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Free reference guide: Structural Load Calculator
About Structural Load Calculator
The Structural Load Reference is a comprehensive, searchable guide to structural design loads based on Korean Design Standard (KDS) provisions and international engineering practice. It covers all primary load categories that structural engineers must consider: dead loads (self-weight of structural elements, finishes, and partitions), live loads by building occupancy type, wind loads with design wind pressure calculations, seismic loads using the equivalent static method, and additional loads including snow, earth pressure, temperature effects, and impact.
Each load category includes specific numerical values ready for design use. Dead load entries provide unit weights for concrete (24 kN/m3), wall types (brick, block, curtain wall, drywall), and roofing materials. Live load tables list values per KDS 41 12 for residential (2.0 kN/m2), office (2.5 kN/m2), retail (4.0 kN/m2), assembly (5.0 kN/m2), and special occupancies. Wind load sections cover basic wind speeds by Korean city, design velocity pressure formulas (qz = 0.5*rho*Vz^2), gust effect factors, and pressure coefficients for walls and roofs.
The seismic load section provides the equivalent static force procedure per KDS 41 17, including base shear calculation (V = Cs*W), response modification factors (R values from 3.25 for OCBF to 8 for SMF and BRBF), importance factors, and story force distribution formulas. The reference also includes complete load combination tables for both ultimate strength design (7 combinations including 1.2D+1.6L) and serviceability checks, as well as special seismic load combinations with redundancy and overstrength factors.
Key Features
- Dead load values for concrete slabs, wall types, roofing, and finish materials with unit weights in kN/m2 and kN/m3
- Live load tables by occupancy per KDS 41 12: residential, office, retail, hospital, factory, library, and more
- Live load reduction formula with tributary area calculation and K_LL factors for columns, beams, and slabs
- Wind load design procedure: basic wind speeds by Korean city (Seoul 26, Busan 30, Jeju 40 m/s) and pressure coefficients
- Seismic load per KDS 41 17: base shear formula, SDS/SD1 calculation, R values for all structural systems
- Snow load, earth pressure, and temperature load parameters with calculation formulas
- Ultimate strength (1.4D, 1.2D+1.6L, etc.) and serviceability load combination tables per KDS 41 12
- Special seismic combinations with redundancy factor (rho=1.0/1.3) and overstrength factor (omega_0=2.5-3.0)
Frequently Asked Questions
What structural loads does this reference cover?
This reference covers all major structural load categories: dead loads (D) including self-weight and superimposed dead loads, live loads (L) with occupancy-specific values, wind loads (W) with pressure calculation procedures, earthquake loads (E) using the equivalent static method, snow loads (S), earth pressure, temperature loads (T), impact loads, and floor vibration criteria. It also provides all standard load combinations for both ultimate strength and serviceability design.
What is the live load for an office building per KDS 41 12?
Per KDS 41 12, the design live load for office spaces is 2.5 kN/m2. Related values include corridors/stairs/lobbies at 5.0 kN/m2, residential at 2.0 kN/m2, retail at 4.0 kN/m2, assembly/restaurants at 5.0 kN/m2, parking (passenger cars) at 2.5 kN/m2, library stacks at 7.5 kN/m2, and light/heavy warehouses at 6.0/12.0 kN/m2. Live load reduction is permitted based on tributary area using the formula L = Lo*(0.25 + 4.57/sqrt(K_LL*A_T)).
How is design wind pressure calculated per KDS 41 12?
Design wind pressure is calculated as p = qz*Gf*Cp - qi*Gf*Cpi, where qz is the velocity pressure (qz = 0.5*rho*Vz^2, rho = 1.225 kg/m3), Gf is the gust effect factor, Cp is the external pressure coefficient (windward wall +0.8, leeward wall -0.5, side walls -0.7), and Cpi is the internal pressure coefficient (+/-0.18 for enclosed buildings). Design wind speed Vd = V0*Kzr*Kt*Kd accounts for height, terrain, topography, and directionality.
What is the seismic base shear formula in KDS 41 17?
The base shear is V = Cs*W, where Cs = SDS/(R/IE). SDS is calculated as S*Fa*2.5*2/3, where S is the mapped spectral acceleration, Fa is the site coefficient, and IE is the importance factor (1.0 for ordinary, 1.2 for schools/assembly, 1.5 for essential facilities). R is the response modification factor, ranging from 3.25 (OCBF) to 8 (SMF and BRBF). Story forces are distributed as Fx = Cvx*V with the vertical distribution factor based on floor weight and height.
What response modification factors (R) are used for different structural systems?
Per KDS 41 17, R values are: Special Moment Frame (SMF) R=8, Intermediate Moment Frame (IMF) R=5, Ordinary Moment Frame (OMF) R=3.5, Special Shear Wall R=6, Ordinary Shear Wall R=5, Special Concentrically Braced Frame (SCBF) R=6, Ordinary Concentrically Braced Frame (OCBF) R=3.25, and Buckling-Restrained Braced Frame (BRBF) R=8. Higher R values indicate greater ductility and energy dissipation capacity.
What are the ultimate strength design load combinations per KDS 41 12?
The seven standard combinations are: (1) 1.4D, (2) 1.2D+1.6L+0.5(Lr or S), (3) 1.2D+1.6(Lr or S)+(1.0L or 0.5W), (4) 1.2D+1.0W+1.0L+0.5(Lr or S), (5) 1.2D+1.0E+1.0L, (6) 0.9D+1.0W, and (7) 0.9D+1.0E. For seismic design, special combinations apply: (1.2+0.2SDS)D+rho*QE+L and (0.9-0.2SDS)D+rho*QE, where rho is the redundancy factor (1.0 or 1.3).
How do I convert slab or wall loads to beam loads?
For one-way slabs transferring to beams, the distributed load is w = q*(L1/2+L2/2) kN/m, where q is the slab load and L1, L2 are adjacent span lengths. For two-way slabs using the 45-degree method, the short-span beam receives a triangular distribution w = q*Lx/3, and the long-span beam receives a trapezoidal distribution w = q*Lx/2*(1-Lx/(3*Ly)). Wall loads transfer as w = wall unit weight per area times wall height in kN/m.
What floor vibration criteria does this reference include?
The reference includes floor vibration serviceability criteria per AISC Design Guide 11. The natural frequency is estimated as fn = 0.18*sqrt(g/delta_s), where delta_s is the static deflection under unit load. Acceptable acceleration limits are 0.5% g for offices, 1.5% g for pedestrian bridges, and 5.0% g for gymnasiums. Generally, a natural frequency above 7-9 Hz is considered acceptable for typical floor systems.