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Showing 8 results for Cho

Khalou A.r., Ghara Chour Lou A.,
Volume 3, Issue 1 (March 2005)

This paper presents the results of analytical studies concerning the flexuralstrengthening of reinforced concrete beams by external bonding of high-strength lightweightcarbon fiber reinforced plastic (CFRP) plates to tension face of the beam. Three groups of beamswere tested analytically and compared with existing experimental results. Results of the numericalanalyses showed that, although addition of CFRP plates to the tension face of the beam increasesthe strength, it decreases the beam ductility. Finite element modeling of fifteen different beams in aparametric study indicates that steel area ratio, CFRP thickness, CFRP ultimate strength andelastic modulus considerably influence the level of strengthening and ductility.
H.m. Noh, Y.o. Cho,
Volume 8, Issue 1 (3-2010)

In this paper, the processes which are currently under development in South Korea, concerning railway

safety management system are introduced. Railway safety management system in South Korea is briefly presented,

making particular attentions to Systems Engineering Management Plan (SEMP). To make huge national R&D projects

successful, systematic management process is essential. In this respect, detailed applying SEMP on railway safety

management system of South Korea is discussed including Systems Engineering process and Verification and

Validation procedures. Furthermore, a computer-aided systems engineering tool (Cradle) is used in order to make the

management process more easily controllable.

A. GharaChorlou, Dr. A.a. Ramezanianpour ,
Volume 8, Issue 4 (December 2010)

The use of epoxy-bonded FRPcomposite for structural repair is emerging as an efficient and cost-effective technique for restoring and upgrading the capacity of concrete structures. Considerable researches have been reported in the last decades on the mechanical behavior and failure modes of the FRPstrengthened RC elements but actual data on its durability are scarce. This study intends to examine the durability of concrete specimens strengthened with FRP laminates under accelerated laboratory conditions and mimic harsh environmental situation which is the penetration of chloride ions. In this study three groups of specimens were examined. Each of these groups includes several concrete cylindrical specimens full confined with FRP laminates for investigating different types of fiber (Glass and Carbon), number of fiber layers and temperature influences. Furthermore, an apparatus was fabricated to simulate wetting and drying cycles for the second group of specimens. Moreover group III specimens were placed in a marine environment for 3 years to monitor their performance. Test results show that addition of FRP laminates reduces chloride ions penetration up to 70 percent. Results also indicate that although chloride ions penetration decreased the ultimate strength of cylindrical specimens up to 11 percent but FRP strengthened specimens achieved their initial strengths. Moreover wetting and drying cycles reduced the strength of cylinder specimens up to about ten percent especially in the high temperature laboratory condition.

Sung-Hoon An, Hunhee Cho, Ung-Kyun Lee,
Volume 9, Issue 1 (March 2011)

In the early stages of a construction project, the reliability and accuracy of conceptual cost estimates are major concerns for clients and cost engineers. Previous studies applied scoring methods and established common rules or mathematical methods to assess the quality of cost estimates. However, those approaches have some limitations in adapting to real-world projects or require understanding of sophisticated statistical techniques. We propose a Conceptual Cost Estimate Reliability Index (CCERI), a simple, easy-to-use, and easy-to-understand tool that incorporates weights for 20 factors influencing the quality of conceptual cost estimates. The weights were obtained by eliciting experts’ experience and knowledge. Cost data from 71 building projects were used in the analysis and validation of the CCERI. The analysis reveals that a conceptual cost estimate with a CCERI score of less than 3000 has a high probability of exceeding 10% error, and such conceptual cost estimates are unlikely to be reliable. With the CCERI score, a decision maker or a client can recognize the reliability of the conceptual cost estimates and the score can thus support decision making using conceptual cost estimates. In addition, with the CCERI and the relative importance weights of factors affecting the conceptual cost estimates, the estimator can find ways to modify a conceptual cost estimate and reestimate it. These alternatives can decrease the risk in the conceptual estimated cost and assist in the successful management of a construction project.
Khaled Farah, Mounir Ltifi, Tarek AbiChou, Hedi Hassis,
Volume 12, Issue 3 (Transaction B: Geotechnical Engineering, July 2014)

The purpose of this study is to compare the results of different probabilistic methods such as the perturbation method, Stochastic Finite Element Method (SFEM) and Monte Carlo Method. These methods were used to study the convergence of direct approach for slope stability analysis and are developed for a linear soil behavior. In this study, two dimensional random fields are used and both the First Order Reliability Method (FORM) and Limited Step Length Iteration Method (LSLIM) have been adopted to evaluate the reliability index. The study found that the perturbation method of the second order is easy to apply using the field’s theory because accuracy is reached even with different coefficients of variation of input variables, while the spectral finite element method yields accurate results only for high levels of solution development.
Ch. Preece, H.y. Chong, H. Golizadeh, J. Rogers,
Volume 13, Issue 3 (Transaction A: Civil Engineering, September 2015)

The management philosophy, namely, Customer relationship management (CRM) has been widely accepted and successfully applied across a range of sectors. However, there has been very little research efforts in the field of CRM in the construction industry. This paper provides a review of the CRM philosophy and technology, and considers the implications benefits and challenges to construction organizations at a strategic business and operational level. Given the generally unstable economic and highly competitive marketplace, implementation of CRM throughout the lifecycle of assets may provide for more effective management of existing and prospective clients. The CRM approach would seem to be compatible with general trends in the construction industry towards more collaborative working and the paper provides that both the philosophy and technologies can be integrated with current initiatives such as building information modeling (BIM). Construction clients in the public and private sector are diverse in nature, complex in their buying processes and at varying levels of knowledge of the Industry. In addition to seeking value for money from their projects and assets, they have become more concerned about sustainability and environmental impact. It has been recognized that management of a broader range of business and project level stakeholders is necessary.
Hynn-Ki Choi,
Volume 14, Issue 6 (Transaction A: Civil Engineering 2016)

Replacement of existing unreinforced masonry (URM) walls, commonly used as a non-structural member in apartments, with new reinforced concrete (RC) components has been used as a reliable method when remodeling is carried out. However, special care needs to be taken when URM walls are removed not to waste construction time and materials. Therefore, retrofitting existing URM walls can be deemed a better solution rather than replacing URM walls with RC ones. Using shotcrete is one of retrofitting techniques of URM walls. However, using normal shotcrete cannot improve adequate ductility and may cause brittle failure at a wall-frame or slab connection. Therefore, new materials such as engineered cementitious composite (ECC) and ultra-high performance concrete (UHPC) have emerged to resolve the problem of normal shotcrete by increasing ductility and toughness of retrofitting materials. In this study, sprayed ECC was used to increase both strength and ductility of existing URM walls. The results of two retrofitted URM walls under lateral quasi-static loading were compared to non-retrofitted one. One strengthened wall, retrofitted masonry wall (RTM)-ECC, was just sprayed and anchored to a wall base. Another strengthened wall, RTM-ECC-WM, was the same as RTM-ECC except for addition of wire mesh. The retrofitted specimens showed significant increase of strength, ductility, and energy dissipation capacity in comparison with the control one. In addition, RTM-ECC-WM indicated better strength degradation due to the load transferring effect of wire mesh than RTM-ECC.

Hyun-Ki Choi,
Volume 15, Issue 4 (Transaction A: Civil Engineering 2017)

This study investigated the structural behaviors of reinforced concrete shear walls containing opening and slab. A series of three half-scale shear wall specimens were tested: a solid wall (WS-Solid), a wall with opening and slab (WS-023), and a wall with opening but no slab (WB-0.23). Using the experimental results, the reduction in the load-carrying capacity of the wall due to the loss of cross section was evaluated. Its contribution to the moment resisting capacity of the total system of coupling elements and its structural behavior was also examined. The results of experiments conducted on the WS-0.23 specimen with artificial damage due to installation of the opening, showed that the load-carrying capacity of the wall decreased as a result of the opening. It is apparent that the influence of cutting reinforcing bars and reduction of effective sectional area lead to early first yield of the reinforcing bars before the allowable limit of the drift ratio of the shear walls is reached. This decrease in the load-carrying capacity of the shear wall because of installation of openings is significantly different from the results of previous studies. This is because slabs and the remaining wall function as coupling elements for the shear wall. The contribution of slabs and residual wall to the lateral load resisting system was investigated via an empirical test and finite element analysis. During the experiment, a U-shaped critical section of coupling slab was observed and its effective width and the total length of the critical section examined. The critical section of coupling slab that functions as a coupling element for shear wall varied marginally from the results of previous studies. The results of the analysis conducted show that slabs and residual walls contribute approximately 30% to the lateral load resisting system.

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