关键词： PPP   新型城镇化   城镇综合开发   风险控制  

摘要： 认为PPP模式下新型城镇化建设中开发企业面临的风险有合规性风险、合作范围风险、融资风险、税务风险及资金回收风险等。指出防控投资风险的方式有合规性风险防控方式、防控合作范围风险方式、融资风险防控方式、税务风险控制及资金回收风险防控。

关键词： self-sensing property   temperature coefficient   strain coefficient   high-temperature experiments   FRP  

摘要： The strain of fiber-reinforced polymer (FRP) bars at high temperatures is currently difficult to measure. To overcome this difficulty, a method of smart FRP bars embedded with optical fibers was proposed and studied, in which an ordinary single-mode optical fiber was applied as a distributed sensor. In this paper, both the distributed temperature and strain-sensing characteristics of optical fiber were studied based on pulse pre-pump Brillouin optical time-domain analysis (PPP-BOTDA) under high temperature. The temperature and strain coefficients were investigated under a thermomechanical coupling environment with consideration of large strain levels. The experimental results show that the temperature and strain coefficients decreased as the temperature increased, because the properties of silica and coating materials changed with temperature. Then, the formulas for determining the temperature and strain coefficients at high temperatures were introduced and discussed. The excellent sensing performance of the optical fiber indicated that smart FRP bars have the potential for use at high temperatures.