D25 Tie-Rod Horizontal Bracing: 56 Rods, 1,466 kg, M24 Threads

English Version

Title: 56 Tie Rods, 1,466 kg: D25 Horizontal Bracing With M24 Threads

Overview

Horizontal bracing in a plant roof is usually a tie rod, not a brace frame. A round bar runs diagonally between two frame lines, takes tension only, and is adjusted by nuts at both ends. It weighs a few kilos, installs in minutes, and does the job a heavy braced frame would do at ten times the steel.

This shed uses D25 round bars: 56 rods in 17 lengths, 1,465.66 kg total, with 300 mm M24 threads at each end.

Material Data (from Drawing)

表格

How the Connection Works

• Threaded ends, not welded lugs. Each rod end is threaded M24 over 300 mm; a nut at each end pulls the rod tight against the frame.
• Tension only. A tie rod works in tension; under the opposite wind direction it goes slack instead of pushing. That is why the rods are crossed in pairs.
• Adjustment on site. The 300 mm thread length allows the rod to be tensioned and to take up erection tolerances in the frame spacing.
• Light and stiff enough. D25 at about 3.85 kg/m gives a 6.9 m rod around 26 kg — one man carries it, and it adds real stiffness to the roof plane.

Advantages

1. Very light — 1,466 kg for 56 rods covers a whole shed roof; a braced frame would weigh several times more.
2. Cheap — round bar plus two threaded ends; no plate fabrication, no welding.
3. Fast to install — two men, a spanner, and a tension check; no crane time beyond lifting the bundle.
4. Adjustable — the 300 mm thread absorbs frame spacing errors and lets you tension the rod after erection.
5. Easy to inspect — a slack rod is obvious; you check tension by hand and by sound.

Disadvantages / Limitations

1. Tension only — the rod cannot take compression; bracing must be crossed so one rod always works.
2. Slender, prone to vibration — long D25 rods can vibrate in wind; pre-tensioning is needed to keep them taut.
3. Thread is the weak point — the M24 thread reduces the section at the ends; that is where a rod fails.
4. No bending capacity — anything that pushes sideways on the rod (a falling object, a person leaning) bends it.
5. Corrosion on the thread — exposed threads rust first; the nut seizes if not greased and painted.

Typical Use Cases

1. Roof plane bracing in portal frames — the standard cross-braced tie rod layout, as in this schedule.
2. Wall plane bracing — same rod, vertical plane, to stop the frame racking.
3. Crane runway and gable bracing — tension rods tying the end frames.
4. Canopies and open sheds — light roofs where a braced frame would be overkill.
5. Temporary and prefab structures — rods ship flat and tension on site.

Fabrication and Installation Notes

• Rod: D25 Q235B, cut to the 17 lengths in the schedule; check the overall length against the frame diagonal before threading.
• Thread: M24, 300 mm at each end; roll or cut, then check with a ring gauge.
• Fit-up: set the rod in the frame diagonal, insert the end into the clevis or plate hole, fit the nut.
• Tension: tighten both ends evenly; a slack rod does nothing, an over-tightened rod pre-loads the frame.
• Cross pairs: install both diagonals of a cross before tensioning either.
• Protection: grease the threads, paint the rod, and re-check tension after the roof deck is complete.

Bottom Line

Fifty-six D25 rods, 1,465.66 kg, 300 mm of M24 thread at each end — that is a whole shed's horizontal bracing for the weight of one small beam. It works because a tie rod only pulls, and a crossed pair always has one rod pulling. Keep them tensioned, keep the threads greased, and the roof plane will stay square.

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