Development and Establishment of Design Method for External Prestressed Concrete Members Using FRP

纤维增强塑料（FRP）是土木工程领域的一种新型结构材料。FRP是由浸渍树脂的高强度连续碳、芳纶或玻璃纤维制成。FRP具有1)抗拉强度高，2)不腐蚀，3)不磁化等优良性能。本研究的目的是明确使用FRP作为外部电缆而不是普通钢筋的PC（预应力混凝土）梁的行为，并建立这种外部PC梁的分析和设计方法。通过试验和分析，得出以下结论：1) FRP加固梁的荷载-位移关系与普通钢加固梁的荷载-位移关系基本相同。2)斜线处的电缆弯曲点成为拉力的薄弱点。碳纤维电缆的断裂载荷约为单轴拉伸试验平均断裂载荷的80%。因此，当FRP在偏差处弯曲时，必须仔细确定FRP的设计强度。3)为了计算FRP外接PC的抗弯性能，提出了一种基于纤维模型的分析方法。计算值与实验值吻合较好。4)在试验的基础上，提出了预应力混凝土外构件的设计方程。

Fiber reinforced plastic (FRP) is a new structural material in the field of civil engineering. FRP is made of high strength continuous carbon, aramid or glass fiber impregnated with resin. FRP has some excellent properties such as 1)high tensile strength, 2)non-corrosion, 3)non-magnetization. The objectives of this study are to make clear the behavior of PC (prestressed concrete) beams using FRP as external cables instead of ordinary steel tendons and to establish analytical and design method for such external PC beams. From the tests and analyzes, the followings are concluded.1) The load-displacement relationships of the beams reinforced with FRP show almost the same behavior as that reinforced with ordinary steel.2) The bending point of the cable at the deviator becomes a weak point for the tensile force. The breadking load of Carbon FRP cable was about 80% of the average breaking load obtained from the uniaxial tensile tests. Therefore, design strength of FRP must be carefully determined when FRP is bent at the deviators.3) In order to calculate the flexural behavior of external PC with FRP, an analytical method using fiber model was newly developed. The calculated values agree well with the experimental ones.4) The design equation for external PC members was proposed based on the tests and the developed analytical method.