Influence of a subway station on the inter-story drift ratio of adjacent surface structures

The existence of a subway station changes the original site conditions, local ground motions and, as a consequence, the seismic response of adjacent buildings. The paper investigates the effects of the Zhujiang Road subway station in Nanjing, China, on the response of buildings close to the station, when subjected to an earthquake with a probability of exceedance of 10% in 100 years. The shape and magnitude of the inter-story drift ratio (IDR) of buildings placed at different distances from the station are investigated using the generalized inter-story drift spectral analysis, in which structures are represented as combined shear-flexural beams. The analysis shows that there are two key factors that affect the response of buildings in the presence of an underground structure: the fundamental period of the building and the distance between the building and the station. Comparisons of the IDR of buildings obtained when the underground structure is included in the calculations and when it is not, indicate that the errors increase as the distance of the building to the subway station decreases, in particular for buildings with short fundamental periods. It is observed that the presence of the subway station increases the flexural deformation demand of short period structures, while for long-period structures, the subway station increases the shear deformation demand. (C) 2012 Elsevier Ltd. All rights reserved.