Load paths: how a load actually gets from a slab to the foundation
Every structural check is really answering the same underlying question for one link in a chain — but the chain itself, the actual route a load travels from where it's applied to where it finally leaves the building, is easy to lose track of once each link is checked in isolation.
A load doesn't act directly on the ground — it has to travel through a specific, physical sequence of structural elements to get there, and every one of those elements has to be sized to carry not just its own share of load, but to safely hand that load on to whatever's next in the chain. The most common vertical load path in a framed building runs: a slab picks up distributed load — people, furniture, its own weight — and spans it to the beams framing its edges; those beams collect the slab's reaction and span it further to the columns they frame into; the columns stack that accumulating load story by story down to the foundation; and the foundation finally spreads it out over the soil at a pressure the ground can actually sustain. Every calculator that checks one of these elements is really checking one specific link — but none of them, on its own, tells you whether the whole chain is actually connected and complete.
Why a broken or misunderstood load path is a real failure mode, not just a bookkeeping error
A structural failure doesn't always mean a member's own material gave out under the load it was actually designed for — it can just as easily mean a load never reached the element that was supposed to carry it, because the real path it took on the finished structure wasn't the one assumed at design time. A slab designed as one-way spanning onto beams that, in practice, deflect and pick up load differently than assumed; a column meant to be continuously supported down to the foundation but that actually transfers load through a beam never sized for that extra transfer; a lateral system whose diaphragm — the slab acting as a horizontal beam, collecting lateral load and delivering it to the vertical bracing, walls or frames — was never explicitly checked for that role at all. All of these are genuine load-path failures, not material failures, and they're exactly the kind of thing a set of individually-correct member checks can still miss if the path connecting them was never actually traced end to end.
Enginus's calculators each check one genuine link in this chain — RC Slab Design and RC Beam/Steel Beam Design for the horizontal spanning elements, RC Column Design for the vertical link, Foundation Design for where the load finally reaches the ground — and Load Combination Generator is what actually carries a consistent, correctly factored load value along that whole path, rather than each element being checked against a load figured out independently. Tracing the path itself, though — confirming which element genuinely supports which, and that nothing was left unsupported by assumption alone — is a design decision made by the engineer laying out the structure, not something any single calculator check can verify on its own (see the related tools below).