Background

A number of significant updates have been made with AS3600:2018 Amdt 2, whose key effects are on the spacing and quantity of shear fitments / ligatures required. ClearCalcs has updated its calculator for consistency with this new amendment. ClearCalc’s concrete calculators affected by Amendment 2 changes are:
  • L-Type Cantilever Retaining Wall
  • Rectangular Concrete Beam
  • Rectangular Concrete Column
  • Concrete Pad Footing
  • One-Way Concrete Flat Slab
  • Concrete Wall Footing

Capacity Reduction Factor (Bending Moment with compression)

  1. Table 2.2.2 (d) has changed the Ξ¦β‚€ factor to be equivalent to Ο•0=0.65Γ—kΟ•\phi_0 = 0.65 \times k\phi. There is a minor impact on the reduction factor where columns are slender or where QG≀0.25\frac{Q}{G} \leq 0.25, refer to calculations for kΟ•k\phi.

Shear Strength

  1. Upper limit shear strength Vu,maxV_{u,\text{max}} has been reduced by 10% in Equation 8.2.3.3(1).
  2. Factor kvk_v (simplified method) increases the concrete shear capacity VucV_{uc} by up to 50% from Amendment 1, in particular for thinner depth sections without reinforcement.
    Previously a limit of kv=0.10k_v = 0.10 was placed for any beam where minimum shear reinforcement was not satisfied or no fitments were provided. This has now been increased to kv=0.15k_v = 0.15. Refer Clause 8.2.4.3(a).

Fitment Detailing / Spacing Requirements

  1. The minimum reinforcement spacing is now relaxed for beams with low shear force. Where Vβˆ—β‰€Ο•Vu,minV^* \leq \phi V_{u,\text{min}}, the fitments may now be spaced at 500mm or 0.75Γ—D0.75 \times D whereas previously 300mm or 0.5Γ—D0.5 \times D limit was imposed under all circumstances apart from very large beams.
  2. For a short column satisfying L<5Γ—depthL < 5 \times \text{depth}, Amendment 2 has introduced minor changes to the max allowable fitment spacing to reflect the actual fitment strength spacing=fsyf500Γ—24Γ—d\text{spacing} = \sqrt{\frac{f_{syf}}{500}} \times 24 \times d instead of spacing=24Γ—d\text{spacing} = 24 \times d previously in accordance with Clause 14.5.4(b).
  3. For beams of depth>300mm\text{depth} > 300\text{mm}, shear fitments are now required even when Vβˆ—β‰€Ο•VucV^* \leq \phi V_{uc}. An additional factor ksk_s has been added factoring down the upper limit shear force that may be taken without adding fitments in Clause 8.2.1.6(1).

Renaming of Variables

  1. DcD_c is now renamed to bb (smaller column cross-sectional dimensions). Refer Clause 1.7.
  2. KsK_s is now renamed to ksk_s (Beam Depth Factor to Determine Reinforcement Required). The definition of KsK_s in Clause 1.7 has not been updated in Amendment 2 from its previous version. It is believed that this definition should be further expanded in future revisions to reflect its use in Clause 8.2.1.6(1).

Assumptions

  1. The above is not a comprehensive list of Amendment 2 changes. However, they do reflect all the changes that are relevant to calculations performed in ClearCalcs.
  2. ClearCalcs concrete calculators utilise the Simplified Method for calculating kvk_v and ΞΈv\theta_v in compliance with Clause 8.2.4.1. Therefore, the Amendment 2 updates for the β€œGeneral Method” in Clause 8.2.4.2 are not listed above. `