http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Peng Cao,Decheng Feng,Changjun Zhou,Wenxin Zuo 사단법인 한국계산역학회 2014 Computers and Concrete, An International Journal Vol.14 No.5
Portland cement concrete, which has higher strength and stiffness than asphalt concrete, has been widely applied on pavements. However, the brittle fracture characteristic of cement concrete restricts its application in highway pavement construction. Since the polypropylene fiber can improve the fracture toughness of cement concrete, Polypropylene Fiber-Reinforced Concrete (PFRC) is attracting more and more attention in civil engineering. In order to study the effect of polypropylene fiber on the generation and evolution process of the local deformation band in concrete, a series of three-point bending tests were performed using the new technology of the digital speckle correlation method for FRC notched beams with different volumetric contents of polypropylene fiber. The modified Double-K model was utilized for the first time to calculate the stress intensity factors of instability and crack initiation of fiber-reinforced concrete beams. The results indicate that the polypropylene fiber can enhance the fracture toughness. Based on the modified Double-K fracture theory, the maximum fracture energy of concrete with 3.2% fiber (in volume) is 47 times higher than the plain concrete. No effort of fiber content on the strength of the concrete was found. Meanwhile to balance the strength and resistant fracture toughness, concrete with 1.6% fiber is recommended to be applied in pavement construction.
Creep Constitutive Model for Frozen Soils Based on Hardening and Damage Effects
Sheng Shi,Feng Zhang,Decheng Feng,Kangwei Tang 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.4
The creep characteristics of frozen soil has significant influences on infrastructure stability in cold regions. It is important for frozen ground engineering to describe the creep properties of frozen soil with accurate models. In this research, a new structure creep model is developed by considering the hardening factor and damage factor which play different roles during various creep stages. According to the experimental results under different stress levels, the proposed model was verified. The calculation results exhibit the proposed model has abilities to predict the creep characteristics of frozen soils, especially the nonlinear stress-strain behavior at acceleration creep stage.