Blast Limits for Transmission Structures. II: Structural Response and Blast Limit Development

Abstract

To ensure power transmission safety, loss of structural integrity of critical transmission facilities due to extreme events, such as strong ground motions induced by blasting, should be avoided. This research intends to establish a vibration safety limit for electric power transmission poles close to blasting events through actual field monitoring and finite-element (FE) simulation of transmission structure dynamic behaviors. In this paper, structural responses of transmission poles during monitored blasting are used to illustrate the methodology for safety limit establishment. The blast response spectra generated based on peak particle velocities were used as a basis for spectrum analysis performed using validated FE models to obtain the structural displacements, reactions, and stress states. The actual recorded ground vibrations as well as modified acceleration time histories were used as input excitations during transient dynamic analysis. A quantitative blast limit was established by comparing structural responses with corresponding design requirements.