• Structural Engineering and Mechanics
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• v.12 no.1
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• pp.1-16
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• 2001

A reliable and accurate method has been developed to predict the flexural deformation response of structural concrete members subject to service load. The method that has been developed relates the extent of concrete cracking, measured as a function of the magnitude of applied moment in a member, to the reduction in the effective moment of inertia of cracked reinforced concrete members under service load conditions. The ratio of the area of the moment diagram where the moment exceeds the cracking moment, to the total area of the moment diagram for any loading, provides the basis for the calculation of the effective moment of inertia. This ratio also represents mathematically a probability of crack occurrence. Verification of this method for the determination of the effective moment of inertia has been achieved from an experimental test program, and has included beam tests with different loading configurations, and shear wall tests subjected to a range of vertical and lateral load levels. Further verification of this method has been made with reference to the experimental investigation of other recently published work.

• Bulletin of the Society of Naval Architects of Korea
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• v.7 no.2
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• pp.3-18
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• 1970

An investigation was made for the added mass moment of inertia induced by the rotational motion of the cylinder with hull section on water in order to obtain the information to estimate the natural frequency of the torsional vibration of ships. The special consideration to the effect of the draught upon the added mass moment of inertia is taken into account in the study. In this paper, the general expression for the added mass coefficients of moment of inertia of arbitary two dimensional forms induced by the torsional vibration, was derived by the author. Hence, the coefficients for these forms are represented as functions of parameters, the section area coefficient and draft beam ratio, from which the added mass coefficients for arbitrary forms can be obtained. The result was shown in a chart for estimation of the added mass moment of inertia induced by the torsional vibration, as first trial, for the convenience of practical use.

• Journal of the Korea Concrete Institute
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• v.20 no.3
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• pp.393-404
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• 2008

The approaches in many design codes for the estimation of the deflection of flexural reinforced concrete (RC) members utilize the concept of the effective moment of inertia which considers the reduction of flexural rigidity of RC beams after cracking. However, the effective moment of inertia in design codes are primarily based on the ratio of maximum moment and cracking moment of beam subjected to loading without proper consideration on many other possible influencing factors such as span length, member end condition, sectional size, loading geometry, materials, sectional properties, amount of cracks and its distribution, and etc. In this study, therefore, an experimental investigation was conducted to provide fundamental test data on the effective moment of inertia of RC beams for the evaluation of flexural deflection, and to develop a modified method on the estimation of the effective moment of inertia based on test results. 14 specimens were fabricated with the primary test parameters of concrete strength, cover thickness, reinforcement ratio, and bar diameters, and the effective moments of inertia obtained from the test results were compared with those by design codes, existing equations, and the modified equation proposed in this study. The proposed method considered the effect of the length of cracking region, reinforcement ratio, and the effective concrete area per bar on the effective moment of inertia, which estimated the effective moment of inertia more close to the test results compared to other approaches.

• Computers and Concrete
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• v.34 no.1
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• pp.49-61
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• 2024

The present study concerns a removal of chloride ions and structural behaviour of concrete beam at electrochemical chloride extraction (ECE). The electrochemical properties included 1000 mA/m2 current density for 2, 4 and 8 weeks. It was found that an increase in the duration of ECE resulted in an increase in the extraction rate of chlorides, in the range of 35-85%, irrespective of chloride contamination. In structural behaviour, the strength and maximum bending moment of specimen was always lowered by ECE. Moreover, the flexural rigidity and bending stiffness were reduced by the loss of effective cross-section area in the linear elastic range. Simultaneously, the inertia moment was substantially subjected to 70% loss of the cross-section by the tensile strain at the condition of the failure. However, a lower rate of the inertia moment reduction was achieved by ECE, implying the higher resistance to the cracking, but the higher risk of deformation.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.489-492
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• 1997

The general pattern of adaptation in the appendicular skeleton with aging is that the subperiosteal apposition of bone occur along with endosteal absorption. This remodeling of diaphysis to a cylinder of larger diameter is hypothesized to serve a mechanical compensatory unction by increasing the moment of inertia as the cortex thins with aging. These findings is only true of the diaphysis of long bone. Measuring the area and inertia at each section of femur, the age-related change of proximal emur and diaphysis is observed. After screening by physical and radiological examination, 200 normal Korean adults divided 5 groups in both male and female based on age. Twenty persons were in each group. One femur in each person was analyzed using CT images. femur scanned with 60 to 80 slices and this images were digitized. Then 2-D images were reconstructed into 3-D images. Using the nonlinear method, normalization and interpolation technique, 7 locations of interest (trochanteric area: 1, 2 subtrochanteric area: 3, 4, isthmic area: 5, 6, 7) were determined. On the each cross section at each location, the area (total, cortical and medullary) and 5 inertia of moment were measured. The results were analyzed statistically. With aging, significant area change occurred mainly in diaphysis and female. In trochanteric area, no significant change was noted. With aging, total and medullary area were increased, but cortical area was not changed. In diaphysis, lateral bendingresistanceincreasedsignificantly. No inertia change was noted in trochanteric area. Anteroposterior bending resistance was constant with aging. In more than age 60, total area and medullary area were larger than that of others. Lateral bending resistance was higher especially in diaphysis. In diaphysis, with aging, the decreased properties is compensated with the increased lateral bending resistance by geometric remodeling. In trochanteric area, no compensation occur. With aging, especially in more than age 60, the higher rate of trochanteric fracture is expected.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.5 no.1
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• pp.13-20
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• 1999

Not only is it important that the physical properties of the paperboards be appropriate for the intended end use, but the proper arrangement of the component in the built-up board is essential for attaining the optimum moment of inertia and the maximum load-carrying ability in a box. It is known to be impossible to estimate the stress distribution and deflection pattern by experiments or theoretical analysis when the corrugated fiberboard get the bending force. This study was tried theoretical and finite element analysis to analyze structural strength characteristics of corrugated fiberboards. If the linerboard and corrugating medium of every corrugated fiberboards is made from the same material, the location of neutral axis comes close to inside liner in order of DMA, DM, DMB, SW and DW, and moment of inertia of area decreases in order of DMA, DMB, DW, DM and SW. With the finite element analysis, deflection of applied loads represented SW, DM, DMA, and TW in the order of their value.

• Bulletin of the Society of Naval Architects of Korea
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• v.11 no.2
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• pp.7-14
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• 1974

Hydrodynamic moments produced by the rolling oscillation on the free surface and the associated swaying force were exactly calculated by Ursell-Tasai method for the cylinders with Kim's chine form sections($a_1,\;a_7$). The coefficient of the added moment of inertia $K_{\varphi^{\tau}}$, the progressive wave height ratio $\bar{A}$, the coefficient of swaying forces $K_{RS}$, ${\alpha}_{RS}$ of rolling oscillations are shown in the several figures. The results of the computation were compared with those of lewis form sections. It is concluded that the effect of the section form on the added moment of inertia is significant for the cylinder with the section of same beam-draft ratio and sectional area coefficient, on the other hand, a little effect appears on the wave damping.

• Earthquakes and Structures
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• v.7 no.6
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• pp.955-967
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• 2014

Storage racks are used worldwide in industries and commercial outlets due to the advantage of lighter, faster erection and easy alteration of pallet level as required. The studies to understand the behaviour of cold formed steel pallet racks, under seismic action is one of the emerging area of research. The rack consists of perforated uprights and beams with hook-in end connector, which enables the floor height adjustments. The dynamic characteristics of these racks are not well established. This paper presents the dynamic characteristics of 3-D single bay two storey pallet rack system with hook-in end connectors, which is tested on shake table. The sweep sine test and El Centro earthquake acceleration is used to evaluate the seismic performance of the cold formed steel pallet racks. Also an attempt is made to evaluate the realistic dynamic characteristics by using STAAD Pro software. Modal analysis is performed by incorporating the effective moment of inertia of the upright, which considers the effect of presence of perforations and rotational stiffness of the beam-to-upright connection to determine the realistic fundamental frequency of pallet racks, which is required for carrying out the seismic design. Finite element model of the perforated upright section has been developed as a cantilever beam through which effective moment of inertia is evaluated. The stiffness of the hook-in connector is taken from the previous study by Prabha et al. (2010). The results from modal analysis are in good agreement with the respective experimental results.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.484-492
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• 2023

The structural behaviour of concrete beam was examined by the three points bending test after the completion of the electrochemical chloride extraction (ECE), rather than bond strength mostly measured in previous studies. It was found that the flexural rigidity of concrete was lowered by the ECE, but the strength was enhanced in terms of the maximum load.The flexural rigidity, in the linear elastic range, was reduced by the loss of effective cross-section area. In fact, the inertia moment was substantially subjected to 70 % loss of the cross-section by the tensile strain at the condition of the failure. However, a lower rate of the inertia moment reduction was achieved by the ECE, implying the higher resistance to the cracking, but the higher risk of deformation.

• Computers and Concrete
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• v.14 no.2
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• pp.109-125
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• 2014

The force transfer mechanism in positive moment continuity details for prestressed concrete girder bridges is investigated in this paper using a three-dimensional detailed finite element model. Positive moment reinforcement in the form of hairpin bars as recommended by the National Cooperative Highway Research Program Report No 519 is incorporated in the model. The cold construction joint that develops at the interface between girder ends and continuity diaphragms is also simulated via contact elements. The model is then subjected to the positive moment and corresponding shear forces that would develop over the service life of the bridge. The stress distribution in the continuity diaphragm and the axial force distribution in the hairpin bars are presented. It was found that due to the asymmetric configuration of the hairpin bars, asymmetric stress distribution develops at the continuity diaphragm, which can be exacerbated by other asymmetric factors such as skewed bridge configurations. It was also observed that when the joint is subjected to a positive moment, the tensile force is transferred from the girder end to the continuity diaphragm only through the hairpin bars due to the lack of contact between the both members at the construction joint. As a result, the stress distribution at girder ends was found to be concentrated around the hairpin bars influence area, rather than be resisted by the entire girder composite section. Finally, the results are used to develop an approach for estimating the cracking moment capacity at girder ends based on a proposed effective moment of inertia.