Worked examples, fundamentals and code notes for engineers and students running early load takedowns. Practical, transparent, and tied to how the tool actually works.
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.
A hospital floor is a set of very different zones, not one rate. Scanner masses, shielding, vibration criteria, and the loads hanging from the soffit.
A lift touches the structure in three places: the head, the rail brackets, and the pit. Dynamic factors, shaft walls, and why pits float.
Shelved paper is heavier per square metre than almost anything else a building holds. Static stacks, mobile shelving on rails, and why deflection governs.
Assembly floors are where people really do reach the code value. Unreduced rates, synchronised movement, barrier horizontal loads, stages and stairs.
The method is the same, the proportions are not. Timber self-weight is a quarter of concrete, so live load dominates and connections govern.
The heaviest load a slab carries usually arrives before the building is finished. Wet concrete, props, stacked pallets, and how load shares between levels.
Water is 9.81 kPa per metre of depth, permanent and exact. Depth profiles, tank self-weight, balance tanks, and why an empty pool can govern.
Earth pressure depends on whether the wall can move, not on what it looks like. At-rest versus active, water as its own case, surcharge, and uplift.
A crane never loads a building the way its tonnage suggests. Wheel reactions, hoisting impact, lateral surge, and where each lands in a column takedown.
