Abstract: A series of incremental dynamic analyses are performed to investigate the significance of a hysteretic model and the peak ground acceleration to the velocity ratio (PGA/PGV) on the shape of IDA curves. The Bouc-Wen model modified by Barber on the rule of pinching and strength degradation is used to represent the structural nonlinearity, and 146 earthquake records with different PGA/PGV are used as input ground motions. The curved surface composed by IDA curves according to the value of PGA/PGV is built up. The relationship between the maximum storey drift and PGA/PGV are discussed, the result presented indicate that the ground motion PGA/PGV has significant effects on IDA curve shape and structural damage distribution regularity.