent. However, soon, Soviet Union disintegrated. The reaction wall facility was left at Turin Polytechnic University in Tashkent (TTPU), Uzbekistan. TTPU tried to make a shaking table as an useful application of the facility by the small construction cost. The shaking table was made with the ready-made hydraulic equipments as the practical training for mechanical students. The shaking table moves with the hydraulic power in one horizontal direction, and has the steel table of 2.4m x 2.3m. The table, guide system and reaction frame were fabricated and assembled with welding of TTPU students. A hydraulic actuator has a single piston rod with the stroke of 30cm. The push area of piston is about 50 cm2 and the pull area of piston is about 25cm2 respectively. A solenoid valve uses for the oil flow control. The cylinder actuator and solenoid valve were imported from Italy. A hydraulic power supply capacity is 37Kw. The power supply was imported from China. Payload is 1.5 tones. Maximum driving force is 5tonf. Maximum velocity is 48cm/s. Mechanical responses of the shaking table were measured in open loop control, using an old analog function generator and DC power source. The actuator made drifts by differences in push-pull piston area, the piston rod made the drifts. The response movements of shaking table were unstable. In order to avoid the drift of piston rod, the baseline of input waves were adjusted with the turning of offset variable. Afterwards, the feedback control devices were prepared. The control device was designed and made in Japan. Next trials were conducted in closed loop with arbitrary inputs, by the use of PC with DA converter. The stable control of shaking table was verified. In this way, the general characteristics of shaking table have been obtained. In analysis, the simple equations of different piston areas of single rod were introduced and calculated. Calculations were conducted for the open loop and closed loop cases. As a matter of course, no drift in the actuator was confirmed in the close loop. In the paper, the outlines of TTPU seismic test facility are described. The paper is considering to construct a low-cost one horizontal direction shaking table. Cost of the shaking table manufacturing was less amounts than twenty thousand Dollars in total.

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