# U1 Beam Examples and documentation **URL:** \ **Category:** Uncategorized\ **Created:** [October 31, 2022, 11:20pm UTC](https://calculix.discourse.group/t/u1-beam-examples-and-documentation/1307 "2022-10-31T23:20:19Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Rob](https://avatars.discourse-cdn.com/v4/letter/r/838e76/32.png) [@Rob](https://calculix.discourse.group/u/Rob)\ **Post date:** [October 31, 2022, 11:20pm UTC](https://calculix.discourse.group/t/u1-beam-examples-and-documentation/1307/1 "2022-10-31T23:20:19Z")
Does anyone have some examples of using a U1 user beam element? The documentation on the U1 seems very sparse. In particular, does the U1 work with different ways of specifying the beam orientation? Can orientation be specified on a per-element basis with the NORMAL definition? What are the tradeoffs of using a U1 vs. a B32? My understanding is that B32 expands to a bunch of solid elements approximating the beam while U1 uses beam theory to provide the element stiffness matrix. My inclination is to prefer U1 – am I missing something? ---
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [November 1, 2022, 8:24am UTC](https://calculix.discourse.group/t/u1-beam-examples-and-documentation/1307/2 "2022-11-01T08:24:59Z")
There is a userbeam.inp file in test examples package. When it comes to orientation of this element, there were 2 bugs related to it: > [@Problem using U1 element (general beam section)](https://calculix.discourse.group/t/problem-using-u1-element-general-beam-section/600): > > Hi, I ran into an issue with the general beam section (element type U1). I tried to make a simple test but aparently failed. So far I tried with ccx 2.15 and 2.17. The example is the following, describing a cantilever with weight at the tip (I think I found a similar example elsewhere): \*NODE, NSET=Nall 1,0.,0.,0. 2,10.,00.,00. 3,20.,00.,00. 4,30.,00.,00. 5,40.,00.,00. 6,50.,00.,00. 7,60.,00.,00. \*ELEMENT, TYPE=U1, ELSET=Eall 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 5, 6, … > [@Doubt about userbeam.inp (U1) from ccx test](https://calculix.discourse.group/t/doubt-about-userbeam-inp-u1-from-ccx-test/668): > > Hi all, Using userbeam.inp from ccx test I have a doubt or a misunderstanding of this CalculiX user type U1 feature. If in userbeam.inp example I change \*CLOAD argument from 2,2,1. to 2,3,1. I expected to obtain the same absolute values for displacements and section forces (sign and position may change). For displacements this effectively happens, but not for sections forces. I expected the same absolute results because properties given in \*BEAM SECTION are symmetrical (same moment of inertia… The second one is fixed but the first one still persists in the current version of CalculiX. It should be fixed in the next version though. U1 element is meant to be used when beam has to be defined with section other than a few predefined ones. ---
**Author:** ![Rob](https://avatars.discourse-cdn.com/v4/letter/r/838e76/32.png) [@Rob](https://calculix.discourse.group/u/Rob)\ **Post date:** [November 1, 2022, 5:50pm UTC](https://calculix.discourse.group/t/u1-beam-examples-and-documentation/1307/3 "2022-11-01T17:50:30Z")
Thanks for the response - and for the links to some discussion using U1 elements. If I was using a simple beam section (say a rectangle) supported by CalculiX, what would be the expected differences of using the built-in B32R with RECTANGLE section vs. a U1 with GENERAL section? ---
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [November 1, 2022, 7:21pm UTC](https://calculix.discourse.group/t/u1-beam-examples-and-documentation/1307/4 "2022-11-01T19:21:35Z")
The documentation only describes this element as a _3D Timoshenko beam element (for static linear elastic calculations and small deformations)_. There’s also a reference to the paper with the formulation of this element and some details regarding keyword syntax. It would be best to run some tests with this element having the same properties as an equivalent B31 element. Here you can find some comparisons: [CalculiX-Examples/Test/BeamSections at c6b5cc68fc5e868afe04ee312763779cad9302ef · calculix/CalculiX-Examples · GitHub](https://github.com/calculix/CalculiX-Examples/tree/c6b5cc68fc5e868afe04ee312763779cad9302ef/Test/BeamSections)