Design Beam

Take a span, a load, and a trial section, and show the arithmetic that says whether it works. The arithmetic is the same everywhere. The factors, the properties, and the limits are not, so they come from you.

Workflow

Step 1. Establish the standard and the method

Ask, in one message:

1. Which design standard governs, and which edition? Name the loading standard separately if it is a different document.
2. Which design method: limit states with factored loads, allowable stress, partial factors, or another? This decides what I ask for next, so I will not assume.
3. Material: steel, sawn timber, glulam, or reinforced concrete.
4. How will you supply values? Type them, paste the table, or name a file.

If the answer to 2 is unclear, stop. Running an allowable-stress check with factored loads, or the reverse, produces a confident number that is wrong by the size of the factors.

Step 2. Collect geometry and loads

Geometry. Clear span. Tributary width. Confirmation that both ends are simply supported. Bracing: continuous, or the brace spacing if discrete. Discrete bracing stops the run unless you confirm the section is fully braced at that spacing.

Loads, unfactored and separated by source. Dead. Live, with the category if your standard reduces live load by category. Snow. Roof live. Rain. Point or partial loads with their locations. Self-weight, either included in the dead load or added after a trial section is chosen, stated either way.

Deflection. The limit, as a fraction of span, and which loads it applies to. Name the row it came from. Camber, if any.

Anything unstated is missing. Never substitute a typical value, and never assume a load is zero because it was not mentioned.

Step 3. Collect the values

For each of these, accept a typed value with its citation, a pasted table to read it out of, or a file to read. If none arrives, the run stops at that point and says which value it is waiting for. Do not proceed with a placeholder.

Value	Needed for
Load combinations, written out	Factoring the loads
Live load reduction rule, if any	Reducing live load
Material strength values	Capacity
Modulus of elasticity	Deflection
Adjustment or resistance factors, each named	Capacity
Section properties for the trial section	Demand and deflection
Deflection limit	Serviceability

For timber, ask which adjustment factors apply and what each one is, rather than accepting a single combined figure. A combined factor nobody can decompose is not checkable.

Step 4. Compute, showing every step

Print the arithmetic, not the result.

Loads
  <each load, as given, with units>
Combination used            <written out, cited>
  factored line load        <arithmetic>
Demand
  moment                    <formula, then arithmetic>
  shear                     <formula, then arithmetic>
Capacity
  <each input, cited>
  moment capacity           <formula, then arithmetic>
  shear capacity            <formula, then arithmetic>
Ratios
  moment demand/capacity    <value>
  shear demand/capacity     <value>
Deflection
  <inputs, cited>
  computed                  <arithmetic>
  limit                     <as given, cited>
  ratio                     <value>

Every line of input carries where it came from. If any input is unverified, the result for that line reads unverified, not a number.

Step 5. If no trial section was given

Do not name one. Instead, rearrange the check and report the section property required: the section modulus or moment of inertia the demand implies at the capacity the user's factors give. Then say plainly that they should pick a section with at least that value from their own tables and come back with it.

This is the one place the skill would be most tempted to recall a section designation, and it is exactly where a recalled number is least detectable.

Step 6. Report

The ratios, the governing check, and the deflection result. The list of anything unverified. Then:

Every factor, property, and limit here came from you. I did the arithmetic and supplied no engineering values. This is preliminary sizing for a fully braced simple span, and it is not a design. The Engineer of Record designs the beam.

Step 7. Save, if asked

Ask whether to write the calculation to a file and where. Write it directly, including the arithmetic. There is no template and no script.

Rules

• Never supply an engineering value. Not a section property, not a strength, not a factor, not a combination, not a deflection limit. There are none in this file.
• Never name a section from memory. Report the property required instead.
• Confirm the design method before collecting values, and never mix factored loads with allowable stresses.
• Show the arithmetic. A result without its steps cannot be checked, and an unchecked structural number is the worst output this catalog can produce.
• Stop on a missing value rather than proceeding with a placeholder.
• Never convert units, and never round an input to a neater figure.
• Say on every run that this is preliminary and not a design.

Anti-patterns

• Naming a trial section because the span and load make it obvious. That is a recalled value with an engineer's authority attached to it.
• Filling a resistance factor, a load factor, or a modulus from memory because the value is standard. Standards change between editions and between countries.
• Combining timber adjustment factors into one number nobody can decompose.
• Reporting a demand-to-capacity ratio when one of its inputs was unverified.
• Assuming a load is zero because the user did not mention it.
• Bundling a section property table or a factor table into this skill later. It has none on purpose.

Resources

None. This skill is one file. Output is written directly at the path you name.