Blast Design Oswald

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    DoD Antiterrorism RequirementsDoD Antiterrorism Requirements UFC 4-010-01 DoD Mimimum Antiterrorism

    Minimum standoff distances from controlled perimeter andparking to inhabited buildings

    Window and window frame design standards

    Progressive collapse avoidance standards

    A lies to new buildin s and renovations orrepairs > 50% of building replacement cost

    Minimum standoffs can be reduced if justified

    y as ana ys s an or u ng ar en ng

    STEER Meeting, March 22, 2007

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    Government Building RequirementsGovernment Building Requirements Interagency Security Committee (ISC) Security

    Antiterrorist design requirements for U.S. governmentbuildings

    Blast design requirements usually apply onlyfor large federal buildings (e.g. courthouses,FBI buildin s

    Building structural member and windows must resist specifiedexternal blast loads depending on required level of protection

    Progressive collapse avoidance requirements

    Requirements for vehicle barriers around building

    STEER Meeting, March 22, 2007

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    Explosive Storage and ManufacturingExplosive Storage and Manufacturing

    State and federal safety requirements for

    Protect against accidental explosion scenario

    Typically requirements satisfied withprescribed standoff distances

    Otherwise, personnel protection from blast,,

    designed

    Personnel may be in same building or in nearby building

    Design to contain explosion effects in explosion room

    Design of surrounding buildings if explosion not contained

    STEER Meeting, March 22, 2007

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    Industrial Building RequirementsIndustrial Building Requirements Many industrial processes may cause accidental

    Petrochemical and chemical manufacturing processes

    OSHA 1910 requires blast siting analysis

    Consequences must be estimated from credible explosionscenarios

    explosion effects

    Typically building occupants more at risk than personnel in

    open ue o n ury rom a e u ng componen s Buildings may require blast resistant structural upgrades to

    provide required protection

    STEER Meeting, March 22, 2007

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    General Blast Design ApproachesGeneral Blast Design Approaches Single-degree-of-freedom (SDOF) approach

    Combines explicit consideration of non-linear dynamicresponse with design level simplicity

    Equivalent static load (ESL) approach

    Used for connections and other stiff members includingbracing and shear walls subject to reaction loads

    Most accurate if dynamic load application is slow compared tocomponent response time, or natural period (i.e. no inertialeffects)

    Dynamic finite element analyses

    Non-linear dynamic analysis

    STEER Meeting, March 22, 2007

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    Basic Blast Design AssumptionsBasic Blast Design Assumptions Material yield strengths increased for strain-

    Fast response causes high strain-rate and greater yieldstrength (10% to 20% increase)

    design

    Yielding of component in ductile response

    Strengthen non-ductile response modes so they dont controlresponse

    es gn ase on a owa e e ec on ra erthan allowable stress Typical design allows one-half of failure deflection

    STEER Meeting, March 22, 2007

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    SDOF Design ProcedureSDOF Design Procedure Calculate dynamic load

    Use dynamic reaction load from cladding on framingcomponents

    Calculate maximum dynamic deflection

    Use equivalent SDOF properties of structural component andblast load to calculate maximum deflection with SDOFprocedure

    Usually ductile flexural response is assumed

    deflection criteria

    STEER Meeting, March 22, 2007

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    SDOF Design Procedure (Contd)SDOF Design Procedure (Contd) Must check for any instability or brittle failure

    Strengthen brittle/instable failure mode so it does not controlultimate strength

    Alternatively, reduce allowable deflection and ultimatecapacity

    Must follow load path to foundation Connections

    Diaphragms

    Rigid body motion of building

    STEER Meeting, March 22, 2007

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    Shock Wave Applying Blast to BuildingShock Wave Applying Blast to BuildingPRESSURE

    TIME

    AMBIENT

    PRESSURE

    PEAK

    PRESSURE

    soP

    Pr Building Pb