August 28, 2013
Hinman Presents at 15th ISIEMS Conference- UPDATED!
by Kim Gayo
Look out for Hinman presenting at the 15th ISIEMS Conference (International Symposium on the Interaction of the Effects of Munitions with Structures) held on September 17-20, 2013 at the Conference Hotel in Potsdam, Germany. Get your first glance of our hot topics here!
Limits to Scaled Distances: When Pseudo-Static Deflected Shapes Don’t Apply
Presenter: Takayuki Yokoyama, MSc., P.E. (Hinman)
Session/Track: Effects of Explosions on Structures
Date: September 17, 2013 @ 3:20pm-3:40pm, Auditorium A
Topic: Design Professionals use the Single Degree of Freedom (SDOF) models to analyze blast effects on components as outlined by Biggs in 1964. It is common knowledge that the SDOF method is an approximation, and is not suitable for large charges with short distances. However, a study by Takayuki Yokoyama using a Multi Degree of Freedom (MDOF) approach shows analytically why the SDOF approach does not work flexurally for scaled distances much greater than what is currently accepted in blast engineering practice. This presentation will outline the SDOF method as defined by Biggs, outline the MDOF method used, and show that pseudo-static beam deflection assumptions do not apply at lower scaled distances. This presentation will tabulate limiting scaled distances for SDOF analyses methodologies and make recommendations regarding analytical methodologies which are more appropriate for lower scaled distances.
Steel Column Subjected to Fire Following an Explosion
Presenter: Shalva Marjanishvili, Sc.D, P.E., S.E. (Hinman) & Spencer Quiel (Lehigh University)
Session/Track: Multiple Hazards
Date: September 18, 2013 @ 8:20am-8:40am, Auditorium C
Topic: Fire following blast is a probable multi-hazard scenario that can lead to progressive collapse even with the implementation of structural hardening as prescribed by current criteria. This study uses a multi-hazard approach to evaluate interior steel columns that are subject to an internal blast design threat and then experience a subsequent fire. Interior columns are considered because, unlike perimeter columns, they are not typically designed for progressive collapse resistance and rely on blast resistance only. It is therefore likely that the loss of an interior column may result in a collapse of supported structure. A multi-hazard analysis approach will be used in which the column is analyzed first for its response to a blast resulting from the DBT. A section that meets the applicable performance limits will be selected, and the deformed state of the column will then be used as input for structural-fire analysis of the column. The fire resistance of the deformed column will be evaluated using both computational and simplified methods, the results and efficiency of which will be compared.
Multiple Weapons Effects and Failure Modes Using “Synthetic” Pressure-Impulse Diagrams in Blast Vulnerability Assessments
Presenter: Andrew Coughlin, P.E. (Hinman)
Session/Track: Failure Modes of Structures
Date: September 18, 2013 @ 8:20am-8:40am, Auditorium B
Topic: Conventional weapons and other explosives have a multitude of weapons effects, including blast, fragmentation, penetration, ground shock, cratering, and more. In addition hardened structures have multiple failure modes such as flexure, shear, breach/spall, dynamic axial load, global collapse, fragment penetration, human injury and other effects. Vulnerability and weaponeering codes such as VAPO and IMEA treat individual weapon effects and element fragilities separately and leave little flexibility for non-standard weapons effects to be considered by the user. This presentation will demonstrate a method where, given the performance goals of a facility, multiple weapon effects and element failure modes can be captured in a single set of element fragility data.