Hong Kong RC beam shear resistance.

Evaluate the applied shear stress, concrete contribution, minimum or designed vertical links, resistance from the selected link arrangement, and the Code’s maximum shear-stress limit.

Current publication basis

This page uses the Code of Practice for Structural Use of Concrete 2013 (2020 Edition) and the Buildings Department amendment state through April 2024. It is not a Buildings Department approval calculation.

declared calculation basis

Move from stress to a buildable link ratio.

The calculation implements the ordinary beam-region route in Hong Kong Concrete Code clause 6.1.2.5. It assumes the longitudinal steel used in A_s continues and is anchored as required beyond the section.

Applied and concrete shear stress

EQUATION 6.19v = V/(b_vd)

TABLE 6.3 EXPRESSIONv_c = (0.79/1.25)(100A_s/b_vd)^1/3(400/d)^1/4(f_cu/25)^1/3

The reinforcement percentage is limited to 0.15–3.0 for the table expression. The concrete-strength multiplier is applied above 25 MPa with f_cu capped at 80 MPa. In the calculator, A_sv/s is derived from the selected link diameter, leg count, and spacing, such as 2-leg T10 @ 200; longitudinal A_s is derived from its beam-bar count and diameter, such as 4T20. Because this page requires minimum links, the (400/d)^1/4 factor is not taken below 1.

Vertical links

TABLE 6.2A_sv/s_v ≥ b_vv_r/(0.87f_yv) or b_v(v − v_c)/(0.87f_yv)

The minimum-link stress v_r is 0.4 MPa up to f_cu = 40 MPa and 0.4(f_cu/40)^2/3 above it. Designed links replace the minimum expression when v exceeds v_c + v_r. The absolute stress limit is min(0.8√f_cu, 7 MPa), and the longitudinal spacing screen is 0.75d.

What this page does not check

Enhanced resistance close to supports, axial-force corrections, prestressing, bent-up bars, torsion, or shear–torsion interaction.
Transverse link-leg spacing, anchorage, curtailment, cover, congestion, laps, fire, fatigue, durability, or SLS.
Deep beams, corbels, pile caps, openings, interfaces, joints, slabs, punching shear, or discontinuity regions.
Loading, combinations, analysis, or professional submission requirements.

code basis

Check the current Code and amendments.

Use the Code of Practice for Structural Use of Concrete 2013 (2020 Edition) with the applicable amendments. This ordinary beam-region subset is not a complete shear, torsion, or detailing design.