> For the complete documentation index, see [llms.txt](https://tlcfem.gitbook.io/suanpan-manual/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://tlcfem.gitbook.io/suanpan-manual/basic/structure.md). # Model Structure The default parser accepts a **three-part** structure. They are: 1. Model Properties Setup 2. Analysis Properties Setup 3. Post-processing The previous cantilever beam example is used here to explain the structure. The model is shown as follows. ``` node 1 0 0 node 2 1.34 0 material Elastic1D 1 132 element EB21 1 1 2 7.213 6.825 1 step static 1 fix 1 E 1 cload 1 0 23 2 2 cload 2 0 17 1 2 analyze peek node 2 exit ``` ## Model Properties Setup Anything before the first `step` command is treated as the setup of model properties. This part may include the definitions of nodes, elements, material models, loads, recorders, boundary conditions, etc. In this part, the order of commands **does not** affect the establishment of the model. So that the following reshuffled command flow creates the same model as the original one does, although, the `EB21` element is created before the creation of its connected nodes. ``` element EB21 1 1 2 7.213 6.825 1 node 2 1.34 0 material Elastic1D 1 132 node 1 0 0 ``` When the program parses those commands, the corresponding objects are only created and stored, but not initialized ( viz., no other information is required during the creation of a particular object). So the order does not affect anything in this part. ## Analysis Properties Setup The command block between the first `step` command the `analyze` command (or the `precheck` command) is the setup of analysis properties. A similar analysis flow which resembles the one of ABAQUS is used, that is, multiple steps can be defined in sequence in this part. In this example, within step 1, a fixed boundary condition is applied to node 1, two concentrated loads are applied to node 2 along two directions. For the purpose of illustration, those two loads can be defined in two different steps as follows. ``` fix 1 E 1 step static 1 cload 1 0 23 2 2 step static 2 cload 2 0 17 1 2 analyze ``` Now the horizontal load is created in step 2 that follows step 1. It shall be noted the BC is created before the first step. By default, there is a step 0 with no step time, so the BC can be defined in either step 0 or step 1. Similar to ABAQUS, the sequence of multiple steps will affect analysis results. ## Post-processing The code block between the `analyze` command and the `exit` command belongs to post-processing. This part is less concerning and most commands have instant response. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://tlcfem.gitbook.io/suanpan-manual/basic/structure.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.