Ideal Weight and Height for Bridge-Earthquake?

Question

my school has a question that i cannot find the answer to. the full question is: Is there an ideal height and width limit when constructing a structurally safe bridge?

Answer 1

Yes.The earthquakes are coming in the range of 0.5 to 15 Hz frequency. Not only the bridge any building constructed in the area where you have problem of earthquakes you have to study the past  records of the frequency recorded in that area from the past events. By increasing or decreasing the width and height you can vary the natural frequency of those bridges.It should not match with the past recorded earthquakes frequency of that area.If it matches the damage will be heavy.That is why the military persons are avoiding march past while crossing the bridges If their steps matches with the frequency of the bridge it will collapse.