• Journal of Korean Association for Spatial Structures
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• v.10 no.2
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• pp.95-103
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• 2010

This paper study on the accuracy improvement of nonlinear stiffness equation. The large structure must have thin thickness for build the large space structure there fore structure instability review is important when we do structural design. The structure instability of the shelled structure is accept it sensitively by varied conditions. This come to a nonlinear problem with be concomitant large deformation. Accuracy of nonlinear stiffness equation must improve to examine structure instability. In this study, space truss is analysis model Among tangent stiffness equation and nonlinear stiffness equation is using nonlinearity analysis program. The study compares an analysis result to investigate accuracy and convergence properties improvement of nonlinear stiffness equation.

• Magazine of the Korea Concrete Institute
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• v.7 no.1
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• pp.156-164
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• 1995

P-${\Delta}$ analysis by use of the equivalent colurnn stiffness determined by Momcnt curvature-Thrust curves provides relatively precise analytical results for unbraced reinforced concrete columns, however it needs a complicated arialytical procedure. Equ~valent col~rnn stiffness equations are proposed for a simple analytical procedure which are ckterrnined by the Moment-Curvature Thrust curves of the practically useable sections. Thc proposed stiffness equations are appiled to P-${\Delta}$ analysis and rnornent magnifier method to compare with the selected test result. Use of the proposed stiffness equations may slrnplify the P-${\Delta}$ i.rialvtica1 procedure and improve the accuracy of moment magnifier niethod.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.1
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• pp.191-198
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• 2003

The pavement stiffness is scarcely used in structural analysis to design the superstructure of bridge. It is reasonable not to consider it in the case of asphalt concrete pavement over concrete deck because the pavement stiffness compared with the concrete deck plate can be ignored. However, sometimes, the pavement materials have a similar amount of elastic modulus to concrete and are applied to the orthotropic steel deck plate which has relatively less stiffness compared with the concrete deck plate. In this paper, the steel plate deck of a real bridge project was analyzed by considering the pavement stiffness by linear elastic FEM. It was assumed that a perfect bond between the steel plate deck and the pavement exited. The results indicated that the structural behavior of the orthotropic steel deck plate can be estimated enough to affect the evaluation result of structural capacity in some cases. Therefore, the investigations by experimental tests and more advanced numerical model are indispensible in figuring the design formula for considering the effects of pavement stiffness in the structural analysis of an orthotropic bridge.

• Geomechanics and Engineering
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• v.16 no.6
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• pp.577-588
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• 2018

A major concern in deep excavation project in soft clay deposits is the potential for adjacent buildings to be damaged as a result of the associated excessive ground movements. In order to accurately determine the wall deflections using a numerical procedure such as the finite element method, it is critical to use the correct soil parameters such as the stiffness/strength properties. This can be carried out by performing an inverse analysis using the measured wall deflections. This paper firstly presents the results of extensive plane strain finite element analyses of braced diaphragm walls to examine the influence of various parameters such as the excavation geometry, soil properties and wall stiffness on the wall deflections. Based on these results, a multivariate adaptive regression splines (MARS) model was developed for inverse parameter identification of the soil relative stiffness ratio. A second MARS model was also developed for inverse parameter estimation of the wall system stiffness, to enable designers to determine the appropriate wall size during the preliminary design phase. Soil relative stiffness ratios and system stiffness values derived via these two different MARS models were found to compare favourably with a number of field and published records.

• Steel and Composite Structures
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• v.39 no.4
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• pp.419-433
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• 2021

In composite structures, shear connectors are crucial components to resist the relative slip between the steel and concrete, and thereby to achieve the composite actions. In the service stage, composite structures are usually in elastic state, so the elastic stiffness of the shear connection is a quite important parameter in the structural analysis of composite structures. Nevertheless, the existing studies mainly focus on the load-slip relationship rather than the tangent stiffness at the initial elastic stage. Furthermore, when composite beams subjected to torque or local load, shear connections are affected by both tensile force and shear force. However, the stiffness of shear connections under combined effects appears not to have been discussed hitherto. This paper investigates the initial elastic stiffness of stud connections under combined effects of biaxial forces. The initial expression and the relevant parameters are obtained by establishing a simplified analytical model of the stud connection. Afterwards, parametric finite element analysis is performed to investigate the effects of the relevant factors, including the stud length, stud diameter, elastic modulus of concrete, elastic modulus of steel and volume ratio of reinforcement. The feasibility of the proposed modelling has been proved by comparing with sufficient experimental tests. Based on the analytical analysis and the extensive numerical simulations, design equations for predicting the initial elastic stiffness of stud connections are proposed. The comparison between the equations and the data of finite element models demonstrates that the equations are accurate enough to serve for engineering communities.

• Journal of Ocean Engineering and Technology
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• v.36 no.4
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• pp.243-250
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• 2022

Subsea power cables are subjected to various external loads induced by environmental and mechanical factors during manufacturing, shipping, and installation. Therefore, the prediction of the structural strength is essential. In this study, experimental and theoretical analyses were performed to investigate the axial stiffness of subsea power cables. A uniaxial tensile test of a 6.5 m three-core AC inter-array subsea power cable was carried out using a 10 MN hydraulic actuator. In addition, the resultant force was measured as a function of displacement. The theoretical model proposed by Witz and Tan (1992) was used to numerically predict the axial stiffness of the specimen. The Newton-Raphson method was employed to solve the governing equation in the theoretical analysis. A comparison of the experimental and theoretical results for axial stiffness revealed satisfactory agreement. In addition, the predicted axial stiffness was linear notwithstanding the nonlinear geometry of the subsea power cable or the nonlinearity of the governing equation. The feasibility of both experimental and theoretical framework for predicting the axial stiffness of subsea power cables was validated. Nevertheless, the need for further numerical study using the finite element method to validate the framework is acknowledged.

• Tribology and Lubricants
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• v.39 no.3
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• pp.94-101
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• 2023

Automotive wheel bearings are a critical component of vehicles that support their weight and facilitate rotation. Life and stiffness are significant performance characteristics of wheel bearings. Designing wheel bearings involves finding optimal design variables that satisfy both performances. CO₂ emission reduction and fuel efficiency regulations attribute to the recent increase in design requirements for lightweight and compact automotive parts while maintaining performance. However, achieving a design that maintains performance while reducing weight poses challenges, as performance and weight are generally inversely proportional. In this study, we perform design optimization of automotive wheel bearings considering life and stiffness. We develop a program that calculates the basic rated life and modified rated life based on international standards for evaluating the life of wheel bearings. We develop a regression equation using regression analysis to address the time-consuming stiffness analysis during repetitive analysis. We perform ANOVA and main effect analyses to understand the statistical characteristics of the developed regression equation. Furthermore, we verify its reliability by comparing the predicted and test results. We perform design optimization using the developed life prediction program, stiffness regression equation and weight regression equation. We select bearing specifications and geometry as design variables, weight as the cost function, and life and stiffness as constraints. Through design optimization, we investigate the influence of design variables on the cost function and constraints by comparing the initial and optimal design values.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.718-721
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• 1996

In this work, an effective stiffness generated by internal loading for a planar 3 degrees of freedom RCC mechanism is investigated. For this purpose, the internal kinematic analysis and antagonistic stiffness modeling for this mechanism are performed. It is shown that the antagonistic stiffness could be effectively created at the center of the mechanism in its symmetric configuration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.562-566
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• 2006

Lightweight body can cause a low stiffness due to the decrease of panel thickness and reinforcing member. The other way, high stiffness body demands an increase of mass. Front pillar section area is decreased due to driver's visual field. Global vehicle stiffness is affected by stiffness distribution ratio between upper part and lower part at side body structure. This paper will describe a process used to evaluate the stiffness distribution ratio based on research of strain energy analysis of the tip rotation method. In addition, optimum design schemes are presented for high stiffness and lightweight body structure considering the investigated stiffness distribution ratio. In this way the designer will be aided by a defined design guide and a set of supporting tool to help him work towards a good design

• Smart Structures and Systems
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• v.24 no.1
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• pp.141-155
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• 2019

This work evaluates the influence of negative stiffness on the performances of various vehicle suspension systems, and proposes a re-centering negative stiffness device (NSD). The re-centering NSD consists of a passive magnetic negative stiffness spring and a positioning shaft with a re-centering function. The former produces negative stiffness control forces, and the latter prevents the amplification of static spring deflection. The numerical simulations reveal that negative stiffness can improve the ride comfort of a vehicle without affecting its road holding abilities for either passive or semi-active suspension systems. In general, the improvement degree of ride comfort increases as negative stiffness increases. For passive suspension system, negative stiffness brings in negative stiffness feature in the control forces, which is helpful for the ride comfort of a vehicle. For semi-active suspensions, negative stiffness can alleviate the impact of clipped damping in semi-active dampers, and thus the ride comfort of a vehicle can be improved.