{
    "title": "Nissen Hut",
    "inventor_name": "Peter Norman Nissen",
    "publication_year": null,
    "device_name": "Nissen Hut",
    "goal": "Provide a quickly erected, affordable, portable shelter for military and civilian use.",
    "problem_addressed": "Need for lightweight, transportable, and easily assembled structures for barracks, storage, and temporary buildings.",
    "concept_summary": "A prefabricated steel structure formed from corrugated iron sheets bent into a half-cylinder and supported by a wooden frame of ribs, purlins, and straining wires. The design allows rapid assembly, efficient storage, and modular expansion.",
    "detailed_description": "The Nissen hut consists of a curved skin of corrugated steel (approximately 10 ft 6 in x 2 ft 2 in per sheet) laid over a steel-and-wood framework. Five wooden purlins attach to eight T-shaped ribs spaced 6 ft apart. Straining wires and ratchets tension the ribs during construction. The interior may be lined with hardboard or asbestos-cement sheeting, and insulation can be added between the lining and exterior. Foundations are simple stumps with sole plates, bearers, and joists. The design supports spans of 16 ft, 24 ft, or 30 ft and lengths in multiples of 6 ft.",
    "principles": [
        "Prefabrication",
        "Modular construction",
        "Arch-type load distribution",
        "Tensioned straining wires"
    ],
    "scientific_domains": [
        "Mechanical Engineering",
        "Materials Science",
        "Structural Engineering"
    ],
    "mechanisms_of_action": [
        "Curved corrugated steel provides bending stiffness",
        "Wooden ribs and purlins transfer loads to the foundation",
        "Straining wires tension the ribs for rigidity",
        "Hook bolts secure purlins to ribs"
    ],
    "materials": [
        "Corrugated steel",
        "Wood (purlins, ribs, joists)",
        "Hardboard",
        "Asbestos-cement sheeting"
    ],
    "energy_sources": [],
    "inputs": [
        "Metal sheets",
        "Wooden components",
        "Labor for assembly"
    ],
    "outputs": [
        "Portable building shelter"
    ],
    "claimed_performance": "Rapid assembly, low material usage, strong structural performance for temporary and semi-permanent use.",
    "experimental_evidence": null,
    "replication_status": "Widely produced and used since WWI; still employed for military barracks, storage, and civilian shelters.",
    "keywords": [
        "prefabricated",
        "portable building",
        "corrugated steel",
        "modular shelter",
        "military architecture"
    ],
    "related_technologies": [
        "Quonset hut",
        "Portable building systems",
        "Modular housing"
    ],
    "controversy_level": "low",
    "confidence_score": 0.92,
    "practicability_score": 0.94,
    "fringe_score": 0.08,
    "evidence_strength": 0.55,
    "risk_score": 0.1,
    "trl_estimate": 9,
    "source_urls": [
        "http://www.rexresearch.com/",
        "http://www.rexresearch1.com/",
        "https://1lib.sk/book/668709/2e3293/quonset-hut.html",
        "https://en.wikipedia.org/wiki/Nissen_hut",
        "https://powerbiltbuildings.com/quonset-huts/nissen-huts"
    ],
    "organizations": [
        "British Army",
        "United States Army"
    ],
    "applications": [
        "Military barracks",
        "Emergency shelters",
        "Storage facilities",
        "Temporary housing"
    ],
    "limitations": [
        "Dependence on steel and wood availability",
        "Potential corrosion of steel sheets",
        "Limited insulation without additional layers"
    ],
    "open_questions": [],
    "red_flags": [],
    "evidence_quotes": [
        "A Nissen hut is a prefabricated steel structure originally for military use, especially as barracks, made from a 210A deg portion of a cylindrical skin of corrugated iron placed over a steel and wood frame.",
        "The exterior is formed from curved corrugated steel sheets 10 feet 6 inches (320 cm) by 2 feet 2 inches (66 cm), laid with a two-corrugation lap at the side and a 6-inch (15 cm) overlap at the ends.",
        "Each rib consists of three sections bolted together using splice plates, and each end is bolted to the floor at the bearers.",
        "The purlins are attached to the ribs using a \"hook\" bolt, which hooks through a pre-drilled hole in the rib and is secured into the purlin.",
        "Nissen huts come in three internal spans (diameters) a16 ft (4.9 m), 24 ft (7.3 m), and 30 ft (9.1 m)."
    ],
    "category": "Mechanical Engineering"
}