According to the previous research achievement of modal flexibility damage indicators

two indicators

the Modal Flexibility Difference Curvature and the Modal Flexibility Curvature Difference

are constructed.The damage identification effect of the two indicators are compared by a numerical simulation of a 100 meter-long steel trestle when various damage cases are settled in different positions of the bottom chord beams of the steel trestle.In addition

the influence of damage identification effect on either bottom chord beam when the other one is also damaged

is taken into consideration in this paper.Results indicate that the two indicators are sensitive to the damage to both bottom chord beams which are the damageprone parts of the trestle

and the damage identification of either bottom chord beam is unrelated to the damage cases of the other one.