The efficient use of precast concrete technology in the construction of elevated guideways

Author(s):  
Gilberto Dreas

<p>Several Elevated Transit Guideway projects in congested urban enviroments have been completed in the last 30 years. A lot more will be built in the near future to minimize the use of private cars, avoid traffic congestion and reduce carbon emissions. The use of precast segmental technology has been largely preferred for the construction of these structures for a number of advantages that the technology offers, including but not limited to: aesthetics, fast construction, durability, limited urban impact, low sensibility to construction constraints. In recent projects a some new governing design factors are being considered, such as sustainable construction, health and safety, materials efficiency, longer design life. Purpose of this presentation is to summarise the last thirty-years experience in design and construction of precast segmental elevated guideways, focusing on the key design factors such as: Urban impact, Train system – structure interaction, Noise emission Riding comfort, Design criteria, etc. In addition to the above, new factors that may govern the design and construction of the projects planned for the near future will be presented and discussed.</p>

2020 ◽  
Vol 5 ◽  
pp. 63-74
Author(s):  
Wolfram Schmidt ◽  
Mike Otieno ◽  
Kolawole Olonade ◽  
Nonkululeko Radebe ◽  
Henri Van-Damme ◽  
...  

Africa is urgently in need of adequate basic infrastructure and housing, and it is one of the continents where massive construction activities are on the rise. There is a vast variety of potentially viable resources for sustainable construction on the continents, and consequently, the continent can bring innovative, greener technologies based on local sources effectively into practice. However, unlike established concrete constituents from industrialised countries in the global North, most of the innovation potentials from the African continent have not yet been the focus of intensive fundamental and applied research. This clearly limits the implementation of more sustainable local technologies. This paper presents a case for the need to first appreciate the rich diversity and versatility of the African continent which is often not realistically perceived and appreciated. It discusses specific innovation potentials and challenges for cementitious materials and concrete technology based on local materials derived from sources on the African continent. The unique African materials solutions are presented and discussed, from mineral binders over chemical admixtures and fibres to reinforcement and aggregates. Due to the pressing challenges faced by Africa, with regards to population growth and urbanisation, the focus is not only put on the technological (durability, robustness and safety) and environmental sustainability, but also strongly on socio-economic applicability, adaptability and scalability. This includes a review of alternative, traditional and vernacular construction technologies such as materials-saving structures that help reducing cementitious materials. Eventually, a strategic research roadmap is hypothesised that points out the most relevant potentials and research needs for quick implementation of more localised construction materials.


2020 ◽  
Vol 20 (1) ◽  
pp. 7-20
Author(s):  
Adrieli Cristina Vieira de Carvalho ◽  
Ariovaldo Denis Granja ◽  
Vanessa Gomes da Silva

Abstract The construction industry is increasingly adopting sustainable strategies to reduce environmental impacts. Despite this increase, some barriers are still perceived in the real estate market for sustainable buildings. One of them is the delivery of products that are not aligned with the needs and values of end users. This paper investigates the aspired sustainability values in housing projects based on the concept of stated preferences. A card game tool was developed based on the AQUA - HQE(tm) rating system and applied to ask a 164-respondent sample, assembled from four social housing projects to identify their preferences regarding sustainable construction. Responses were statistically analyzed based on bootstrap confidence values and on the index of general significance (IGS) of each sustainable value attribute. Results show a sustainable value hierarchy, in which the health and safety parameters were the most valued. This study confirms the validity of using a set of illustrated cards as a potential tool for identifying sustainability values end users bear and consequently improving decision-making process within sustainable products development.


2021 ◽  
Vol 16 (1) ◽  
pp. 39-48
Author(s):  
Peter Uchenna Okoye

The success of every construction projects largely depends on the level of commitment of the clients. This study examined the factors influencing the level of clients’ commitment to sustainable construction practices in Nigeria. A questionnaire survey was use to collect data from the public and private construction clients on the level of influence of 16 factors extracted from the literature. A total of 182 valid questionnaires were used for analysis. The result revealed that nine factors with weighted average (W) 0.8≤W≤1 have a high level of influence, whereas seven factors with 0.6≤W≤0.8 have a high-medium level of influence on the clients’ commitment. However, the five most influential factors were: client knowledge and awareness, Cost implication and mechanism of financial involvement, economic value and return on investment, end-user/client perception and preference, and health and safety implications. The result further revealed that there is significant difference on how these factors influence the level of commitment of sustainable construction practices of the public and private clients. The study suggested that the disparity was due to the differences in the level of knowledge, awareness, involvement and commitment of the public and private clients to sustainable construction concept. Hence, it is important to optimize the level of knowledge and awareness of the clients, about the cost, benefits/profits, and health and safety implications of sustainable construction practices so as to promote the level of client’s commitment to sustainable construction practices. It recommended for adequate client involvement throughout the sustainable construction life cycle and a sustained awareness campaign, championed by relevant government agencies and professional organizations through different public programs so as to increase the clients’ commitment and desirability to demand for more sustainable construction projects.


2010 ◽  
Vol 16 (1) ◽  
pp. 85-94 ◽  
Author(s):  
Gul Polat

Precast concrete technology is recognized worldwide as offering significant advantages. Despite the advantages they offer, precast concrete building systems’ share in both Turkey and the U.S. is very low, especially when compared to many European countries. Since Turkey is a developing country that is technologically dependent on the developed world, low share of industrialized building systems is highly expected in that country. However, the U.S. is a developed and industrialized country, so it was very interesting to see that these systems are not extensively used in that country either. This study investigated the factors that prevent the extensive use of precast concrete systems in the U.S. and Turkey through an extensive questionnaire survey. The survey results revealed that the perceptions of the American vs. Turkish respondents on most of the factors that affect the use of precast concrete systems are significantly different from each other. While American respondents considered size and load restrictions on transportation, poor communication among parties, and lack of qualified contractors specialized in precast concrete systems as three most important barriers to the extensive use of precast concrete systems in the U.S. building construction market, Turkish respondents ranked lack of good communication among parties and lack of structural engineers and contractors specialized in precast concrete systems as the most important three factors that prevent the extensive use of these systems in Turkey. This study indicated that precast concrete users and manufacturers should recognize that the main reasons for low utilization of precast concrete systems predominantly depend on the prevailing conditions of the country in question. Santrauka Surenkamojo gelžbetonio technologija visame pasaulyje pripažistama del daugelio svarbiu pranašumu. Nepaisant ju, surenkamojo gelžbetonio statybos sistemu dalis Turkijoje ir JAV, palyginti su kitomis Europos šalimis, yra labai maža. Turkija yra besivystanti šalis, kurios technologiju pletote priklauso nuo išsivysčiusiu šaliu, tad maža surenkamosios statybos sistemos dalis yra pagrista. Tačiau JAV yra išsivysčiusi ir industrializuota šalis, bet šiu sistemu naudojimo mastas šalyje yra mažas. Remiantis išsamia apklausa straipsnyje atlikta maža surenkamuju betono sistemu naudojimo JAV ir Turkijoje apimti lemiančiu veiksniu analize. Apklausos rezultatai parode, kad JAV ir Turkijos respondentu nuomonL del daugelio veiksniu labai skyresi. JAV respondentai nurode, kad trys pagrindiniai veiksniai, ribojantys surenkamuju gelžbetonio sistemu naudojima JAV statybos rinkoje, yra: transportavimo apribojimai del dydžio ir svorio; silpnas ryšys tarp statybos proceso dalyviu; kvalifikuotu statybos rangovu, kuriu specializacija ‐ surenkamieji statybos elementai, trūkumas. Turkijos respondentai pagrindinLmis priežastimis laiko bendradarbiavimo tarp statybos proceso dalyviu stoka ir specializuotu statybos projektuotoju bei rangovu trūkuma. Atlikta studija parodL, kad surenkamojo gelžbetonio sistemu naudotojai ir gamintojai turetu pripažinti, jog menka surenkamuju gelžbetonio sistemu naudojimo apimtis pirmiausia priklauso nuo šalyje dominuojančiu statybos salygu.


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