A Failure Witness for Informal Construction Scaffolds: Design and Computed Detection Budget of a Low-Cost Tell-Tale Set for Bamboo and Timber Scaffolds

Design and computed detection budget of a passive witness set (plumb lines, tie presence tags, sacrificial annealed-copper tie-load links, latching ledger-deflection tear strips, and water-tube settlement markers against an independent datum) for informal bamboo and timber construction scaffolds. SIMULATED, NOT MEASURED; nothing was built or field-tested. For a 12 m high, 20 m long reference scaffold the set costs $44.70. It detects gradual overload at 1.5x service load (2.54x below ledger bending failure), tie overload at 3.0 kN against anchor pull-out at 5.0 kN (the anchor itself fails at 22.6 m/s wind, below the 28 m/s design wind), and settlement at 3 mm with 44 days lead at 0.5 mm/day. It does not detect lateral impact at all: a forklift strike carries 5.2x the energy a standard can absorb.