# Ringlock Beam Shoring Calculator (Under-Beam Densification) Under-beam densification: how many rows, which transom size the pitch lands on, jacks and braces. - Page: https://jianzhujisuan.com/en/ringlock-beam-shoring - Category: Temporary Works (https://jianzhujisuan.com/en/c/temporary-works) - Chinese version: https://jianzhujisuan.com/zh/ringlock-beam-shoring.md - Data checked: 2026-10-25 ## Quick result With the default inputs (Beam width 0.3 m, Beam depth 0.7 m, Clear span 8 m, Shoring height (floor to beam soffit) 6 m, Standard spacing along the beam 0.9 m, Under-beam standard rows 2 rows, Lift height 1.5 m, Design axial force per standard 15 kN): **Total ringlock weight 1.01 t** ## Inputs | Parameter | Type | Default | Unit | Note | |---|---|---|---|---| | Beam width | number | 0.3 | m | Section width, excluding flanges or slab edges | | Beam depth | number | 0.7 | m | Section depth from soffit to slab underside | | Clear span | number | 8 | m | Clear distance between column faces | | Shoring height (floor to beam soffit) | number | 6 | m | The beam soffit sits one beam depth below the slab, so this is lower than under the slab | | Standard spacing along the beam | number | 0.9 | m | Along the beam, multiples of 0.3 m; 0.6 or 0.9 is usual under a beam | | Under-beam standard rows | number | 2 | rows | Rows across the beam width. Two rows for 300-500 mm beams, three above 600 mm, a single centred row for narrow beams | | Lift height | number | 1.5 | m | 1.5 or 2.0 only; vertical braces are made in those two rises | | Design axial force per standard | number | 15 | kN | Used to select the brace class; take the maximum within one independent frame | | 3.0 m standard | select | In stock | — | | | 2.5 m standard | select | In stock | — | | | 2.0 m standard | select | In stock | — | | | 1.5 m standard | select | In stock | — | | | 1.0 m standard | select | In stock | — | | | 0.5 m standard | select | In stock | — | | ## Formula - **Rows along the beam**: n = floor(clear span ÷ spacing along beam) + 1, one at each end - **Total standards**: N = rows along × rows across - **Even pitch**: b = beam width ÷ (rows across - 1) - **Actual pitch**: Snap b to the nearest B-SG fixed size (300-2400 in 300 mm steps) - **Standard make-up**: Complete knapsack over the ticked lengths only (six stock sizes, each switchable), total length between height - 0.85 m and height - 0.15 m; remainder shared by head and base jacks - **Ledger levels**: n = ceil(actual standard length ÷ lift) + 1; the closing length needs a ledger - **Transverse ledgers**: N = levels x rows along x (rows across - 1), sized to the actual pitch - **Longitudinal ledgers**: N = levels x rows across x (rows along - 1), sized to the spacing along the beam - **Brace class k**: From Table 6.2.2-1 by axial force N and height H, as for slab shoring - **Face braces**: N = 2 x [floor((rows along - 1) ÷ k) + 1] x lifts, one plane on each beam face - **Top lift above 16 m**: Braced in every bay above 16 m, with the normal arrangement counting (lifts - 1) - **Head and base jacks**: One of each per standard - **Beam self-weight line load**: gk = width(m) x depth(m) x 25 kN/m³, plain concrete, excluding formwork, live load and load factors - **Line load per row**: gk ÷ rows across (kN/m) - **Weight**: W = sum of quantity x unit mass from Table A.0.1 (kg) - **Steel per metre of beam**: W ÷ clear span (kg ÷ m = kg/m); the clear span is the beam length on this page, not the overall frame width ## Worked example A 300 x 700 beam over an 8 m clear span with 0.9 m spacing along it, two rows, 6 m shoring height and 1.5 m lifts: nine rows along the beam times two across gives 18 standards, and the 300 mm pitch lands exactly on B-SG-300. Five ledger levels give 45 transverse and 80 longitudinal ledgers, the table puts the braces at three-bay spacing for 18 braces on both faces, and 18 head jacks and 18 base jacks bring the total to about 1.01 t, or 126 kg per metre of beam. Beam self-weight is 5.25 kN/m, or 2.63 kN/m per row and 2.36 kN per standard, before formwork and live load. ## Questions ### How should I set the pitch under a 400 or 500 mm wide beam? This is the awkward band for ringlock beam shoring. The even pitch is 400 or 500 mm, but ledgers only come in 300, 600, 900 and so on. Snapping to 300 keeps both rows inside the beam width with the head jacks directly under the soffit, but the bearers then have to cantilever 50 to 100 mm each side to catch the side forms; snapping to 600 puts the standards outside the beam and loads the head jacks eccentrically, where clause 6.2.4 wants the bearer centred on the jack. Two things are done on site: either go to three rows at 200 to 250 mm pitch, which is not a ringlock ledger size and needs short members or coupler tube, or keep the 600 pitch with the standards outside and use double-channel bearers to bring the load back. Whichever you choose, it has to be drawn in the method statement rather than left to a verbal instruction to tighten up under the beam. The tool shows you the deviation so you know how far the arrangement sits from a standard component. ### Why can't I enter 750 mm spacing under a beam when that is what we use on site? Because 750 mm is not a ringlock ledger size. The B-SG series in Table A.0.1 runs 300, 600, 900, 1200, 1500, 1800, 2100 and 2400 in 300 mm steps, with no 750. The habit comes from coupler scaffolding, where 6 m tube is cut to length and couplers go wherever you put them, so 750 is perfectly possible there. Ringlock is different: the end connectors are fixed, and a ledger either engages the rosette or it does not. Laying out at 0.75 m and ordering 0.9 m members leaves 150 mm in every bay, which accumulates to 1.5 m over ten bays and makes the last member impossible to fit. If you genuinely need 750 mm you are in coupler territory, which is a different system. The practical spacings along a beam are 600, 900 and 1200 mm. ### Should the beam frame be tied to the slab frame? Yes, and it is a favourite thing for inspectors to look at. Under-beam standards and slab standards follow different grids, and if the two frames are built independently with only the beam side form between them, the beam and slab are loaded together at the pour while the two frames settle and sway differently — the beam soffit drops first. Clause 6.2.9 requires the shoring around an opening to act as one frame; it is written about openings, but the reasoning is the same for overall integrity. There are two practical routes: where an under-beam standard sits within 300 mm of the nearest slab standard, share one standard and align the ledgers at the same level; where they are further apart, build them separately but tie the two frames together across the beam with ledgers at every lift. The two outer faces of the beam frame also both need vertical braces, which the tool already counts. ### Can I use the 2.36 kN self-weight figure directly to look up the brace class? No, it is far short. That figure is only the concrete self-weight of the beam carried by one standard. Four things are missing: formwork and falsework weight (soffit and side forms plus bearers and joists, typically 0.5 to 0.75 kN/m²), construction load from pumping and vibration, load coming down from the slab either side over half a bay each, and the load factors of 1.3 for permanent and 1.5 for variable actions. Combined, the design axial force under a beam is commonly 15 to 30 kN, an order of magnitude above the self-weight figure. The tool therefore labels it as reference only: it tells you the order of magnitude is sensible, it does not set the brace class. Use the N from the shoring design, taken as the maximum within one independent frame. ### When the beam and slab are poured together, what gets missed in the shoring take-off? The standards under a beam carry not only the beam but half a slab bay on each side, and that is the usual omission. Take the under-beam frame as carrying the beam plus the affected slab width — beam width plus half a bay each side, so 3.6 m of slab on a 3.6 m bay — total the load over that strip and divide by the number of under-beam standards to get the axial force. Under-beam standards are also spaced tighter than slab standards, 0.6 to 0.9 against 1.2, so the two frames differ in stiffness and must be tied together with ledgers as described above, or the beam soffit settles first and the side forms crack first. On beams deeper than 700 mm the through-ties in the side forms and the soffit shoring are two separate failure modes: a soffit collapse is a shoring shortfall, a blowout is a tie shortfall, and both have to be checked. ## Related tools - [Scaffolding Calculator](https://jianzhujisuan.com/en/scaffolding): Enter the wall perimeter and scaffold height to get the area plus tube, coupler and board quantities. - [Formwork Turnover Calculator](https://jianzhujisuan.com/en/formwork-turnover): Initial formwork area and replacement allowance from total area and cycles. - [Full Scaffold Material Calculator](https://jianzhujisuan.com/en/full-scaffold): Standards, tube length and weight, couplers and board area. - [Formwork Lateral Pressure Calculator](https://jianzhujisuan.com/en/formwork-pressure): Smaller of the two GB 50666 Annex A.0.4 expressions, plus head and critical rate. - [Scaffold Tie Calculator](https://jianzhujisuan.com/en/scaffold-tie): Tie count from perimeter and height, with spacing limits checked. - [Scaffold Dismantle Sequence Calculator](https://jianzhujisuan.com/en/scaffold-dismantle): Lifts to strip, allowable step height, and where the raking props start. --- Generated by BuildCalc. All calculations run in your browser; no data is uploaded. Formulas follow national standards and common trade practice; local codes govern.