4 research outputs found
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Form finding and dimensioning of reinfornced concrete shell roof for Akrotiri (Santorini)
Shells are long-span and inherently light-weight structures used for both their aesthetic and structural benefits. This paper develops a robust methodology for the reinforced concrete (RC) roof shell design of Akrotiri, an archaeological site in Santorini island, Greece. The methodology uses Oasys GSA and finite element package Abaqus which allow both form finding analysis and dimensioning to be conducted. Through the step-by-step application of this method, a protective shell cover is designed and its applicability demonstrated
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Designing efficient grid structures considering structural imperfection sensitivity
At the initial design stage of a grid structure, shape optimisation is an effective way to find the optimal structural form. However, most of the shape optimisation methods do not take into consideration the imperfections, thus the actual buckling load capacity of the optimised structure is usually low. In this paper, an improved shape optimisation method is proposed, one that is considering the effect of structural imperfection sensitivity. In this method, the bending strain energy ratio is taken as a constraint, and when the total strain energy decreases, yet there is a certain proportion of bending strain energy in the structure. Consequently, the resulted shape is not sensitive to the initial geometry imperfection, and therefore, an efficient structure with higher buckling load capacity and low imperfection sensitivity is obtained. In order to evaluate the redundancy performance of the optimised structure, an index called structural overall redundancy, based on damage model is proposed herein. The damage model is simulated by removing a key rod of the structure. The results demonstrate that the overall redundancy of the structure obtained by the proposed method is higher than that obtained by the traditional method, thus an optimal design of a grid structure is obtained
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A novel progressive grid generation method for free-form grid structure design and case studies
Due to its high structural efficiency and aesthetics, free-form grid structures have been widely used in various public structures. However, it is neither a convenient nor an obvious task for engineers to create a discrete grid on a free-form surface that manifests the architect's intent. This paper presents an efficient design approach based on Coulomb's law to generate well-shaped and fluent grids for free-form grid structural design. In the method, nodes of the grid structure are considered to be interacting particles in an electric field and are added to the surface in a progressive way. The nodal position is determined by Monte Carlo simulation and the grid is generated by connecting the particles that are already in equilibrium. According to the different ways of adding particles, two variations of the method are introduced in this paper: point-based progressive method (PBPM), and curve-based progressive method (CBPM). Case studies are provided to demonstrate the effective execution of the proposed method. The results show that the proposed method can effectively avoid mapping distortion and generate grids with regular shape and fluent lines to meet the aesthetic requirements. Furthermore, the proposed method provides flexible control over the direction and size of the grid, which gives architects a more flexible choice
Haemonchus contortus: genome structure, organization and comparative genomics
One of the first genome sequencing projects for a parasitic nematode was that for Haemonchus contortus. The open access data from the Wellcome Trust Sanger Institute provided a valuable early resource for the research community, particularly for the identification of specific genes and genetic markers. Later, a second sequencing project was initiated by the University of Melbourne, and the two draft genome sequences for H. contortus were published back-to-back in 2013. There is a pressing need for long-range genomic information for genetic mapping, population genetics and functional genomic studies, so we are continuing to improve the Wellcome Trust Sanger Institute assembly to provide a finished reference genome for H. contortus. This review describes this process, compares the H. contortus genome assemblies with draft genomes from other members of the strongylid group and discusses future directions for parasite genomics using the H. contortus model