• Smart Structures and Systems
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• v.19 no.6
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• pp.679-694
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• 2017

The complexity, enlargement and irregularity of structures and multi-directional dynamic loads acting on the structures can lead to unexpected structural behavior, such as torsion. Continuous torsion of the structure causes unexpected changes in the structure's stress distribution, reduces the performance of the structural members, and shortens the structure's lifespan. Therefore, a method of monitoring the torsional behavior is required to ensure structural safety. Structural torsion typically occurs accompanied by displacement, but no model has yet been developed to measure this type of structural response. This research proposes a model for measuring dynamic torsional response of structure accompanied by displacement and for identifying the torsional modal parameter using vision-based displacement measurement equipment, a motion capture system (MCS). In the present model, dynamic torsional responses including pure rotation and translation displacements are measured and used to calculate the torsional angle and displacements. To apply the proposed model, vibration tests for a shear-type structure were performed. The torsional responses were obtained from measured dynamic displacements. The torsional angle and displacements obtained by the proposed model using MCS were compared with the torsional response measured using laser displacement sensors (LDSs), which have been widely used for displacement measurement. In addition, torsional modal parameters were obtained using the dynamic torsional angle and displacements obtained from the tests.

• Journal of Powder Materials
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• v.27 no.1
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• pp.1-7
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• 2020

In this research, a new medium-entropy alloy with an equiatomic composition of FeCuNi was designed using a phase diagram (CALPHAD) technique. The FeCuNi MEA was produced from pure iron, copper, and nickel powders through mechanical alloying. The alloy powders were consolidated via a high-pressure torsion process to obtain a rigid bulk specimen. Subsequently, annealing treatment at different conditions was conducted on the four turn HPT-processed specimen. The microstructural analysis indicates that an ultrafine-grained microstructure is achieved after post-HPT annealing, and microstructural evolutions at various stages of processing were consistent with the thermodynamic calculations. The results indicate that the post-HPT-annealed microstructure consists of a dual-phase structure with two FCC phases: one rich in Cu and the other rich in Fe and Ni. The kernel average misorientation value decreases with the increase in the annealing time and temperature, indicating the recovery of HPT-induced dislocations.

• Journal of Powder Materials
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• v.19 no.3
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• pp.204-209
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• 2012

In this work, powder metallurgy and severe plastic deformation by high-pressure torsion (HPT) approaches were combined to achieve both full density and grain refinement at the same time. Pure Cu powders were mixed with 5 and 10 vol% diamonds and consolidated into disc-shaped samples at room temperature by HPT at 1.25 GPa and 1 turn, resulting in ultrafine grained metallic matrices embedded with diamonds. Neither heating nor additional sintering was required with the HPT process so that in situ consolidation was successfully achieved at ambient temperature. Significantly refined grain structures of Cu metallic matrices with increasing diamond volume fractions were observed by electron backscatter diffraction (EBSD), which enhanced the microhardness of the Cu-diamond composites.

• Computers and Concrete
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• v.32 no.2
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• pp.173-184
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• 2023

In this study, mechanical, flexural post-cracking, and torsional behaviors of recycled steel fiber-reinforced concrete (RSFRC) incorporating steel fibers obtained from recycling of waste tires were investigated. Initially, three concrete mixes with different fiber contents (0, 40, and 80 kg/m³) were designed and tested in fresh and hardened states. Subsequently, the flexural post-cracking behaviors of RSFRCs were assessed by conducting three-point bending tests on notched beams. It was observed that recycled steel fibers improve the post-cracking flexural behavior in terms of energy absorption, ductility, and residual flexural strength. What's more, torsional behaviors of four RSFRC concrete beams with varying reinforcement configurations were investigated. The results indicated that RSFRCs exhibited an improved post-elastic torsional behaviors, both in terms of the torsional capacity and ductility of the beams. Additionally, numerical analyses were performed to capture the behaviors of RSFRCs in flexure and torsion. At first, inverse analyses were carried out on the results of the three-point bending tests to determine the tensile functions of RSFRC specimens. Additionally, the applicability of the obtained RSFRC tensile functions was verified by comparing the results of the conducted experiments to their numerical counterparts. Finally, it is noteworthy that, despite the scatter (i.e., non-uniqueness) in the aspect ratio of recycled steel fiber (as opposed to industrial steel fiber), their inclusion contributed to the improvement of post-cracking flexural and torsional capacities.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.179-184
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• 2002

The evaluation equation of torsional moment for prestressed concrete members in ACI 318-95 ignores the contribution of concrete, T$_{c}$. Several research indicates that the current ACI code is not successful in predicting the observed torsional moment of the PSC beams with reasonable accuracy. This paper proposes an evaluation equation of torsional moment taking into account the inter-effects between concrete and torsional reinforcement on the torsional resistance of the PSC beams. According to the comparison with the 31 test results, the torsion equation in ACI code underestimated or overestimated the real torsional moment of prestressed concrete beams. On the other hand, the proposed torsional equation is shown to be in a good agreement with experimental results.s.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.247-252
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• 2002

The evaluation equation of torsional moment for reinforced concrete members in ACI 318-99 ignores the contribution of concrete, T$_{c}$. Several research indicates that the torsional moment of concrete is in effect, specially for the members in which the longitudinal and transverse reinforcement content is small. This paper proposes an evaluation equation of torsional moment taking into account the contribution of concrete. According to the comparison with the 66 test results, the torsion equation in ACI code underestimated or overestimated the real torsional moment of reinforced concrete beams. On the other hand, the proposed torsional equation is shown to be in a good agreement with experimental results.s.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.290-295
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• 1993

The purpose of the present study is to propose a realistic method to analyze the prestressed concrete members subjected to pure torsion. The present study device a method to realistically take into account the tensile stiffness of concrete after cracking. The effect of biaxial compressive and tensile loading on the compressive and tensile strength of concrete is also taken into account in the present model. The present model can predict not only the service load behavior, but also up to the behavior of ultimate load stages. The comparison of the present theory with experimental data indicates that the proposed model dipicts reasonably well the actual behavior of prestressed concrete members.

• Computers and Concrete
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• v.3 no.5
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• pp.335-355
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• 2006

The application of radial basis function neural networks (RBFN) to predict the ultimate torsional strength of reinforced concrete (RC) beams is explored in this study. A database on torsional failure of RC beams with rectangular section subjected to pure torsion was retrieved from past experiments in the literature; several RBFN models are sequentially built, trained and tested. Then the ultimate torsional strength of each beam is determined from the developed RBFN models. In addition, the predictions of the RBFN models are also compared with those obtained using the ACI 318 Code equations. The study shows that the RBFN models give reasonable predictions of the ultimate torsional strength of RC beams. Moreover, the results also show that the RBFN models provide better accuracy than the existing ACI 318 equations for torsion, both in terms of root-mean-square error and coefficients of determination.

• The Pure and Applied Mathematics
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• v.10 no.3
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• pp.177-183
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• 2003

In this paper, we initiate the study of some annihilator conditions on polynomials which were used by Kaplansky [Rings of operators. W. A. Benjamin, Inc., New York, 1968] to abstract the algebra of bounded linear operators on a Hilbert spaces with Baer condition. On the other hand, p.p.-rings were introduced by Hattori [A foundation of torsion theory for modules over general rings. Nagoya Math. J. 17 (1960) 147-158] to study the torsion theory. The purpose of this paper is to introduce the near-rings with Baer condition and near-rings with p.p. condition which are somewhat different from ring case, and to extend a results of Armendariz [A note on extensions of Baer and P.P.-rings. J. Austral. Math. Soc. 18 (1974), 470-473] and Jøndrup [p.p. rings and finitely generated flat ideals. Proc. Amer. Math. Soc. 28 (1971) 431-435].

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.1
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• pp.561-568
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• 2014

A modular fish-bone girder pier consists of one main girder system named as "Spine Girder". Therefore, this pier can be most affected by torsion as well as flexural bending. The design considerations of the fish-bone girder pier are proposed to assure the reasonable design in this study. In order to investigate the behavior characteristics, structural analysis F.E model is developed, and the verification of the developed model is performed by comparison with experimental data. From the investigation of the structural behavior, the vertical stiffener is required at the bottom of bone-beams to prevent the excessive local stress. Also, it is found that the normal stress of the flange and the shear stress of the web and flange are dominantly affected by the warping torsion and pure torsion, respectively.