- Volume 22 Issue 1
The wind velocity profile over the height of a structure in high intensity wind (HIW) events, such as downbursts, differs from that associated with atmospheric boundary layer (ABL) winds. Current design codes for lattice transmission structures contain only limited advice on the treatment of HIW effects, and structural design is carried out using wind load profiles and response factors derived for ABL winds. The present study assesses the load-deformation curve (capacity curve) of a transmission tower under modeled downburst wind loading, and compares it with that obtained for an ABL wind loading profile. The analysis considers nonlinear inelastic response under simulated downburst wind fields. The capacity curve is represented using the relationship between the base shear and the maximum tip displacement. The results indicate that the capacity curve remains relatively consistent between different downburst scenarios and an ABL loading profile. The use of the capacity curve avoids the difficulty associated with defining a reference wind speed and corresponding wind profile that are adequate and applicable for downburst and ABL winds, thereby allowing a direct comparison of response under synoptic and downburst events. Uncertainty propagation analysis is carried out to evaluate the tower capacity by considering the uncertainty in material properties and geometric variables. The results indicated the coefficient of variation of the tower capacity is small compared to those associated with extreme wind speeds.
transmission towers;downbursts;extreme winds;nonlinear analysis;Monte Carlo technique
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- Two case studies on structural analysis of transmission towers under downburst vol.22, pp.6, 2016, https://doi.org/10.12989/was.2016.22.6.685
- Critical load cases for lattice transmission line structures subjected to downbursts: Economic implications for design of transmission lines vol.159, 2018, https://doi.org/10.1016/j.engstruct.2017.12.043
- Nonlinear inelastic responses of transmission tower-line system under downburst wind vol.123, 2016, https://doi.org/10.1016/j.engstruct.2016.05.047
- New Perspective on Application of First-Order Reliability Method for Estimating System Reliability vol.143, pp.9, 2017, https://doi.org/10.1061/(ASCE)EM.1943-7889.0001280
- Reliability of Tower and Tower-Line Systems under Spatiotemporally Varying Wind or Earthquake Loads vol.143, pp.10, 2017, https://doi.org/10.1061/(ASCE)ST.1943-541X.0001835
Supported by : National Sciences and Engineering Research Council of Canada (NSERC)