Experimental Investigation on Flexural Behaviors in Framed Structure of PST Method
Existing underground pipe jacking methods use a reinforcing rod in a steel tube to obtain structural stiffness. However, some problems such as inconvenience of works and expensive materials resulted from limited working space and reinforcing works are existed. To resolve these problems, a new pipe jacking method, namely PST (Prestressed Segment Tunnel) method, was developed which used joint to connect the steel segment and form erection structure. For evaluating the flexural capacity of the PST method structure, a experimental test was conducted. The parameters considered in the test were span-to-depth ratio of segment, diameter of steel tube at the corner, prestressing force, and welding of joint. The flexural behaviours with the effect of load capacity in serviceability state according to different parameters were examined.. The frame with long segments could increase flexural stiffness and the specimen with large diameter of concave corner showed excellent resistance ability to the negative moment. In addition, welding of joints increased the flexural capacity. Keywords—PST method, Pipe jacking method, Flexural behavior, Prestressed concrete.
Experimental investigation of the flexural mechanism and performance of channel steel tube slab structure under concentrated loads
Experimental studies about the flexural performance of channel steel tube slab (CSTS) structure subjected to concentrated loads were carried out, with considering various spacing of adjacent tubes, longitudinal spacing between the channel steel and missing tensile channel steel. A self-designed flexural device equipped with particle image velocimetry (PIV) technology was used to monitor continuous structure deformation and concrete cracking characteristics. In this study, the mechanism and performance of CSTS structure serving in underground engineering were analyzed, and a theoretical model for the bearing capacity of the CSTS structure was proposed. The results show that the failure mode of the test specimens exhibits ductile failure with an average ductility coefficient 2.52. The large shear strain of the concrete was obtained from PIV speckle contour, and it shows the same propagation trend compared with the main cracks appearing in the tests. In addition, the tensile channel steel along with decreasing the spacing of adjacent tubes can increase the bearing capacity of the specimens. The proposed theoretical model shows a reasonable prediction of the ultimate bearing capacity of specimens compared with the experimental results.
Clinical chemical values and variations in Rasa Aragonesa ewes and lambs
Reference values of biochemical parameters in serum of Rasa Aragonesa ewes and their physiological variations were determined. Total proteins were 53.0–80.0 g/l, glucose 2.17–5.13 mmol/l, cholesterol 0.83–2.31 mmol/l, total bilirubin 1.85–6.49 μmol/l, urea 3.15–10.39 mmol/l, GGT 36–93 U/l (37°C), ALAT 11–33 U/l (37°C) and ASAT 71–209 U/l (37°C). Ewes were divided into three groups: A, 1- and 2-year-old ewes; B, ewes 3 and 4 years old; C, older ewes. Age had significant influence (P<0.05) on ASAT only during pregnancy, with higher levels for younger ewes. Blood parameters in lambs were determined at 5–10 d of life (nursing), 25 to 30 d of life receiving their mother's milk and 80–90 g of feed; and 45 to 50 d of life, weaned, receiving only solid feed. Serum urea and ALAT tended to increase with age, whereas total protein, globulins, cholesterol and GGT decreased with age. These values are of practical importance in the diagnosis of diseases and metabolic disorders in Rasa Aragonesa ewes and lambs under field conditions.