经过格雷戈里哈维尔
这些轻质钢桁架由镀锌钢带制造，这些钢带已轧制成形状以增加强度。它们通常用于住宅和商业建筑。照片1显示了所设置的这些桁架，以支持兽医诊所的屋顶。照片2显示了这些桁架，以支持学校建筑的屋顶。
（1）作者照片。
（2）
Photo 3 shows the end view of a bundle of trusses. Note that the cross-section of a top or bottom chord has eight 90° bends as well as several other bends, which give these truss members great rigidity when compared to the flat strip of steel from which they were formed.
（3）
照片4显示了另一家制造商的桁架的最终视图。注意，顶部或底部弦的横截面具有六个90°弯曲加上两个纵向肋，其与形成它们的钢条相比，使这些桁架成员具有很大的刚性。
（4）
自钻螺钉是在工厂组装桁架的最常见方式，将它们连接到建筑工地的墙壁和其他承载构件。
In photos 3 and 4, note that a single screw will penetrate all of the layers of the components of a truss and that several screws will be used at each panel point. These screws are designed to be installed with electric or pneumatic screw guns. The screw gun uses the drill tip of the screw to make a hole through the layers of metal to be jointed. As part of the same procedure, the screw threads into the hole when drilling is complete. An adjustable clutch on the screw gun allows the operator to set the gun so that the completed screw connectors have the proper amount of torque for maximum strength. If the clutch on the screw gun is set too tight, the screws may strip in the metal of the studs, making a loose or weak joint. If the screws are not driven home, the joint will also be weak. In either of these cases, adding moisture from weather or leaky pipes will accelerate the rusting and weakening of the joints.
有关的：汤普森对轻质钢结构的危险‖钢铁框架建设的消防策略的英里和托宾188金博网网址多少‖Avillo在“新千年”多个住宅
木螺钉用于将轻型钢桁架连接到墙壁上的木顶板，而自钻螺钉用于连接钢托梁或钢螺柱组件。如果桁架具有配置的成员，如照片4所示，将螺钉驱动穿过桁架成员的底部法兰。如果配置类似于照片3中所示的内容，则可以使用附件板（照片5）将桁架连接到墙壁的顶部。
(5)
Firefighters working inside a building with a roof supported by this type of truss should be concerned with the following:
- 由于这些桁架具有很少的质量，它们将开始在低于闪络温度的温度下失去它们的强度，无论是屋顶护套都由波纹钢，胶合板或定向股线（OSB）制成。这些桁架可能不会在没有面板点的情况下没有发生故障的桁架成员的加热和软化。
- 自钻螺钉始终长，具有尖锐点（如图3,4和5所示）。
- 使用桁架构件的金属形状通常使用磨料锯片（照片3）造成磨料锯片（照片3）并且可以损坏个人防护设备（PPE）衣服以及PPE内的皮肤来切割长度。
- Any vertical ventilation on a roof supported by these trusses is most safely done from an aerial platform or ladder
- Roofs and other structural assemblies using these lightweight trusses deserve a note on our preincident plans for these buildings.
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格雷戈里哈维尔is a member of the Town of Burlington (WI) Fire Department; retired deputy chief and training officer; and a 35-year veteran of the fire service. He is a Wisconsin-certified fire instructor II, fire officer II, and fire inspector; an adjunct instructor in fire service programs at Gateway Technical College; and safety director for Scherrer Construction Co., Inc. Havel has a bachelor’s degree from St. Norbert College; has more than 35 years of experience in facilities management and building construction; and has presented classes at FDIC.
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