图片内容 

Who says I need to stay in shape to keep up with you guys? Problem solved!!

谁说的我要保持身材才能不掉队？问题解决！！

双语：

Chapter 2

第二章

Concepts of Construction

建筑基本常识

OBJECTIVES

目标

At the conclusion of this chapter, you will be able to:

学完本章后，您将习得以下技能：

• Identify the variety of forces to which buildings are subjected.

理解建筑物受力类型

• Identify the different types of loads and explain how they are applied to buildings.

理解建筑物荷载类型及其对建筑物的影响

• Define safety factor and explain how it affects the choice of materials used in a building assembly.

定义安全系数并能够解释其如何指导选择合适的建筑材料。

• Identify composite materials and explain how the combination of two different materials affects structural elements.

理解复合材料并能够解释两种不同材料的混合是如何影响建筑结构元素。

• Identify and define key types of structural members, such as beams, trusses, columns, walls, roofs, and arches.

理解建筑结构的核心要素，例如梁、桁架、柱、墙，屋顶和拱门。

• Identify the various types of structural connections and explain how they affect transmission of loads and behave in a fire.

理解各种类型的结构连接件，能够解释它们是如何影响荷载传递以及在火灾中的可能变化。

Case Study

典型案例

Roof collapse has always been a danger for fire fighters.

屋顶坍塌对消防员危害巨大。

On March 10, 1941, in Brockton, Massachusetts, fire fighters responded to a report of a fire at the Strand Theatre (Figure 2-1).

1941年3月10日，马萨诸塞州布罗克顿，斯特兰德剧院发生火灾，消防员到场处置。

This structure was of ordinary construction, with brick load-bearing walls and wood joists.

该剧院是常见的砖砌承重墙、木制横梁结构。

The theater included seats for more than 1,600 people, including a balcony that spanned the width of the building.

剧院有1600个坐席，包括一个二层看台。

To cover this large distance between the exterior walls (and to avoid columns in the balcony itself), the wood roof joists were supported by long-span unprotected steel trusses. A plaster and wire lath ceiling was installed under the trusses.

为了支撑宽大的木制屋顶（二层看台还不能设置承重柱），屋顶下方设置了无防火保护的大跨度钢制桁架，桁架下面还做了石膏板和丝网的吊顶

（作为一名21世纪的消防员，看到这里大家也应该明白了，这结构、这建材，火一旦烧大不塌是没天理了……）

The fire began in the basement and quickly ran up the wall void spaces and vertical ductwork to the roof.

起火点位于地下室，但很快沿着墙内的中空部分和垂直管道蔓延至顶。

Fire fighters ascended to the balcony to attack the roof fire; even though fire was breaking through the roof on the outside, little fire was visible on the inside.

消防员爬到二层看台向屋顶射水，虽然火势已经烧穿屋顶，但建筑内部几乎看不到火焰。

The roof suddenly collapsed onto the balcony, trapping fire fighters between the roof and the balcony seats.

转瞬之间，屋顶发生坍塌，所有在二层看台的消防员均被碎片掩埋。

A portion of the balcony itself then collapsed.

随后一部分看台发生坍塌。

A total of 13 fire fighters died.

13名消防员殉职。

Subsequent investigations revealed that the steel trusses, heated by the burning wood joists, had twisted and likely elongated, dropping their load.

灾后调查显示，横跨整个建筑的钢桁架，受到燃烧的木制托梁烘烤加热，扭曲变形导致承载能力下降。

A moderate snow load on the roof was discounted as causing the collapse.

近期一场中雪又使得屋顶负荷增加。（这个观点不太靠谱，多数照片显示屋顶基本没有残雪）

This incident raised serious questions about the relationship between construction and firefighting operations, which continue to plague modern-day fire fighters:

这起火灾事故引发了大量关于建筑和灭火之间关系的疑惑，仍困扰着当代消防员：

1. Is it possible that fire conditions can appear different on the outside of a building than they appear inside a building?

建筑火灾内部与外部发展状况是否会出现不一致？

2. How does the span of a truss relate to load-carrying capacity?

桁架的跨度和承载能力的关系？

3. When a truss fails, how much area is involved?

当桁架失稳坍塌，会影响多大的区域？

往期内容：

1001页：A008 消防建筑施工

1001页：A009 消防建筑施工