Author(s)

J. Plesek

Abstract

In the response spectrum method, the complete time histories of modal responses are not known. Therefore, we must adopt some approximate technique, for instance the SRSS rule, in order to estimate the probable maximum reached by a quantity over the time interval of interest. It is generally believed that any response, e.g. the component of a vector or a tensor, may be treated this way. The opposite is true, however, and we show that the pseudotensors composed of the unsigned real numbers violate the frame invariance principle. As a consequence of this, the use of approximate summation methods that provide but the response amplitudes should be restricted to manipulation with scalars. The implications for engineering analysis are examined in details. In conclusion, the SRSS summation of invariant effective stresses leads to approximate but objectiv

Keywords