> For the complete documentation index, see [llms.txt](https://manual-1-3.karamba3d.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://manual-1-3.karamba3d.com/chinese_1_3_3/2-getting-started/2-getting-started-1/setting-up-a-structural-analysis/2.2.6-provide-cross-sections.md).
# 2.2.6: 提供断面 – 或使用默认值
这里有两个将断面添加到构件的选项：
1. 如图2.2.6.1 所示，直接附加在创建元素的运算器上。
2. 通过元素名称（图2.2.6.2中的“B”和“S”）或将断面接入**“Assemble（模型构建）”** 运算器中的正则表达式。
图2.2.6.1显示了如何将自定义断面附加到某一构件之上。图例显示的是一个工字梁，其高度和宽度均为50厘米。当鼠标指针悬停在相应的端口时，即会弹出帮助文本中所提及的所有输入或输出值的物理单位。
{% hint style="info" %}
直接附加的方式将覆写通过**“Assemble（模型构建）”**运算器做出的定义。
{% endhint %}
图2.2.6.2显示了如何通过元素名称“Elem|Id”定义横截面：梁断面的定义（1）；中：壳体断面的定义（2）；右：从默认断面库中选择断面（3） Arbitrary I-, hollow box, filled
任意的工字型、空心箱形、实心梯形以及空心圆形断面等均可被定义为梁。此外，Karamba3D允许用户选择预定义的标准断面。在设计壳体的情况下，可以将不同的断面连接到各个构件。
Karamba3D断面可作为多元运算器使用：可通过单个运算器**“Cross Sections（断面）”**使用；用户可以通过下拉菜单则选择断面类型。
{% hint style="info" %}
如果用户未曾为梁或壳体单元指定横截面，程序将使用[默认横截面](/chinese_1_3_3/2-getting-started/2-getting-started-1/karamba3d-entities.md)。
{% endhint %}
---
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