Vol 2 No 1 (2023)

• The Mental Health of Migrant Workers in the Australian Construction Sector: A Literature Review

  Jose Cuenca, Iftekhar Ahmed, Lynne McCormack, Mark Rubin, Kavitha Palaniappan, Liyaning Tang, Elsa Licumba

  There is a high proportion of migrants in the construction industry; however, little is known of the factors that increase the risk of mental health difficulties among this group and in particular in Australia.Research studies on the mental health of migrant construction workers in Australia were searched in Web of Science, Scopus, PubMed and Google Scholar. The literature search found seven studies, of which five included a subgroup of migrant construction workers or stakeholders in the field and two studies sampled specifically from this population but from higher educational backgrounds. Three of the studies used crosssectional surveys and the other four used qualitative interviews in combination with either other qualitative techniques or a literature review. The limited evidence suggests that migrant construction workers living in Australia are likely to experience psychological distress in the context of adverse working conditions, financial hardships and interpersonal stressors. Common methodological limitations of the literature reviewed for this paper were a lack of comparison groups, combined samples of workers from different occupations, limited use of standardised measures of psychological distress and a focus mainly on occupational factors. Implications include operationalizing interventions in a manner that is accessible to migrants and their culture. The review stresses that more research is required in this field sampling specifically from the migrant construction workers population, using comparison groups, prospective designs, and qualitative methods to help better understand the unique experiences of mental ill-health in this group.

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• Developing a Voxel-Based Sightline Sampling Algorithm for Calculating Panoramic Visible Green Index in High-density Urban Environment

  Yipeng Feng, Feng Yang

  Studies have shown that view to greenery and other natural landscape elements may have a beneficial restorative effect on urban residents, and the effect may be evaluated by the Visible Green Index (VGI) which refers to the proportion of green landscape represented by plants and waterscape in people's vision. This article proposes a method based on Sightline Sampling Algorithm (SSA) that can quickly calculate the VGI distribution in urban space. This method is operated on a voxel model, scans the distribution of plants around the viewpoint by constructing sampling sightline rays to quickly obtain the corresponding VGI information. Parametric analysis shows that for optimized combinations of voxel size and sampling size, the method can quickly calculate VGI at continuous locations with a fairly satisfactory accuracy. As a case study, the distributions of VGI in three campuses of a university in Shanghai, China is examined using the SSA method. The result shows that the method can evaluate the existing green view levels. Potential areas for improvement, i.e. high pedestrian density while poor green view percentages are identified, and the improved VGI distribution with renovation design scheme is predicted. The VGI method can be a potential tool to support architects and landscape designers in analyzing green visual quality and assessing the restorative benefits of urban landscape design.

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• Comparison between the life cycle carbon footprint of refurbished and new buildings: A case study of Community centre

  Fadoua Zhour, Mawada Abdellatif, Yassin Osman, Denise Lee

  Buildings are a huge carbon emitter. Efforts are being made to cut both embodied and operational carbon emissions to reduce the impact on the built environment. This study aims to compare the Life Cycle Carbon Footprint (LCCF) and LCC of two alternatives: refurbishment and radical replacement of an existing community centre building in Liverpool to identify options that could achieve significant CO2 emission reductions in an economically viable way. The calculation methods are standardised by the UK's RICS (Royal Institute of Chartered Surveyors) to overcome the limitations of LCAs undertaken in previous research. This refers to the Inventory of Carbon and Energy (ICE) database from which embodied calculation factors were extracted to get the greenhouse gases. While the operational emissions data were obtained from a thermal simulation through IES software. The results of this study showed that the refurbishment scenario is the best option since it emits 50% less GHG and reaches 64% lower costs compared to the new build case throughout the building’s life cycle. Such that the LCCF of the refurbishment scenario was 215,084.36 kgCO2e/m2 and its LCC £ 88,135.32, while the replacement scenario achieved 429,397.44 kgCO2e/m2 and £ 246,213.59. It can be deducted that to reach significant reductions in carbon emissions rates with a lower economic impact, refurbishment is preferable to demolition and new construction, even if the building shows several damages and defects, which suggests that the UK government should incentivise and encourage re-use for faster environmental rehabilitation.

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• Finite Element Modelling with Abaqus and Tosca for Topology Optimization of Steel

  Tiago Ribeiro, Luís Bernardo, Ricardo Carrazedo

  Finite Element Method (FEM) is widely employed for solids and multiphysics problems analysis in practically all engineering and science fields. Yet, when it comes to Topology Optimization (TO), significant issues arise concerning the geometry, hence the mesh, and non-stationary condition. Contrarily to broader Finite Element Modelling, FEM for TO has much less bibliographic support and research. Herein we depict, apply and discuss the major challenges and options concerning modelling with finite elements within TO problems. It is shown that, for the optimization of a steel connection part, mesh refinement is critical for effective yet computationally efficient analysis. Moreover, a case-based and user-friendly approach, in the form of tutorial, is proposed to address the practical FE meshing for TO.

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• Verification of seismic enforced-displacement pushover procedure on torsionally flexible, asymmetric, multi-storey r/c buildings

  Triantafyllos Makarios, Athanasios Bakalis

  A recently proposed direct Displacement-based procedure of nonlinear static (pushover) analysis on multi-storey reinforced concrete (r/c) buildings is verified here against the results of Nonlinear Response History Analysis. An asymmetric, regular in elevation, torsionally flexible, multi-storey r/c building designed according to Eurocode EN 1998 is investigated. Taking fully into account the inelastic torsion and the higher mode effects, as well as the P-Delta effects, the proposed procedure applies a pattern of seismic floor enforced-displacements along on the “Capable Near Collapse Principal Axes of the building”, aiming at Near Collapse state.  The envelope of the results of sixteen final non-linear static analyses on the investigated building shows that the main aspects of the spatial seismic action effects can be safely captured by the proposed procedure, especially regarding the inelastic interstorey drift ratios, as well as the plastic mechanism of the building.

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• Research on air pollution characteristics and planning strategy of urban street environment

  Shen Yang, Qingming Zhan, Liu Wen

  Dense buildings in modern cities make street pollutants more and more difficult to disperse, and the exposure level of urban residents to pollutants has increased significantly. This study focuses on the spatial and temporal distribution of ambient air pollution in urban streets and the relationship between street morphology and pollutant dispersion, and explores ways to reduce ambient air pollution in streets through spatial design. The study used the CityGrid urban grid data monitoring station to conduct an empirical study on an urban trunk road in Wuhan during the winter of 2020 to 2021, monitoring pollutants including NO₂, O₃, PM_2.5, and PM₁₀. The results showed that pollutant concentration changes in the near-road environment are affected by a combination of meteorological elements and traffic flow characteristics. The wind parallel to the road is more favorable to evacuate pollutants inside the street canyon, and the ambient wind above the canyon perpendicular to the road causes vortices in the canyon that cause gaseous pollutants to accumulate on the leeward side of the canyon. The distribution of particulate pollutants is mainly related to the distance of road pollutant sources. Building access ventilation can effectively evacuate street pollutants, and NO₂ and O₃ decay to stable levels in shorter distance from the road than PM_2.5 and PM₁₀ in downwind direction. The future urban street planning can effectively alleviate street pollution levels through strategies such as street canyon morphology control, green landscape facilities arrangement, increasing the building interface opening, and building bottom overhead.

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