Assessing the effect of soil-structure interaction on damage indices of reinforced concrete frames

Abstract

Damage indices (DIs) are widely used as quantitative measures for evaluating performance of structures under ground motion. The effect of soil-structure interaction (SSI) on Park-Ang damage index of reinforced concrete frames is studied in this article. Various performance levels corresponding to 3, 4 and 5 ductility demand values are considered for structures with 5, 7, 10, 12, 15, 18 and 20 stories accurately covering a wide range of period domain. The underneath soil is modelled using cone elements and nonlinear dynamic response of each structure is obtained for a suite of 7 ground motion records. SSI effects reduced the damages predicted for low-rise non-slender structures. However, with increase of structures’ height, slenderness and ductility, DIs of a few stories (mainly the upper stories) experienced increases by as much as 15% due to SSI effects while other stories still underwent DI reductions. The overall building DIs computed for these structures was seen to decrease in presence of SSI effects. The overall effect of SSI was represented using the ‘sum of absolute DI changes’ parameter. The value of this parameter computed at storey level was shown to decrease by increase in the ductility demand level particularly for structures positioned on loose soils.

Keywords:

• Damage index
• soil-structure interaction
• ductility demand
• RC frame
• inelastic behaviour
• far-fault motion