Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 19Citation - Scopus: 19Effect of Aggregate Microtexture Losses on Skid Resistance: Laboratory-Based Assessment on Chip Seals(American Society of Civil Engineers, 2020) Ergin, Basri; Gökalp, İslam; Uz, Volkan EmreSkid resistance has long been recognized as one of the most important pavement surface characteristics for safer roads. Evaluation of skid resistance of pavement is crucial but it is not an easy task. Moreover, it depends on numerous parameters such as pavement type, materials and tire properties, and environmental conditions. Aggregate texture changes significantly according to its origin and affects the skid resistance performance of the road surfaces. In the current study, chip seal samples were produced with different aggregate types at different polishing levels to evaluate the effect of aggregate microtexture on skid resistance performance. The Micro-Deval (MD) test device was utilized to obtain polished aggregates. Different polishing levels were provided by distinct revolutions of the MD drum. To monitor the change in aggregate surface with the polishing process, aggregates were monitored by scanning electron and optical microscopes at each level. Mean texture depths (MTDs) of chip seals were determined with outflow meter test. On the other hand, dynamic friction tester (DFT) and British pendulum tester (BPT) were implemented for assessment of skid resistance according to the relevant ASTM standards. Skid resistance and texture measurements were further used to identify the International Friction Index (IFI) for each sample. In addition, a correlational analysis was conducted between DFT and BPT results, and variable relationships were set for different speeds. Consequently, better skid resistance values were observed for chip seals produced by slags than the ones with natural aggregates at each polishing level. After fulfilling the economic and environmental requirements, using metallurgical by-products is recommended for long-lasting skid-resistant pavement surfaces. Additionally, it can be concluded that MD apparatus may be considered an easier, more cost-effective, and faster way to assess the polishing resistance of aggregates.Conference Object Citation - Scopus: 1Evaluating the Project Coordination Performance Using Information Centrality(American Society of Civil Engineers, 2014) Timurcan, Pelin İpek; Doğan, Sevgi ZeynepEvaluation of coordination performance in a project network requires reliable measures and monitoring methods for effective management. Recent literature includes studies addressing the relationship between coordinative activity and the configuration of communication networks. In these works, the role of network centrality is investigated through the basic standard centrality measures of degree, betweenness, and closeness. Current social network analysis research emphasizes new formulations of centrality measures for robust structural analysis of project networks. This paper presents a novel approach for measuring network centrality using the concept of information centrality. It is based on the idea that all paths carry information. The significance of information centrality values for the actors in a directional signage project at Istanbul Sabiha Gokcen International Airport is investigated. A centrality index is defined for each firm based on the average of the four measures of centrality. Findings suggest the existence of a high correlation between coordination scores and the centrality indexes. A centrality index augmented by an information centrality measure has potential for assessing the coordination performance in construction management research, and it is promising for the structural analysis of project communication networks. © 2014 American Society of Civil Engineers.Conference Object Citation - Scopus: 3Coordination Process and Network Centrality in Isgi Airport's Wayfinding Project(American Society of Civil Engineers, 2012) Doğan, Sevgi Zeynep; Günhan, Suat; Erbasaranoglu, BengiCoordination is integral to operational efficiency of construction projects. Coordination process relies on managing dependent activities and the structural centrality in social networks is strategic to project actor's management activity. This study aims to explore the effects of network centrality on coordination performance. Network centrality concepts and coordination theory are examined via Email communication data of Istanbul Sabiha Gökçen International Airport's (ISGIA) New Terminal Building Wayfinding and Signage Design Project (WSDP) actors. E-mail data mining for identifying different coordination dependencies is derived from the constructs of Malone's (1988) coordination theory and used to measure the actors' coordination scores. Social network matrix of information exchange network is constructed to calculate degree, betweenness and closeness centrality measures. ISGIA data analysis suggests a significant relationship between out-degree, outcloseness centrality and coordination. Findings highlight that out- network centralities support the ability of an actor to coordinate the dependent actions of other project actors; and the design and construction practices rely on the central position in a network in mapping effective coordination processes. © 2012 ASCE.