Abstract
This paper propose a method to estimate overall building responses during an earthquake using acceleration records from two seismographs those have single input-output relationship. At first, natural frequencies are found through frequency response function of top and basement records. Then, to obtain each modal response of top layer, band-pass filter is applied. Frequency ranges for band-pass filters are determined by middle points of adjacent points. Each story response is assumed to present by sum-up of each modal response with considering modal coefficient of each layer. To evaluate the accuracy of the method, the method was applied to existing building where responses of each layer have been recorded. The response estimation results substantially match the actual observations.