Compression Behavior Of Thin-walled Circular Short Tubes With Large Diameter-to-thickness Ratio

Wind power is the conversion of wind energy into a useful form of energy, such asusing wind turbines to make electricity, which is widely used in the world. The turbinetower, which plays an important role in supporting the equipment, is mainly subjected tobending moment caused by lateral wind load or earthquake load. Commonly,thin-walled Circular Hollow Section (CHS) is widely used in wind turbine towers toincrease the flexural rigidity. With the increase of the tower height, the tower is alsosubjected to higher vertical load. The wind turbine tower is under the state of bendingmoment combined with axial load. The study on axially loaded CHS tubes is thefoundation of design and analysis of wind turbine towers. In the past, most of researchwork is focused on axially loaded CHS tubes with small diameter-to-thickness ratio,which is used in buildings.Up till to now,there has been little research work for thin-walled circular steel tubessubjected to axial compression. To improve the development of thin-walled wind tuberstowers, it is necessary to study the axial behavior of thin-walled circular steel tubes.Themain works are as follows:(1) Sixteen axial compression tests were performed up to failure on different sizesof thin-walled tubes with diameter-to-thickness ratios D/t ranging from75to300. Theinfluence of diameter-to-thickness ratio on load carrying capacity, failure modes anddeformation abilities is studied. The tests results show that the stability capacitydecreases evidently with the increasing of diameter-to-thickness ratio. Specimens withdifferent diameter-to-thickness ratio exhibit different failure modes.(2)The finite element software ABAQUS is used to develop the model to analysethe axially loaded behaviour of CHS tubes. In the model, the influence of residualstress,, initial geometric imperfections and etc. is considered. The experimental resultsare used to validate the accuracy of finite element results. Based on the finite elementmodel, the influence of initial geometric imperfections, diameter-to-thickness ratio andsteel yield strength on thin-walled circular steel tubes is analyzed.(3) The design methods on thin-walled steel tubes are introduced clearly, whichinclude AISC Specification, Canada S16-09Standard, The Eurocode3Standard and AS4100code. The results based on different design codes are compared with each other,and compared with plenty of experimental results. Based on the comparison, the designguidelines are proposed.