• International conference on construction engineering and project management
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• 2007.03a
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• pp.563-572
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• 2007

Transportation infrastructure is critical to economic growth of a country such as China. Careful evaluation of investments in traffic infrastructure projects is therefore pertinent. As traditional evaluation methods do not consider the uncertainty of future cash flows and mobility during project execution, the real option approach is gradually gaining recognition in the context of valuing construction and infrastructure projects. However, many of the cases only evaluate individual options separately although multiple options often exist in a typical large infrastructure project. Using a highway project in China as a case study, this paper first evaluates a deferment option and a growth option embedded in the project. Subsequently, the values are combined using the fuzzy analytical hierarchy process. It is found that the combined value is less than the sum of the two option values. This finding is consistent with the theoretical observations given in past real option literature despite the use of a different approach.

• Ecology and Resilient Infrastructure
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• v.11 no.1
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• pp.24-24
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• 2024

• Computers and Concrete
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• v.30 no.1
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• pp.19-32
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• 2022

This paper presents an investigation into the failure of RC columns under impact loadings. A numerical simulation of 19 identical RC columns subjected to single and repeated impact loadings was performed. A free-falling hammer was dropped at midspan with the same total kinetic energy input but varying mass and momentum. The specimens under the repeated impact test were struck two times at the same location. The colliding index, defined as the impact energy-momentum ratio, was proposed to explain the different impact responses under equal-energy impacts. The increase of colliding index from low to high indicates the transition of the impact response from static to dynamic and failure mode from flexure to shear. This phenomenon was more evident when the column had a greater axial load and was impacted with a high colliding index. The existence of the axial load had an inhibitory effect on the crack development and increased the shear resistance. The second impact changes the failure mode from flexural to brittle shear as found in the specimen with 20% axial load subjected to high a colliding index. Moreover, a deflection prediction equation based on the impact energy and force was limited to the low colliding index impact.

• Computers and Concrete
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• v.6 no.5
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• pp.377-390
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• 2009

In this paper an improved one-dimensional frame element for modelling of reinforced concrete beams and columns subjected to impact is presented. The model is developed in the framework of a flexibility fibre element formulation that ignores the shear effect at material level. However, a simple shear cap is introduced at section level to take account of possible shear failure. The effect of strain rate at the fibre level is taken into account by using the dynamic increase factor (DIF) concept for steel and concrete. The capability of the formulation for estimating the element response history is demonstrated by some numerical examples and it is shown that the developed 1D element has the potential to be used for dynamic analysis of large framed structures subjected to impact of air blast and rigid objects.

• Smart Structures and Systems
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• v.6 no.5_6
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• pp.439-459
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• 2010

Structural health monitoring (SHM) of civil infrastructure using wireless smart sensor networks (WSSNs) has received significant public attention in recent years. The benefits of WSSNs are that they are low-cost, easy to install, and provide effective data management via on-board computation. This paper reports on the deployment and evaluation of a state-of-the-art WSSN on the new Jindo Bridge, a cable-stayed bridge in South Korea with a 344-m main span and two 70-m side spans. The central components of the WSSN deployment are the Imote2 smart sensor platforms, a custom-designed multimetric sensor boards, base stations, and software provided by the Illinois Structural Health Monitoring Project (ISHMP) Services Toolsuite. In total, 70 sensor nodes and two base stations have been deployed to monitor the bridge using an autonomous SHM application with excessive wind and vibration triggering the system to initiate monitoring. Additionally, the performance of the system is evaluated in terms of hardware durability, software stability, power consumption and energy harvesting capabilities. The Jindo Bridge SHM system constitutes the largest deployment of wireless smart sensors for civil infrastructure monitoring to date. This deployment demonstrates the strong potential of WSSNs for monitoring of large scale civil infrastructure.

• Nuclear Engineering and Technology
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• v.51 no.6
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• pp.1540-1553
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• 2019

A nuclear power plant (NPP) is a highly complex system-of-systems as manifested through its internal systems interdependence. The negative impact of such interdependence was demonstrated through the 2011 Fukushima Daiichi nuclear disaster. As such, there is a critical need for new strategies to overcome the limitations of current risk assessment techniques (e.g. the use of static event and fault tree schemes), particularly through simulation of the nonlinear dynamic feedback mechanisms between the different NPP systems/components. As the first and key step towards developing an integrated NPP dynamic probabilistic risk assessment platform that can account for such feedback mechanisms, the current study adopts a system dynamics simulation approach to model the thermal dynamic processes in: the reactor core; the secondary coolant system; and the pressurized water reactor. The reactor core and secondary coolant system parameters used to develop system dynamics models are based on those of the Palo Verde Nuclear Generating Station. These three system dynamics models are subsequently validated, using results from published work, under different system perturbations including the change in reactivity, the steam valve coefficient, the primary coolant flow, and others. Moving forward, the developed system dynamics models can be integrated with other interacting processes within a NPP to form the basis of a dynamic system-level (systemic) risk assessment tool.

• Steel and Composite Structures
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• v.33 no.2
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• pp.277-298
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• 2019

Concrete filled steel tubular (CFST) column joints with composite beams have been widely used as lateral loading resisting elements in civil infrastructure. To better utilize these innovative joints for the application of structural seismic design and analysis, it is of great importance to investigate the dynamic behavior of the joint under cyclic loading. With this aim in mind, a novel phenomenal model has been put forward in this paper, in which a Bouc-Wen hysteresis component is employed to portray the strength and stiffness deterioration phenomenon caused by increment of loading cycle. Then, a modified chicken swarm optimization algorithm was used to estimate the optimal model parameters via solving a global minimum optimization problem. Finally, the experimental data tested from five specimens subjected to cyclic loadings were used to validate the performance of the proposed model. The results effectively demonstrate that the proposed model is an easy and more realistic tool that can be used for the pre-design of CFST column joints with reduced beam section (RBS) composite beams.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.980-985
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• 2005

Since the 1980s, Build-Operate-Transfer and its variations have become a common approach to develop large-scale infrastructure projects. Despite the slight variations in contractual settings, the key issue for all parties concerned is to assess the risks and uncertainties inherent in a project. The risk factors studied and highlighted by past researchers are very diverse. This paper starts with an objective to compare the risk factors in different sectors of infrastructure, and then categorize them into two kinds: general and specific. Following this classification, risk mitigation strategies should be adopted differently at the corporate and project levels. A few short cases have also been used to illustrate the flexible measures or "options" that some project participants have designed to address risks and uncertainties at the two levels.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.1
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• pp.77-86
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• 2017

Industry Foundation Classes(IFC) is the core product schema for ensuring the interoperability of information in Building Information Modeling(BIM) environment. However, since current IFC is mainly focused on building structure. there are limitations in the generation of functional information of components when applied to civil infrastructures. Previous studies have proposed IFC-based new entities for the civil infrastructures, it takes long time to support them in BIM authoring software packages. In this study, we proposed practical rules to apply IFC-based information modeling using BIM authoring software and additional new entities for the civil infrastructure through attributes and information mapping. The availabilities of proposed method were examined using the rail and sleeper information models based on an extended IFC data schema for the railway infrastructures.

• Journal of KIBIM
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• v.12 no.3
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• pp.18-29
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• 2022

Recently, research on the application of BIM has continuously been active not only in architecture but also in civil engineering in order to improve work efficiency across the project's planning, design, construction and maintenance phases. However, the empirical applications of BIM targeting to civil engineering scope of construction sites still lags compared to architectural sized projects. This is because BIM tools are mainly based upon vertical structures of architecture, thereby most of them have difficulties and limitations to get utilized on horizontal structures of civil engineering. Therefore, this study intends to propose automation technology of design using BIM library and to indicate its field availability through case application on a railway project representing linear infrastructure. In addition, it put forward the utilization plan of the automation technology upto 4D and 5D by continue making use of the BIM model created in the project's design stage up through the maintenance stage. The novel method of the technology proposed in this paper incorporates the automatic creation of the BIM library based on two-dimensional tunnel cross-sections and sweeping of it over three-dimensional alignment to create a BIM model of linear infrastructure. The proposed technology is anticipated to improve the efficiecny of modeling process of railway projects based on linear structures.