Experimental study on the joint load-bearing behaviour of segmented concrete towers under combined loading

Abstract

Hybrid towers have become increasingly established for tall wind turbines. The concrete part of these towers consists of several stacked circular ring segments. To reduce the amount of fabrication and erection effort, the joints between the segments are usually designed as dry ground joints. This paper presents experimental investigations aimed at determining the torsional load-bearing capacity of such dry ground concrete joints subjected to combined loading of prestressing, bending and torsion. Based on previous investigations, a test set-up consisting of three circular ring segments was developed. The torsional load-bearing capacity was determined by monitoring the tangential joint displacements in detail. The test results demonstrate that an increasing bending load leads to a uniform decrease in the torsional load-bearing capacity. The comparison with the current calculation model shows significant differences and confirms the weaknesses of the model regarding its inadequate interaction with the bending load. In contrast, numerical simulations agree well with the test results.