Procedure to attach signs to the column reactions in seismic analysis

In seismic analysis by Response Spectrum Method, the seismic response is combination of the individual modal responses. The methods employed for modal combination, involve square and square-root operations. They have been referred here as non-linear combination methods. The reactions obtained by these methods do not carry any signs due to the non-linear nature of the combination methods. This poses a problem if these reactions are required to be input for analysis of foundation-mat. The present paper describes two methods to arrive at a consistent set of signs for these reactions. (author). 1 fig., 6 tabs