1,720,952 research outputs found
Relationship Between Construction Costs and Reliability of Quay Walls
No full textStructures have to meet a particular level of safety. Therefore, in the European design codes (Eurocodes), three reliability classes (RC) are introduced based on the potential consequence of failure of the structure. For each of the RC a maximum allowable probability of failure is introduced, corresponding to a reliability index. In recent research by Roubos et al. (2018), it is suggested that the marginal costs of safety investments for quay walls is quite low. Therefore, it is questionable whether the current reliability classes and the corresponding set of partial factors, as defined in the Eurocodes and CUR 211, are functional for quay walls. This gave rise to the present study. This thesis investigates the relationship between the construction costs and the reliability index for two quay walls located in the Port of Rotterdam; 1) a double anchored combi-wall and 2) a combi-wall with a relieving platform.In this study, more insight is acquired into the relationship between the construction costs and the reliability index of quay walls. Firstly, the two quay walls are designed semi-probabilistic in RC1, RC2 and RC3, using D-Sheet Piling for the double anchored combi-wall and using Plaxis 2D for the combi-wall with a relieving platform. Thereafter, the construction costs of these designs are calculated and compared. Besides that, the influence of the partial safety factors, which are defined in the Eurocodes and distinguish the reliability classes, on the construction costs is quantified. The same was done for the influence of three of the critical failure mechanisms; ‘passive resistance inadequate’, ‘sheet pile profile fails’ and ‘tension member anchorage fails’. For these failure mechanisms the reliability indices are estimated using the reliability analyses module of D-Sheet Piling, which is based on a probabilistic level II analysis, the First Order Reliability Method (FORM).It appeared that the marginal costs of safety investments for both quay walls is relatively low, even significantly lower than suggested by Roubos et al. (2018). It followed that the differentiation in construction costs between the reliability classes is considerably less than the differentiation in construction costs between quay walls in practice. Therefore, it seems that the current reliability classes and the corresponding set of partial safety factors, as defined in the Eurocodes and CUR 211, are non-functional for quay walls. Besides that, it can be concluded that when designing a quay wall, the determination of the angle of internal friction of the soil strongly influences the construction costs, followed by the surface- and crane loads. The influence of the cohesion of the soil and the bollard load on the construction costs is very small. Furthermore, the influence of the failure mechanisms ‘passive resistance inadequate’ and ‘tension member anchorage fails’ on the construction costs of the double anchored combi-wall is relatively low. Therefore, it is suggested that the reliability index of the quay wall can be increased in a economically attractive manner by increasing the length of the tubular piles of the combi-wall or the steel sectional area of the anchor rod. Due to these influences, it can be economically beneficial to increase the target reliability index of the failure mechanism ‘passive resistance inadequate’ and decrease the target reliability index of ‘sheet pile profile fails’.Civil Engineering | Hydraulic Engineering | Hydraulic Structures and Flood Ris
Inclination behaviour of historic quay walls: A study into the value of inclination sensing for quay wall failure assessment in Amsterdam
No full textThe inner-city of Amsterdam contains a large network of vulnerable, historic quay walls. Most of these quay walls consist out of masonry gravity walls placed on wooden relieving floors and wooden foundation piles. Due to the changing surface loading conditions behind the wall and the degradation of the masonry and wooden structures over the last century, the safety of the quay walls is in critical condition. Insight into the behaviour of the masonry wall tilt and its relationship with several failure mechanisms is still limited. Therefore, the objective of this thesis is to provide this insight into the behaviour of the tilt approaching failure in the center of Amsterdam. Additionally, the use of monitoring data from SmartBrick devices is analyzed to assess the value of quay wall inclination monitoring.Using PLAXIS 2D, quay wall models are made aimed to create a sensitivity analysis towards the wall tilt using multiple variations in quay structure dimensions and parameters. These variations investigate the wall height, wall thickness, floor length (and the amount of pile rows), the canal depth and the pile diameters based on a typical Amsterdam soil profile. For the tested geometry variations, there is a linear relationship seen between the wall tilt and the horizontal wall displacement towards the canal, during the addition of the surcharge load behind the wall. The relationship between the wall tilt and the surcharge load is predominately linear at lower/realistic surface loads, at higher loads, towards failure, the wall tilt becomes exponentially larger, this is also seen by setting the varied dimensions towards failure scenarios. The most sensitive variations for inclination are the change in the masonry wall height and thickness, the pile distribution underneath the floor and the addition of a surcharge load directly behind the masonry wall.The failure mechanism describing the horizontal displacement of the masonry wall and the piles is recognized by increasing the height of the masonry wall and by decreasing the pile diameters (pile degradation). By increasing the wall height, the quay structure also settles vertically, which in combination with the horizontal displacement, initiates wall tilt. During the addition of the surcharge load, the crossbeam (kesp) and the piles can deform, and their bending moments can exceed their bending capacity, indicating another failure mechanism with initiates wall tilt. The failure mechanism describing rotation of the masonry wall on the floor towards the canal is activated by decreasing the wall thickness and therefore decreasing its lateral capacity. This causes the masonry wall to fall over. Damage to the foundation elements has an important impact on the tilt of the wall, due extensive axial displacements of the front pile row or cracks in the masonry wall.To compare the SmartBrick inclination and PLAXIS inclination, it is important to know the exact degradation, erosion and loading conditions during the time between two SmartBrick measurements. The linear relation between the wall inclination and the wall displacement is useful for SmartBrick because it shows that monitoring the inclination also predicts the wall displacement and the state of the quay wall. Pile degradation and canal erosion only give a small wall tilt increase, but a larger increase in horizontal displacement of the wall is seen. Therefore, high measuring accuracy and resolution are necessary to monitor only the wall tilt. To conclude, approaching quay wall failure shows that wall tilt in combination with horizontal displacement is expected, this behaviour can be monitored using SmartBrick. High wall tilt is often a first consequence of the exceedance of the bending capacities in the wooden elements.Geo-Engineerin
Container terminal development for the Port of Bahía Blanca: A research on the future container throughput in the Port of Bahía Blanca and the adaptation to the container terminal to these developments
No full textBahía Blanca in Buenos Aires province is located 600 kilometres south of Buenos Aires city. The port complex of Bahía Blanca has the second largest throughput in Argentina considering tons, mainly attributed to the agro – and petrochemical industry. The port handles containers as well, however with an average of 30 thousand TEU/year this throughput is rather small. The authority of the Port of Bahía Blanca sees opportunities to increase container throughput in the port due to recent developments in the region. The container throughput is estimated for 2040, considering the petrochemical cluster and fruits. Four different trends show a container throughput of respectively 30, 155, 250 and 360 thousand TEU/year. The capacity of the container terminal is estimated at 50 thousand TEU/year, based on the equipment, the dwell time and the terminal area. The terminal should improve when throughput will increase. To start, number of calls and call size are assumed based on future throughput, decreasing the average dwell time for export containers. Additionally, a larger quantity and more advanced equipment is required to handle the increase in throughput. Lastly, the terminal area itself can be increased significantly from 8ha to 22ha in its maximum configuration. The increase in storage area allows the capacity to grow from 50 thousand TEU/year to 215 thousand TEU/year. It is important to realize that further expansion of the terminal is not possible and a new location has to be considered. A multi criteria analysis in combination with a financial analysis on the possible location showed that two out of four possible new locations are suitable for the development of a new container terminal. The new container terminal should have the capacity to handle the expected container throughput generated locally. The possibility to attract additional cargo to the port was researched as well, since the Port of Bahía Blanca has an advantageous depth compared to the Port of Buenos Aires. However, on the short term it is not expected that Bahía Blanca can profit from the draught limitations in Buenos Aires since port calling cost are almost the same, Buenos Aires is located conveniently and not operating at capacity and current shipping routes are not expected to change their routes majorly.MP22
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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