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This study aims at the investigation of GNSS-PP method to determine the dynamic characteristics of structures. Cantilever steel bars having lengths of 70, 100 and 120 cm were tested under dynamic excitation. The GNSS was used to measure the natural frequencies and damping values of all the tested cantilever structures. The GNSS data were processed using relative GNSS positioning and PPP methods. The results obtained using these two methods were also compared with the dynamic characteristics obtained by applying the theoretical and finite element (FE) methods. Furthermore, it is investigated the impact of the stable data length before oscillation events on kinematic PPP. The study showed that the maximum difference among the experimental results in terms of natural frequencies proceeded using PPP is 0.08 Hz when compared with the theoretical and FE results. Furthermore, there is no difference between the PPP and relative GNSS positioning in determining the dynamic behaviour of structures eventhough roving GNSS antenna remains motionless for short-time, such as a few-minutes, before an event occurred. [ABSTRACT FROM AUTHOR]

The number of bridges in South Korea has almost tripled in the past few decades. Monitoring the structural behavior of these bridges is essential to maintain their performance in the infrastructure network and keep them in the best possible condition. The study presented in this paper aims to evaluate the Tun Bridge, located in Seoul, Korea. The bridge was tested under static and dynamic loads following the American Association of State Highway and Transportation Officials (AASHTO) standards. Twenty load cases and a wide range of truck speeds were applied during the bridge test. The bridge responses were captured using a short-period structural health monitoring system. Statistical analysis and signal processing for all the measurements were used to assess the structural behavior and fatigue life of the bridge. Bridge deformation/deflection and fatigue responses were evaluated. Furthermore, comparison with the available data from previous tests on the same bridge (17 years earlier) showed that the changes in static deflection and dynamic frequency were 13.87% and 2.73%, respectively. In addition, deflection and fatigue responses were found to be negligible under static and dynamic loads. Therefore, it was concluded that the bridge's behavior during its operational state was shown to be safe. [ABSTRACT FROM AUTHOR]

The clinical success of ceramic restorations is affected by the ceramic bonding procedure. The objective of the study was to evaluate the effect of different surface treatments, including the use of self-etching ceramic primer (SECP), on resin cement-glass ceramic bond strength. Thirty lithium disilicate ceramic (LDC) rectangles (3 mm × 3 mm × 8 mm) were fabricated Specimens were randomly assigned into three experimental groups (n = 10) according to the surface treatment: Group 1-hydrofluoric acid [HF acid]+ silane + universal adhesive; Group 2-HF + universal adhesive; Group 3-SECP + universal adhesive. All specimens were stored in distilled water for 24 h at 37 °C and shear bond strength (SBS) was tested at a crosshead speed of 0.5 mm (Universal Testing machine-Instron). Failure modes were evaluated using a digital microscope for all specimens. Analysis of variance and the Tukeypost hoctests using SPSS (Version 22.0, IBM, New York, USA) were used to analyze data. The SBS of groups 1 (19.74 ± 1.28 MPa) and 3 (21.11 ± 2.07 MPa) were significant higher than group 2 (14.80 ± 1.94 MPa). The SBS values for specimens in groups 1 (19.74 ± 1.28 MPa) and 3 (21.11 ± 2.07 MPa) were comparable. Adhesive, mixed and cohesive failure modes were observed and mixed failure was the most common in all groups. Therefore, the use of SECP and universal adhesive is recommended as an alternative to the use of HF acid in combination with ceramic primer while bonding to LDC. [ABSTRACT FROM AUTHOR]