Revisiting the 5% Accidental Eccentricity Provision in Seismic Design Codes for Multi-Story Buildings

Abstract eng:
The accidental eccentricity provision is revisited in order to evaluate the suitability of its worldwide assumed code value of 5% for multi-story buildings. The question is whether such value realistically models the accidental torsion at any story of a multi-story building irrespective of the number of floors above, or it is just a conservative upper bound that does not mimic the actual response. A series of time history analyses under one horizontal component of a selected ground record is thus performed using Opensees analysis platform on a set of hypothetical three-dimensional reinforced concrete multi-story buildings with a symmetric plan and rigid diaphragms. Eight different buildings in terms of height: 1-, 2-, 3-, 4-, 5-, 10, 15- and 20-story, are studied but with the same geometric layout. Monte Carlo Simulation technique is used to define statistically-independent input random accidental eccentricities at various floor levels by sampling from an assumed Probability Density Function (PDF). Retrieved accidental eccentricities computed from the analyzed models at each floor level that are associated with the maximum story shear at the same floor level are reported. The main results clarify that: (1) the computed accidental eccentricities are highly affected by the number of floors above the floor of interest; and (2) such accidental eccentricity demands are often lower than the typical value of 5% specified in building codes especially for the floors with a larger number of stories (45) above.

• Export as: BibTeX | MARC | MARCXML | DC | EndNote | NLM | RefWorks
• Add to your basket