Reliability assessment of compression columns in seismic EBFs

• Reliability level of the columns of the seismic EBFs with short shear links, designed based on the current seismic design provisions, is examined.
• An analytical model of minimally designed EBFs is developed for this purpose.
• A parametric study is performed to evaluate the safety level for a wide range of the EBF columns.
• The results indicate that the current design provisions result in a less safe design relative to the target values for a wide range of the EBF columns.
• Equations are proposed for capacity reduction factor, ϕ, of the columns to achieve a more reliable design.

In recent years, eccentrically braced frames (EBFs) have widely been used in steel structures in different countries. These systems are known to provide relatively high ductility, strength, and stiffness against seismic loads and to offer architectural flexibility by giving large openings. Seismic performance of EBFs is subjected to statistical uncertainties of both input excitations and performance of the system. This study aims at examining the current seismic design provisions and the reliability level of compression columns in EBFs with short shear links. An analytical model of minimally designed EBFs has been developed which is based on the LRFD design approach. For reliability analysis, analytical equations have been derived. The studies show that the current seismic provisions result in a less safe design relative to the target values for a wide range of the EBF columns. To cover this, an empirical equation is proposed for resistance factor of such columns. The study also includes a sensitivity analysis for five stochastic parameters that are presented and discussed.