{"schemaVersion":1,"recordId":"wtc7-nist-case-b-storyboard-v1","caseId":"nist-case-b-4h-with-debris","case":{"name":"NIST debris-damaged baseline, Case B, 4.0 h handoff","thermalCase":"B","thermalDamageHandoffHours":4.0,"debrisImpactDamage":true,"localAnalysis":"16-story ANSYS fire-response model","globalAnalysis":"47-story LS-DYNA model","sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed pp. 535, 571\u2013573; PDF pp. 601, 637\u2013639"},{"sourceId":"NIST_NCSTAR_1_9A","locator":"Printed pp. 56\u201358 and 76\u201380; PDF pp. 107\u2013109 and 127\u2013131"}]},"excludedCaseIds":["nist-case-b-3p5h-with-debris","nist-case-b-4h-without-debris","nist-column79-removal-without-fire-or-debris"],"timeBases":{"historical_edt":{"unit":"local civil time","zero":null,"meaning":"Reported September 11 observations, often approximate; never inferred from thermal-model elapsed hours."},"thermal_elapsed_h":{"unit":"hours","zero":"start of the simulated fire/structural heating sequence","meaning":"Time in the fire and 16-story structural analysis; not a real-time timestamp for a filmed floor."},"global_solver_s":{"unit":"seconds","zero":"start of selected LS-DYNA calculation, including gravity initialization","meaning":"Selected case's simulation time."},"collapse_reference_s":{"unit":"seconds","zero":"first observed kink in the east-penthouse roofline, viewed from the north","meaning":"NIST's comparison anchor; the selected model reaches this condition at global_solver_s = 16.0."},"north_roofline_descent_s":{"unit":"seconds","zero":"first perceived downward motion of the tracked north-face roofline feature in Camera 3","meaning":"Origin for NIST's three-stage measured roofline trajectory, 6.9 s after the observed east-penthouse anchor."},"presentation_progress":{"unit":"ordered static state","zero":"opening scene","meaning":"Authored navigation order only; no physical duration or animation rate is implied."}},"timeRelations":[{"caseId":"nist-case-b-4h-with-debris","from":"collapse_reference_s","to":"global_solver_s","operation":"add_seconds","amount":16.0,"sourceRef":{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed p. 572; PDF p. 638"}},{"caseId":"observation-camera-3","from":"north_roofline_descent_s","to":"collapse_reference_s","operation":"add_seconds","amount":6.9,"sourceRef":{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed pp. 599\u2013601; PDF pp. 665\u2013667"}}],"memberClaimIds":{"F13-east-office-primary-44-79":["f13-girder","c79-physical-seat-detail","f13-a2001-girder-studs","nist-c79-corrected-seat-analysis","nist-noncomposite-girder","f13-thermal-response","f13-bolt-shear-horizontal-loss","f13-girder-walkoff"],"F13-east-office-C41":["f13-east-beam-girder-shear-plates","f13-thermal-response"],"F13-east-office-C40":["f13-east-beam-girder-shear-plates","f13-thermal-response"],"F13-east-office-C39":["f13-east-beam-girder-shear-plates","f13-thermal-response"],"F13-east-office-C38":["f13-east-beam-girder-shear-plates","f13-thermal-response"]},"floor13StudyStateIds":["f13-intact","f13-thermal-response","f13-support-loss"],"presentationContract":{"layoutReference":"site/index.html guided 3D chapter sequence","progressBasis":"presentation_progress","sequenceMode":"Authored direction cues evaluated from drawing-member rest matrices; visual travel, length change and tilt are not source measurements, NIST coordinates, thermal strain outputs or a structural-response solution.","sourceMode":"Registered drawing members remain at their original positions while report states and source evidence are inspected.","scope":"Only the Floor 13 tributary beams and C44\u2013C79 receiver have authored 3D motion. Later scenes use source geometry, camera focus and attributed report/observation evidence."},"physicalUnknowns":{"a2001PhysicalFabricationSheet":null,"a2001CutEnd":null,"c79ExactPhysicalBearingPolygon":null,"c79SeatPlateRevisionReconciliation":null,"a2001PhysicalStudCount":null,"a2001PhysicalCompositeFraction":null,"fourIndividualMatingPlateGeometries":null,"s8RevisionI":null,"floor13DeckDirectionAndPanelBoundaries":null},"scenes":[{"id":"scene-0-intact-load-paths","title":"Intact load paths","summary":"Locate C79, C80, C81, the east penthouse, and the floor framing that braces the eastern columns.","status":"storyboard","states":[{"id":"intact-load-paths","title":"Steel frame before the fires","evidenceClass":"drawing_evidence","description":"Orient the intact building: the east penthouse outline is schematic, while C79\u201381 labels locate the eastern core above the Floor 13 bay. Open Scene 2 to inspect that bay and its connection evidence; no slab geometry is claimed here.","claimIds":["f13-girder","c79-tier-map","typical-slab-deck"],"focus":{"memberIds":["F13-east-office-primary-44-79","F13-east-office-C41","F13-east-office-C40","F13-east-office-C39","F13-east-office-C38"],"columnIds":[44,79,80,81]},"time":{"basis":"presentation_progress","order":0},"camera":{"preset":"east-core-orientation","direction":"from southeast, with north/east labels"},"visibility":{"mode":"whole_building_context","note":"Penthouse outline is a schematic proxy. Do not describe C79 as directly borne by a transfer truss."}}]},{"id":"scene-1-damage-fires","title":"Damage and fires","summary":"Distinguish observed exterior evidence from NIST's inferred hidden damage and simulated heating.","status":"storyboard","states":[{"id":"damage-and-fire-context","title":"Debris context and uncontrolled fires","evidenceClass":"nist_analysis","description":"Annotate south/west debris damage and reported fires on Floors 7\u20139 and 11\u201313; any temperature overlay is explicitly a NIST model field.","claimIds":["damage-and-fire-context","thermal-case-and-handoff","released-nist-inputs-status"],"focus":{"memberIds":[],"columnIds":[79,80,81]},"time":{"basis":"historical_edt","value":null,"label":"September 11 afternoon; fire regions changed over time"},"camera":{"preset":"building-south-east-context"},"visibility":{"mode":"whole_building_context","note":"Do not depict debris as directly severing C79."}}]},{"id":"scene-2-floor13-study","title":"Floor 13: the C44\u2013C79 connection","summary":"Three inspectable states show the intact drawing frame, NIST's thermal loading, and modeled loss of support.","status":"guided_3d_study","states":[{"id":"f13-intact","title":"1. Intact frame","evidenceClass":"drawing_evidence","description":"Isolate A2001 and four tributary W24\u00d755 members at Floor 13. Show the C76\u2013C79 and C79\u2013C80 members only as adjacent drawing context, not as the initiating connection. Label C44/C79 and show the seated connection family without fabricating unresolved A2001 ends or individual fin plates.","claimIds":["f13-girder","c79-tier-map","c79-physical-seat-detail","f13-east-beam-girder-shear-plates","f13-a2001-girder-studs","typical-slab-deck"],"focus":{"memberIds":["F13-east-office-primary-44-79","F13-east-office-C41","F13-east-office-C40","F13-east-office-C39","F13-east-office-C38","F13-interior-76-79","F13-interior-79-80"],"columnIds":[44,79]},"time":{"basis":"presentation_progress","order":0},"camera":{"preset":"f13-east-bay","direction":"oblique plan, seat visible at C79"},"visibility":{"mode":"isolate_floor_and_bay","floor":13,"includeColumnContext":[44,79],"pickableOnlyVisible":true}},{"id":"f13-thermal-response","title":"2. Heating and lateral load","evidenceClass":"nist_analysis","description":"Highlight the model's east beam expansion toward A2001 and the analytical one-sided loading. The C76\u2013C79 and C79\u2013C80 members remain adjacent context, not initiating members in this state. The 3D beam extension is an authored direction cue, not a measured displacement, calculated strain or uniform real-fire temperature.","claimIds":["f13-thermal-response","nist-noncomposite-girder","f13-east-beam-girder-shear-plates","thermal-case-and-handoff"],"focus":{"memberIds":["F13-east-office-primary-44-79","F13-east-office-C41","F13-east-office-C40","F13-east-office-C39","F13-east-office-C38","F13-interior-76-79","F13-interior-79-80"],"columnIds":[44,79]},"time":{"basis":"thermal_elapsed_h","value":null,"label":"Case B heating before C44\u2013C79 walk-off"},"camera":{"preset":"f13-east-bay","direction":"oblique plan, seat visible at C79"},"visibility":{"mode":"isolate_floor_and_bay","floor":13,"includeColumnContext":[44,79],"pickableOnlyVisible":true}},{"id":"f13-support-loss","title":"3. Bolt shear, buckling, walk-off","evidenceClass":"nist_analysis","description":"Show horizontal restraint loss at the modeled C79 seat after bolt shear, then A2001 buckling and westward walk-off with loss of vertical bearing. The 3D movement is a direction cue, not a NIST displacement sample or a reconstructed buckle shape. The C76\u2013C79 and C79\u2013C80 members remain adjacent context, not the initiating seat. Keep the corrected analytical seat dimensions separate from the unknown physical polygon.","claimIds":["f13-bolt-shear-horizontal-loss","f13-girder-walkoff","nist-c79-corrected-seat-analysis","c79-physical-seat-detail"],"focus":{"memberIds":["F13-east-office-primary-44-79","F13-east-office-C41","F13-east-office-C40","F13-east-office-C39","F13-east-office-C38","F13-interior-76-79","F13-interior-79-80"],"columnIds":[44,79]},"time":{"basis":"thermal_elapsed_h","min":3.7,"max":4.0,"qualifier":"reported interval, not a sampled trajectory"},"camera":{"preset":"f13-east-bay","direction":"oblique plan, seat visible at C79"},"visibility":{"mode":"isolate_floor_and_bay","floor":13,"includeColumnContext":[44,79],"pickableOnlyVisible":true}}]},{"id":"scene-3-local-floor-failure","title":"Local floor-support loss","summary":"NIST's Floor 13 connection failure combined with other damage; the global handoff included Floor 14.","status":"storyboard","states":[{"id":"f13-f14-northeast-sections","title":"Northeast floor sections fail","evidenceClass":"nist_analysis","description":"Show NIST's reported local floor-section failure around C79\u201381 after the 4.0 h handoff. The listed Floor 14 members are intact drawing-model context, not an identified deformed or failed member set; this state encodes no deformed geometry.","claimIds":["f13-girder-walkoff","local-f13-f14-floor-failure","thermal-case-and-handoff"],"focus":{"memberIds":["F13-east-office-primary-44-79","F13-east-office-C41","F13-east-office-C40","F13-east-office-C39","F13-east-office-C38","F14-east-office-primary-44-79","F14-east-office-C41","F14-east-office-C40","F14-east-office-C39","F14-east-office-C38"],"columnIds":[79,80,81]},"time":{"basis":"collapse_reference_s","value":-6.5,"qualifier":"Figure 12-42 snapshot; model only"},"camera":{"preset":"northeast-floors-13-14"},"visibility":{"mode":"floor_range","minFloor":12,"maxFloor":14}}]},{"id":"scene-4-cascade-c79","title":"Cascade and C79 buckling","summary":"The reported downward cascade reaches Floor 5, leaving C79 insufficiently braced before it buckles eastward.","status":"storyboard","states":[{"id":"cascade-to-floor5","title":"Failure travels downward","evidenceClass":"nist_analysis","description":"Depict successive northeast floor-section failures and debris accumulating at the stronger Floor 5 slab.","claimIds":["floor-cascade-to-five","local-f13-f14-floor-failure"],"focus":{"memberIds":[],"columnIds":[79,80,81]},"time":{"basis":"collapse_reference_s","value":null,"label":"after modeled floor cascade begins near -6.6 s"},"camera":{"preset":"east-core-floors-5-14"},"visibility":{"mode":"floor_range","minFloor":5,"maxFloor":14}},{"id":"c79-buckles","title":"C79 buckles eastward","evidenceClass":"nist_analysis","description":"Identify this modeled column buckling as NIST's initiating local event for global collapse; retain direction-specific surviving restraints.","claimIds":["c79-buckling-initiation"],"focus":{"memberIds":[],"columnIds":[79]},"time":{"basis":"collapse_reference_s","value":-1.3,"globalSolverS":14.7},"camera":{"preset":"east-core-floors-5-14"},"visibility":{"mode":"floor_range","minFloor":5,"maxFloor":14}}]},{"id":"scene-5-east-penthouse","title":"Eastern interior and penthouse","summary":"C80/C81 failures overlap the east-penthouse roof kink; observed motion has a separate evidence label.","status":"storyboard","states":[{"id":"east-penthouse-kink","title":"East-penthouse roofline kink","evidenceClass":"observed_motion","description":"Pair a separately labeled observed north-side roof feature with NIST's modeled C79\u201381 sequence. The current physical penthouse is a schematic proxy.","claimIds":["east-core-and-penthouse","east-penthouse-kink-observed"],"focus":{"memberIds":[],"columnIds":[79,80,81]},"time":{"basis":"collapse_reference_s","value":0,"globalSolverS":16.0},"camera":{"preset":"north-east-penthouse"},"visibility":{"mode":"upper_east_with_lower_core_context"}}]},{"id":"scene-6-westward-and-exterior","title":"Interior progression and exterior onset","summary":"The model's interior failures travel west; exterior support fails in the debris-damaged baseline.","status":"storyboard","states":[{"id":"westward-core-progression","title":"Core failure moves west","evidenceClass":"nist_analysis","description":"Show sequential C76 and other core-column failures; transfer-truss damage follows falling debris, not the original floor-13 mechanism.","claimIds":["core-westward-progression","east-core-and-penthouse"],"focus":{"memberIds":[],"columnIds":[76,77,78,79,80,81]},"time":{"basis":"collapse_reference_s","min":3.5,"max":6.1,"qualifier":"reported core-buckling interval for selected case"},"camera":{"preset":"core-east-to-west"},"visibility":{"mode":"floor_range","minFloor":5,"maxFloor":18}},{"id":"exterior-onset","title":"Exterior descent begins","evidenceClass":"nist_analysis","description":"Identify modeled lower exterior buckling in the selected debris-damaged run and compare it to the later observed north-face onset without claiming exact late debris trajectories.","claimIds":["exterior-onset-baseline","late-simulation-uncertainty"],"focus":{"memberIds":[],"columnIds":[]},"time":{"basis":"collapse_reference_s","value":6.3,"qualifier":"modeled north-face roofline onset"},"camera":{"preset":"north-face-wide"},"visibility":{"mode":"whole_building_context"}}]},{"id":"scene-7-observed-descent","title":"Observed roofline descent","summary":"The Camera 3 roof feature has its own clock and a displacement fit from which NIST estimated velocity and acceleration.","status":"storyboard","states":[{"id":"north-roofline-three-stages","title":"Three measured-motion stages","evidenceClass":"observed_motion","description":"Plot NIST's tracked north-face point, fitted displacement, derived velocity, and Stage 2 acceleration. Stop before an invented detailed debris field.","claimIds":["roofline-observed-trajectory","roofline-three-stages","late-simulation-uncertainty"],"focus":{"memberIds":[],"columnIds":[]},"time":{"basis":"north_roofline_descent_s","min":0,"max":5.4},"camera":{"preset":"camera-3-north-face-reference"},"visibility":{"mode":"tracked_roof_feature","note":"Do not transfer the fitted displacement to every structural member."}}]}]}