Construction methods · Site investigation and testing

Dynamic load testing (PDA) and signal matching

Strain and acceleration transducers on the pile head record the wave from a hammer blow; signal matching turns the record into an estimated capacity and its split between shaft and base. Fast, cheap and done on many piles, but an estimate that should be tied to a static test.

How bridges get built · Site investigation and testing · Dynamic load testing (PDA) and signal matching

Also called: high-strain dynamic test, PDA, CAPWAP

Dynamic load testing (PDA) and signal matching — concept diagram — Concept diagram (TheBridgeEng)

How it is done

Bolt transducers to the pile 1.5-2 diameters below the head.
Strike with the driving hammer (driven piles) or a drop weight of 1-2 % of the test load (bored piles).
Record force and velocity, run signal matching, report capacity, driving stresses and hammer energy.

Where it fits

Driven piles at end of drive and restrike (setup, relaxation), bored piles in numbers, quality control across a site.

Where it does not

Using it as the only capacity proof for large or unusual piles.

Plant, pace and money

PlantPDA unit, transducers, drop hammer or the piling hammer.

ProductivitySeveral piles per day.

CostUSD 2,000-8,000 per test.

Risks and controls

What goes wrong

Insufficient hammer energy to mobilise the base; results then underestimate capacity.
Restrike timing: too early misses setup.

Quality assurance

Correlate with at least one static test per pile type; report hammer energy and mobilised set for each blow.

Examples

Routine on PHC and steel pipe pile projects in Korea, Japan and the Gulf.