Musical Instrument Design Practical Information for Instrument Making Hopkin Bart
Dr. Danny Hopkin CEng 11th April 2017 · DJH_STiFF_110417 Author: David Rush Created Date:...
Transcript of Dr. Danny Hopkin CEng 11th April 2017 · DJH_STiFF_110417 Author: David Rush Created Date:...
Dr. Danny Hopkin CEng
11th April 2017
• Aresearcher– interestedintheminutiae
• Aconsultant– managingriskanduncertainty• Lessbotheredabouttheminutiae,moreinterestedinthebiggerpicture
Goals
ConstraintsSolutions
Acrackingjob
Credit.N.Butterworth
TargetReliability
TheFiresThe‘FireResistive’Solution
Acrackingjob
TargetReliability
TheFiresThe‘FireResistive’Solution
Doingacrackingjobisabitmoretough
• Safetyinfinitum?• That’snotwhatsocietyexpects• Ifa‘satisfactory’levelofsafetyisouronlygoal,safetyinfinitumisn’tagreatinvestment• Tolerablerisk(andreliability)iscentraltowhat‘we’do
Ourvs.society’slifesafetyexpectation?
Instructuralengineering
Reducethistoanappropriatelevel
Considertheconsequencesoffailure
Definetheacceptableprobabilityoffailure
Formostapplications1.3E-06fora1YRP
In‘fireengineering’
• Reasonable=fulldurationofappropriate fires
• Theappropriatefiresdependupontherisk(likelihood&consequence)
Likelihood&Consequence
In‘fireengineering’(2)
• Absolute-• Areasonableworstcase- subjective• Kirby,et.al.- limitedapplicabilitytomulti-use• EN1990/NFSC– quitegeneralised• LQI– estimationoffatalitiesandawarenessofcosts
• Comparative–• Requiresanunderstandingofwhattheguidancedelivers…
AcceptancecriterioninPBD
Approx.Pf inherentwithinADBFRPeriods
• Probabilisticeventsleadingtoafireinducedstructuralfailure
Credit.R.Van-Coile
ThermalAction Resistance Model
Likelihood
Geometrical
Development
Mech Action
Startingliveload
Timevar.Qk
Perm.Materials
Strength
Temp.Dep
Geometrical
Loading
Resistance
SomeSourcesofUncertainty
ThermalAction Mech Action Resistance Model
Likelihood
Geometrical
Development
Startingliveload
Timevar.Qk
Perm.Materials
Strength
Temp.Dep
Geometrical
Loading
Resistance
SourcesofUncertainty(2)
Some‘simple’enclosures
Metric/Input Office Residential
Area(sq.m) 500 30Height(m) 3.0 2.4Ventilation Area(sq.m) 175 6.0GlazingFraction(-) 0.1– 1.0 0.1– 1.0Linings GYPB GYPB
Elementaffectedbythefireisontheflooroforigin
Noverticalfirespread
OnlyareaofthecompartmentoforigininfluencesPig
Somekeyassumptions
Some‘stochastic’inputs
AspertheNFSC– C.O.V=0.3
AsperPD7974-1
Abestguess….
AfterJ.Stern-Gottfried(mean1,050°C)
Anecdotal– min5mm/s– max20mm/s
• Steelbeamsupportingaconcreteslab• Protectedwithgypsumboard• FLSutilisationcorrespondingtoalimitingtemperatureof620°C• For355MPasteelà 150MPaapplied• TestdifferentprotectionregimesforFR30– FR120• Element/sub-framefailure:
• Utilityratio>1.0• Utility150/kyϴfy
Asimplestructuralelement
Firefragilitycurve- LHS
Utilityvs.fractile foroneFR60protectionsolution
FromfragilitytoPf
Pf,s =0.10
Thestructuralelementisperfect!100%certaintyofload
Results– 500sq.m Office
Pfofanisolatedelement,NOTTHESTRUCTURE
Results– 30sq.m Apartment
Pfofanisolatedelement,NOTTHESTRUCTURE
FireResistance Solution(min) Pf – Office(500sqm) Pf – Apartment(30sqm)
30 1.4E-04 2.2E-0560 1.3E-05 1.9E-0590 3.2E-06 1.2E-05120 1.3E-06 6.8E-06120+Sprinklers 1.3E-07 6.8E-07
Summary&Comparison
PfofanelementwhenaffordeddifferentFRsolutions
Forcomparison– theNFSC(AnnexBWG5)
Forcomparison– EN1990(Ambient)• RC1– 1E-05• RC2– 1E-06• RC3– 1E-07
Potentiallyexcessive?
AWiP….
Transientvariationinreliabilityindex– FR30–500sqm office
Theneedfortwoacceptancecriteria?
• TheinherentlifesafetyPf foranisolatedelementwithinADBhavebeencrudelyestimated• Theyareverysensitivetoareaand,thus,thechoiceofbenchmark• TheorderofmagnitudesnotedarebroadlyconsistentwiththosetentativelyproposedintheNFSC• ThePf valuesgiveameansofestimatingwhatFRisrequiredofelementsinstraightforwardbuildingsfordifferingconsequences&likelihood• FR120+sprinklersà RC3
• TheconceptofformingtwolifesafetyFLS:• Atargetfortheevacuationphase(wherefailureislesstolerable)• Atargetfortheburnoutphase(wherefailuremightbeanacceptableoutcome)• Convergenceofthetwotargetsforhigh-rise
• Furtherwork:• Aproperreliabilityassessment– theadditionalsourcesofuncertainty• AcontinuousdescriptionofthetargetPf asafunctionoflikelihoodandconsequence