TY - CONF

T1 - Experimental investigations of concrete segment tower structures for wind turbines

AU - Klein, Fabian

AU - Marx, Steffen

N1 - Publisher Copyright: © Fédération Internationale du Béton (fib) – International Federation for Structural Concrete.

PY - 2021

Y1 - 2021

N2 - In recent years, so-called hybrid towers have been successfully established to further reduce the costs of wind power generation, especially with large hub heights. The lower part of these tower structures consists of stacked concrete ring segments, whereas the upper part is composed of several steel sections. The individual segment rings are connected by external tendons placed inside the tower and anchored in the foundation and the transition piece. With this innovative tower generation, horizontal joints divide the concrete structure into even smaller components, so that circular ring segments increase transportability and reduce installation effort. At the Institute of Concrete Construction in Hannover, the structural behaviour of segmented tower constructions is analysed and evaluated in large-scale experimental investigations. For this purpose, a tower model with horizontal joints on a scale of approx. 1:10 and bending-resistant restraint at the tower base is constructed and loaded. The objective of these large-scale investigations is to determine the load-bearing behaviour of pre-stressed concrete segment towers with dry joints under normal force (external pre-stressing), bending, lateral force and torsion and to derive more efficient and realistic design models. This paper deals with the results of experimental investigations on the load-bearing behaviour of segmented tower structures. The transfer of shear stresses between individual segments is ensured by frictional resistance in the horizontal joints due to pre-stressing. The current design models are based on plane flange surfaces at the top and bottom of the segments as well as their ideal circular ring shape. This assumes a constant normal stress distribution for the compression connection. Within the large-scale experimental tests, findings for uneven force distribution in the horizontal joints were obtained, that have a significant impact on the design models. However, for the evaluation of the results and the projection onto the real construction components, the scale effects must be urgently taken into account.

AB - In recent years, so-called hybrid towers have been successfully established to further reduce the costs of wind power generation, especially with large hub heights. The lower part of these tower structures consists of stacked concrete ring segments, whereas the upper part is composed of several steel sections. The individual segment rings are connected by external tendons placed inside the tower and anchored in the foundation and the transition piece. With this innovative tower generation, horizontal joints divide the concrete structure into even smaller components, so that circular ring segments increase transportability and reduce installation effort. At the Institute of Concrete Construction in Hannover, the structural behaviour of segmented tower constructions is analysed and evaluated in large-scale experimental investigations. For this purpose, a tower model with horizontal joints on a scale of approx. 1:10 and bending-resistant restraint at the tower base is constructed and loaded. The objective of these large-scale investigations is to determine the load-bearing behaviour of pre-stressed concrete segment towers with dry joints under normal force (external pre-stressing), bending, lateral force and torsion and to derive more efficient and realistic design models. This paper deals with the results of experimental investigations on the load-bearing behaviour of segmented tower structures. The transfer of shear stresses between individual segments is ensured by frictional resistance in the horizontal joints due to pre-stressing. The current design models are based on plane flange surfaces at the top and bottom of the segments as well as their ideal circular ring shape. This assumes a constant normal stress distribution for the compression connection. Within the large-scale experimental tests, findings for uneven force distribution in the horizontal joints were obtained, that have a significant impact on the design models. However, for the evaluation of the results and the projection onto the real construction components, the scale effects must be urgently taken into account.

KW - Concrete segment towers

KW - Dry joints

KW - Large-scale test

KW - Pre-stressed concrete

KW - Wind energy

UR - http://www.scopus.com/inward/record.url?scp=85125532381&partnerID=8YFLogxK

M3 - Paper

SP - 1040

EP - 1049

T2 - fib Symposium

Y2 - 14 June 2021 through 16 June 2021

ER -