Abstract: The mechanism of dam’s earthquake response to 2 dimensional multi-point input is analyzed in detail; and it is pointed that the inner points, on which the differential force acts are in the finite elements with outer points. With the input of outer points’ horizontal and vertical artificial earthquake waves whose velocity is zeroized, the response of damage value, dynamic shear stress and permanent displacement is analyzed. As for the large-sized dam of 200 meters height, the damage value and dynamic shear stress computed by multi-point input at some position at the bottom of the dam are bigger, while in other parts are obviously smaller than that computed by one-point input; especially in the slope of the dam where is prone to wreck; and the permanent displacement computed by multi-point input is smaller, obviously at the top of the dam. But for the flat dam of 80 meters height or so, dam’s response to multi-point input is tenser than that by one-point input, so multi-point input is necessary in earth-rock dam’s designing.

Key words: multi-point input, differential force, artificial earthquake wave, damage value, permanent displacement