• Computers and Concrete
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• v.14 no.5
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• pp.503-526
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• 2014

Concrete is a versatile construction material used in many engineering structures. The design of concrete structures requires a thorough understanding of their material properties under various loading conditions. Several experimental investigations have been carried out to examine the behavior of concrete. This paper is an attempt to summarize the behavioral aspects of concrete under different loading conditions. Failure models developed out of these experimental investigations are reported in this paper with their merits and demerits.

• International Journal of Fluid Machinery and Systems
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• v.4 no.1
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• pp.47-56
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• 2011

Our previous experimental and numerical investigations of decelerated swirling flows in conical diffusers have demonstrated that water jet injection along the symmetry axis mitigates the pressure fluctuations associated with the precessing vortex rope. However, for swirling flows similar to Francis turbines operated at partial discharge, the jet becomes effective when the jet discharge is larger than 10% from the turbine discharge, leading to large volumetric losses when the jet is supplied from upstream the runner. As a result, we introduce the flow-feedback approach for supplying the jet by using a fraction of the discharge collected downstream the conical diffuser. Experimental investigations on mitigating the pressure fluctuations generated by the precessing vortex rope and investigations of pressure recovery coefficient on the cone wall with and without flow-feedback method are presented.

• Geomechanics and Engineering
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• v.5 no.2
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• pp.165-185
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• 2013

In the present study, the numerical and experimental investigations were performed on the backfill- exterior wall-fluid interaction systems in case of empty and full tanks. For this, firstly, the non-linear three dimensional (3D) finite element models were developed considering both backfill-wall and fluid-wall interactions, and modal analyses for these systems were carried out in order to acquire modal frequencies and mode shapes by means of ANSYS finite element structural analysis program. Secondly, a series of field tests were fulfilled to define their modal characteristics and to compare the results from proposed approximation in the selected structures. Finally, comparing the theoretical predictions from the finite element models to results from experimental measurements, a close agreement was found between theory and experiment. Thus, it can be easily stated that experimental verifications provide strong support for the finite element models and the proposed procedures themselves are the meritorious approximations to the real problem, and this makes the models appealing for use in further investigations.

• Computers and Concrete
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• v.7 no.2
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• pp.169-190
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• 2010

The focus of this research effort was characterization of the flexural and tensile properties of a specific ultra-high-strength, fiber-reinforced concrete material. The material exhibited a mean unconfined compressive strength of approximately 140 MPa and was reinforced with short, randomly distributed alkali resistant glass fibers. As a part of the study, coupled experimental, analytical and numerical investigations were performed. Flexural and direct tension tests were first conducted to experimentally characterize material behavior. Following experimentation, a micromechanically-based analytical model was utilized to calculate the material's tensile failure response, which was compared to the experimental results. Lastly, to investigate the relationship between the tensile failure and flexural response, a numerical analysis of the flexural experiments was performed utilizing the experimentally developed tensile failure function. Results of the experimental, analytical and numerical investigations are presented herein.

• Steel and Composite Structures
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• v.20 no.4
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• pp.813-832
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• 2016

This research deals with the behavior of Composite Box Girder Bridges (CBGBs) subjected to environmental effects such as solar radiation, atmospheric temperature, and wind speed. It is based on temperature and thermal stress results, which were recorded hourly from a full-scale experimental CBGB segment and Finite Element (FE) thermal analysis. The Hemi-cube method was adopted to achieve the accuracy in temperature distributions and variations in a composition system during the daily environmental variations. Analytical findings were compared with the experimental measurements, and a good agreement was found. On the other hand, parametric investigations are carried out to investigate the effect of the cross-section geometry and orientation of the longitudinal axis of CBGB on the thermal response and stress distributions. Based upon individual parametric investigations, some remarks related to the thermal loading parameters were submitted. Additionally, some observations about the CBGB configurations were identified, which must be taken into account in the design process. Finally, this research indicates that the design temperature distribution with a uniform differential between the concrete slab and the steel girder is inappropriate for describing the thermal impacts in design objective.

• Structural Engineering and Mechanics
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• v.18 no.6
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• pp.709-729
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• 2004

This paper presents numerical and experimental investigations on damage detection of mono-coupled multistory buildings using natural frequency as only diagnostic parameter. Frequency equation of a mono-coupled multistory building is first derived using the transfer matrix method. Closed-form sensitivity equation is established to relate the relative change in the stiffness of each story to the relative changes in the natural frequencies of the building. Damage detection is then performed using the sensitivity equation with its special features and minimizing the norm of an objective function with an inequality constraint. Numerical and experimental investigations are finally conducted on a mono-coupled 3-story building model as an application of the proposed algorithm, in which the influence of modeling error on the degree of accuracy of damage detection is discussed. A mono-coupled 10-story building is further used to examine the capability of the proposed algorithm against measurement noise and incomplete measured natural frequencies. The results obtained demonstrate that changes in story stiffness can be satisfactorily detected, located, and quantified if all sensitive natural frequencies to damaged stories are available. The proposed damage detection algorithm is not sensitive to measurement noise and modeling error.

• Journal of Korean Elementary Science Education
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• v.31 no.2
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• pp.227-242
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• 2012

This research explores the scientific reasoning of pre-service elementary teachers in experimental design. The article focuses on pre-service teachers' responses to the questions in the worksheets which involve making their knowledge claims on extinguishing of a burning candle in a closed container, evaluating anomalous data, and designing experiment to test their ideas. Their responses are interpreted in terms of categories developed by Tytler and Peterson(2003, 2004). The interrelationship between conceptual knowledge and scientific reasoning is explored using the data. It is argued that coordination of ideas and evidence must be emphasized in the scientific investigations rather than fair test.

• Journal of Powder Materials
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• v.22 no.5
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• pp.337-343
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• 2015

Powder compaction is a continually and rapidly evolving technology where it is a highly developed method of manufacturing reliable components. To understand existing mechanisms for compaction, parameter investigation is required. Experimental investigations on powder compaction process, followed by numerical modeling of compaction are presented in this paper. The experimental work explores compression characteristics of soft and hard ductile powder materials. In order to account for deformation, fracture and movement of the particles, a discrete-finite element analysis model is defined to reflect the experimental data and to enable investigations on mechanisms present at the particle level. Effects of important simulation factors and process parameters, such as particle count, time step, particle discretization, and particle size on the powder compaction procedure have been explored.

• Ocean Systems Engineering
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• v.1 no.2
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• pp.131-155
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• 2011

Liquid sloshing constitutes a broad class of problems of great practical importance with regard to the safety of liquid transportation systems, such as tank trucks on highways, liquid tank carriages on rail roads, ocean going vessels and propellant tanks in liquid rocket engines. The present work attempts to give a review of some selected experimental investigations carried out during the last couple of decades. This paper highlights the various parameters attributed to the cause of sloshing followed by effects of baffles, tank inclination, magnetic field, tuned liquid dampers, electric field etc. Further, recent developments in the study of sloshing in micro and zero gravity fields have also been reported. In view of this, fifteen research articles have been carefully chosen, and the work reported therein has been addressed and discussed. The key issues and findings have been compared, tabulated and summarized.

• Structural Engineering and Mechanics
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• v.69 no.2
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• pp.163-175
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• 2019

Structural deterioration arises due to aging, environmental effects, deficiencies during design and construction phase, and overloading. Experimental and numerical investigations are carried out in this study to evaluate the performance of control and flexural deficient reinforced concrete (RC) beams under monotonic loading. Three levels of flexural deficiency are considered in this study. After confirming load carrying capacities of control and flexural deficient beams, the flexural deficient RC beams are strengthened with carbon fibre reinforced polymer (CFRP) fabric. CFRP strengthened RC beams are tested under monotonic loading and compared with the performance of control specimen. Further, non-linear finite element analyses are also carried out to evaluate the flexural performance of control, deficient and CFRP strengthened flexural deficient RC beams. There is good correlation between results of experimental and numerical investigations. Numerical approach presented in this study can be adopted for assessing the adequacy of CFRP retrofit measure.