Six Beam Shapes To Build With, +1

Whether you’re an experienced DIY builder or brand new to the party, there are often quandry’s about beam shapes.  Well, I need to do this, but I only have material like that.  I’ll just use it  because I have it.  These kinds of decisions happen all the time in my shop.  How about in yours?

Actually, that’s a great idea! — Please take a minute and share in the comments. — Please tell us about a silly thing you’ve built from an obviously wrong piece of material.

OK, back to discussing beam shapes.

The Importance of Beam Shapes

Selecting the right beam shapes (aka section or profile or beam type) is rather important for each purpose.  Each and every beam shape has different characteristics, and probably a bunch of different sizes.  There are many different standard beam types, and really, an unlimited number when we include the +1, fabricated beams.  To start, let’s look at some beam shapes that are common for DIY projects.

This chart has some standard beam profiles with a ranking for each property in the first column.  For your convenience, think of the table in these terms:
– We use Stars for general ratings.  More Stars mean Stronger, Easier, or More Robust.
– The Stars are comparative, so 1 star does not mean it’s bad.
– Fewer stars means it’s not as good for that property in comparison to others.
Hover Your Mouse over the stars (and “Profiles”) for information about categories and ratings.

 

Beam Profile  >>>>

Functional Property
(Down)

Rectangle
Tube *
Rectangular Tube Profile
Round
Tube
Hollow Round Beam Profile
C-Channel
Section
C-Channel Beam Shapes
L-Angle
Section
L-Angle Profile
I-Beam
Section
I-Beam Shapes Area
Solid
Section
Solid Rectangular Beam Profile
Vertical Strength
Per Weight
(Bending)
DIY 4 Big Stars DIY 3 Stars DIY 4 Stars DIY 2 Stars DIY 5 Stars DIY 3 Stars
Horizontal Strength
Per Weight
(Bending)
DIY 4 Beam Profile Stars DIY 3 Beam Shapes Stars Do It Yourself 2 Star Rating DIY 2 Stars for beam shapes DIY 2 Stars Beam Shapes 1 Star Beam Shapes
Torsional Strength
Per Weight
4 Beam Shapes Stars Beam Profile 5 Stars DIY 2 Big Beam Shapes Stars Do It Yourself 2 Star Rating Do It Yourself 3 Star Rating 1 Star Beam Profile Rating
Open / Closed
Section
Closed.
Convex
Closed.
Convex
Open.
Concave
Open.
Concave
Open.
Double Concave
Open.
Convex
Ease of Work
(Cutting Angles, Holding,
Fixture setup.)
Beam Profile 5 Stars DIY 3 Stars for beam shapes Beam Shapes 4 Stars Beam Profile 4 Star Rating DIY 3 Stars Beam Profile 5 Star Rating
Ease of Protecting
(From Corrosion)
Do It Yourself 4 Star Rating Do It Yourself 3 Star Rating Do It Yourself 5 Star Rating Do It Yourself 5 Star Rating Do It Yourself 5 Star Rating Do It Yourself 5 Star Rating
Easy Bolting
(Angles / Squish?)
Do It Yourself 3 Star Rating DIY 2 Big Stars DIY 3 Stars in beam shapes Do It Yourself 5 Star Rating DIY 3 Stars for beam shapes Do It Yourself 4 Star Rating

 

Again, Hover over the Stars to read our thoughts for ranking them.  * Rectangular Tube discussion includes Square Tube.

About The Stars Table

The ratings for each beam shape (or beam profile) are based on personal experience.  I accept a variation of a star or so in any of the columns since it’s pretty hard to define.  Some differences exist when thinking about a vertical beam versus a horizontal beam.  Some items like corrosion (rust) are not as applicable when the conversation turns from steel to aluminum.   I also recognize that there are many other beam shapes that can be fabricated.  Impossible to put every option on the list.

Let’s take a look in more detail for some of the beam profiles as they apply for DIY projects.

Each Beam Profile Is Really Good At Something

Rectangular Tube

. . . (including square tube) is probably the most common material for DIY project.  It does well, for instance, in smaller trailer frames.  Which stands to reason because it does well at most everything and especially because it’s easy to work with.  Also, it’s easy to get in a ton of different sizes and thicknesses.  These beam shapes are strongest in the height direction, but certainly not weak in the width direction.  Tubes also handle torque well.  Painting on the convex shape is easy and you don’t have to worry about spacing to inside flanges.

Disadvantages:  There are 2 potential downsides for Tube . . . . 1) You can’t paint on the inside very well, so you must seal it to protect from corrosion.  That’s usually easy unless you plan to run wires or other things through the very nice and protected central passageway.  2) Depending on the wall thickness, if you place bolts through tube then tighten them, you can squish the tube.  The bolts are also longerish.  Note that placing holes in the tube goes right back to #1, sealing.  Also, holes in tube at the wrong places (typically top and bottom for a trailer) will weaken the beam.

Applications:  DIY project plans here at Mechanical Elements use a lot of Rectangle and Square beam shapes.

Round Tube

. . . is much like rectangular or square tube for advantages, and this beam profile is superior for torque per weight.  It also has the nice advantage of being great to tie to.

Disadvantages:  Again, round tube has the same disadvantages as above, yet with the distinct additional one of being harder to align and center holes parallel simply because it doesn’t have a flat side to reference.  (That doesn’t mean it’s impossible, it just requires a little more effort.)  Also, round tube is harder to fabricate because you must shape the ends to Tee into other round tubes.

Applications:  Round beam profiles are in many DIY projects, especially for connection and spacers.  They also appear for things to hold (with a hand) or tie-on.

C-Channel

. . . is a really popular beam profile for auxiliary beams.  Though we also see it for main beams, it’s a lot more common for cross members and other places.  In the vertical direction (as oriented for the beam profile chart image above), C-Channel is typically stronger for the weight than tube.  That makes it attractive, but it doesn’t come in as many different sizes, thicknesses or varieties.  Finally, the open section means you can easily finish it all over.

Disadvantages:  C-Channel is bias one side, so under high stress it can twist some, or bend sideways.  C-Channel is not the best for long unsupported spans, but it’s awesome for cross members and other duties.  It does well for main beams if cross members tie in so it’s not a long unsupported span.  While it finishes all over to avoid corrosion, the concave section sometimes makes it harder to smooth out and finish the interior surfaces.  Finally, when bolting to the flanges, the angled portion makes tightening a little harder.  (Angled washers are available to help that.)

Applications:  A lot of the Mechanical Elements trailer plans use C-Channel — especially for the front and back frame members.  It is also in the Crane Plans for the pedestal foot cross beam.

L-Angle

. . . Also called “Angle Iron” but most of the time it’s steel or aluminum not “iron” like the name implies.  This is the “do all” beam profile for a ton of different jobs.  Like C-Channel it’s not so good for long unsupported spans, but it’s great for things like cross members and rails because it’s easy to bolt to and easy to join (weld or both) with other members.  It’s also easy to protect from the elements.  Perhaps most important, Angle is often joined with other materials for a particular job – like this.  Angle comes in dozens of sizes and configurations (equal length legs or different length legs).

Disadvantages:  When using Angle for auxiliary beams, it does many jobs really well.  It’s not the strongest section in any direction, so use it for braces, and where you need things attached.

Applications:  Too many options to list.  Angle is in most of our metal fabricating plans in one way or another.  It is one of the most versatile beam shapes.

I-Beam

. . . is the quintessential beam profile.  The design is super strong in the vertical direction, yet has a uniform and equal response to other forces.  It has the best strength to weight ratio (vertical) making it a great DIY beam profile — for Cranes, and for the main beams of big and/or long trailers.  Also, it’s open section makes it fairly easy to protect.

Disadvantages:  The classic I-Beam shapes have angled flanges which do cause some issue when bolting.  (Not the case with non-classic beam profiles.)  Also, there are not a lot of sizes (in comparison to rectangular tube).  That said, there are variations of the classic I-Beam — like W sections and H sections shown below.  Others also exist — especially when you look at shapes for aluminum and other materials.  Finally, I-Beams don’t handle torque very well.

Some I-Beam Shapes as Variations.

Applications:  As in the advantages above, I-Beams do well for longer beams with a higher load.  Things like Crane top beams and things like long trailers with stiffness and/or strength concerns.  H-Beams are frequent for vertical columns.

Solid Sections

. . . are represented above by flat stock, but this category covers all of the variations of height and thickness.  Solid sections include things like sheetmetal up to thick, square bar stock, so it’s hard to categorize.  Solid beam shapes are easy to bolt to and are easy to use for short connective pieces like gussets.  The flat and perpendicular sides make drilling easy too (at least in one direction).  This beam profile is very versatile especially when we add in all the fabricated and bent beam shapes.

Disadvantages:  These materials are usually quite strong in one direction, but (depending on thickness) flimsy in the other. They do not handle long unsupported spans well.

Applications:  Frequently used as gussets and connectors, and for overlapping strengthening pieces.  Also for shims or thickness stacks.  Flat, solid sections are often bent to provide additional function or places for bolting.  Here’s an example of how to bend metal in a reasonably accurate way.

Fabricated Beams

There are an infinite number of different ways to fabricate a beam.  The sky is truly the limit.  While many DIY projects like trailers use standard beam shapes, sometimes a fabricated beam satisfies a special need.  Mostly, fabricated beams are made from standard shapes, but when complete, they are their own animal.  Sometimes we fabricate beams to address space concerns, or special strength or stiffness concerns.  However, the biggest need is to achieve strength and stiffness with a lower overall weight.  Here is an example.

Fabricated Beam Construction Example

Disadvantages:  The big loss with fabricated beams is the time and effort to set them up and fabricate them.  Often they require a lot of cutting and welding and measuring.  Sometimes special jigs or fixtures.  However, if they make what you’re going for happen, then the amount of work is less of an issue.

Applications:  All sorts of special reasons.  The sky’s the limit.

Note:  Fabricated beam shapes are exactly what you get when adding material to strengthen a trailer frame.  Or, when welding in added sections to lengthen a frame.

Choosing The Best Beam Shapes Profile

Beams come in all the different types because we need them for many reasons.  In the table above we mentioned several characteristics that are common to certain beam shapes in the context of DIY projects, and especially trailers.  In other words, different areas of a project need different things, so we select a beam profile for those needs.

Think about why each beam is there.  Does it have bending loads?  Or Torsional loads?  Or loads parallel to the axis?  What about ease of construction via welding or bolting or both?  Does finish or not matter for it?  Are there pieces that require a bent shape?  (Not many of the shapes above will form well even in a press.)

The above applies generally to most DIY projects that use Steel or Aluminum for structural integrity.  Certainly Cranes, Presses, and other tools fit this as well.  Next up is applying the above information to specific areas of a trailer frame.

Let us know if this information helps as you plan your next DIY project.

Comments

2 Comments
Inline Feedbacks
View All Comments

We Found These For You . . .

Article
DIY Drilling Steel
Need a hole?  Many of our plans require drilled holes, so here are some Tips about drilling in metal, like steel, as well as in wood, and other materials.

Read The Article

Product
Wider 12 x 32 Tiny House Trailer Plans

For a little more interior room, our widest Tiny House Trailer plans also include full engineering as a mobile foundation.  Low 12’ x 30’ or 32’ top deck.  Up to 18,000 lbs total capacity.

Article
Trailer Sway Video Review
Understanding Trailer Dynamics like Sway is a really important.  If you look for it, there are many articles and some great YouTube videos discussing and demonstrating the many factors and issues.

Read The Article

Article
Low & Lean Trailer Suspension
A unique trailer suspension offering a low profile, tuning possibilities, and more. By design, the concept offers complete tandem axle load sharing via a common coil spring which is a big plus. Though different than a torsion axle suspension, this…

Read The Article

Article
Study of Torsion Axles In Triple
Torsion axles are awesome, so Why not use torsion axles in tandem?  It’s a frequent question, along with the corollary “Why shouldn’t I have torsion axles in triple?” Good questions, especially in light of all the misinformation

Read The Article

Article
How To Make A Trailer Longer
Sometimes I wish my trailer was longer.  Is there an easy way to make a trailer longer?  Is that even possible?  And, what are the limits

Read The Article

Product
Water Barrel Storage Center

Store water for emergencies in a system that’s easy to use, and more important, easy to replenish the water -- so it’s always fresh when you need it.  Uses plastic 55 gallon barrels for an easy build.

Article
There's More To Just Mounting Trailer Axle Springs
As with many things, there’s a lot more to mounting trailer axle springs than first meets the eye.  Here are 2 tips to make your trailer frame stronger.

Read The Article

Article
Aligning Misaligned Holes
Sometimes, despite your best efforts, holes you drill for a project don’t quite align with those in the mating parts.  It’s maddening, and sometimes you feel dumb because it’s messed up, but there are ways to fix

Read The Article

Article
Failure -- Trailer Hitch / Unhitch Crash
The trailer hitch and surrounding hardware are OH so important — with safety as the priority.  Here are examples illustrating one success and one horrific failure.

Read The Article

Article
A Unique Trailer Project
There is always something to learn when looking at someone’s DIY project.  This customer story about a unique trailer build is no exception.

Read The Article

Product
6x14 Utility Trailer Plans

Get your 6x16 Utility Trailer Plans here, then build your own 7000 lb. capacity tandem axle workhorse.  These plans include all the details and instructions.  Build it, and make it better than you can buy it.

Article
Finishing or Trailer Frame Painting
(And finishing other DIY Projects.) Now you’ve invested all that time and effort into building an awesome trailer, how should you finish it?   Of course we don’t want it to rust.  And, we want it to last. 

Read The Article

Product
5x10.5, 2 Place, ATV Trailer Plans

Our smallest ATV and off road vehicle specific trailer plans.  Great for taking 2 ATV’s out, yet small enough for towing without a big truck.  The size also makes for easier storage between the fun trips.

Article
Ways to Make a Trailer Wider
So, I have this trailer, but it needs it to be bigger.  Is it possible to make a trailer wider?  Can I make it wider to carry more?  And, what are the limits or problems with making it wider?

Read The Article

Article
Good Trailer Design Article Updates
The most popular pages on Synthesis about Trailer Design now have a fresh revision.  May, 2017.  They include more content, more pictures, and a mobile friendly web design.

Read The Article

Product
20ft Tiny House Trailer

Since a great house starts with a solid foundation, these Tiny House Trailer plans focus on that goal.  Low 8.5’ x 20’ top deck height.  Up to 14,000 lbs total capacity.  Fully Engineered.

Product
6'10" x 16' Flatbed Trailer Plans

A large utility trailer, at full (legal) width and 16’ length -- with options for 12,000 lbs or 16,000 lbs capacity.  Trailer plans include many options for you to configure it to your specific needs.

Product
8.5' x 16' 7000 lbs Deck Over Trailer Plans

With a full flat deck, these plans show how to build a workhorse of a deck-over trailer.  Options are plentiful, including ramp sizes, deck types, sides options, rub rails, front rise rail and more.

Article
Converting a Trailer
The concept of re-purposing or converting a trailer is absolutely awesome.  My hat’s off to anyone who can find a way to reuse and convert something from end-of-life to new-again.  We need more of that in our world!

Read The Article