A macro-element based practical model for seismic analysis of steel-concrete composite high-rise buildings

This is the post-print version of the final paper published in Engineering Structures. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2012 Elsevier B.V.Seismic behaviour of steel–concrete composite high-rise buildings, composed of external steel frames (SFs) and internal concrete tube (CT), with rectangular plan is investigated in this paper. A macro-element based model is established for seismic analysis of composite high-rise buildings aiming at predicting their global responses under earthquakes. By employing this macro-element based model, natural frequencies and vibration modes, storey and inter-storey drifts, overturning moments and storey shear forces of composite structures, induced by earthquakes, are able to be obtained with much less computation time and cost compared with using micro-element based analytical models. To validate its efficiency and reliability, the macro-element based model is employed to analyse a 1/20 scaled-down model of a 25-storey steel–concrete composite high-rise building subjected to simulated earthquakes with various intensities through a shaking table. Natural frequencies and storey drifts of the model structure are obtained from numerical analyses and compared with those from shaking table test results. It has been found that the calculated dynamic responses of the composite model structure subjected to minor, basic, major and super strong earthquakes agree reasonably well with those obtained from experiments, suggesting that the proposed macro-element based model is appropriate for inelastic time-history analyse for global responses of steel–concrete composite high-rise structures subjected to earthquakes with satisfactory precision and reliability. This research thus provides a practical model for elastic and inelastic deformation check of high-rise composite buildings under earthquakes.Ministry of Science and Technology of Chin

Enhancing off-site manufacturing through early contractor involvement (ECI) in New Zealand

Procurement strategies that enable early contractor involvement (ECI) in design may enhance off-site manufacturing (OSM) by overcoming previously identified barriers to its uptake. Involving constructors during the design stage can reduce the risk of design buildability issues, and standardising traditionally bespoke ECI processes may help overcome cultural resistance to unfamiliar OSM technology. Following literature review and using case studies, document analysis and legal doctrine, a two-stage ECI conceptual process model for New Zealand is proposed. This was tested and refined following feedback at a conference. The model comprises a first-stage pre-construction contract and a second-stage standard-form construction contract. Key process variables are considered with solutions to provide collaboration and transparency while maintaining competitive fixed pricing across the supply chain. Legal doctrine analysis is used to distinguish between design buildability obligations and design codes compliance. The model contributes towards the development of a standard form for pre-construction contracts

Contribution to sustainable seismic design of reinforced concrete members through embodied CO2 emissions optimization

The embodied CO2 emissions of reinforced concrete (RC) structures can be significantly reduced by structural optimization that maximizes structural efficiency. Previous studies dealing with design of RC structures for minimum CO2 emissions do not address seismic design provisions. This is the case despite the fact that in many countries around the world, including most of the top-10 countries in CO2 emissions from cement production, RC structures have to be designed against earthquake hazard. To fill a part of this gap, this study, using exhaustive search, examines optimum designs of RC beam and column members for minimum embodied CO2 emissions according to Eurocode-8 for all ductility classes and compares them with optimum designs based on material cost. It is shown that seismic designs for minimum CO2 footprint lead to less CO2 emissions but are more expensive than minimum cost designs. Their differences strongly depend on the assumed values of the environmental impact of reinforcing steel and concrete materials. Furthermore, it is concluded that seismic design for high ductility classes can drive to significant reductions in embodied CO2 emissions

The indispensability of good operation & maintenance (O&M) manuals in the operation and maintenance of low carbon buildings

Increase in energy usage, particularly from fossil fuel sources is widely understood to be responsible for the environmental problems (Climate Change) experienced globally today. Response to mitigating this anthropogenic induced consequence created the need for innovative low carbon and renewable technologies in buildings. In the UK presently, every new building is expected to be low-carbon and energy-efficient. However, it is widely acknowledged that significant differences often exist between designed and in-use performances of the buildings. Clients and end-users of these technologies appear not to be getting long term value for their investments; much attention has not been given to how these innovative technologies can be operated and maintained long into the future. Recent researches also underpin the fact that the wide information gap existing between designers and building end-users is one of the factors responsible for the performance-gap. This paper therefore presents excerpts of a research aimed at exploring a best practice approach to operability and maintainability of low-carbon-buildings. The research methodology involved the use of interviews, surveys and case study. Findings suggest that a properly prepared O&M manual is a potential document that that could bridge this gap and that it is an indispensable tool for the effective and efficient operation and maintenance of low carbon buildings

Stakeholders' role in improving Ghana's construction safety

Health and safety (H&S) management has traditionally been the responsibility of the contractor. Most often, contractors are blamed for the accidents and other ill health that occur on their construction sites. H&S performance is, however, enhanced when there is effective collaboration between those involved in the construction process. This paper therefore explores the role of stakeholders in promoting construction H&S in Ghana through public works procurement. The four main stakeholders identified and evaluated in this study are the government, the client (employer), the contractor and the employee(s). Seven interviewees (comprising procurement managers, consultants and quantity surveyors) from public institutions in Ghana participated in the research. Data were collected using semi-structured interviews and were thematically analysed. Results indicate a conflict in the perceived functions and relation of these stakeholders in the construction process. To address the constraint to improving construction H&S, certain recommendations are offered. These include the identification of specific individuals responsible for supervision and employee training, the development of H&S policies by the government and contracts that clearly outline the contractual obligations of all parties involved. Additionally, the specific roles and involvements of other stakeholders in the procurement process in improving construction H&S are also outlined

A systematic assessment of architectural approaches for solving the housing problem in Iraq

© 2018 The Authors Iraq experiences housing shortage of around 1–1.5 million units with low production rate. Managing this challenge requires integrated efforts across a number of fields. One way forward is to develop an integral and appropriate architectural solution. In Iraq, it remains unknown which of the possible architectural approaches is adequate to address its housing challenges while considering occupants׳ preferences. Aiming at helping in forming a solution, this study critically assesses the possible building patterns and construction approaches, which represent the main architectural solutions׳ framework. To achieve this aim, an extensive literature review was conducted that explores possible alternatives and housing requirements. Alternatives were assessed by comparing and contrasting their adequacy in satisfying Iraqis׳ preferences and the housing sector requirements. The assessment included conducting two surveys: a public Iraqis survey and an experts survey. The former was used to determine Iraqis׳ residential priorities and the latter to evaluate the adequacy of the defined alternatives in satisfying a set of housing requirements. A total number of 410 Iraqis participated in the first survey and fourteen Iraqi experts in the second. Based on the results, this paper suggests mass construction of multi-family courtyard residential buildings as a solution and discusses future research efforts

Environmental impact assessments of the Three Gorges Project in China: issues and interventions

The paper takes China's authoritative Environmental Impact Statement for the Yangzi (Yangtze) Three Gorges Project (TGP) in 1992 as a benchmark against which to evaluate emerging major environmental outcomes since the initial impoundment of the Three Gorges reservoir in 2003. The paper particularly examines five crucial environmental aspects and associated causal factors. The five domains include human resettlement and the carrying capacity of local environments (especially land), water quality, reservoir sedimentation and downstream riverbed erosion, soil erosion, and seismic activity and geological hazards. Lessons from the environmental impact assessments of the TGP are: (1) hydro project planning needs to take place at a broader scale, and a strategic environmental assessment at a broader scale is necessary in advance of individual environmental impact assessments; (2) national policy and planning adjustments need to react quickly to the impact changes of large projects; (3) long-term environmental monitoring systems and joint operations with other large projects in the upstream areas of a river basin should be established, and the cross-impacts of climate change on projects and possible impacts of projects on regional or local climate considered. © 2013 Elsevier B.V.Xibao Xu, Yan Tan, Guishan Yan

Occupational safety and health management in developing countries: A study of construction companies in Malawi

Purpose: Whilst occupational safety and health (OSH) management is recognised as an important mechanism for addressing poor OSH performance, limited empirical insight is available on OSH management by construction companies in sub-Saharan Africa. This study investigated OSH management by construction companies (i.e. contractors) in Malawi in order to unpick implementation issues that need attention. Materials and methods: 46 OSH management practices were probed through a survey of contractors. Results: Implementation of OSH practices amongst contractors is low, particularly for practices related to the policy, organising, measuring and reviewing, and auditing elements of OSH management. Company size, is associated with implementation of nearly a half of the 46 OSH practices. Certification of company to Standard No. OHSAS 1800:2007 is associated with the implementation of fewer practices. Conclusions: OSH management improvement efforts would need to focus on the elements with particularly low implementation of practices as well as include initiatives that focus on helping micro enterprises to improve their OSH management. Association between business characteristics and OSH management may be more evident with certain elements such as the organising element. Furthermore, certification to Standard No. OHSAS 1800:2007 may not necessarily translate into greater implementation of OSH management practices, especially in developing countries

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