Subsystem Instability Conditions in Steel Frames Associated with Extreme Lateral Loading Charlie Burchfield – Univ. of Mississippi Tezeswi Tadepalli – Univ. of Cal. at San Diego, SDSC Christopher Mullen – Univ. of Mississippi

Overview Introduction Hazard Exposure Preliminary Design Blast Live Loads Load Combinations Beam Column Lateral Loads Blast Conclusions

Introduction University Of Mississippi is evaluating the blast resistance of moment-frame structures. Damage Mapping has been developed and applied to RC columns subjected to air blast loading. Work is currently being done on the performance of steel columns subjected to air blast loading.

Multi-Hazard Design and Blast Vulnerability Analysis Characterize multi-hazard loading parameters Structural design procedure (IBC 2006- LL,DL,WL & EQ) Seismic design Defines member capacities Member capacity curves Damage levels P-I curves Blast damage mapping

Hazard Exposure Source: usgs.gov

Hazard Exposure Lafayette County/Oxford, MS Area Approximately 270 miles from the Gulf of Mexico Coast. Approximately 150 mile from the southern termination of the New Madrid fault. Also, several high value buildings within the area. Federal Court House Federal Office Buildings Etc.

Hazard Exposure Building Size 3 Story Two 20 foot transverse bays Three 40 foot longitudinal bays.

Preliminary Design Complete design was in accordance with the International Building Code 2006. References ASCE/SEI 7-05 ANSI/AISC 360-05

Dead, Live, and Earthquake Preliminary Design Live Loads Determine from the “Minimum Uniformly Distributed Live Loads and Minimum Concentrated Live Loads” from IBC 2006 Used “Office Use” and “Ordinary Flat Roof” Load Combinations From ASCE 7-05, Load and Resistance Factor Design Dead Dead and Live Dead, Live, and Earthquake 1.4D 1.2D+1.6L 1.2D+1.0E+f1L f1 = 0.5

Preliminary Design Beam Design Using AISC 360-05 W18x50 7.5” 18”

Preliminary Design Column We looked at an interior column due to it being the worst case scenario. Determined to be a W8x31 Axial Load Capacity Ratio is 0.75 8” 8”

Preliminary Design Completed SAP2000 Model

Preliminary Design Completed SAP2000 Model

Preliminary Design Lateral Loads Seismic Loading controls even though in a moderately low seismic area. Developed the seismic load using IBC 2006 and ASCE 7-05. Applied these loads to a computer model using SAP 2000 v.12 to determine moments. Section size was still efficient. Capacity Ratio increased from 0.75 to 0.77 for an interior lower level column

Preliminary Design SAP 2000 view of lateral load displacements

Blast Blast Pressures are estimated New Load Case developed Leads to acquiring standoff distances and charge weights. New Load Case developed Using a Military Technical Manuel, TM5-1300, “Structures to Resist the Effects of Accidental Explosion.”

Blast The threshold of acceptable blast resistance can be determined by considering alternate pressure scenarios and column and beam damage levels. Severe Moderate Slight No damage

Acknowledgments Department of Civil Engineering At the University of Mississippi Subcontract from the Department of Homeland Security-sponsored Southeast Region Research Initiative (SERRI) at the Department of Energy's Oak Ridge National Laboratory.

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