liminfoRebar Reference
Free reference guide: Rebar Reference
About Rebar Reference
This Rebar Reference provides a comprehensive quick-lookup for reinforcing bar specifications based on the Korean Design Standard (KDS 14 20 50). It covers deformed bar sizes from D10 through D35, including nominal diameter, cross-sectional area, unit weight, perimeter, and typical structural applications for each size. Steel grades SD400, SD500, and SD600 are documented with yield strength, tensile strength, and elongation requirements.
Development and splice length calculations are a critical part of reinforced concrete design. This reference includes tension development lengths for both small bars (D10-D16) and large bars (D19-D35), hooked development lengths with the Ldh formula, and compression development lengths. Modification factors for top bars, epoxy-coated bars, and lightweight concrete are provided alongside each calculation.
Reinforcement detailing for beams, columns, slabs, walls, and footings follows KDS provisions with practical values. The reference covers stirrup and tie spacing, minimum steel ratios, cover requirements, standard hook geometry (90-degree, 180-degree, 135-degree), bar spacing rules, mechanical splice grades, and quantity takeoff methods including standard allowances for waste.
Key Features
- Complete D10-D35 rebar specifications with nominal diameter, area, unit weight, and perimeter
- SD400, SD500, and SD600 grade properties including yield strength, tensile strength, and elongation
- Tension development length tables for small and large diameter bars per KDS 14 20 50
- Hooked and compression development length formulas with modification factors
- Class A and Class B tension lap splice lengths with practical rounded values
- Mechanical splice types (coupler, sleeve, swaging, grouted) with SA/A/B performance grades
- Standard reinforcement details for beams, columns, slabs, walls, and footings
- Quantity takeoff calculation methods with standard allowances for straight, bent, and field waste
Frequently Asked Questions
What rebar sizes does this reference cover?
It covers all standard Korean deformed bar sizes from D10 (9.53mm nominal diameter) through D35 (34.9mm). Each entry includes nominal diameter, cross-sectional area, unit weight in kg/m, perimeter, and recommended structural applications such as stirrups, slab main bars, or column main bars.
How are tension development lengths calculated?
Tension development lengths follow KDS 14 20 50 for fck=27MPa and SD400 steel. For small bars (D10-D16), basic Ld values range from 300mm to 500mm. For large bars (D19-D35), values depend on the cover-to-bar spacing ratio (cb+Ktr). Modification factors of 1.3x for top bars, 1.5x for epoxy coating, and 1.3x for lightweight concrete apply.
What is the difference between Class A and Class B lap splices?
Class A splices (1.0x Ld) require that the provided steel area is at least twice the required area and that no more than half the total reinforcement is spliced at the same location. If either condition is not met, Class B splices (1.3x Ld) must be used. The reference shows rounded practical values for each bar size.
What steel grades are included?
Three grades are documented: SD400 (fy=400MPa, fu>=560MPa), SD500 (fy=500MPa, fu>=620MPa), and SD600 (fy=600MPa, fu>=720MPa). Elongation requirements vary by bar size, and the elastic modulus Es is 200,000 MPa for all grades.
Does the reference include reinforcement detailing?
Yes. It provides standard reinforcement details for beams (main bars, stirrup spacing at D10@200 general and D10@100 near supports), columns (minimum bar counts, tie spacing, hoop requirements for seismic zones), slabs (one-way main bar and distribution bar spacing), walls (vertical and horizontal bar ratios), and footings (bar direction, cover, and dowel bar anchorage).
How do I calculate rebar quantities?
The reference includes the quantity takeoff method: total weight equals total bar length multiplied by unit weight. It covers straight bar length calculations (member length minus cover plus splice/development length), stirrup length formulas including hooks, and standard allowances of 3% for straight bars, 5% for bent bars, and 2-3% for field waste.
What hook geometry dimensions are provided?
Three standard hook types are documented: 90-degree hooks (12db extension, minimum inside bend radius of 3db for D10-D25 or 4db for D29-D35), 180-degree hooks (extension of max 4db or 65mm), and 135-degree stirrup hooks (6db extension). These dimensions follow KDS standards for proper anchorage.
Are mechanical splice specifications included?
Yes. Four mechanical splice types are covered: threaded couplers, sleeve compression, swaging (cold-formed), and grouted splices. Performance grades include SA (1.25x fy, for seismic applications), A (fy minimum), and B (0.9x fy minimum), allowing engineers to select the appropriate grade for their design requirements.