06.07: Comparison of Blast Performance of Steel Modular Buildings with Anchored and Sliding Foundations

Abstract

A two-module blast-resistant steel building with overall dimensions of 12 m by 6 m floor plan and 3.4 m height was designed to resisted 80 kPa free field overpressure with 140 microsecond duration. The building was designed to remain within "high damage/response" level when it is anchored to its foundation. The effect of anchored and unanchored or sliding (free-to-slide) foundation on blast performance of structural elements on the wall and roof, foundation loads, building sliding, and building total friction and kinetic energy were investigated using nonlinear dynamic finite element analysis tools. The comparison of analyses results revealed that building foundation reactions and maximum deflection demands for structural members can significantly decrease with unanchored foundation. For unanchored foundation, several friction coefficients (i.e., 0.2, 0.5, and 0.8) for the interaction between the building and its foundation were considered. The analyses results show that the maximum relative deflections of the structural members of the building with unanchored foundation to be between 43% and 120% with an average of 80% of that for the building with anchored foundations. The most significant effect of unanchored foundation on blast performance of the building was the significant decrease in the foundation maximum horizontal reaction, which was approximately 15% to 60% of that for the building with anchored foundation. However, the unanchored foundation had negligible effect on building vertical foundation reactions. The computed maximum sliding displacements were approximately 10 m, 2 m and 0.3 m for the building with unanchored foundation for friction coefficient of 0.2, 0.5, and 0.8, respectively. For the building with unanchored and anchored foundations, both friction energy and kinetic energy versus time plots were very similar for initial stages of the blast loading. The overall results show that providing even limited permissible sliding between blast resistant structures and their foundation can significantly reduce their foundation reactions and improve blast performance of structural members. A controlled-sliding mechanism between blast resistant structures and their foundation with steel cables is recommend to improve blast performance of the structure while limiting maximum sliding within desired permissible limits.

Performance of Structural Blast Mitigation Measure for Oil and Gas Industrial Facilities

“…The latest trends in design of buildings in seismically active zones show the great potential of friction connections for energy dissipation [30]. Similar concept was used by Erkman for study of blast performance of steel modular buildings where the response of buildings with anchored and sliding foundations was compared [7]. This study showed that providing even limited sliding between blast resistant structures and their foundation can significantly reduce their foundation reactions and improve blast performance of structural members.…”

“…On the other hand, studies showed that this approach has its limitations and that it is not reliable in the presence of severe plastic yielding [6] For the purpose of this study numerical modelling was performed in order to assess the behaviour of the blast wall undergoing large deformations and the effect of its geometry on the transfer of dynamic reaction onto the primary steelwork and energy dissipation. This attempt was made because similar studies in the past were focused mainly on the hinge rotation and ductility ratio [7]. The bulkhead type of blast walls was modelled without and with one stiffener while varying both the thickness of the plate and the stiffener.…”