Unveiling Nonlinear Statics and Capacity Profiles of Pre-stressed Spun-Cast Transmission Poles Under Complex Loading via an Efficient Co-Rotational Tapered Beam Element

This paper presents an in-depth investigation into the nonlinear behavior of spun-cast pre-stressed concrete transmission poles when subjected to combined loading from uniform self-weight and a lateral point load applied at the top free end. To accurately capture the pole's capacity and response under these conditions, a nonlinear static (Pushover) analysis is conducted, yielding critical capacity curves that reflect the pole's load-bearing and stability characteristics. An efficient co-rotational tapered displacement-based beam-column element, implemented in the OpenSees software, is utilized to account for large deformations and rotations, enhancing the accuracy of the finite element model. For fully numerical integration, the structure is divided into multiple segments, with nine Newton-Cotes integration points applied along the pole, which enables a precise load distribution and response calculation throughout its length. Modeling the pre-stress strands within the pole is achieved through an initial strain technique applied to an elastic-perfectly plastic element, specifically designed to simulate the response of tension-only members. This approach allows for a realistic representation of the pre-stressed strands' contribution to the pole's overall stability. Additionally, a comprehensive set of geometric and material nonlinear properties is incorporated to reflect the true structural behavior of the pole under complex loading conditions. The findings provide valuable insights into the nonlinear equilibrium paths, load-bearing capacity, and failure mechanisms of pre-stressed transmission poles, offering critical information for the design and assessment of such structures in practice.