Why is there so much BIM software?
There is Revit, there is Tekla, there are structural analysis packages. And yet deciding the hook angle and development length of a single bar is still done by a person. Let us start with why.
Published July 22, 2026·Last checked · July 2026
Key points
- BIM is a process; BIM software is the tool that carries out that process — no single tool does all of it
- Integrated structural calculation, BIM authoring, detailing/fabrication and rebar add-ins solve different problems
- Between them lies the layer that determines the physical reality of each individual bar, and neither the standards nor the platforms have filled it
1BIM is not the name of a tool
BIM (Building Information Modeling) is a process. It is a way of collecting and using the information generated across a building's life cycle on the basis of a three-dimensional information model, and BIM software is the tool for carrying out that process effectively.
So “we have adopted BIM” carries almost no information on its own. It only means something once you say with which tool, at which stage, and how far.
Designing and building a single structure involves software of quite different kinds. For an RC frame, it divides roughly like this.
Integrated structural calculation
Structural analysis
BIM authoring
Detailing & fabrication
Clash & coordination
Visualisation
Automation & programming
2Each tool solves a different problem
Of these, four families bear directly on reinforcement in an RC frame. Each solves a different problem.
| Family | Representative tools | Problem solved |
|---|---|---|
| Integrated structural calculation | SS7 · BUILD.一貫 · SEIN La CREA analysis-focused — MIDAS Gen · ETABS · SAP2000 · RFEM · STAAD.Pro | Determines member sizes and the required amount of rebar — is it safe? |
| BIM authoring platform | Revit · Archicad · Civil 3D · SketchUp | Models the whole building and produces drawings — what does it look like? |
| Detailing · fabrication | Tekla Structures · Advance Steel | Details members to a fabrication-ready level — a lineage that began with steel |
| Rebar add-ins | SOFiSTiK Reinforcement · GRAITEC PowerPack · Naviate Rebar · CADS RC3D | Generate rebar inside the BIM platform |
Each tool solves its own problem well. Structural calculation gets the rebar quantity right, the BIM platform handles the whole building, and detailing tools produce fabrication information. The problem is what sits between them.
3Structural calculation only answers “how much”
What structural calculation gives you is a section/rebar schedule table. Column main bars 12-D25, hoops D13@100 — grade, diameter, count and pitch. Up to that point it is an answer to “how much is needed”.
But that is not enough to cut, bend and assemble rebar on site. Whether to bend the hook to 90° or 135°, where and how far to take the development, where to put the lap splices, how column bars and beam bars pass one another at a joint — those judgements remain.
But the calculation is closer to the beginning of design than the end of it. Its results pass through structural design to become drawings, and those drawings must then be translated into reinforcement for construction before anyone can cut a bar on site. Each step answers a different question.
| Step | Question it answers | What gets decided here | Output | Who does it today |
|---|---|---|---|---|
| ① Structural analysis | Is it safe? | Member sizes · required amount of rebar grade · diameter · count · pitch | Calculation report · section schedules | Analysis software — automated |
| ② Structural design | On what basis will it be reinforced? | Member layout · how the code and the standard details are to be applied | Structural drawings general arrangement · standard details | The structural engineer — supported by CAD and BIM |
| ③ Reinforcement for construction | How will it actually be built? | The shape of each individual bar hook angle · development length · splice position and method · clash avoidance at joints · order length | Rebar placing drawings · bar bending schedule (BBS) | A person — the judgement of an experienced engineer |
| ④ Fabrication · assembly | Can it be made as drawn? | Cut lengths · bend shapes · assembly sequence | Cut and bent bar · site assembly | The fabricator · the steel fixer |
Between “how much is needed” and “how it will be built” lies one layer.
It is in that layer that the actual geometry of each individual bar is decided. And until now, that layer has been filled by people.
4Why that layer is empty
The reason is simple. These judgements sit in an area where code interpretation and site experience mix. Rebar placement codes give conditions but do not enumerate every situation, and where bars crowd together — at joints, for instance — adjustments are needed to satisfy the code while still physically fitting.
So this work has long remained the tacit knowledge of experienced engineers. Judged from experience on 2D drawings, then resolved on site. Software left this space empty not out of laziness, but because translating the codes into program logic is hard.
Sources
This article is a summary compiled from published material. It is not a legal interpretation and does not constitute advice. Regulation changes frequently, so please check the original documents and the latest notices from the responsible authority before relying on it in practice.