> For the complete documentation index, see [llms.txt](https://enercalc.com/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://enercalc.com/docs/sel-user-manual/calculation-modules/foundation/beam-on-elastic-foundation.md).

# Beam on Elastic Foundation

How to design a single-span concrete beam on a continuous compression-only elastic soil support.

The **Beam on Elastic Foundation** module is a single-span version of the **Concrete Beam** module that provides special support conditions to represent an idealized, compression-only, continuous elastic support.

The significant variation between the **Beam on Elastic Foundation** module and the **Concrete Beam** module is the fact that the Beam on Elastic Foundation module collects a Soil Subgrade Modulus for use in modeling the spring support.

Note that code modifications for lightweight concrete are not applied in this module. The purpose of this input is mainly to allow the user to specify something in the range of 145 to 150 pcf.

{% hint style="info" %}
***Note: This module will stop if it finds any locations where the soil springs tend to go into tension, so be sure to use realistic load combinations. For instance, don't run +W Only or +Lr Only, without the corresponding dead load that would also be applied concurrently. Also be careful when allowing automatic reversals of wind or seismic loads that could result in net tension at the soil interface.***
{% endhint %}

Refer to the [Concrete Beam](/docs/sel-user-manual/calculation-modules/beams/concretebeam.md) module information in this document for other details.


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