Research On Seismic Performance And Seismic Control Of Combo Steel Tube Towers With Large Crossing Transmission Lines

Towers with Large Crossing Transmission lines (TLCTL) are high-rise and long span structural systems, which are widely used important lifeline power engineering establishment. It has important economic and social significance to remain TLCTL's main structures safe and reliable under accidental earthquake. TLCTL is 3-dimensional complicated tower-line coupled vibration system, which have an obvious characteristic is continuum that it consists of high-rise steel towers and long span transmission lines. At present, the high-voltage transmission towers which are TLCTL's main supporting parts, are usually assembled by steel angles at home and abroad. Lately, steel tube towers and combo steel tube towers are extensively adopted in transmission line engineering because steel tubes have good sectional mechanical property and beautiful external shapes. The main reason to cause transmission tower to be failed is dynamic action besides static load. So to ensure TLCTL safe and reliable under accidental earthquake is paid more and more attention to by engineers and researchers.With ANSYS, a finite-element-method program, it is established a new analytical-numerical model combining beam and truss elements of combo steel tube TLCTL, which is one practical 220 kV transmission line engineering over Pearl River. Dynamic characteristics of the TLCTL and single towers are analyzed by subspace iteration method. By comparing the first period of theoretic value with that of approximate formula value, a revised approximate formula to estimate the 220SZK's free vibration period without cables is gained which improve result accuracy. Then, by analyzing parameter of the TLCTL's dynamic characteristics and single tower, qualitative coupled effects of the transmission lines on towers along transverse and longitudinal directions are obtained. In addition, by deducing the simplified formula of transmission lines tower which consulted interrelated theories and researches, a practical and visualized simplified model with equivalent stiffness is obtained. Dynamic characteristics of equivalent stiffness simplified model is analyzed by introducing the optimum equivalent stiffness coefficient α,β along transverse and longitudinal directions. Analytical data indicate that vibration mode of the TLCTL are extraordinary close, and majority is cable's vibration modes. In order to simply-exactly acquiring dynamic characteristics of the tower coupled cable effects, the time-history responses of the tower are acquired by inputting White-noise wave. Using frequency-domain analyses, the vibration mode of tower coupled cable effects can be identified. Environmental vibration test was carried out in engineering site, which further verified FEA model and vibration mode validity.On the other hand, firstly, nonlinear static calculation for finite element model was analyzed subjected to deadweight action. Secondly, considering TLCTL's structure strain...