🏋️ Structural Load Calculator

Dead load (DL) is the permanent, static weight of the structure itself — concrete slab, beams, columns, finishes, and fixed partitions. It does not change over time. Live load (LL) is variable and depends on the occupancy and use of the building — people, furniture, stored goods, and equipment. Live loads are less predictable, which is why they have a higher load factor in design codes (1.5–1.6×) compared to dead loads (1.2–1.35×).

Tributary area is the floor area whose load is carried by a specific structural member (column, beam, or wall). For an interior column in a regular grid, it is typically the product of half the bay spans in each direction. For example, a column in a 6×8 m bay grid supports 3×4 = 12 m² tributary area. Tributary area is used to convert distributed floor loads (kN/m²) to a point load (kN) on the column.

Load factors (also called partial safety factors) are multipliers applied to characteristic loads to account for uncertainty and variability. BS EN 1990 (Eurocode) uses 1.35 for dead loads and 1.5 for live loads. ACI 318 uses 1.2 DL + 1.6 LL. These factors ensure the structure has adequate safety margin against unforeseen overloads, material variability, and construction tolerances. The factored load is used for strength design (checking member capacity).

A 150mm reinforced concrete slab weighs approximately 3.75 kN/m² (150mm × 25 kN/m³). Adding 50mm screed (~1.2 kN/m²), floor finishes (~0.5 kN/m²), and lightweight partitions (~1.0 kN/m²) gives a typical total dead load of 5–6.5 kN/m² for a standard office floor. Heavier finishes (stone, thick screed) or heavy plant equipment can increase this significantly.