Monopile Foundation Stiffness Estimation of an Instrumented Offshore Wind Turbine through Model Updating

Table 5

Equivalent seabed level macro-element properties of embedded depthwise-varying-foundation models, predicted using the PISA, API/DNVGL, and API/DNVGL-Kallehave soil reaction models. High stiffness represents a manually derived overstiff foundation model, for use in the subsequent model updating.

Foundation model	Equivalent coupled spring )			Equivalent compliance )
	k11 (N/m)	k22 (Nm)	k12 (Nm/m)	C11 (m/N)	C22 (Nm^−1)	C12 (m/Nm)
PISA	3.73	162.29	−16.73	49.78	1.15	−5.13
API/DNVGL	1.64	122.94	−9.994	121.59	1.62	−9.88
API/DNVGL-Kallehave	2.59	131.38	−12.50	71.64	1.41	−6.81
High stiffness	4.41	175.52	−18.00	39.00	0.98	−4.00
Ensemble model updated	2.87	190.35	−16.78	72.05	1.085	−6.35