Article and photos by Gregory Havel
Mercantile担任较倾向于展示他们的货物销售给经过街上的人们。在大型玻璃玻璃窗中可供商店窗户使用之前，所有者都会挂在门上一个签到他制造或售出的商品的形状：鞋匠的鞋子;剪出一辆车助理器的轮子或马车;书籍书;等等。
When window glass became less expensive, the merchandise for sale was displayed in large windows facing the street. Since glass has little compressive strength, the weight of the wall and floors above is carried by a beam that spans the front of the store from side wall to side wall (Photo 1).
In early buildings, this beam was usually wood. In the late 1800s, this beam was often made of wrought iron. Since the early 1900s, this beam usually has been made of steel. This beam is usually concealed behind the exterior cladding of the building: brick, tile, stone, wood, or other material.
Photo 1 shows parts of four storefronts.
- 在左左右右侧的建筑物中，板玻璃店面的梁支持上面的砖石，包括入口上方的栏杆。
- In the two-story building at the left, the beam over the plate glass storefront supports the second-story front wall and the parapet with brick cornice above. The beam is enclosed by the band of sheet metal between the top of the plate glass and the bottom of the brick masonry.
- 在右边的两层建筑物中，板上玻璃店面的梁支持上面的第二层前墙和栏杆。该梁由板玻璃顶部和砖砌体底部之间的涂料木材封闭。
Modern commercial construction is similar. For security, these buildings often have no windows except for those near the main entrance, which limits our options for ventilation. “Big box” stores are usually single-story, although their ceilings may be more than 30 feet (9.14 m) above the floor.
On our arrival, if the fire has self-vented or if firefighters remove the window glass for ventilation or fire attack, it is critical that we place a hoseline to protect and cool the beam above the main entrance and windows and that this hoseline and crew be placed outside the collapse zone. If we do not protect the beam supporting the structure, we set ourselves up for a significant structural collapse when the beam fails. A collapse zone must be set up early in the incident and enforced for our own safety.
For a more detailed discussion of this building feature, seeCollapse of Burning Buildings by Vincent Dunn (Fire Engineering Books and Videos)。
将本文下载为PDF这里。
Gregory Havelis a member of the Town of Burlington (WI)Fire Department; retired deputy chief andtraining officer; and a 30-year veteran of thefire service。他是威斯康星州认证的fire instructorII, fire officer II, and fire inspector; an adjunct instructor in fire service programs at Gateway Technical College; andsafetyScherrer Construction Co.，Inc.Avel董事哈德尔担任圣诺伯特学院学士学位;拥有30多年的设施管理和建筑施工经验;并在FDIC上提出了课程。
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