Abstract: It?is?well?acknowledged?that?the?rationality?of?force?of?arch?ring?can?be?measured?by?the?level?of?concord?between?the?pressure?line?and?arch?axis?concerning?traditional?concrete?arch?bridges.?So?this?concept?is?further?applied?to?all?concrete?structures?like?concrete?beam?bridges?（bending?members）,?multi-line?rigid?frame?bridges?（compression-flexure?members）,?and?soon.?It?is?proved?that?on?the?premise?of?proper?prestress?to?all?concrete?structures,?the?extent?of?eccentricity?of?pressure?line?and?axis?can?always?be?brought?under?control?so?as?to?make?full?section?compressed.?On?this?basis,?an?advantageous?kind?of?eight-shaped?prestressed?concrete?rigid-frame?arch?bridge?is?created?under?certain?circumstance,?and?its?control?area?of?enveloping?curve?of?line?of?pressure?also?applicable?to?all?concrete?structures?is?deduced?to?be?-Ks≤E≤Kx.

Key words: concrete structure , pressure line , axis , concord , enveloping curve of line of pressure , eigh-shaped rigid-frame arch bridge ;

摘要： 对常规混凝土拱桥习惯用压力线与拱轴线的吻合程度来衡量拱圈受力是否合理,将此概念延伸引用于所有 混凝土结构,如混凝土梁桥(受弯构件),多折线刚架(压弯构件)等,提出在合理施加预应力条件下,总可以使压力 线与构件轴线的偏离程度控制在一定范围之内,使全截面处于受压状态。在此基础上提出在适宜条件下具有综合 优势的预应力混凝土八字形刚架拱桥,并推导了其压力线包络图控制区为-Ks??E??Kx。

关键词: 混凝土结构, 压力线, 轴线, 吻合, 压力线包络图, 八字型刚架拱桥