• 作者： 楊永斌; 徐慶昌
• 作者服務機構： 國立台灣大學木工程學系
• 中文摘要： 本文採用連體力學中之虛功法，來推導I型梁之控制方程式及邊界條件，不論為守恒或非守恒荷載均可適用，本文所建立之增量平衡式可作為特徵值或增量非線性分析之基礎。在推導中，曾以Vlasov的薄壁梁假設來描述斷面之位移，同時引進各種非線性應變，使得各種構件力不穩定效應，皆能被考慮到。文中所提及的非守恒荷載有從動力，軸向力矩及從動力矩等三種，非守恒力之特性在於受旋轉時會產生引量，此種引量對外虛功之貢獻必須加以考慮。本文之理論因具廣義性，可作為複雜構架穩定分析之依據。
• 英文摘要： A systematic approach is used to derive the governing differential equations and boundary condi-tions for an I-beam subjected to nonconservative as well as conservative loadings. Using the present ap-proach, either an eigenvalue or incrementally nonlinear analysis can be performed. The method of formula-tion adopted here is the principle of virtual work in its updated Lagrangian form. Vlasov's assumptions forthin-walled beams are used for describing the cross-sectional displacements of the I-beams. Due to theinclusion of various nonlinear strains in the virtual work equation, the instability effects caused by variousmember actions have been taken into account. Three types of nonconservative forces are considered：thefollower force, axial moment, and follower moment. The effects of nonconservative forces are consideredby incorporating their induced quantities due to rigid body rotations in the external virtual work terms.The generality of the present theory enables one to study the instability of structural frames subjected tovarious nonconservative lodings.
• 中文關鍵字： beam; flutter; farmed structures; instability; nonconservative systems; stability
• 英文關鍵字： --