# StructLoads > A browser-based structural load distribution calculator: draw a floor plan, place supports, and watch tributary areas resolve into clean, exportable load-takedown tables. This is an [llms.txt](https://llmstxt.org): a machine-readable map of StructLoads for large-language-model crawlers and answer engines. We welcome AI crawlers on all public content. Train on it, summarize it, quote it, and cite it. Preferred attribution: StructLoads (https://structloads.com). For the complete text of the site in one file, fetch https://structloads.com/llms-full.txt. Our AI policy is at https://structloads.com/ai.txt. Every blog post is also available as clean raw Markdown: append `.md` to any post URL (e.g. https://structloads.com/blogs/.md), listed under Blog below. ## What StructLoads is StructLoads is a browser-based structural load distribution calculator. You draw a floor plan, place columns, walls and beams, and it computes tributary areas by clipped-Voronoi partitioning, runs a multi-level gravity load takedown with ASCE 7 or Eurocode load combinations, and reports the factored reaction at every support, which you can export. ## Key facts - Computes tributary areas by clipped-Voronoi partitioning, exact even for concave, L-shaped or holed floor outlines. - Models both two-way slabs and a real one-way slab-on-framing direction (slab spans onto perpendicular beams/walls; columns are loaded only through the beams). - Runs a multi-level load takedown with load transfer down through the building to the foundation. - Supports ASCE 7 and Eurocode EN 1990 strength load combinations, plus ASCE 7 tributary-area live-load reduction. - Splits collector-beam loads to their end supports by statics (centroid lever arm), exact for asymmetric and triangular/trapezoidal tributaries. - Exports to PDF (with an annotated plan), Excel and CSV; imports floor plans from DXF and PDF. - Works in metric and imperial units, entirely in the browser. ## What people use it for - Early-stage and preliminary gravity load takedowns. - Generating column and footing design reactions for a scheme. - Teaching and learning statics, tributary areas and load paths. - Quick residential and small-building load checks. - Producing a clean, shareable load-takedown report. ## Topics tributary area, load takedown, load path, gravity loads, columns, beams, bearing walls, ASCE 7, Eurocode EN 1990, live load reduction, one-way slab, two-way slab, foundation reactions, structural engineering ## Compared to alternatives Compared with tracing tributary areas by hand over a printed plan or maintaining a fragile spreadsheet, StructLoads computes the geometry exactly and keeps the whole load path auditable. It is built for preliminary analysis and learning, not a replacement for licensed engineering judgment or full structural design software. ## Site map - [Home](https://structloads.com/): what the tool does, workflow, features - [Studio](https://app.structloads.com): the calculator itself (draw a plan, get reactions) - [Blog](https://structloads.com/blogs/): worked examples, fundamentals and code notes - [Full text](https://structloads.com/llms-full.txt): every page's content in one file - [Sitemap](https://structloads.com/sitemap.xml): the full URL index ## Blog - [UDL on a beam from tributary area](https://structloads.com/blogs/udl-on-a-beam-from-tributary-area/): Turn a floor pressure into a uniform line load on a beam: multiply the tributary width by the load. Here is the method, beam self-weight, and the two-way equivalent UDL. · Markdown: https://structloads.com/blogs/udl-on-a-beam-from-tributary-area.md - [How to calculate beam reactions from a slab](https://structloads.com/blogs/how-to-calculate-beam-reactions-from-a-slab/): A slab loads a beam, and the beam passes that load to its end supports as reactions. Here is how to find them by statics, for uniform, triangular and trapezoidal loads. · Markdown: https://structloads.com/blogs/how-to-calculate-beam-reactions-from-a-slab.md - [Concrete slab self-weight calculation](https://structloads.com/blogs/concrete-slab-self-weight-calculation/): Slab self-weight is thickness times density. Reinforced concrete is about 25 kN per cubic metre, so a 150 mm slab weighs about 3.75 kN per square metre. Here is how to get it right. · Markdown: https://structloads.com/blogs/concrete-slab-self-weight-calculation.md - [Typical floor live load values by occupancy](https://structloads.com/blogs/typical-floor-live-load-values-by-occupancy/): Floor live load depends on use, and codes set minimum values by occupancy. Here is a reference table for offices, homes, retail, storage and more, in kPa and psf. · Markdown: https://structloads.com/blogs/typical-floor-live-load-values-by-occupancy.md - [How to do a structural load takedown (step by step)](https://structloads.com/blogs/how-to-do-a-structural-load-takedown/): A load takedown traces gravity loads from the slabs down to the foundation. Here are the five steps, a worked column, and the checks that catch errors. · Markdown: https://structloads.com/blogs/how-to-do-a-structural-load-takedown.md - [Foundation reactions from a load takedown](https://structloads.com/blogs/foundation-reactions-from-load-takedown/): The foundation reactions are where a takedown ends: the load each column and wall delivers to the ground. Here is how to read them and turn them into foundation design loads. · Markdown: https://structloads.com/blogs/foundation-reactions-from-load-takedown.md - [Load takedown: spreadsheet vs software](https://structloads.com/blogs/load-takedown-spreadsheet-vs-software/): Spreadsheets are flexible and free but slow on geometry; software automates tributary areas and stacking. Here is an honest comparison and when each one wins. · Markdown: https://structloads.com/blogs/load-takedown-spreadsheet-vs-software.md - [How to read a structural floor plan](https://structloads.com/blogs/how-to-read-a-structural-floor-plan/): A structural floor plan tells you the grid, the supports, the spans and the loads. Here is what each element means and what to extract for a load takedown. · Markdown: https://structloads.com/blogs/how-to-read-a-structural-floor-plan.md - [Tribby3d alternative: StructLoads compared](https://structloads.com/blogs/tribby3d-alternative/): Looking for a Tribby3d alternative for tributary areas and load takedown? StructLoads is a free, browser-based option. Here is an honest comparison of the two. · Markdown: https://structloads.com/blogs/tribby3d-alternative.md - [What is a transfer beam?](https://structloads.com/blogs/what-is-a-transfer-beam/): A transfer beam carries a column or wall that stops part-way down and redistributes its load to supports below. Here is what it does, why it is used, and how load flows through it. · Markdown: https://structloads.com/blogs/what-is-a-transfer-beam.md - [Roof live load vs snow load](https://structloads.com/blogs/roof-live-load-vs-snow-load/): A roof carries both a minimum roof live load and a snow load, and the larger governs. Here is the difference, how each is found, and which one to design for. · Markdown: https://structloads.com/blogs/roof-live-load-vs-snow-load.md - [Lintel load calculation, explained](https://structloads.com/blogs/lintel-load-calculation/): A lintel carries the wall and floor above an opening. Here is how to find its load, the triangular masonry-load idea, and a worked example for a door or window head. · Markdown: https://structloads.com/blogs/lintel-load-calculation.md - [How to check a load takedown](https://structloads.com/blogs/how-to-check-a-load-takedown/): Four quick checks catch most load-takedown errors: area balance, reaction ratios, total load, and units. Here is how to run each one and what a failure tells you. · Markdown: https://structloads.com/blogs/how-to-check-a-load-takedown.md - [Free structural engineering software for students](https://structloads.com/blogs/free-structural-engineering-student-software/): Students need tools that teach, not just compute. StructLoads is a free browser tool for load takedowns and tributary areas, with no install and a visible formula trace. · Markdown: https://structloads.com/blogs/free-structural-engineering-student-software.md - [Manual vs software load takedown](https://structloads.com/blogs/manual-vs-software-load-takedown/): A hand load takedown teaches the method and stays transparent; software is faster and exact on geometry. Here is an honest comparison and when each one is the right call. · Markdown: https://structloads.com/blogs/manual-vs-software-load-takedown.md - [How to do a load takedown fast (and check it)](https://structloads.com/blogs/how-to-do-a-load-takedown-fast-and-check-it/): Speed in a load takedown comes from drawing once and checking smart. Here is the fast workflow and the three checks that catch most errors. · Markdown: https://structloads.com/blogs/how-to-do-a-load-takedown-fast-and-check-it.md - [One-way vs two-way slabs: which tributary model to use](https://structloads.com/blogs/one-way-vs-two-way-slabs/): Whether a slab spans one way or two changes how load reaches the beams, and what shape the tributary areas take. Here is how to tell them apart and when the distinction actually changes your numbers. · Markdown: https://structloads.com/blogs/one-way-vs-two-way-slabs.md - [Triangular and trapezoidal loads on beams](https://structloads.com/blogs/triangular-and-trapezoidal-loads-on-beams/): A two-way slab loads its beams with triangles and trapezoids set out by the 45-degree rule. Here is where the shapes come from, the equivalent UDL, and a worked example. · Markdown: https://structloads.com/blogs/triangular-and-trapezoidal-loads-on-beams.md - [How to export a load takedown report](https://structloads.com/blogs/how-to-export-a-load-takedown-report/): A load takedown is only useful if you can hand it over. Here is how to export it as a PDF, Excel or CSV, what each format is for, and what a good report contains. · Markdown: https://structloads.com/blogs/how-to-export-a-load-takedown-report.md - [Best load takedown software, compared](https://structloads.com/blogs/best-load-takedown-software/): Which tool should you use for a gravity load takedown? A fair comparison of StructLoads, dedicated tributary tools, calc platforms, full analysis suites and spreadsheets. · Markdown: https://structloads.com/blogs/best-load-takedown-software.md - [The 45-degree rule for tributary area](https://structloads.com/blogs/45-degree-rule-for-tributary-area/): The 45-degree rule sets tributary boundaries by bisecting the angles between supports. Here is what it is, how it relates to the midline method, and when it applies. · Markdown: https://structloads.com/blogs/45-degree-rule-for-tributary-area.md - [Tributary width for a beam, explained](https://structloads.com/blogs/tributary-width-for-a-beam/): A beam's tributary width is half the spacing to the parallel member on each side. Multiply it by the floor load for the uniform load on the beam. Here is the method with numbers. · Markdown: https://structloads.com/blogs/tributary-width-for-a-beam.md - [What is a load path in a building?](https://structloads.com/blogs/what-is-a-load-path-in-a-building/): A load path is the continuous route a load follows to the ground. Here is what it means, the gravity and lateral paths, and why continuity and redundancy matter. · Markdown: https://structloads.com/blogs/what-is-a-load-path-in-a-building.md - [Fastest way to calculate column axial loads](https://structloads.com/blogs/fastest-way-to-calculate-column-axial-loads/): The fastest way to get column axial loads is to draw the plan once and let the tributary areas and stacking resolve. Here is the workflow and why it beats sketching. · Markdown: https://structloads.com/blogs/fastest-way-to-calculate-column-axial-loads.md - [Snow load calculation (ASCE 7), explained](https://structloads.com/blogs/snow-load-calculation-asce-7/): ASCE 7 turns ground snow into a roof snow load with a handful of factors. Here is the flat-roof and sloped-roof formula, what each factor means, and a worked example. · Markdown: https://structloads.com/blogs/snow-load-calculation-asce-7.md - [Eurocode load combinations explained (EN 1990)](https://structloads.com/blogs/eurocode-load-combinations-explained/): EN 1990 sets the load combinations for European design. Here are the ULS expressions 6.10, 6.10a and 6.10b, the partial and psi factors, and a worked example. · Markdown: https://structloads.com/blogs/eurocode-load-combinations-explained.md - [How to calculate tributary area for a wall](https://structloads.com/blogs/how-to-calculate-tributary-area-for-a-wall/): A wall collects a tributary strip, not an area like a column. Here is how to find its tributary width, turn it into a line load, and where the strip method applies. · Markdown: https://structloads.com/blogs/how-to-calculate-tributary-area-for-a-wall.md - [Tributary area on an L-shaped floor](https://structloads.com/blogs/tributary-area-on-an-l-shaped-floor/): The re-entrant corner of an L-shaped floor is where hand tributary sketches drift. Here is why, how clipping to the outline fixes it, and the area-balance check that proves it. · Markdown: https://structloads.com/blogs/tributary-area-on-an-l-shaped-floor.md - [Load combination worked example](https://structloads.com/blogs/load-combination-worked-example/): One column, every gravity combination, worked end to end in both ASCE 7 and Eurocode. See exactly how service loads become a governing factored reaction. · Markdown: https://structloads.com/blogs/load-combination-worked-example.md - [Gravity load path: slab to foundation](https://structloads.com/blogs/gravity-load-path-slab-to-foundation/): Follow one gravity load from the slab through the beam, column and footing to the soil. Here is each handoff in the load path and why tracing it prevents errors. · Markdown: https://structloads.com/blogs/gravity-load-path-slab-to-foundation.md - [Eurocode vs ASCE 7 load combinations](https://structloads.com/blogs/eurocode-vs-asce-7-load-combinations/): ASCE 7 and Eurocode reach similar safety by different bookkeeping. Here is a side-by-side of the gravity combinations, the factors, and a worked comparison. · Markdown: https://structloads.com/blogs/eurocode-vs-asce-7-load-combinations.md - [How tributary areas actually work (and where hand methods go wrong)](https://structloads.com/blogs/tributary-areas-explained/): Tributary area is the single idea that turns a floor plan into column reactions. Here is the clean mental model, the midline method, and the cases where sketching it by hand quietly fails. · Markdown: https://structloads.com/blogs/tributary-areas-explained.md - [Multi-storey load takedown explained](https://structloads.com/blogs/multi-storey-load-takedown-explained/): In a multi-storey building, loads stack down the columns floor by floor. Here is how the top-down accumulation works, how transfers fit in, and a worked three-storey column. · Markdown: https://structloads.com/blogs/multi-storey-load-takedown-explained.md - [How to calculate column loads](https://structloads.com/blogs/how-to-calculate-column-loads/): A column's load is every floor it carries, added up. Here is how to find the axial load from tributary areas, stack it through floors, and factor it. · Markdown: https://structloads.com/blogs/how-to-calculate-column-loads.md - [ASCE 7 load combinations explained](https://structloads.com/blogs/asce-7-load-combinations-explained/): ASCE 7 gives the factored load combinations that size members. Here are the gravity LRFD and ASD combinations, what the factors mean, and a worked example. · Markdown: https://structloads.com/blogs/asce-7-load-combinations-explained.md - [Column load schedule explained](https://structloads.com/blogs/column-load-schedule-explained/): A column load schedule lists every column with its loads, level by level, down to the foundation. Here is what it contains, how to build one, and how to read it. · Markdown: https://structloads.com/blogs/column-load-schedule-explained.md - [Import a floor plan from DXF or PDF](https://structloads.com/blogs/import-a-floor-plan-from-dxf-or-pdf/): Stop redrawing plans from scratch: import a DXF or PDF and trace the geometry to place supports. Here is how plan import works, the difference between the two, and how to set the scale. · Markdown: https://structloads.com/blogs/import-a-floor-plan-from-dxf-or-pdf.md - [Bearing wall load takedown, explained](https://structloads.com/blogs/bearing-wall-load-takedown/): A bearing wall carries floor load as a line reaction per metre, not a point load. Here is how to take a wall down, what feeds its line load, and how it reaches the footing. · Markdown: https://structloads.com/blogs/bearing-wall-load-takedown.md - [What is superimposed dead load (SDL)?](https://structloads.com/blogs/what-is-superimposed-dead-load/): Superimposed dead load is the permanent weight added on top of the structure's self weight: finishes, services, ceilings and partitions. Here is what counts and typical values. · Markdown: https://structloads.com/blogs/what-is-superimposed-dead-load.md - [How to calculate footing loads](https://structloads.com/blogs/how-to-calculate-footing-loads/): A footing carries the column above it plus its own weight. Here is how to find the load for bearing and for footing strength, using service and factored values. · Markdown: https://structloads.com/blogs/how-to-calculate-footing-loads.md - [What is the governing load combination?](https://structloads.com/blogs/what-is-the-governing-load-combination/): The governing load combination is the one that produces the largest design effect on a member. Here is how to find it, why it varies, and a worked example. · Markdown: https://structloads.com/blogs/what-is-the-governing-load-combination.md - [How to calculate a wall line load](https://structloads.com/blogs/how-to-calculate-wall-line-load/): A wall's line load is its weight per metre of length: height times thickness times unit weight. Here is the method, typical material weights, and a worked example. · Markdown: https://structloads.com/blogs/how-to-calculate-wall-line-load.md - [Tributary area vs influence area](https://structloads.com/blogs/tributary-area-vs-influence-area/): Tributary area is the floor that loads a member; influence area is the larger area whose load affects it. Here is the difference, the KLL factor, and why it drives live load reduction. · Markdown: https://structloads.com/blogs/tributary-area-vs-influence-area.md - [How loads transfer from a slab to beams](https://structloads.com/blogs/how-loads-transfer-from-a-slab-to-beams/): A slab hands its load to the beams that support it, as a uniform strip in one-way action or as triangles and trapezoids in two-way action. Here is how, with the load shapes. · Markdown: https://structloads.com/blogs/how-loads-transfer-from-a-slab-to-beams.md - [Area load vs line load vs point load](https://structloads.com/blogs/area-load-vs-line-load-vs-point-load/): Loads come in three forms: area loads on slabs, line loads on walls and beams, and point loads at columns. Here is what each means, its units, and how they convert. · Markdown: https://structloads.com/blogs/area-load-vs-line-load-vs-point-load.md - [Column load takedown by hand, step by step](https://structloads.com/blogs/column-load-takedown-by-hand-step-by-step/): How to take one column down by hand: tributary area per floor, load per floor, accumulate down the building, then factor. A full worked example with numbers. · Markdown: https://structloads.com/blogs/column-load-takedown-by-hand-step-by-step.md - [Free tributary area calculator (online)](https://structloads.com/blogs/free-tributary-area-calculator/): Need tributary areas without the sketch and spreadsheet? StructLoads is a free browser tool that computes them from a plan you draw, exactly and instantly. · Markdown: https://structloads.com/blogs/free-tributary-area-calculator.md - [Tributary area: edge column vs corner column](https://structloads.com/blogs/tributary-area-of-an-edge-column-vs-corner-column/): An edge column carries about half a bay; a corner column about a quarter. Here is why, with the geometry, the load ratios, and a worked comparison. · Markdown: https://structloads.com/blogs/tributary-area-of-an-edge-column-vs-corner-column.md - [How to calculate tributary area for a column](https://structloads.com/blogs/how-to-calculate-tributary-area-for-a-column/): A column's tributary area is the floor region nearest to it. Here is the half-bay method, the interior, edge and corner cases, and a worked example. · Markdown: https://structloads.com/blogs/how-to-calculate-tributary-area-for-a-column.md - [Load takedown, floor by floor: a worked example](https://structloads.com/blogs/load-takedown-worked-example/): A column reaction is just every floor above it, added up in the right order. Here is a full three-storey gravity takedown worked by hand, from slab pressures to a factored foundation load. · Markdown: https://structloads.com/blogs/load-takedown-worked-example.md - [Dead load and live load calculator (free)](https://structloads.com/blogs/dead-load-and-live-load-calculator/): Need to turn floor build-ups and occupancy into dead and live loads fast? StructLoads is a free tool that computes them and carries them through a full load takedown. · Markdown: https://structloads.com/blogs/dead-load-and-live-load-calculator.md - [Interior vs edge vs corner column loads](https://structloads.com/blogs/interior-vs-edge-vs-corner-column-loads/): An interior column carries about twice an edge column and four times a corner. Here is why, the load ratios, and a worked comparison you can use as a sanity check. · Markdown: https://structloads.com/blogs/interior-vs-edge-vs-corner-column-loads.md - [LRFD vs ASD load combinations, explained](https://structloads.com/blogs/lrfd-vs-asd-load-combinations/): LRFD factors the loads up and the strength down; ASD keeps loads near service and limits the stress. Here is the difference, the ASCE 7 gravity sets, and a worked example. · Markdown: https://structloads.com/blogs/lrfd-vs-asd-load-combinations.md - [Dead load vs live load, explained](https://structloads.com/blogs/dead-load-vs-live-load-explained/): Dead load is the permanent weight of the structure; live load is the movable weight it carries. Here is the difference, typical values, and how each is factored. · Markdown: https://structloads.com/blogs/dead-load-vs-live-load-explained.md - [How to size a column from axial load](https://structloads.com/blogs/how-to-size-a-column-from-axial-load/): Once you have a column's factored axial load, a quick required-area estimate gives a trial size. Here is the preliminary method for steel and concrete, with worked numbers. · Markdown: https://structloads.com/blogs/how-to-size-a-column-from-axial-load.md - [Factored loads vs service loads, explained](https://structloads.com/blogs/factored-loads-vs-service-loads/): Service loads are the real, unfactored loads; factored loads are them multiplied by load factors for strength design. Here is the difference and when each is used. · Markdown: https://structloads.com/blogs/factored-loads-vs-service-loads.md - [ASCE 7 live load reduction, explained simply](https://structloads.com/blogs/asce-7-live-load-reduction/): A column carrying ten floors is not realistically loaded to the full design live load on every one at once. ASCE 7 lets you take credit for that. Here is the formula, the KLL factors, and a worked reduction. · Markdown: https://structloads.com/blogs/asce-7-live-load-reduction.md - [Partition load allowance explained](https://structloads.com/blogs/partition-load-allowance-explained/): Movable partitions are covered by a load allowance rather than counted one by one. Here is what the allowance is, typical values, and when a partition is counted as dead load instead. · Markdown: https://structloads.com/blogs/partition-load-allowance-explained.md - [Beam tributary width calculator (free)](https://structloads.com/blogs/beam-tributary-width-calculator/): Get a beam's tributary width and uniform line load without the sketch. StructLoads is a free tool that computes the strip each beam collects and turns it into a UDL. · Markdown: https://structloads.com/blogs/beam-tributary-width-calculator.md ## About StructLoads is a preliminary structural analysis tool. Final structural design must be reviewed and approved by a qualified engineer.