Beam Diagrams
This guide is aimed at civil engineers. It shows how Hurmet can produce a beam diagram, like this one:
A service load analysis, as shown above, is a two-step process. The first step is to define the beam parameters. To do this, open a math zone and write a data frame like this one:
beam =
``#item value
plan △ 12′ △ 10′ △
E 29000 ksi
I 131 in⁴
dead -0.031 kips/ft
live -0.4 kips/ft
live -2 kips, 4′``Let’s go through that data line-by-line.
Line 0 contains headings, but Hurmet doesn't read the words in that line. Write headings in whatever language you want.
Line 1 describes the beam’s nodes and span lengths. Span units can be m, ft, or ′. Nodes are written with the following symbols:
| Restraint Type | Symbol | Alternate Symbol |
|---|---|---|
| pinned | p | △ |
| fixed | f | ⫢ |
| hinge | h | ∘ |
| spring | s | ⌇ |
| pinned hinge | ph | ⫯ |
| no restraint | - | - |
Next come two optional lines. One must be named I, for moment of inertia in in⁴ or cm⁴. The other must be named E, for modulus of elasticity in ksi or MPa. If you omit E and I, Hurmet will not create a displacement diagram.
If the beam contains one or more spring supports, include a line named k, for a spring constant in kips/in or kN/m.
The default moment diagram shows positive moment on the compression side. If you prefer the other convention include a line named +M, whose only datum is ←→.
All the remaining lines will describe loads. Name your loads whatever you want. Point loads can take units of kips or kN. Distributed loads can take units of kips/ft or kN/m. Load locations are measured from the left end of the beam. Moments take units of k·ft or kN·M.
The second step is the easy part. Open a math zone and call the beamDiagram function, like this:
beamDiagram(beam) = @Variations
Distributed Loads
Write the location of a distributed load as a start:stop range. Like the live load in this example:
Write a sloping load as a startLoad:endLoad range.
Units
Hurmet can write output in either SI units or imperial units. It takes its cue from the span lengths in line 1. If those lengths are written in ft or ′, output will be in kips and feet. Input lengths in m or mm will result in output in KN and m. Remember that span lengths without units will be taken as mm.
Load Combinations
Strength-level analysis requires load factors in several different combinations. You can define your own combinations in a data frame.
… then the function call includes an optional argument:
beamDiagram(beam, loadFactors) = @… and the result looks like this:
Yes, the shapes of this diagram are very similar to the first diagram. But look closely. The shear and bending magnitudes are larger.
You can also get patterned live loads by marking a load type with an asterisk:
To get diagrams that automatically update with new data, use string interpolation to define values. For instance, you can write ${L_1} to get the value of .
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