THEORETICAL ANALYSIS AND COMPUTATIONAL METHOD FOR NON-UNIFORM TORSION OF THIN-WALLED SPATIAL HELICOID GIRDERS(PART Ⅰ: FUNDAMENTAL THEORY)

in this paper, based on the vector analysis and the warping torsion theory of curved thin-walled girders, a set of governing differential equations for the non-uniform torsion of thinwalled spatial helicoid girders is developed. The method of initial parameters is employed to solve for the bimoment B. The present theory. lays down the foundation for further analysis of thinwalled spatial helicoid girders.