Application of SMA anchors to the seismic performance of tanks
This paper is aimed at investigating the feasibility of using shape memory alloy (SMA) materials as anchor bolts in steel liquid storage tanks. The seismic performance of a case study liquid storage tank anchored with steel and SMA bolts is evaluated. For this purpose, a parametric study is performed to determine the optimum length and diameter of the anchor bolts which results in the minimum tank uplift. Furthermore, incremental dynamic analyses (IDAs) are performed to gain insights into the effects of the axial stiffness of the anchor bolts on the uplift of the tank. The uncertainties regarding the seismic input, i.e., the record-to-record variability and seismic intensity, are taken into account by selecting a set of near-field earthquake ground motion records with and without forward directivity. It should be noted that peak ground acceleration (PGA) is chosen as the intensity measure in IDAs. According to the results, using steel anchor bolts significantly reduces the uplift of the tank due to their high axial stiffness, which may result in a severe damage at the connection as a result of high axial forces in the bolts. Conversely, the self-centering feature of SMA anchor bolts allow the tank to undergo a limited uplift, which also leads to significant energy absorption. Furthermore, the Incremental dynamic analysis results show that tanks anchored with SMA bolts are less sensitive to the frequency content of the seismic input compared to the tanks anchored with steel bolts. Based on the findings of this research, it is possible to reduce the required diameter of the anchor bolts and eliminate the residual deformation of the anchorage system after a severe seismic event by using SMA anchor bolts.