// Numbas version: finer_feedback_settings {"name": "Momentkapacitet balk - h\u00e5llfasthetsdom\u00e4nen", "extensions": [], "custom_part_types": [{"source": {"pk": 1, "author": {"name": "Christian Lawson-Perfect", "pk": 7}, "edit_page": "/part_type/1/edit"}, "name": "Yes/no", "short_name": "yes-no", "description": "

The student is shown two radio choices: \"Yes\" and \"No\". One of them is correct.

", "help_url": "", "input_widget": "radios", "input_options": {"correctAnswer": "if(eval(settings[\"correct_answer_expr\"]), 0, 1)", "hint": {"static": true, "value": ""}, "choices": {"static": true, "value": ["Yes", "No"]}}, "can_be_gap": true, "can_be_step": true, "marking_script": "mark:\nif(studentanswer=correct_answer,\n correct(),\n incorrect()\n)\n\ninterpreted_answer:\nstudentAnswer=0\n\ncorrect_answer:\nif(eval(settings[\"correct_answer_expr\"]),0,1)", "marking_notes": [{"name": "mark", "description": "This is the main marking note. It should award credit and provide feedback based on the student's answer.", "definition": "if(studentanswer=correct_answer,\n correct(),\n incorrect()\n)"}, {"name": "interpreted_answer", "description": "A value representing the student's answer to this part.", "definition": "studentAnswer=0"}, {"name": "correct_answer", "description": "", "definition": "if(eval(settings[\"correct_answer_expr\"]),0,1)"}], "settings": [{"name": "correct_answer_expr", "label": "Is the answer \"Yes\"?", "help_url": "", "hint": "An expression which evaluates to true or false.", "input_type": "mathematical_expression", "default_value": "true", "subvars": false}], "public_availability": "always", "published": true, "extensions": []}], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"name": "Momentkapacitet balk - h\u00e5llfasthetsdom\u00e4nen", "tags": [], "metadata": {"description": "

Calculation of bending resistance of wooden beams exposed to fire. The students have to calculate charring and effective cross sections ending in the bending resistance of the cross section.

", "licence": "Creative Commons Attribution-NonCommercial 4.0 International"}, "statement": "

Klarar träbalken krav motsvarande R {rKrav}?

\n
    \n
  1. Virkeskvalitet: $\\var{gl}$
  2. \n
  3. Bredd: $b=\\var{b}$ $mm$
  4. \n
  5. Höjd: $h=\\var{h}$ $mm$
  6. \n
  7. Verksamheten ovan bjälklaget är {occupancy}
  8. \n
  9. Egentyngden för bjälklaget är {gk} kN/m²
  10. \n
  11. Centrumavstånd mellan balkar, $cc$ - {cc} m
  12. \n
  13. Balken kan anses fritt upplagd med längden $l$ - {length} m
  14. \n
  15. Säkerhetsklass {SK_rand}
  16. \n
\n

Antag att balken är brandutsatt på 3 sidor (under och på sidorna) samt att ingen vippning kan ske, dvs $k_{crit} = 1$. Använd metoden reducerat tvärsnitt.

", "advice": "

$M_{Ed,fi}$

\n

Momentpåkänningen för en fritt upplagd balk beräknas som

\n

$M_{Ed,fi}=\\frac{qL^2}{8}$

\n

Där $q$ är den utbredda lasten vilken beräknas utifrån den dimensionerande lasten i brandfallet.

\n

$E_{d,fi}=g_k+\\psi_1 q_k$

\n

För {occupancy} är $q_k$ = {qk} kN/m² och ur tabell kan vi läsa att $\\psi_1$ = {psi_1}. Då egentyngden, $g_k$, ges i uppgiften till {gk} kN/m² beräknas $E_{d,fi}$ till

\n

$E_{d,fi}=\\var{precround(gk,1)}+\\var{psi_1}\\cdot \\var{qk}=\\var{precround(Ed_fi,1)}$ $kN/m²$

\n

Ett centrumavstånd motsvarande {cc} meter gör att $E_{d,fi}$ kan antas som

\n

$\\var{precround(Ed_fi,1)}\\cdot \\var{precround(cc,1)} = \\var{precround(Ed_fi_tot,1)}$ $kN/m$

\n

Den första ekvationen kan därför justeras till

\n

$M_{Ed,fi}=\\frac{E_{d,fi}L^2}{8}=\\frac{\\var{precround(Ed_fi_tot,1)}\\cdot\\var{length}^2}{8}=\\var{precround(MEd_fi,1)}$ $kNm$

\n

$M_{Rd,fi}$

\n

Inbränningshastighet

\n

I första steget beräknas inbränningshastigheten genom att beräkna den minsta bredd, $b_{min}$, som krävs för att rundningen av hörnen inte ska tas med

\n

$b_{min}=\\huge\\{ \\normalsize{2d_{char,0}+80 \\atop 8.15d_{char,0}}\\text{    }{d_{char,0}\\geq13\\text{ }mm \\atop d_{char,0}<13\\text{ }mm}\\Rightarrow b_{min}=2 t_R \\beta _0+80=\\var{bmin}$ $mm$

\n

$b_{min}=\\huge\\{ \\normalsize{2d_{char,0}+80 \\atop 8.15d_{char,0}}\\text{    }{d_{char,0}\\geq13\\text{ }mm \\atop d_{char,0}<13\\text{ }mm}\\Rightarrow b_{min}=8.15d_{char,0}=\\var{bmin}$ $mm$

\n

med $t_R = \\var{rkrav}\\text{ }min$ och $\\beta_0 = \\var{beta0}\\text{ }mm/min$ blir $b_{min} = \\var{bMin}\\text{ }mm$ vilket är $\\var{betaTrue}$ än $b=\\var{b}\\text{ }mm$ varför $\\beta_{design}=\\underline{\\underline{\\var{betaDesign}\\text{ }mm/min}}$.

\n

Effektivt tvärsnitt och böjmotstånd

\n

Med tresidig inbränning beräknas $b_{eff}$ som:

\n

$b_{eff}=b-2(\\beta_{design}t_R+k_0d_0)=\\var{b}-2\\left(\\var{betaDesign}\\cdot\\var{rKrav}+\\var{kZero}\\cdot\\var{dZero}\\right)=\\var{precround(bEff,1)}$ $mm$

\n

och $h_{eff}$ som

\n

$h_{eff}=h-(\\beta_{design}t_R+k_0d_0)=\\var{h}-\\left(\\var{betaDesign}\\cdot\\var{rKrav}+\\var{kZero}\\cdot\\var{dZero}\\right)=\\var{precround(hEff,1)}$ $mm$

\n

Utifrån det beräknas böjmotståndet som:

\n

$W_{eff}=\\frac{b_{eff}h_{eff}^2}{6}=\\frac{\\var{bEff}\\cdot\\var{hEff}^2}{6}=\\underline{\\underline{\\var{precround(wEff,1)}\\text{ }mm^3}}$

\n

Materialegenskaper

\n

I brandfallet beräknas dimensionerande materialvärden med:

\n

$f_{md,fi}=k_{mod,fi}\\frac{k_{fi}f_{mk}}{\\gamma_{M,fi}}=1\\frac{\\var{kFi}\\cdot\\var{fm}}{1}=\\underline{\\underline{\\var{precround(fmFi,1)}\\text{ }MPa}}$

\n

Momentkapacitet

\n

Med $k_{crit}$ = 1, beräknas $M_{Rd,fi}$ som:

\n

$M_{Rd,fi}=k_{crit}f_{md,fi}W_{eff}=1\\cdot\\var{precround(fmFi,1)}\\cdot\\var{precround(wEff,1)}=\\underline{\\underline{\\var{precround(mToT,1)}\\text{ }kNm}}$

\n

Sammanfattning

\n

Kontrollera om hållfastheten, $M_{Rd,fi}$, är större än belastningen, $M_{Ed,fi}$, dvs.

\n

$M_{Ed,fi}\\leq M_{Rd,fi}$

\n

$\\var{precround(MEd_Fi,1)}\\leq\\var{precround(Mtot,1)}$

\n

Om ovanstående är sant så kan konstruktionen anses klara krav motsvarande R {rKrav}.

", "rulesets": {}, "extensions": [], "builtin_constants": {"e": true, "pi,\u03c0": true, "i": true, "j": false}, "constants": [], "variables": {"rKrav": {"name": "rKrav", "group": "Ungrouped variables", "definition": "random(15, 30, 60, 90, 120)", "description": "

Klassificeringstid

", "templateType": "anything", "can_override": false}, "b": {"name": "b", "group": "Ungrouped variables", "definition": "random(42, 56, 66, 78, 90, 115, 140, 165, 190, 215)", "description": "

Tvärsnittsbredd

", "templateType": "anything", "can_override": false}, "h": {"name": "h", "group": "Ungrouped variables", "definition": "random(90, 115, 135, 180, 225, 270, 315, 360, 405, 450, 495, 540)", "description": "", "templateType": "anything", "can_override": false}, "beta0": {"name": "beta0", "group": "Ungrouped variables", "definition": "0.65", "description": "", "templateType": "anything", "can_override": false}, "betaN": {"name": "betaN", "group": "Ungrouped variables", "definition": "0.7", "description": "", "templateType": "anything", "can_override": false}, "bMin": {"name": "bMin", "group": "Ungrouped variables", "definition": "if(beta0*rKrav<13,8.15*beta0*rKrav,2*beta0*rKrav+80)", "description": "", "templateType": "anything", "can_override": false}, "betaDesign": {"name": "betaDesign", "group": "Ungrouped variables", "definition": "if(bMin1.4,1/lambdaRel^2,1.56-0.75*lambdaRel)))", "description": "", "templateType": "anything", "can_override": false}, "fmList": {"name": "fmList", "group": "Ungrouped variables", "definition": "[28,30,32]", "description": "", "templateType": "anything", "can_override": false}, "fcList": {"name": "fcList", "group": "Ungrouped variables", "definition": "[24,24.5,26.5]", "description": "", "templateType": "anything", "can_override": false}, "ftList": {"name": "ftList", "group": "Ungrouped variables", "definition": "[16.5,19.5,19.5]", "description": "", "templateType": "anything", "can_override": false}, "eList": {"name": "eList", "group": "Ungrouped variables", "definition": "[10400,10800,11100]", "description": "", "templateType": "anything", "can_override": false}, "gList": {"name": "gList", "group": "Ungrouped variables", "definition": "[720,540,780]", "description": "", "templateType": "anything", "can_override": false}, "kvalitet": {"name": "kvalitet", "group": "Ungrouped variables", "definition": "if(b > 80, 1, 0)", "description": "", "templateType": "anything", "can_override": false}, "fcFi": {"name": "fcFi", "group": "Ungrouped variables", "definition": "fcList[kvalitet] *kFi", "description": "", "templateType": "anything", "can_override": false}, "eModulFi": {"name": "eModulFi", "group": "Ungrouped variables", "definition": "eList[kvalitet] * kFi", "description": "", "templateType": "anything", "can_override": false}, "gModulFi": {"name": "gModulFi", "group": "Ungrouped variables", "definition": "gList[kvalitet] * kFi", "description": "", "templateType": "anything", "can_override": false}, "lambdaRel": {"name": "lambdaRel", "group": "Ungrouped variables", "definition": "sqrt(fcFi*1000000/sigmaCritFi) ", "description": "", "templateType": "anything", "can_override": false}, "iFi": {"name": "iFi", "group": "Ungrouped variables", "definition": "(hEff/1000)^3*(bEff/1000)/12", "description": "", "templateType": "anything", "can_override": false}, "iTorFi": {"name": "iTorFi", "group": "Ungrouped variables", "definition": "hEff/2000*(bEff/2000)^3*(16/3-3.36*(bEff/2000)/(hEff/2000)*(1-(bEff/2000)^4/(12*(hEff/2000))^4))", "description": "", "templateType": "anything", "can_override": false}, "sigmaCritFi": {"name": "sigmaCritFi", "group": "Ungrouped variables", "definition": "pi*sqrt(eModulFi*iFi*gModulFi*iTorFi)/(0.9*elementLength*5*wEff/1000000000)*1000000 ", "description": "", "templateType": "anything", "can_override": false}, "elementLength": {"name": "elementLength", "group": "Ungrouped variables", "definition": "1.0", "description": "", "templateType": "anything", "can_override": false}, "fm": {"name": "fm", "group": "Ungrouped variables", "definition": "fmList[kvalitet]", "description": "", "templateType": "anything", "can_override": false}, "gl": {"name": "gl", "group": "Ungrouped variables", "definition": "if(h > 180, \"GL\"+fm+\"c\", \"GL\"+fm+\"h\")", "description": "", "templateType": "anything", "can_override": false}, "length": {"name": "length", "group": "Ungrouped variables", "definition": "random(5..7#1)", "description": "", "templateType": "anything", "can_override": false}, "occupancy": {"name": "occupancy", "group": "Ungrouped variables", "definition": "[\"kontor\", \"bostad\"][randomizer]", "description": "", "templateType": "anything", "can_override": false}, "sk_rand": {"name": "sk_rand", "group": "Ungrouped variables", "definition": "random(1..3#1)", "description": "", "templateType": "anything", "can_override": false}, "cc": {"name": "cc", "group": "Ungrouped variables", "definition": "random(3..6#1)", "description": "", "templateType": "anything", "can_override": false}, "randomizer": {"name": "randomizer", "group": "Ungrouped variables", "definition": "random(0,1)", "description": "", "templateType": "anything", "can_override": false}, "psi_1": {"name": "psi_1", "group": "Ungrouped variables", "definition": "[0.5, 0.5][randomizer]", "description": "", "templateType": "anything", "can_override": false}, "STR_B": {"name": "STR_B", "group": "Ungrouped variables", "definition": "SK*(1.35*0.89*gk+1.5*qk)", "description": "", "templateType": "anything", "can_override": false}, "gk": {"name": "gk", "group": "Ungrouped variables", "definition": "0.5", "description": "", "templateType": "anything", "can_override": false}, "qk": {"name": "qk", "group": "Ungrouped variables", "definition": "[2.5, 2.0][randomizer]", "description": "", "templateType": "anything", "can_override": false}, "sk": {"name": "sk", "group": "Ungrouped variables", "definition": "[0,0.89,0.93,1.0][sk_rand]", "description": "", "templateType": "anything", "can_override": false}, "eta_fi": {"name": "eta_fi", "group": "Ungrouped variables", "definition": "Ed_fi / max(str_a, str_b)", "description": "", "templateType": "anything", "can_override": false}, "ed_fi": {"name": "ed_fi", "group": "Ungrouped variables", "definition": "gk+psi_1*qk", "description": "", "templateType": "anything", "can_override": false}, "str_a": {"name": "str_a", "group": "Ungrouped variables", "definition": "SK*1.35*gk", "description": "", "templateType": "anything", "can_override": false}, "MEd_fi": {"name": "MEd_fi", "group": "Ungrouped variables", "definition": "Ed_fi_tot * length^2 / 8", "description": "", "templateType": "anything", "can_override": false}, "compliance": {"name": "compliance", "group": "Ungrouped variables", "definition": "med_fi b\nand\nbeff > 0\nand\nmTot>0\nand\nkCrit = 1", "maxRuns": 100}, "ungrouped_variables": ["rKrav", "b", "h", "kvalitet", "elementLength", "beta0", "betaN", "bMin", "betaDesign", "kZero", "bEff", "hEff", "kMod", "kFi", "t0", "betaTrue", "dZero", "wEff", "mTot", "wEffInt", "mTotInt", "mTotPrecision", "kCrit", "fmList", "fcList", "ftList", "eList", "gList", "fmFi", "fcFi", "eModulFi", "gModulFi", "lambdaRel", "iFi", "iTorFi", "sigmaCritFi", "fm", "gl", "length", "occupancy", "sk_rand", "cc", "randomizer", "psi_1", "STR_B", "gk", "qk", "sk", "eta_fi", "ed_fi", "str_a", "MEd_fi", "compliance", "Ed_fi_tot"], "variable_groups": [], "functions": {}, "preamble": {"js": "", "css": ""}, "parts": [{"type": "numberentry", "useCustomName": true, "customName": "Momentp\u00e5k\u00e4nning", "marks": 1, "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "prompt": "

Vad är den dimensionerande momentpåkänningen, $M_{Ed,fi}$? Svara i kNm.

", "minValue": "MEd_fi", "maxValue": "MEd_fi", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": "0", "displayAnswer": "", "precisionType": "dp", "precision": "2", "precisionPartialCredit": "0", "precisionMessage": "You have not given your answer to the correct precision.", "strictPrecision": true, "showPrecisionHint": true, "notationStyles": ["plain", "plain-eu"], "correctAnswerStyle": "plain"}, {"type": "numberentry", "useCustomName": true, "customName": "Momentkapacitet", "marks": 1, "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": "0.5", "exploreObjective": null, "prompt": "

Antag att $k_{crit}$ = 1, vad är momentkapaciteten, $M_{Rd,fi}$ för tvärsnittet? Svara i $kNm$.

", "minValue": "mTot", "maxValue": "mTot", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": 0, "displayAnswer": "", "precisionType": "dp", "precision": "1", "precisionPartialCredit": 0, "precisionMessage": "You have not given your answer to the correct precision.", "strictPrecision": true, "showPrecisionHint": true, "notationStyles": ["plain", "plain-eu"], "correctAnswerStyle": "plain-eu"}, {"type": "yes-no", "useCustomName": false, "customName": "", "marks": 1, "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "prompt": "

Klarar konstruktionen krav motsvarande R {rKrav}?

", "settings": {"correct_answer_expr": "compliance"}}], "partsMode": "all", "maxMarks": 0, "objectives": [], "penalties": [], "objectiveVisibility": "always", "penaltyVisibility": "always", "contributors": [{"name": "Chris Graham", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/369/"}, {"name": "Joakim Sandstr\u00f6m", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/7645/"}], "resources": []}]}], "contributors": [{"name": "Chris Graham", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/369/"}, {"name": "Joakim Sandstr\u00f6m", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/7645/"}]}