{
  "id": "C04",
  "title": "塔科马抗风：两侧桥缘与阻尼",
  "checked_at": "2026-09-22",
  "case": {
    "name": "1940 Tacoma Narrows Bridge",
    "date": "1940-11-07",
    "primary_span_m": 853.44,
    "side_span_m": 335.28,
    "girder_depth_m": 2.4384,
    "geometry_source": "https://wsdot.wa.gov/TNBhistory/1940-bridge.htm",
    "note": "图中Eldridge初始方案不同于1940实际Moisseiff方案。默认三维以1940最终方案主要尺寸建立；不是原桥施工图CAD或实桥动力求解。"
  },
  "reused_model": {
    "url": "/sources/wind/structure-modal-lab-github/engine/index.html",
    "metadata": "/sources/wind/structure-modal-lab-github/assets/suspension.metadata.json",
    "prototype": "Forth Road Bridge",
    "source_components": 4329,
    "render_meshes": 11,
    "main_span_m": 1006,
    "deck_width_m": 36.026,
    "model_length_m": 1822,
    "canonical_axes": "x longitudinal/y transverse/z up; exported Godot axes already converted",
    "geometry_unchanged": true,
    "role": "课外独立对照链接，不作为默认塔科马模型"
  },
  "math": {
    "model": "qdd+2*zeta*omega*qdot+omega^2*q=0",
    "q0": 0.16,
    "v0": 0,
    "frequency_hz": 0.25,
    "structural_zeta": 0.02,
    "aero_zeta_range": [
      -0.055,
      0.06
    ],
    "duration_s": 32,
    "alpha_reference_rad": 0.017453292519943295,
    "vertical_reference_m": 0.01,
    "torsion_display_gain": 20,
    "vertical_display_gain": 1500,
    "not_real_bridge_fem": true,
    "not_critical_wind_prediction": true,
    "edge_reference_width_m": 11.8872
  },
  "sources": [
    {
      "title": "UW Tacoma Narrows Bridge Film Collection",
      "url": "https://content.lib.washington.edu/filmarchweb/tacoma.html",
      "kind": "大学原始影片收藏与馆藏说明",
      "review": "馆藏介绍已读；本页未下载影片、未凭剪辑设置时间戳"
    },
    {
      "title": "WSDOT 1940 bridge geometry",
      "url": "https://wsdot.wa.gov/TNBhistory/1940-bridge.htm",
      "kind": "政府原桥图纸与数据"
    },
    {
      "title": "WSDOT collapse chronology",
      "url": "https://www.wsdot.wa.gov/tnbhistory/collapse.htm",
      "kind": "政府事故历史与照片"
    },
    {
      "title": "Billah and Scanlan (1991)",
      "url": "https://doi.org/10.1119/1.16590",
      "kind": "原研究论文，颤振与共振解释"
    },
    {
      "title": "AIP authors film analysis",
      "url": "https://students.aip.org/radiations/the-tacoma-narrows-bridge-collapse",
      "kind": "原作者影片帧率核查说明"
    },
    {
      "title": "AAPT Twin Views guide",
      "url": "https://www.aapt.org/Store/upload/tacoma_narrows2.pdf",
      "kind": "教学影片镜头表与活动指南"
    }
  ],
  "limitations": [
    "默认是按真实主要尺寸构建的Tacoma参数模型；Forth课程仅在对照链接中，未混淆原型",
    "时间函数与空间振形是教学给定，不是实桥FE或测量结果",
    "小角度线性模型，增长不延伸至材料破坏",
    "原片各版本帧率与剪辑须逐段核实",
    "形变显示放大与物理曲线分离"
  ],
  "default_model": {
    "file": "tacoma-model.mjs",
    "prototype": "1940 Tacoma Narrows",
    "coordinate_system": "Three.js X纵向/Y向上/Z横向，米；未做非等比缩放",
    "dimensions_m": {
      "main_span": 853.44,
      "side_span_each": 335.28,
      "suspension_length": 1524,
      "cable_spacing": 11.8872,
      "roadway_width": 7.9248,
      "sidewalk_width_each": 1.524,
      "plate_girder_depth": 2.4384,
      "hanger_interval": 15.24,
      "main_cable_diameter": 0.4445,
      "road_slab_thickness": 0.13335,
      "tower_above_pier": 129.54,
      "tower_above_water": 135.0264,
      "tower_above_roadway": 70.104,
      "main_cable_sag": 71.12
    },
    "source": "https://wsdot.wa.gov/TNBhistory/1940-bridge.htm",
    "assumptions": [
      "主缆采用抛物线近似，边缆线形示意",
      "道路跨中195ft、塔处由443-230ft推得213ft，主跨采用连续抛物线连接；边跨道路高程作水平简化",
      "塔柱截面、横梁位置、锚碇外形、海岸地形、涂色和附属细节简化",
      "桥面板、主缆与吊索采用给定运动学，保持连接；不是求解出的空间振型",
      "板梁下方用开敞横梁与横向风撑表达，未建成封闭箱形底板；这些杆件截面为示意"
    ],
    "sample_points": {
      "torsion": "x=-213.36m，左侧四分之一跨，sin(2πu)=1",
      "vertical": "x=0m，主跨跨中，sin(πu)=1",
      "close_camera_note": "当前断面近景相机固定在左侧四分之一跨。竖弯采样点在跨中，不应把此相机近景直接读作跨中探针的同位置实测。"
    },
    "vehicles": "无车辆，避免加入没有依据的车辆尺寸"
  },
  "audio": {
    "dialogue": "dialogue.json",
    "script": "narrator.txt",
    "url": "media/dialogue-v2.mp3",
    "turns": 12,
    "roles": [
      "curious",
      "expert"
    ],
    "synthesis": "主代理统一火山双人对话合成",
    "synchronization": "dialoguecue 按12轮 index联动，同轮比较按实际语音段落时长比例；手动控制当轮优先，不宣称逐字对齐",
    "timing": "media/dialogue-v2-timing.json",
    "timing_resolution": "优先复用通用播放器已核稿的dialogueready/audio.dialogueTiming；漏接时从当前audio.src派生同版本*-timing.json，避免旧版时长",
    "readiness": "通用播放器先逐轮匹配正文、role、数量；C07另等有效audio metadata后显示播放器并启用按钮，模型加载不决定配音就绪"
  },
  "consistency_audit_at": "2026-09-23"
}