In 2016, a countermeasure against long-period ground motions from the Nankai Trough was announced. However, the response spectrum method specified in Ministry of Construction Notification No. 2009 was excluded from the countermeasure framework due to its inadequacy in representing the effects of long-period ground motions. Deficiencies in the damping correction formula, especially in specific period ranges, have also been identified. This study proposes a modified response spectrum method introducing separate damping correction formulas for displacement and acceleration responses, as different corrections are required for accurate prediction. The effectiveness of the proposed method is validated through comparison with the time-history analysis.
