Spirally welded steel wind towers: Buckling experiments, analyses, and research needs

Abstract

The most common wind tower structure, a tapered tubular steel monopole, is currently limited to heights of ~80m due to transportation constraints which arise because tower sections are manufactured at centralized plants and transported to site for assembly. The need to transport the sections imposes a limit on their size, whereby maximum tower diameters are dictated by bridge clearances rather than by structural efficiency. New manufacturing innovations, based on automated spiral welding, may enable on-site production of wind towers, thereby precluding transportation limits and permitting the manufacture of taller towers, which can harvest the steadier, stronger winds at higher elevations. Taller towers, however, are expected to have crosssections with slenderness that is uncommon in structural engineering (i.e., diameter-to-thickness ratios up to ~500) and much larger than those of conventionally manufactured towers (i.e.,

00.02: Developments in research and assessment of steel structures: Highlights from the perspective of an American researcher

“…KTS is a startup company focused on efficient on-site production of high hub height steel wind turbine towers using tapered spirally welded steel towers. Spiral welding has long been used in pipeline production, the novelty here is in (a) the introduction of the taper, and (b) the fact that the on-site nature of the system allows for much larger diameter towers than can currently be shipped/trucked [119]. The spiral welding introduces unique imperfections into the tower and large-scale testing [120] and detailed shell finite element collapse modelling [121] has been conducted to determine the impact of these manufacturing changes and to support structural engineering design of future towers.…”

Erratum

“…In terms of steel wind turbines (WT), factors playing a key role in design are: the large number of cycles which are relevant to fatigue; the stability behavior of the tubular tower, and connections. [2][3][4][5] Besides these constraints directly affecting measurement of the loadbearing structure, cyclical excitation by the rotor also causes many further dynamic phenomena in the area surrounding the WT. The heated debate about thresholds for vibration and the disruptive influences uncovered during seismic measurements motivated the authors to undertake the present study.…”

“…As can be seen in Figure10, local curvature in the elastic line increases as the number of bending half cycles increases. This local curvature indicates the restraining moment and correlates directly to movement of the foundations 4…”

A Novel Tripod Concept for Onshore Wind Turbine Towers

“…Other interesting concepts for steel towers include telescopic towers [64,65], wavy shells for improved local buckling resistance [66,67], self-erecting towers [68] and spirally welded steel tubes [69]. For the latter solution, on-site welding has also been contemplated [70], which if realized would create new opportunities for a wide range of promising concepts.…”