Shaking Table Test on Indoor Substation Prefabricated Steel Frames with a Partial Isolation System

Abstract:

To address the issue of excessive floor-mounted equipment acceleration in existing non-isolated indoor substations， a partial isolation retrofit strategy was proposed by introducing isolation bearings between the equipment and the floor slab. Based on this concept， a shaking table test was conducted on a prefabricated steel frame structure representative of an indoor substation. Three isolation schemes were considered： a fixed-base system （FBS）， a base isolation system （BIS）， and a partial isolation system （PIS）. BIS was further categorized into BIS-LNR and BIS-LR， corresponding to the use of linear natural rubber （LNR） bearings and lead rubber （LR） bearings， respectively. Experimental results show that the maximum equipment acceleration in FBS reaches 1.42g， significantly exceeding the allowable limit of 0.6g. In contrast， BIS-LNR， BIS-LR， and PIS reduce the average equipment acceleration by 87%， 69%， and 77%， respectively. In terms of structural response， the maximum inter-story drift of BIS is only 38% of that of FBS， while PIS shows a drift similar to FBS. Both remain well below the code-specified limit of 1/50. These results demonstrate that the proposed PIS retrofit strategy can effectively achieve the dual control of structural and equipment responses in existing indoor substations.