> For the complete documentation index, see [llms.txt](https://docs.enercalc.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.enercalc.com/sel-faq/using-the-software/calculation-modules/foundations2/general-footing/percentage-of-edge-length-for.md). # Percentage of Edge Length for M\&V What the Percentage of Edge Length for M\&V input means and how it averages soil pressure for footing design. ## What is the meaning of the input for "Percentage of Edge Length for M\&V"? It is a way for the user to apply engineering judgment in the determination of the soil pressure to use for design. Think about a footing with a linear-varying soil bearing pressure where the pressure is high on the east and low on the west. If you consider the design of the bars that run North-South, you would need heavier reinforcing for the N-S bars that are on the east, and lighter reinforcing for the N-S bars that are on the west. But structural engineers generally want a consistent size and spacing of rebar in a particular direction in a general footing. So the question boils down to deciding what pressure to use to design those N-S bars. If you used the lowest soil pressure, the rebar could be under-designed for a large portion of the footing. If you used the highest soil pressure, the rebar could be over-designed for a large portion of the footing. Most engineers are going to select some value of soil bearing pressure that is somewhere between the lowest and the highest soil bearing pressures experienced along an edge. That’s what this control is really doing. It is specifying the percentage of the footing dimension over which to average the soil bearing pressure to arrive at a single value that is judged to be appropriate for design. If you use 100%, then you are telling the program to use a value that represents the average pressure along the full length of the footing edge. If you use 10%, then you are telling the program to use a value that represents the average pressure along the most heavily loaded 10% of the footing edge. --- # 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://docs.enercalc.com/sel-faq/using-the-software/calculation-modules/foundations2/general-footing/percentage-of-edge-length-for.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.