土木畢業(yè)設(shè)計(jì)外文翻譯--近表面埋置加固的鋼筋混凝土梁抗彎性能實(shí)驗(yàn)研究-文庫吧
2025-05-13 22:31 本頁面
【正文】 d narrow space. 2. EXPERIMENTAL PROGRAM MANUFACTURE OF SPECIMENS A total of 6 specimens of simply supported RC beams with span of 3m have been cast. 2 The details andcrosssection of the specimens are illustrated in Figure 1. A concrete with pressive strength MPa at 28 days has been used. Steel reinforcements D10(φ) of SD40 have been arrangedwith steel ratio of and a layer of three D13(φ) has been arranged as pressionreinforcements. Shear reinforcements of D10 have been located every 10 cm in the shear zone to avoidshear failure. Table 1 summarizes the material properties used for the test beams. EXPERIMENTAL PARAMETERS Table 2 lists the experimental parameters. The control specimen, an unstrengthened specimen, has been cast to pare the strengthening performances of the various systems. CPL50BOND, EBR specimen, has been strengthened with CFRP strip. The remaining 4 specimens were strengthened with NSM CFRP strips. Among the specimens strengthened with NSM reinforcements, an embedding64 depth of NSMPL15 and NSMPL25 is 15mm and 25mm, respectively. A space between grooves of NSMPL25*2 and NSMPL2S is 60mm and 120mm, respectively. The strengthened length of all thespecimens has been fixed to 2,700 mm 3 INSTALLATION OF THE FRP REINFORCEMENTS Figure 2 shows the details of crosssections of the specimens. The strengthening process of EBR specimen (CPL50BOND) was proceeded by the surface treatment using a grinder, followed by the bonding of the CFRP strip. The strengthened beams were cured at ambient temperature for 7 days for the curing of epoxy adhesive. The process for NSM strengthening progressed by cutting the grooves at the bottom of the beams using a grinder, cleaning the debris, and embedding the CFRP strip after application of the adhesive. The strengthened beams were cured for 3 days so that the epoxy adhesive achieves its design strength. LOADING AND MEASUREMENT METHODS All specimens were subjected to 4point bending tests to failure by means of UTM (Universal Testing Machine) with capacity of 980 kN. The loading was applied under displacement control at a speed of mm/sec until the first 15 mm and mm/sec from 15 mm until failure. The measurement of alltest data was recorded by a static data logger and a puter at intervals of 1 second. Electrical resistance strain gauges were fixed at midspan and L/4 to measure the strain of steel gauges to measure the strain of concrete were located at the top, 5 cm and 10 cm away from the top on one side at midspan. Strain gauges were also placed on the FRP reinforcement located at the bottom of the midspan and loaded points to measure the strain according to the loading process. 3. EXPERIMENTAL RESULTS FAILURE MODES Before cracking, all the strengthened specimens exhibited bending behavior similar to the unstrengthened specimen. This shows that the CFRP reinforcement is unable to contribute to the increase of the stiffness and strength in the elastic domain. However, after cracking, the 4 bending stiffness and strength of the stre
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