The bond performance of glass fiber-reinforced polymer (GFRP) bars embedded in steel fiber-PVA hybrid fiber concrete plays an important role in their integration. In the present work, hybrid fiber concrete in different volume ratios of hybrid fibers with GFRP was investigated. Pullout tests with two amplitude regimes were conducted on hybrid fiber concrete specimens integrated with GFRP bars to investigate its ultimate bond strength, bond-slip curve, energy dissipation characteristics, and bond stiffness. The results indicate that when the total fiber volume ratio was fixed at 0.9%, the bond strength between the GFRP bars and hybrid fiber concrete increased gradually as the steel fiber volume increased, and the energy consumption increased gradually during the pullout. The slip corresponding to the ultimate bond strength under variable-amplitude repeated loading is in good agreement with the experimental results under monotonic loading. The specimen P1S8 (0.1% PVA, 0.8% steel fiber) hybrid exhibited sufficient energy dissipation capacity and deformation capacity under repeated loads, and the bond stiffness is relatively higher and more stable during the loading and unloading stages.

Coefficient of performance of air conditioning system is the ratio of cooling capacity and power consumption, and also is an important parameter to characterize the performance of the system. Based on an actual ground source heat pump system in Wuhan, China, this paper calculated the coefficient of performance of the system under long-term continuous cooling operation and then evaluated the performance of the system through experiment. The continuous testing time ranged from June 1, 2017, to June 15, 2017, and the outside air temperature ranged from 21 °C to 32 °C during the testing progress. The experimental results show that the coefficient of performance of the system changes non-linearly with time, and varies greatly with the atmospheric temperature. The results also show that the coefficient of performances average value of the system is about 3.3, and the system has good performance under refrigeration conditions. This paper helps to understand the changes in the distribution characteristics of the coefficient of performance of the ground source heat pump system and promote the wide application of the ground source heat pump system.

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