When to use: This is an educational animated diagram, not a numeric calculator — it shows how a structural load path actually travels from where a load is applied down through the roof/floor diaphragms, the lateral system, and the columns or bearing walls, into the foundation and finally the supporting soil. Pick a load type below and watch the real path animate in sequence.
Dead and live load on the roof (and every floor above) is carried by tributary area to the roof and floor framing, which deliver it to the columns and bearing walls below. Each column carries the accumulated axial load from every level above straight down to its own footing, which spreads that concentrated load over enough soil area to keep bearing pressure within capacity.
An interactive animated diagram showing how gravity, wind, and seismic loads actually travel through a building's structural system — from roof or floor, through diaphragms and the lateral system, down the columns or shear walls, into the foundation and finally the supporting soil. This is a pedagogical tool, not a numeric calculator: it teaches the real load path each load type follows, using the same terminology as the site's own Structural Engineering Fundamentals and Construction Drawing Handbook illustrated guides.
Pick a load type — Gravity, Wind, or Seismic — and the diagram animates the real structural load path for that load in sequence, using staggered highlighting of the roof, diaphragms, shear wall, and foundation. A text panel explains the path in words, and a numbered sequence list spells out each step alongside the animation.
Gravity loads (dead + live) flow straight down: roof/floor framing to columns and bearing walls to footings to soil. Lateral loads (wind and seismic) flow sideways first — collected by roof and floor diaphragms acting as horizontal beams — then down through the shear walls or braced/moment frames to the foundation. The key difference between wind and seismic: wind is an external pressure on the windward face, while seismic force is generated internally, at each floor's own mass, by ground acceleration (F = m·a).
A load path is only as reliable as its weakest link. A missing connection, an undersized diaphragm nailing pattern, a discontinuous shear wall, or an under-anchored foundation can compromise the entire chain above it — which is why ASCE 7 and the IBC require an unbroken, positively-connected load path from the point of load application all the way to the supporting soil.
No. This is a visualization/education tool that shows the direction and sequence a load path follows — it does not compute load magnitudes, member forces, or capacities. For actual numeric design use the Seismic ELF Simulator, Wind Uplift Calculator, Beam Reactions Calculator, or Shear Wall Design Calculator.
Because that's physically how seismic force is generated: ground shaking accelerates the mass of the structure itself (F = m·a at each floor), producing an inertial force at each level rather than an external pressure like wind. That inertial force still gets collected by the same diaphragms and delivered to the same shear walls as a wind force would be.
A diaphragm is a roof or floor deck (plywood/OSB sheathing, a concrete slab, or metal deck) acting as a horizontal beam that collects lateral force distributed across its area and delivers it, as shear, to the vertical lateral-force-resisting elements (shear walls or frames) at its edges.
A broken load path — a missing hold-down, an under-nailed diaphragm, a discontinuous shear wall from one story to the next — means the load that reaches that point has nowhere positively connected to go, which is one of the most common causes of structural failure in wind and seismic events even when every individual member was otherwise adequately sized.
Try our Civil & Structural Studio
More calculators, simulators, and guides for this discipline.