Failure Interstory Drift

Failure ID Tool (Inter-story drift limit for the fourth story of a six-story building.)

Inter-story drift limit for the fourth story of a six-story building.


The failure ID for any story can be estimated by following the steps shown below along with the failure ID tool given below. The method does not account for instability failure associated with large deformations. Thus, the obtained values need to be checked as explained by Sultana and Youssef (2016).

  1. Assume all columns of the considered story to be fixed at their lower ends (i.e. ignore the lower stories).
  2. Apply gravity loads to the considered story as well as to the ones above it.
  3. Apply a displacement controlled pushover analysis to the considered story to define the inter-story drift (ID) causing collapse for that story.
  4. Calculate the stiffness-reduction factor for each column of the considered story using the failure ID tool given below. The partially-fixed stiffness is equal to the stiffness-reduction factor multiplied by the fully-fixed condition stiffness.
  5. Calculate the ID magnification factor as: the summation of the fully-fixed stiffnesses of the story columns divided by the summation of their partially-fixed stiffnesses.
  6. Magnify the obtained ID in step 3 using the ID magnification factor obtained in step 5 to get the Failure ID for the considered story.



For more information, please refer to:

Sultana, P., Youssef M.A., 2016, “Prediction of local seismic damage in steel moment resisting frames”, Journal of Constructional Steel Research, 122: 122-137.

Youssef M.A., Elfeki M.A., 2013, “Predicting Local Seismic Damage of RC Framed Buildings considering the Horizontal Seismic Component”, Magazine of Concrete Research, 65(23): 1411-1428.



Simplex Engineering Inc. cannot be held liable for actual designs that follow information presented on this site. The design engineer must adhere to the rules governing practicing of professional engineering and follow the requirements of prevailing design standards, regulations, and codes of practice. Simplex Engineering Inc. will be delighted to discuss potential collaborations in structural engineering related projects. Please contact us to be informed about our services and associated fees.