Identification of Site Frequencies from Building Records

Abstract

A simple procedure to identify site frequencies using earthquake response records from roofs and basements of buildings is presented. For this purpose, data from five different buildings are analyzed using only spectral analyses techniques. Additional data such as free-field records in close proximity to the buildings and site characterization data are also used to estimate site frequencies and thereby to provide convincing evidence and confirmation of the site frequencies inferred from the building records. Furthermore, simple code-formula is used to calculate site frequencies and compare them with the identified site frequencies from records. Results show that the simple procedure is effective in identification of site frequencies and provides relatively reliable estimates of site frequencies when compared with other methods. Therefore the simple procedure for estimating site frequencies using earthquake records can be useful in adding to the database of site frequencies.Such databases can be used to better estimate site frequencies of those sites with similar geological structures.

Response of a 14-Story Anchorage, Alaska, Building in 2002 to Two Close Earthquakes and Two Distant Denali Fault Earthquakes

“…The reason why determination of site frequency is necessary is to infer possible resonation that can be caused by closeness of the site frequency to the structural frequency. It is possible to identify the site frequency of a building site by spectral analysis of the recorded responses of that building (Celebi 2003). In Figure 8a-d, for each of the four earthquakes, the amplitude spectra of CH1 (EW) at the roof and CH9 (EW) at the basement are plotted.…”

The Accelerometric Network of the Indes-Musa Project in the Kalochori Area: Configuration, Documentation and Preliminary Data Interpretation

“…The former refers to an accelerometric station installed on the top of a representative structure of each urban sub-zone whereas the latter refers to a ground installation (either on open ground or in a small low-rise structure) within each urban sub-zone where minor contamination of earthquake recordings by the dynamic response of the housing building itself is anticipated. In this manner, a pair of "S" -"UF" accelerometric stations is installed in each urban sub-zone of the broader Kalochori area, allowing for the assessment of the instrumented structures natural period by means of structural top-to-ground base response ratios in the frequency domain (Faccioli et al, 1996;Meli et al, 1998;Celebi, 2003), as explained in the ensuing. The INDES-MUSA accelerometric network is complemented with a free-field station (denoted with "FF") installed on open ground at 3km approximately away from the built environment.…”