Enzyme is a green, efficient and easily degradable substance. In the present investigation, the papain and 100-c enzyme instead of part of surfactants were used in degreasing process. The results indicated that when wet-blue sheepleather was treated by the enzymatic compound, protein content in the effluent was about 9 times more than that of the non-ionic degreasing agent with less damage to collagen. Moreover, the degreasing rate for enzyme degreasing was 40.1% which was much higher than that of non-ionic degreasing agent. Mechanical properties of the crust leather treated by enzymatic compound were matchable to those treated by non-ionic degreasing agent. Color difference values of the leather indicated that the wet-blue sheepleather was easy to be dyed after being treated by enzymatic compound. The K/S value of the leather treated by enzymatic compound was much higher than that treated by non-ionic degreasing agent. Histological analysis of wet-blues visually showed efficient fat removal by enzymatic compound. Enzymatic compound used in degreasing of greasy wet-blues could improve the leather' quality.
The connection joint of prestressed concrete pipe piles is a typical steel–concrete structure, and its bending strength has evolved into a critical factor affecting the safety of supporting structures in underground engineering. Based on full-scale bending tests of five specimens of large-diameter prestressed reinforced concrete (PRC) pipe piles and connection joints, as well as the corresponding finite element numerical simulation, the bending bearing and deformation characteristics of connection joints of PRC pipe piles were analyzed, together with the effects of concrete strength, precompression stress, and connection mode of joints. The results showed that the crack resistance of the welded joint of PRC pipe piles was equivalent to that of the pipe pile shaft, but the ultimate bending moment of the joint was about 58–87% of that of the pile shaft. The bending failure mode of the pipe pile joint was mainly manifested in the end plate yielding into a drum shape, with the tension side of the pile hoop and the end plate clearly separated from the pipe pile, and crushed concrete at the upper edge of the pile hoop. The bending strength of the joint can be improved by increasing the bonding strength between the end plates of the joint or embedding Rachel reinforcement in concrete. In addition, synchronously increasing the strength grade and reinforcement ratio of concrete or strengthening the precompression stress of concrete are favorable measures.
To protect the external wall panel of the steel frame in prefabricated construction, a kind of ring-shaped energydissipating device (RSED) was proposed and further studied, which can connect the wall panel and steel frame. The hysteretic performance of steel frame-external wall panel system (SFEWPS) with RSED as the joint is analyzed via the finite element method, to quantify the protective effect of RSED on a wall panel. The results are that even under extremely rare earthquakes, RSED can still effectively control the energy consumption of wall panels, and play a protective role for it. In addition, combined with failure mechanism analysis, this paper proposes the best parameter selection for RSED.
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