本文介绍的方法——指数内力法(Index stress method),对于分析平行弦桁架的杆力非常简捷,应用此法可很快计算出桁架各杆件的内力。 桁架各杆件的内力(指数内力和实际内力)均可在桁架示意图上直接写出。所谓指数内力,就是用杆件的垂直分力来表示的杆件内力。斜杆和直杆的垂直分力可用静力法直接求 The method described in this paper, the Index stress method, is very simple for analyzing the rod forces of parallel chords. Using this method, the internal force of each rod of the truss can be quickly calculated. Internal forces (exponential internal force and actual internal force) of each member of the truss can be written directly on the truss diagram. The so-called index of internal force, is the vertical component of the rod to represent the internal force of the rod. Oblique and straight rod vertical component can be used directly static method