{"schemaVersion":1,"recordId":"wtc7-nist-observation-and-model-time-ledger-v1","reviewedDate":"2026-09-23","selectedCaseId":"nist-case-b-4h-with-debris","comparisonCases":[{"id":"nist-case-b-4h-without-debris","thermalCase":"B","thermalDamageHandoffHours":4.0,"debrisImpactDamage":false,"notMergedIntoSelectedCase":true,"table12_2CollapseReferenceS":{"floorCascadeStart":-6.6,"c79Buckling":-1.4,"eastPenthouseBelowFromNorthwestAndBelow":2.3,"eastPenthouseBelowFromNorthAtRoofline":2.6,"coreBuckling":{"min":3.2,"max":13.5},"northFaceRooflineFirstDownwardMotion":9.8},"sourceRef":{"sourceId":"NIST_NCSTAR_1_9","locator":"Table 12-2, printed p. 599 / PDF p. 665"}},{"id":"nist-case-b-3p5h-with-debris","thermalCase":"B","thermalDamageHandoffHours":3.5,"debrisImpactDamage":true,"notMergedIntoSelectedCase":true,"reportedResult":"The earlier transferred damage did not cause interior-column buckling or global collapse in the tested global analysis.","sourceRef":{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed p. 573 / PDF p. 639; Section 12.4.5"}}],"timeContract":{"collapseReferenceZero":"First observed kink in the east-penthouse roofline viewed from the north, not generic first descent.","selectedCaseGlobalSolverAtCollapseReferenceZeroS":16.0,"northRooflineZero":"First perceived downward motion of the tracked north-face roofline feature in Camera 3.","observedNorthRooflineZeroAfterCollapseReferenceS":6.9,"thermalTimeIsIndependent":true,"historicalCivilTimeIsIndependent":true,"presentationTimeIsIndependent":true,"sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed pp. 572, 599\u2013602; PDF pp. 638, 665\u2013668"}]},"events":[{"id":"event-f13-girder-walkoff","label":"C44\u2013C79 girder buckles and walks off the analytical C79 seat","evidenceClass":"nist_analysis","caseId":"nist-case-b-4h-with-debris","time":{"basis":"thermal_elapsed_h","kind":"interval","min":3.7,"max":4.0},"claimIds":["f13-bolt-shear-horizontal-loss","f13-girder-walkoff","nist-c79-corrected-seat-analysis"],"sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed p. 527 and Figure 11-48 p. 530; 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PDF pp. 664\u2013665"}],"visibility":"video_derived_horizontal_motion","comparisonGroupId":"precollapse-horizontal-versus-internal-cascade","limit":"This observation does not show an internal floor collapse."},{"id":"event-modeled-floor-cascade-start","label":"Floor cascade around C79 starts in the selected global model","evidenceClass":"nist_analysis","caseId":"nist-case-b-4h-with-debris","time":{"basis":"collapse_reference_s","kind":"point","value":-6.6},"globalSolverTime":{"basis":"global_solver_s","kind":"point","value":9.4},"claimIds":["local-f13-f14-floor-failure","floor-cascade-to-five"],"sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Table 12-2, printed p. 599 / PDF p. 665; Figure 12-42, printed p. 573 / PDF p. 639"}],"visibility":"hidden_internal_model_result","comparisonGroupId":"precollapse-horizontal-versus-internal-cascade"},{"id":"event-modeled-c79-buckling","label":"C79 buckles in the selected global model","evidenceClass":"nist_analysis","caseId":"nist-case-b-4h-with-debris","time":{"basis":"collapse_reference_s","kind":"point","value":-1.3},"globalSolverTime":{"basis":"global_solver_s","kind":"point","value":14.7},"claimIds":["c79-buckling-initiation"],"sourceRefs":[{"sourceId":"NIST_NCSTAR_1_9","locator":"Printed pp. 572\u2013573 and Table 12-2 p. 599; 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