When designing a steel building in a high-seismicity region, engineers face a choice early on: Special Moment-Resisting Frame (SMF), Special Concentrically Braced Frame (SCBF), or Eccentrically Braced Frame (EBF)? Each system dissipates energy differently. Each has different stiffness, ductility, and cost. But until now, no study had statistically compared their collapse performance within the same framework — specifically, the FEMA P-695 guideline.
Our new paper in the Interdisciplinary Journal of Civil Engineering (IJCE) at Shahid Beheshti University (SBU) does exactly that — using FEMA P-695 methodology, 108 steel archetypes, and rigorous statistical analysis. The research team — Parsa Rashvand, Nemat Hassani, Mohammadjavad Hamidia, and myself — collaborated through the Faculty of Civil, Water and Environmental Engineering at SBU to produce the first systematic comparison of its kind.
What Is FEMA P-695 and Why Does It Matter?
FEMA P-695 is the gold standard for quantifying seismic performance factors. It defines the Collapse Margin Ratio (CMR) — the ratio of the ground motion intensity that causes collapse to the design-level intensity. A higher CMR means more collapse resistance. But CMR varies by structural system, building height, and configuration.
Despite extensive research on each system individually, no one had asked: statistically, does system type actually matter for collapse performance? Parsa Rashvand led the archetype modeling, with Nemat Hassani and Mohammadjavad Hamidia supervising the analysis framework at Shahid Beheshti University.
How We Tested It
We selected 108 steel archetypes at a common seismic hazard level (SMT = 0.5g) and evaluated their collapse margin ratios under the FEMA P-695 protocol. Then, instead of just reporting averages, we applied one-way analysis of variance (ANOVA) and Tukey's post-hoc test to determine whether differences between systems were real or just noise.
The result? System type matters significantly (F = 8.19, p < 0.001, η² = 0.135). But only the SMF vs. EBF gap clears the 95% confidence threshold. This work, conducted at SBU's structural engineering lab, provides the first statistical benchmark for comparing these systems.
What This Means for Engineers
If you're designing for maximum collapse resistance, SMF gives you a measurable edge over EBF — about 30% higher mean CMR. SCBF offers intermediate performance and may be the right choice when balancing cost, stiffness, and constructability.
These findings, developed by our team at Shahid Beheshti University — Parsa Rashvand, Nemat Hassani, Mohammadjavad Hamidia, and myself (Pouya H. Khosravi) — also provide a quantitative foundation for revising Iran's seismic design provisions...
Connecting to Broader Seismic Assessment Research
This work on collapse margin ratio and FEMA P-695 methodology complements my research in computer vision and machine learning for post-earthquake damage assessment — understanding both how structures collapse and how we detect that collapse in the field.
Read the full paper: IJCE at Shahid Beheshti University — Volume 2, Issue 1, Pages 507-529