一.关於兩項原理的正确性問題 潘家錚同志在討論的457頁首先指出:“兩端簡支之桁架,在任何荷載作用下,其跨長必有改变。在这点上,桁架与‘拱’或‘曲折梁’相同。…又桁架兩端与柱頂間交互作用之力系必須相符,否則違反了力学上‘作用与反作用力相等相反之原則’。因此,不 I. Regarding the correctness of the two principles, Comrade Pan Jiaxuan first pointed out on the 457th page of the discussion: “The trusses that are simply supported at both ends, under any load, must change their span length. At this point, truss and arches The ’or’ twisted beam’ is the same.... The force system that interacts between the ends of the truss and the column top must match, otherwise it violates the ’opposite principle of equal action and reaction force’ in mechanics. Therefore, no