# 2.1: Karamba3D Entities

Grasshopper (GH) is an object oriented, visual scripting environment. It provides items like points, curves, surfaces, . . . for geometric computing. The full range of geometric items can be inspected in the subcategory **“Geometry”** of the toolbar section **“Params”**. Karamba3D adds seven entities for building structural models:

| Entity        | Typology                                                                                |
| ------------- | --------------------------------------------------------------------------------------- |
| Model         | contains all the information related to a structure                                     |
| Element       | can be a beam, truss, shell or spring                                                   |
| Element Set   | groups together elements in a given order, makes them accessible under a common name    |
| Joint         | defines the connectivity between neighboring elements                                    |
| Load          | external action which is imposed on the structure                                       |
| Cross-section | defines a structural element’s geometry in section                                       |
| Material      | provides information regarding the physical behavior of what a cross section is made of |
| Support       | defines how a structure connects to the ground.                                          |

Karamba3D objects behave like GH entities.

* They can be stored in containers (see the **“Params”** subcategory of the **“Karamba3D”** toolbar). 
* When converted into text by plugging them into a panel they provide textual output regarding their fundamental properties.

## Default Settings

In order to build a structural model not all of the above entities need to be present. Karamba3D assumes default settings for materials and cross sections:

* If no material is given, Karamba3D chooses steel (S235 according to EC3 with$$f\_{yk} =  23.5 kN/cm^2$$) for all cross sections. 
* For beams the default is a circular hollow cross sections (CHS) with an outer diameter of$$114.4mm$$and a wall thickness of $$4mm$$. The default thickness of shells amounts to $$10mm$$.