建筑建筑评论

By Nick Salameh

Photo above courtesy of the U.S. Navy

Within the fire service, building construction can be defined as the study of how buildings are put together; materials and connections used, how fire affects the materials and connections, what may fail, how it may fail, and what happens when it fails. So why should we study building construction? The late Francis L. Brannigan said it best, “Because your life depends on it!”

The fire service must evolve to stay ahead of new technologies. Research organizations such as the National Institute of Standards and Technology (NIST) and Underwriter Laboratories (UL) are helping us to do that through their studies, by arming us with information and knowledge to make us better, faster, and safer, without taking away from our sworn duties to protect life and property.

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新技术不断用于建筑构建。开发人员正在寻求更好的方法来建造更便宜的结构，同时保持或增加承载能力。在许多情况下，这些新的施工功能比以前的建筑类型提供了更大的强度，但成本降低。降低的成本意味着减少质量，因此，尽管结构可能更强，但其结构完整性在火灾条件下削弱了更快。例如，旧式木框构造类型，从火开始开始约18-20分钟，直到崩溃成为一个问题。同时，更现代的轻质木材结构可能会在起火开始后的四到八分钟内开始失去其结构完整性。

建筑物建筑领域的变化正在引入更多的工程，复合和绿色的结构技术和元素，以及合成材料的使用。对于消防员而言，这转化为改变的火力动力学，结构质量较小，较大的空间空间，用于垂直和水平的火力扩展以及早期塌陷潜力。结果，尽可能快地在大火所在的地方获取足够的水，将为消防员和被困的乘员增加安全和生存机会。

当涉及到建筑,我们作为火灾fighters must:

• Study it
• Recognize it
• Preplan it
• Size it up
• Read the smoke
• Anticipate fire travel
• Anticipate collapse

Building Construction Types

• 耐火- I型
• Non-combustible/limited combustible – Type II
• Ordinary – Type III
• Heavy timber – Type IV
• Wood frame – Type V

Note: As engineers and architects push the structural limitations of building materials, buildings may be built using all five types of construction or a variety such as in hybrid construction. More engineered lumber, synthetics (plastics), glues, and other engineering in construction components make them cost-effective and strong and durable for building construction, but much worse for firefighters under fire conditions.

Fire Resistive (Type I) Building Construction

General

• 一座结构良好的建筑物，其中没有结构钢暴露并保护所有垂直开口。
• Reinforced concrete, precast concrete, and protected steel frame construction meet the criteria for Type I construction.
• Generally seen in high-rise residential and commercial buildings.

优势

• Highest level of protection from fire development and spread, as well as collapse.
• All structural materials composed of noncombustible or limited-combustible materials with a high fire-resistive rating.
• Components such as walls, floors, and ceilings must be able to resist fire for three to four hours.
• Expected to remain structurally stable during fire and considered to be the most collapse-resistant.
• Structural components do not contribute to the spread of fire, but目录做.
• Often employ fire protection systems and fire-rated assemblies.

弱点

• Sprayed-on fire protection on steel may be removed, exposing the steel.
• Spalling of concrete is possible under prolonged attack by fire.
• 隔室可以保留热量，从而有助于快速开发开发。
• 由于建筑材料和设计，屋顶很难穿透通风。
• Windows may be difficult to open for ventilation.
• 开阔的平面图可以促进热量/烟气旅行和快速射击。
• There is the potential for vertical fire spread through auto-exposure, unprotected poke-through(s), HVAC duct work, elevator shafts, exterior curtain walls, and open access stairs between floors.

防火性能

• Structural members generally receive three- to four-hour fire protection.

Collapse Potential

• Only under sustained attack by fire does failure occur, and in those cases, it is usually localized collapse. The 9/11 World Trade Center collapse is extreme example.

Non-Combustible (Type II) Building Construction

General

• Ordinarily composed of unprotected metal structural components.
• Often recognizable from the exterior. From the interior, evidence of unprotected steel at ceiling level is a giveaway.
• Metal framing members, metal cladding, or concrete-block construction of the walls with metal deck roofs supported by unprotected open-web joists are the most common forms of Type II construction.
• 这些结构取决于建筑组件（I型一半）的评级为一到两个小时。

弱点

• Unprotected metal components make this construction type prone to early collapse.
• Combustible products used for built-up roof materials (insulation foam, asphalt water proofing, felt paper, rubber) may be highly flammable and can lead to a separate fire above and below the roof (metal roof deck fire), which can self-sustain and spread due to generated heat and flammable vapors from these highly combustible materials.
• 天花板空隙可以使大​​量的加热气体在头顶上收集，这可能会迅速下降，导致触发事件（flashover, backdraft) on the introduction of sufficient air.
• Failure to cool the ceiling area early will allow heat to weaken unprotected steel, prompting potential failure and collapse, as well as contribute to a metal roof deck fire and trigger events.

防火性能

• The structural elements rarely receive fire protection and are exposed to the heat of a fire.
• Design may include sprinkler system fire protection.

Collapse Potential

• 由于结构性成员受到保护并暴露于火/热量，因此他们将迅速失败，应提前崩溃。
• Steel expansion can cause collapse of exterior walls and parapets.
• 钢开始在800º处伸长，并且在1,000º高的温度下可能会失败。

普通（III型）建筑建筑

General

• Generally found in older schools, mercantile, business, and residential structures.
• Full dimensional lumber.
• 火切托梁（允许地板倒塌，砌体墙保持站立）。
• Exterior walls and structural members constructed of non-combustible materials.
• 内壁，圆柱，横梁，地板和屋顶是完全或部分由木头构造的。

弱点

• 普通聚会墙。托梁可能坐在同一墙壁插座（潜在的水平火伸展，威胁结构稳定性）。
• Common cocklofts or attics may exist, allowing for fire spread.
• Vertical and horizontal void spaces exist inside the wooden channels created by roof and truss systems, vertical pipe chases, and between wall studs. These will allow fire spread unless fire stops are installed in the voids.
• Older Type III structures may have undergone renovations that have contributed to greater fire risk due to the creation of large hidden voids above ceilings and below floors that may create multiple concealed voids.
• In some cases, rain roofs may have been installed over existing flat roofs.

防火性能

• Structural members are usually protected by plaster or drywall construction.
• Exterior walls are non-combustible.

Collapse Potential

• Older buildings of ordinary construction contain structural members of substantial size, which hold up well under fire attack but can and will fail, causing collapse.
• 轻巧的木结构成员将在火灾攻击下容易失败。
• 火切托梁将使建筑物的内部倒塌，而砌体墙保持完整。此功能会影响建筑物内运行的消防员。

Heavy Timber (Type IV) Building Construction

General

• 由由6×6、8×8和较大尺寸木材组成的固体结构构件构建。
• Modern heavy timber structural members are often engineered by using laminated lumber. These members can fail much faster as the laminate glues that hold them together can degrade and vaporize under heat conditions.
• Found in mill factories, barns, churches, new and renovated office spaces, etc.

优势

• Large structural members will support a structure for an offensive attack.
• Load-bearing walls are noncombustible.
• There may be floor drains to drain water used in firefighting. This feature reduces water weight and collapse potential.
• 通常，没有空间空间。

弱点

• 从当前或以前的机械使用中，地板可能是浸泡的。
• Unprotected openings may exist between floors.
• There may be an excessive fire load of stock, manufacturing process, or storage of finished goods.
• Alterations can create concealed spaces.
• Mortise/tenon joints reduce wood fat and can be vulnerable under heat conditions.
• Like unprotected metal components, metal joint connections can fail (800-1,000º).

防火性能

• Structural members are of a substantial size and will contribute a large fuel load to a fire.
• 大火过去的初期阶段之后，很难控制，并且可以长时间燃烧。

Collapse Potential

• Though constructed of substantially sized pieces of lumber and not prone to collapse, under prolonged fire attack, these buildings will fail.
• Joint connections can be vulnerable, depending on the connection point type.

Wood Frame (Type V) Building Construction

General

• Used in the construction of single- and multiple-family dwellings, commercial, out buildings, etc.
• Interior wall coverings may be of plaster or drywall.
• May be composed of solid dimensional lumber (Legacy-allows for more burn time and better structural integrity under fire conditions).
• May be composed of engineered light weight wood and laminate components (promotes rapid fire spread and reduced structural stability) used in ceiling and floor trusses, and other composite structural components.
• 平台、气球、日志、梁柱和木板nd beam are all forms of wood frame construction.

优势

• Platform construction provides some barriers for vertical extension of fire.
• Log, post and beam, and plank and beam buildings have substantially sized structural members.

弱点

• Wood will burn.
• Older buildings may have dry rot, water damage, or damage from wood-boring insects.
• 空间很常见，在气球框架中可能是广泛的。
• Renovations are commonplace in older structures.
• Vertical voids begin in basements and can lead to significant vertical fire spread to the attic.
• Today’s engineered lumber is weaker than legacy wood, which had much tighter growth rings.
• 与遗产等效相比，今天的尺寸木材通常尺寸较小。那时，2×4实际上是两英寸乘4英寸。当今的一些木材的尺寸稍小。
• Lightweight wood construction elements and techniques have redefined wood frame construction making modern wood structures more susceptible to rapid fire spread and early collapse, and a danger to firefighters.

防火性能

• 石膏或石膏板可以为结构成员提供一些保护。
• Exposed wooden members and the use of plastics/vinyl will contribute fuel to a fire.

Collapse Potential

• 框架结构确实引起了人们的关注，因为它们在燃烧时失去了负载能力。
• The type of frame construction will determine collapse potential, lightweight more vulnerable than legacy construction.
• Log cabins are substantial and usually sustain only roof collapse.
• 其他框架结构容易局部和一般崩溃。

下面的比较图表来自文森特·邓恩（Vincent Dunn）的书《消防策略》，并显示了每种建筑施工类型与火灾蔓延和倒塌潜力之间的关系。188金博网网址多少

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尽管不同的construction types, all structures burn as a result of their contents (mainly synthetics today), and, in the case of some of today’s construction, their structural and aesthetic elements. Each construction type is unique, and firefighters must have a good working knowledge of building construction, the materials and connections used, how smoke and fire will spread inside and outside of structures, how fire affects the materials and connections, what may fail, how it may fail, and what happens when it fails.

Theodore Lee Jarboe said, “There is no greater influence of change in the fire service than the line of duty death of a firefighter.” Since your life depends on it, do your best to avoid lessons learned through your own tragedy by staying abreast of new technology and building construction industry changes.

References

Frances L. Brannigan, Glenn Corbett,Brannigan’s Building Construction for the Fire Service, Fifth Edition

Gordon Graham,Organizational and Operational Risk Management,www.gordongraham.com,www.firefighterclosecalls.com,www.firefighternearmiss.com,www.Lexipol.com， 和gordongraham@earthlink.net

James P. Smith,Strategic and Tactical Considerations on the Fireground, Fourth Edition

Vincent Dunn,消防策略188金博网网址多少

NIST –https://www.nist.gov/

UL –https://www.ul.com/

NICK J. SALAMEHis a 36 year veteran of the fire service. He was a Fire/Emergency Medical Services Captain II and previous Training Program Manager for the Arlington County (VA) Fire Department, where he served 31 years. He is a former Chair of the Northern Virginia Fire Departments Training Committee. Nick is a contributor to Fire Engineering Magazinewww.fireengineer.comand Stop Believing Start Knowing (SBSK).