Being a relatively young industry in the US, the utility-scale wind industry has recently started to produce domestic design documents-standards and guidelines-to better coordinate requirements of the US building codes with the international (European) standards in dominant use throughout the wind industry. While wind farm tower structural analysis and design are becoming more and better documented, this paper will attempt to go yet further into unknown and undocumented tower structural engineering topics as encountered in daily practice. Examples of such topics with little or no treatment in the engineering literature include the causes and repairs of tower dents, flange gaps, and splice bolt fatigue failure. Also discussed are unresolved questions regarding mysterious out-of-round creep of tower sections and whether conventional transport methods could cause tower damage. This paper's target audience includes stakeholders in the utility-scale wind energy industry, specifically: (1) structural design professionals; (2) project/construction managers; (3) plant operations and maintenance managers; (4) engineers involved in tower transport or erection; and (5) subsets of the aforementioned groups involved in code and standards development. This paper has the following learning outcomes: (1) to provide examples of typical tower damage and their repairs; (2) to provide a glimpse of tower structural engineering practice issues that are seldom documented in the industry literature; and (3) to describe unresolved issues as a first step for more industry discussion.
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