Search

Steel bearings have been commonly used to counteract induced loading from thermal and traffic conditions in numerous bridges. However, their effectiveness has been compromised due to aging and maintenance limitations, potentially impacting the overall bridge system performance. Existing monitoring techniques for detecting malfunctioning steel bearings lack automation and precision, making them inadequate for long-term and real-time bridge dynamics assessment. This study proposes a response-based approach to identify bearing malfunction by analyzing the traffic-induced response in the bearing vicinity. To implement this approach, laser displacement sensors and wireless acceleration sensors were employed to monitor both malfunctioning and well-functioning steel bridge bearings. Significant differences in bearing performance were observed through response analysis and comparison. Laser sensor measurements revealed larger vertical deflections in the girder at malfunctioned bearing under traffic loading. Moreover, the investigation of the acceleration response in the bearing locality indicated that bearing malfunction could alter the vibrational characteristics of the vicinity, significantly affecting Cross Power Spectral Density (CPSD) and cross-correlation. To quantitatively evaluate the performance of steel bearings, a Condition Score (CS) was introduced. The CS exhibited a strong correlation with bearing damage, providing valuable insights for maintenance and decision-making processes in bridge asset management. This study offers a comprehensive and automated method for identifying steel bridge bearing malfunction by utilizing advanced monitoring techniques and introducing the CS for assessment. The results obtained from this approach can enhance bridge maintenance strategies and contribute to effective bridge asset management. [ABSTRACT FROM AUTHOR]

A key factor in ensuring the stability and ductility of asphalt pavements is interlayer fatigue resistance. Interlayer bonding characteristics are one of the most significant elements influencing the lifespan of asphalt pavements. Poor bonding properties often lead to debonding, slippage cracking, and pavement deformation. The primary cause of interlayer slippage cracking is a lack of interface bonding between an asphalt overlay and underlayer, which is typically triggered by vehicle braking and turning. Emulsified asphalt, modified asphalt, and hot asphalt are just a few of the materials that are used as tack coats to address this issue. This paper examines five different bonding types between interlayers: a model with no tack coat, a model with SBS-modified hot asphalt, a model with SBS-modified asphalt emulsion, a model with an epoxy resin binder, and a model with SK-90 hot asphalt. This study evaluates the shear fatigue of asphalt pavement under a single wheel cycle load. A model is created using the Abaqus software to predict fatigue life while taking into account the various tack coat materials listed above. Considering the outcomes of this study, the best bonding type for asphalt pavement is SBS-modified hot asphalt. After selecting this material, various tack coat thicknesses were used until the optimum thickness of 6 mm was determined. The proposed model can withstand more load cycles and less rutting depth, which helps to prevent interlayer fatigue failure over the course of a pavement's design life. [ABSTRACT FROM AUTHOR]

Introduction: Historically, serum alanine transaminase (ALT) has been used as a surrogate marker in the detection of hepatitis viruses in blood donors. With the availability of newer sensitive technologies for the detection of seroconversion, the value of ALT becomes questionable but continues to be used for this purpose with subsequent discarding of ALT elevated blood units. Objective: The present study aims to evaluate the significance and cost effectiveness of ALT as a surrogate marker for hepatitis C virus infection in healthy asymptomatic blood donors who were serologically negative. Materials and Methods: The study was conducted at clinical laboratory of a tertiary care hospital for a period of one year from November 2006 to October 2007. All donors were screened serologically for hepatitis B, C and HIV I and II, syphilis and malaria and those tested positive were excluded from further evaluation. Gender-wise reference ranges and minimal and markedly raised results for ALT (described respectively as one and two folds increase above reference range) were defined and, accordingly, donors were grouped into three. Two hundred seronegative blood donors were randomly selected from all three groups of ALT results and tested for hepatitis C nucleic acid through Amplicor; HCV RNA test. The cost of discarding an ALT -only elevated blood unit was also assessed. During the study period, 25117 subjects donated blood. Eight hundred and Results: seventy two donors (3.4%) were positive for one or more serological tests. ALT of all donors ranged from 0-1501 U/L (Mean ± SD; 33.4 ± 25.45U/L). The donors seronegative for all disease markers were 24245 (96.6%). Of these, 21164 (87.2%) donors had their ALT within reference range while 2874 (11.8%) and 207 (0.8%) of donors had minimal and markedly elevated results. Thus, 621 blood bags (red cells, platelets and plasma) costing $ 39200.0 were discarded based on ALT results alone. Of 200 seronegative donors evaluated for hepatitis C nucleic acid, only one within markedly elevated ALT levels was found to be positive. The present work did not support a positive association between hepatitis C virus nucleic acid and elevated ALT in healthy serologically negative blood donors. Conclusion: We did not find serum ALT testing in donors as cost effective strategy for detection of hepatitis C virus ribonucleic acid. As the number of samples tested by us was small we suggest further work to evaluate the value of ALT levels in serologically negative donors in association with hepatitis C antigen and NAT testing to elucidate the true burden of disease in geographical regions where hepatitis C is endemic and voluntary blood donation is sparse.