【摘要】 本文述一空腹桁架之分析法.該項空腹桁架,不論其上下弦桿之勁度是否相同,只須有平行之腹桿,均可利用本法分析.更多还原

【Abstract】 Vierendeel girders may be divided into two types, the "longitudinally equistiff" and the "longitudinally unequistiff". The term "longitudinally equistiff" means that the upper and the lower chords of the same panel have the same stiffness factor. Longitudinally equistiff Vierendeel girders may be analysed by the Theorem of Three Forces, which is well known in the litera- ture. In this paper, this theorem is presented again but in a more generalized form. The derivations are believed to be more direct. Longitudinally un- equistiff Vierendeel girders may be analysed by the Method of Transformations and Corrections, which is a new method and will be treated in detail. With the method, all the Vierendeel girders, whether they are longitudinal- ly equistiff or unequistiff, whether their loads are applied at or between the joints, whether their chords are curved or parallel, whether their ends are with or without verticals, may be analysed. For longitudinally equistiff Vierendeel girders, the horizental forces in the chords are found first with Formula (1): Then the moments, shears and direct stresses in all the members are found with statics. For longitudinally unequistiff Vierendeel girders, besides the calculations necessary for longitudinally equistiff ones, the end moments in the verticals and chords should be corrected with Formulas (2) and (3): To show the brevity and precision of the method, a numerical example is given.更多还原