Double bolt circle T-flange as an alternative for highly loaded foundation anchor flanges
With constantly growing turbine sizes, in general loads on structural components are increasing. However, for onshore towers transport restrictions still apply. This combines increased loading with fixed geometries which reach the structural limits.
One of these components is the foundation anchor flange. Different to an intermediate steel flange just above it, they suffer in the number of bolts by the minimum secant distance required for concrete works. It creates a bottle neck of structural capacity.
T-Flanges for foundation fit well to intermediate L-flanges within the tower. But with increasing loads with the same diameter - what is the next level of capacity? Intermediate L-flange at low heights may evolve to T-flanges but the foundation anchor T-flange requires an higher capacity too.
The following presentation explains options for a T-flange with double bolt circle at each side. It is technically feasible due to the adequate stiffness ratio between flange and bolt.