Mechanical Behavior of Concrete filled FRP and Steel Double Skin Tube Bridge Column

本文研究了FRP管和钢管双层桥柱(CDST)的受力性能，并与目前公路建设中的高墩标准--埋管混凝土桥柱进行了比较。首先，对轴力和弯矩共同作用下的钢管混凝土构件的强度共同作用曲线进行了估算。特别强调了钢管在强度上的最佳布置。结果表明，内筒尺寸较大的单根内筒截面比多根内筒相对较小的截面具有更好的强度和延性。其次，对钢管混凝土的抗压强度进行了试验研究，与普通钢管相比，FRP外管的抗压强度有明显的提高。据了解，较厚的内部钢管对填充混凝土的限制是不利的，因为它的双向压应力很大。纤维方向的FRP管对填充混凝土具有良好的约束作用，CDST的强度可与CFT相当甚至更好，总重量明显减轻。

Studied herein is the mechanical behavior of FRP tube and steel tube double skin bridge columns (CDST), which have compared with the standard of high piers in the construction of highways recently, namely steel tube embedded concrete bridge columns. First of all, the strength interaction curve of CDST members subjected to axial force and bending moment is assessed. Particular emphasis is placed on the optimum arrangement of steel tubes in strength. It is concluded that the cross section with single and large size of inner tube is superior in strength and ductility compared to that with multiple inner relatively small tubes. Secondly, the compressive strength of CDST was studied experimentally, where the effectiveness of FRP outer tube compared to the ordinary steel tube used in CFT. It is understood that the thicker inner steel tube is eccential to confine the filled concrete, because of its severe biaxial compressive stress condition. It is also concluded that FRP tube with fiber direction in the circumference of tube can provide the good confinement to filled concrete and the strength of CDST can be equivalent or even better that that of CFT, with the significant reduction of the total weight.