Researchproject
Service life extension of steel structures exposed to dynamic loads in industrial construction
Prof. Dr.-Ing. André Dürr
Department of Civil Engineering
Due to the unstoppable ageing process of the German infrastructure, it is required to develop innovative conservation concepts. Especially the strengthening and refurbishment of steel structures exposed to dynamic loads like e.g. crane runways are essential due to their importance for industrial production processes as the central hub in conveyor technology. It is to be presumed that about half of the existing crane runways exceeded their designed lifetime and their usage is now unregulated by national standards, because there are no concepts of lifetime extension supported by scientifically relevant evidence by now. So there is the danger of spontaneous collapses all the time. This research project is dedicated to the question how a safe and efficient continued use of existing crane runways is possible without the risks of sudden loss of production, accidents and damage to persons.
Crane runways are exposed to dynamic loads and thus at risk of fatigue fracture. Depending on the type of use crane runways are designed for a lifetime of 25 years in accordance with national standards.
The valuation of existing crane runways is significantly more extensive than of structures exposed to static loads. Additional to the VDI-guideline 6200 there are further recommendations and regulations like e.g. regularly inspecting crane runways to detect cracks.
Especially in the case of crane runways the owner is faced with the question what to do after the runway exceeded its designed lifetime. Due to operational processes a complete replacement is often rather inefficient and technically problematic. Because of that there are multiple attempts to extend the lifetime of the crane runway e.g. more detailed design methods, strengthening and increased inspection effort.
The scatter of damages resulting from fatigue loads is larger than that resulting from static loads. Therefore after the calculated lifetime has expired no visible damages have to occur in the form of macro cracks. Due to the unratable influence of non-measurable micro cracks a safe continued use is not possible, which makes the following considerations necessary:
- 1. How can crack-free crane runways strengthened?
- 2. How can a cracked crane runway rehabilitated?
- 3. At what intervals should an existing crane runway inspected?
This results in the following research objectives:
- strengthening solutions for crack-free existing crane runways: investigation of the application of high frequency impact treatment to typical crane runway details
- rehabilitation measures for cracked, existing crane runways: investigation of innovative rehabilitation solutions in form of local reinforcements applied by notch-free executed welding, bolting or adhesives
- determination of inspection intervals: elaboration of recommendations based on component examinations and measures of crack growth
- concluding elaboration of recommendations for practical use and transfer of results to industry
Running duration:
01.04.2021 - 31.03.2024
Funded by:
Bavarian State Ministry for Science and Art