Numerical investigation of the seismic response of RC buildings on soil replaced with rubber-sand mixtures

The use of granulated scrap tires in mixtures with sand has been proposed the last years as an alternative way to exploit the vast stockpiles of available scrap tires for the improvement of the seismic performance of structures. The objective of the present paper is to investigate whether the use of rubber-sand mixtures (RSM) instead of clean sand as a foundation layer affects in a beneficial way the seismic performance of reinforced concrete (RC) moment resisting frames (MRF). Specifically, the effectiveness of utilizing RSM in the foundation soil of different MRF typologies is assessed through numerical simulations. Soil-structure interaction is modeled applying the direct one-step coupled approach considering nonlinear soil behavior. Dynamic analyses of the soil-structure systems are performed for different input motions taking into account the variation in the RSM layer thickness and the building's height. The effects of the RSM layer are investigated in terms of the input acceleration at the foundation level, the base shear force, the maximum interstorey drift, the deformation of the foundation and the stress distribution of the soil under the structure's foundation. Results highlight the beneficial effects of the use of RSM as a foundation layer on the structures' response under dynamic loading, particularly for the mid- and high-rise buildings, leading to a reduction of the base shear and maximum interstorey drift up to 40% and 30% respectively in comparison to the clean sand profile. (c) 2015 Elsevier Ltd. All rights reserved.