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

本文研究了与近年来高速公路高墩即钢管预埋混凝土桥柱的标准相比较的FRP管、钢管双蒙皮桥柱的受力性能。首先，评估了CDST构件在轴力和弯矩作用下的强度相互作用曲线。特别强调的是钢管在强度上的最佳布置。结果表明，单根大尺寸内管截面的强度和延性优于多根小尺寸内管截面的强度和延性。其次，对CDST的抗压强度进行了试验研究，将玻璃钢外管与普通钢管在CFT中的有效性进行了对比。据了解，较厚的内钢管由于其严重的双轴压应力状态，对混凝土的限制是不利的。结果表明，纤维向管周的FRP管对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，且总重明显减轻。

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.