Investigation of 30% rule for the combination of component response with the unidirectional principal response spectrum

The paper investigates the validity of the [Max +30%] rule by comparing the results for a typical six-story steel building with the exact results based on the response spectrum in the principal direction and, the critical response spectrum providing an upper bound to the multi-directional component response. Three different sets of real earthquake ground motions with widely differing characteristics are used. It has been found that the [Max + 30%] rule, which is included in IS 1893 (2016) may not lead to realistic results in all the cases