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In the last decades, the demand and use of renewable energies have been increasing. The increase in renewable energies, particularly wind energy, leads to the development…
In the last decades, the demand and use of renewable energies have been increasing. The increase in renewable energies, particularly wind energy, leads to the development and innovation of powerful wind energy converters as well as increased production requirements. Hence, a higher supporting structure is required to achieve higher wind speed with less turbulence. To date, the onshore wind towers with tubular connections are the most used. The maximum diameter of this type of tower is limited by transportation logistics. The purpose of this paper is to propose an alternative wind turbine lattice structure based on half-pipe steel connections.
In this study, a new concept of steel hybrid tower has been proposed. The focus of this work is the development of a lattice structure. Therefore, the geometry of the lattice part of the tower is assessed to decrease the number of joints and bolts. The sections used in the lattice structure are constructed in a polygonal shape. The elements are obtained by cold forming and bolted along the length. The members are connected by gusset plates and preloaded bolts. A numerical investigation of joints is carried out using the finite element (FE) software ABAQUS.
Based on the proposed study, the six “legs” solution with K braces under 45° angle and height/spread ratio of 4/1 and 5/1 provides the most suitable balance between the weight of the supporting structure, number of bolts in joints and reaction forces in the foundations, when compared with four “legs” solution.
In this investigation, the failure modes of elements and joints of an alternative wind turbine lattice structures, as well as the rotation stiffness of the joints, are determined. The FE results show good agreement with the analytical calculation proposed by EC3-1-8 standard.
The design methods currently proposed by the codes prescribe the strength assessment of structures to be based on their strength limit state. These design methods can be…
The design methods currently proposed by the codes prescribe the strength assessment of structures to be based on their strength limit state. These design methods can be applied to isolated steel members to determine their design strengthin fire. The real response of a structural member is, however, more complex due to the thermal expansion and the presence of restraints against this expansion by the surrounding structure. It is therefore imperative to study the response of a structural member at high temperature in a way which includes its interaction with its surroundings. This paper focus on the numerical investigation of steel beams in structural frames connected to concrete filled tubular (CFT) columns through reverse channel connections and comparison to hand calculation procedures. Finite element models (FEM) of the sub-frames were validated against fire tests conducted on sub-frames and then their results were compared to the proposed simplified hand calculation procedures (HCM).
A localized fire is a fire which in a compartment is unlikely to reach flash-over and uniform temperature distribution. Designing for localized fires is generally more…
A localized fire is a fire which in a compartment is unlikely to reach flash-over and uniform temperature distribution. Designing for localized fires is generally more difficult than for flash-over compartment fires because of the complexity of the problem. There is also a lack of experimental data. We report here on a full scale test series on a steel column exposed to localized fires. The setup is a 6 meters tall hollow circular column, ϕ = 200 mm with a steel thickness of 10 mm. The unloaded column was hanging centrally above different pool fires. Temperatures of gas and steel were measured by thermocouples, and adiabatic surface temperatures at the steel surface were measured by plate thermometers of various designs. The results are compared with estimates based on Eurocode 1991-1-2 which in all cases studied overestimate the thermal impact for this setup. The input from plate thermometers was used to compute the steel temperatures using finite element methods. Excellent agreement was found if the radiation exchange within the column due to asymmetry of the exposure was taken into account.
This study aims to propose strategies to address the identified major barriers for giving the public open access to government data. The study adopts fuzzy analytical…
This study aims to propose strategies to address the identified major barriers for giving the public open access to government data. The study adopts fuzzy analytical hierarchy process and technique for order performance by similarity to ideal solution (AHP-TOPSIS) to weigh the barriers and strategies, and it subsequently involves experts to identify and weigh the barriers and strategies. A case of Indonesia is used to contextualize the study.
The data were collected using fuzzy AHP-TOPSIS-based questionnaires given to several government representatives who had been working with data and information. The respondents were given sets of pairwise comparisons of which they were asked to compare the level of importance using one to nine fuzzy numbers between barriers and strategies. The data were then calculated using the fuzzy AHP-TOPSIS formula to obtain each weight of the barriers and strategies. The weight is used to prioritize the barrier and strategies.
In total, five barrier categories in the order of importance, namely, legal and privacy; government culture; social; technical; and economic, were identified from 27 barriers. In total, ten strategies of open government data (OGD) adoption were identified and ranked in the order of importance, and they can be grouped into five priorities. Priority 1 is to involve stakeholders in OGD planning and establish an OGD competence center. Priority 2 is to develop a legal compliance framework. Priority 3 is to adopt OGD gradually. Priority 4 is to create a collaboration feature on the portal for stakeholder communication and raise public awareness of OGD. Priority 5, finally, is to conduct training for government officials, develop standard operating practice for OGD management, use standard data formats and provide metadata.
This study provides a perspective from the government’s view. One suggestion for future research is to conduct a study from the public’s perspective to formulate strategies based on the identified citizens’ barriers in using OGD. In addition, cross-country (of different characteristics) studies were required to generalize the findings.
The first strategy of the first priority implies that government institutions should be able to develop a preliminary plan to involve relevant stakeholders in OGD planning, which includes identifying relevant stakeholders and continuously engaging them to participate in the planning phase of OGD. The second strategy in the first priority entails that government institutions should realize an OGD competence center by creating a virtual team whose members are from various backgrounds and who are very knowledgeable about OGD and how to manage OGD in government institutions.
This research provides key strategies to address the main barriers to giving the public open access to government data.