Civil Engineering/Near source factor and Dynamic Analysis
QUESTION: assalam o alekum!
Sir I am checking ETABS Model of a building located in zone 3 just near to an inactive fault but the designer of a bulding didnot take it to account and the building is just 200 meters away from the fault,also he is using only eigen vector for dynamic analysis.I am from client side and i have to check it and sign the drawings for construction and i think it is a serious mistake kindly give your valuable comments on this issue...
ANSWER: Dear Asad
What is your structure system ? number of story of the building? what is its natural period of vibration?
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QUESTION: Dear sir,
The structure is 8 basements plus pool deck level and 11 upper stories,as far as the structural system is concerned it is a special moment resisting frame system comprising of beams and columns,previously the project have core walls also but the designer is not considering the shear walls as a lateral load resisting elements.
I prefer to use modal-spectral method in every situation because it is more backgrounded by experience of earthquakes. A linear dynamic check seems more accurate but in my opinion it is so complicated and hard to conclude that I use it only to make modifications in details.
I appreciate your precision in this matter and agree with you to perform extra dynamic analysis to modify some details.
Near field action is a near impact white noise type motion which may stimulate higher mode in high rise buildings.