International Journal of Coastal, Offshore and Environmental Engineering
Volume:6 Issue: 2, Spring 2021

Steel rebar corrosion because of the cracks in marine reinforced concrete (RC) structures is the main type of deterioration that leads to decrease the load-carrying capacity, ductility, and service life. The use of different fibers such as steel fiber (SF), glass fiber (GF), and polypropylene fiber (PF) in RC beams can reduce the cracks and increase the load-bearing capacity and toughness of RC beams. Moreover, it seems that RC beams containing hybrid of SF, GF, and PF have been higher flexural capacity and toughness rather than RC composites with only one type of fiber. However, the role of mono or hybrid fiber will be depended on environmental conditions. Consequently, load-bearing capacity and toughness of Green RC beam with 15% metakaolin (MK) as a cement replacement, containing SF, PF, GF, (S+P)F, and (S+G)F as fibers, at 28, 90, and 180 days in tidal zone of Oman Sea were determined. The dimension of the beams was 200×200×750 mm. The fibers included macro and microfibers. Macro fiber was steel with 50 mm length. Microfibers were GF and PF with 12 mm length. Results indicated that by the addition of PF, GF, SF, (S+P)F, and (S+G)F to RC beams the load-bearing capacity and toughness are increased up to 41%. Meanwhile, the hybrid effect of fiber was more than the mono one.

As one of the most important components of an offshore oil and gas complex, Catwalk (access bridge) provides support for equipment and act as a passage for staff. Therefore, any damage in this structure may result in casualties as well as financial and environmental losses. Hence, identifying the location and severity of damage in these structures is of a great importance. As a common SHM method, modal strain energy uses the changes in the dynamic properties of the structure for identifying the damage location and severity. Considering natural frequencies in the process of the damage localization is one of modifications that has been successfully applied to this method. In order to show the robustness of this method for identifying damages in real class offshore structures with a large number of elements, the improved modal strain energy (IMSE) method is applied for damage localization and quantification in the access bridge of Foroozan platform in the Persian Gulf. The results showed that the IMSE damage index is more accurate than the original Stubbs index. Both the single and multiple damages were predicted with a good accuracy with this method. However, the method was more accurate in locating the damages in horizontal elements as well as the elements far from the supports of the structure.

The truly complex element of modern times is not the technology, but the engineers who develop, design, manufacture, and maintain it. An engineer’s job is to change/improve existing situations into more desirable ones, as well as to respond to the demands or needs of society. Engineers cannot wait until all phenomena and their implications are well understood. Engineers have worked for centuries solving problems with limited information and knowledge and are presumed to be rational decision-makers. Then, how do engineers make their decisions with limited knowledge, time, and cognitive capacity in a variety of domains? Engineers require understanding what part of information can be ignored, and what situations require fast, and timely response, resulting hopefully in a better decision by freeing cognitive capacity to make it.  A rational decision-maker should choose an option that maximizes the expected benefits (utilities), although there may be significant hurdles in achieving such goals, especially in emergencies where time pressure is acute.  To overcome these hurdles, most engineers revert to “rules-of-thumb”, also known as heuristics. Heuristics are experience-based methods of gut feelings that can be used as an aid to solve specific problems in a particular environment. Heuristics, however, are imperfect; thus, engineers must understand their limitations. Their applicability is also limited by the context under which they were derived as well as their fit with the environment of the problem at hand.  The overall objective of these four-part papers is to discuss heuristics and how they can make decision-making easier and faster for engineers. These papers also remind them of their own cognitive biases and describe ways of avoiding them. This first part aims to set the scene by providing background information. These papers address the type of rationality that engineers need to be effective build on the existing literature and liberally draws from them. Engineers cannot march on the spot while thinking for a solution, they must think while moving forward, thus there is a danger not starting on the right foot.

Ports always play a strategic role in the development of a country's domestic and international trade, whether it is developing or developed. Ports as a base of maritime trade have changed a lot in recent decades, but in line with these changes, the Ports and Maritime Organization, as the main custodian of port and maritime policy, must adapt quickly, and this adaptation and the process of change in the next generations of ports of the country should lead to good governance in the management of port affairs. The evolutionary process of port governance shows that a single version cannot be used for governance reforms in all ports of the world, so in this study we try to examine the factors affecting good governance at the organizational level. The present study is a descriptive-survey research in terms of applied purpose and based on its nature and method. The statistical population in this study includes 22 experts of the Ports and Maritime Organization and the sampling method is random and purposeful due to the large number of experts. In this study, we first identify the factors affecting good governance by examining past literature studies in a hybrid manner and then  examine the components by surveying experts using the Fuzzy Delphi method and finally to show the causal reasoning between the components of the technique. Fuzzy Cognitive Mapping is used. Findings indicate that the components of  Equal Rights and Equity, Responsiveness & Accountability,  Defining Outcomes have the highest degree of centrality, respectively, and this indicates the importance of the above components compared to other components of good governance in the Ports and Maritime Organization.

In this study, a numerical third-generation wave model was performed to generate 10 years (2000-2010) of wave hindcast in the Persian Gulf. The modified wind field data of European Center for Medium Range Weather Forecasts (ECMWF) and bathymetry data were used as the input data to model. In situ measurements and satellite-derived wave height were performed for model calibration, and validation the results. The results show that the overall accuracy is more than 80% over the whole Persian Gulf. Geographical Information System (GIS) was used to handle all datasets through a user-friendly software which provides required tools for data visualization and manipulation. Data management was carried on using the integration of Relational Database Management Systems (RDBMS) and GIS components.

Dynamic performance of the 3D train–bridge system (TBW model) subjected to different hydrodynamic loads and applying AAR track irregularity is established in this study. By taking a continuous bridge (32 + 48 + 32) m with box girders as a case study, the dynamic responses of the bridge which is under train passing and subjected to several sea hydrodynamic loads are analyzed. The substructure of the bridge includes four concrete solid piers with rectangular sections and piers are fixed at seabed. Piers and decks are designed and analyzed based on dynamic finite elements methods, and hydrodynamic forces are applied on piers according to Morison's theory. Also, car body is modeled by a 27-DoFs dynamic system. Model validation has been performed with another research by considering vessel collision load. Then, the dynamic responses of the bridge and the running safety indices of the train on the bridge under several types of sea wave states when train speed is 300 km/h analyzed. Results of TBW's sensitive analyzes have shown the importance of sea-states conditions for train safe and comfortable running. Also, irregularity has an obvious effect on the dynamic responses of the bridge. It has greater effect on vertical acceleration and displacement than horizontal ones in presence of hydrodynamic load. Combination of these two phenomena (wave and irregularity) jeopardizes the running safety of train when crossing the bridge.