51.如下图所示等直杆两端固定,设AC、CD、DB三段的轴力分别为FN1、F、F,则AFNFN=0, FN=FB FN=FN=-F, Fn=0C FN =f0
57.如下图所示等直杆两端固定,设AC、CD、DB三段的轴力分别为FN1、F、F,则AFNFN=0, FN=FB FN=FN=-F, Fn=0C FN =f0