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

本文研究了FRP管和钢管双层皮桥梁柱的受力性能，并与目前公路建设中的高墩标准--钢管混凝土桥梁柱进行了对比。首先，评估了CDST构件在轴力和弯矩作用下的强度相关曲线。特别强调的是，在强度上的钢管的最佳安排。结果表明，单根大尺寸内管截面比多根相对较小内管截面具有上级的强度和延性。其次，对钢管混凝土的抗压强度进行了试验研究，对比了玻璃钢外管与普通钢管的抗压强度。由于钢管混凝土的双向压应力作用，必须采用较粗的内钢管对混凝土进行约束。纤维方向沿管周的FRP管对填充混凝土具有良好的约束作用，其强度可达到甚至优于钢管混凝土的强度，但总重量显著降低。

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.