鋼薄肉I形桁の横ねじれ耐荷力に関する研究 ULTIMATE STRENGTH OF THINI-WALLED I-SHAPED BEAMS DUE TO LATELAL-TORSIONAL INSTABILITY

博士論文

In general, beams and girders are accompanied by bending moments about the major axis due to the applied loads. They are proportioned to have a greater stiffness in the loading plane. When they are not surriciently braced against lateral derlection and twisting, they become an unstable state before the in-plane strength is reached. This dissertation presents the theoretical and experimental study concerning the lateral-torsional instability of thin-valled I-beams and it consists or six chapters. Brief description on each chapter is given below : Chapter 1 : The statement of the problem and review of previous investigations. Chapter 2 : Two methods of analyzing the elastic and inelastic large-displacement bebavior of horizontally curved I-beams are presented. One is based on the transfer matrix method and the other based on the finite element method. Two computer programs based on these methods have been developed and some numerical examples are also presented. Chapter 3 : The relationship between the lateral-torsional buckling load and the ultimate load-carrying capacity of- beams and the effect of the types of residiual stress distribution, as Well as the loading conditions and the geometrical imperfection levels on the ultimate load-carrying capacity are analytically examined using the transfer matrix method. Chapter 4 : The lateral-torsional buckling behavior or welded steel girders is studied experimentally and analytically. The experimental program was designed to clarify the effect of- moment gradient against the lateral instability of girders in the inelastic range. The experimental ultimate load-carrying capacity or girders is compared with the analytical predictions by the finite element method based on the finite displacement theory. Chapter 5 : Based on the analytical and experimental study, the lateral-torsional strengths or rolled beams and welded girders under moment gradient are determined by the simplified formulas. Manual method of calculating the lateral-torsional strengths of laterally continuous beams and girders is also presented. Chapter 6 : The conclusions obtained from Chapters 2 through 5 are summarized.

名古屋大学博士学位論文 学位の種類 : 工学博士(論文) 学位授与年月日 : 昭和61年1月8日