The structural performance of a vehicle can be evaluated by the static and dynamic structural analyses which predict the amount of deformation, stiffness. And the static analysis should be done first. Another important aspect to be considered in the design process is crashworthiness, because a structurally sturdy vehicle body may be overdesigned with excessive strength and durability standards. The ideal condition of a body structure is to absorb impact load at a certain level of local deformation, to distribute the load to each structure adequately, and to prevent excessive stress concentration and deformation. This paper is the result of the consideration of automotive body, bending and torsional stiffness for structure stiffness estimation of automotive body through finite element modeling.

Beam bracing is applied to prevent the relative displacement of the top and bottom flanges or to effectively control the twisting of the section, and the lateral stability of the beams are provided by lateral bracing, torsional bracing or a combination of both. Modular steel I-girders are laterally interconnected by torsional bracings that are installed to increase the resistance to lateral torsional buckling. In this paper, numerical parametric study was carried out by varying the crossbeam web height to examine the effects of the web torsional stiffness. Three-dimensional finite-element analysis using the commercial finite element software ABAQUS was obtained for the parametric numerical analyses of a series of feasible two-girder models, and the failure mode, lateral-torsional buckling strength and the moment-displacement behavior of the main girders was determined.

The stiffness of a bicycle frame is a major factor of a bicycle performance related to safety, stability, and weight. In this study, the torsional and bottom bracket stiffness of a bicycle frame were experimentally investigated. The torsional and bottom bracket stiffness for 63 bicycle frames were evaluated and analyzed by measuring the displacement of frames. The torsional stiffness is related with turning performance and the bottom bracket stiffness is related with power transmission. The experimental results show that the average stiffness varies up to 20 % according to the frame materials and types. The torsional stiffness has a strong corelation with the bottom bracket stiffness even though they have different effects on a bicycle frame. It seems that the experimental results can be applied to the quality criteria of racing bicycles and also design standard of a bicycle frame.

The present authors recently gave an analytical method for estimating three spring constants Kr, Ks, and Kt, for sidewall stiffnesses of radial tires. These represent the radial, lateral, and in-plane rotational directions respectively. The method is based on netting theory with special consideration to stiffness of the rubber matrices in the sidewall These theoretical results were verified by experiment to have sufficient accuracy. In order to confirm the availability of these spring constants, the twisting stiffness Rt of a radial tire has been analyzed in the present paper by using a spring-supported ring model. An explicit formula for Rt, expressed in terms of the three components of the spring constant, was obtained. Experiments were conducted on a 175SR14 radial tire by increasing the inflation pressure while keeping the tread circumference constant. The theoretical results agreed well with the experimental results. A related problem is also referred to; this is the forced lateral vibration with fundamental eigen-modes of the inflated sidewall-rim system when the tread is fixed. Eigen-frequencies calculated by using those spring constants coincide well with the experimental results.

본 연구에서는 비틀림 거동을 일으키는 편심구조물의 효율적인 제어를 위한 비틀림 강성을 가지는 동조질량감쇠기의 제어성능을 검토하고자 한다. 이를 위하여 지진하중을 받는 편심구조물에 동조질량감쇠기의 설치위치와 비틀림강성에 따른 제어성능을 평가한다. 반복되는 시간이력해석시 소요되는 해석시간을 줄이기 위하여 등가해석 모델을 사용하였고 비비례감쇠시스템인 동조질량감쇠가 설치된 구조물의 해석을 효율적으로 수행할 수 있었다. 본 연구를 통하여 일반적인 동조질량감쇠기에서 무시되어온 동조질량감쇠기의 비틀림 속성이 비틀림 거동이 발생하는 편심구조물에서는 효과적일 수 있음을 검증하였다. 그리고 편심구조물의 경우에는 동조질량감쇠기의 최적 설치 위치가 구조물 평면의 중심이 아닐 수 있음을 확인하였다.

고강도 콘크리트 보의 극한상태의 거동을 강도에 따라 연구하였다. 13개의 보를 해석하고 그 결과를 제시하였다. 변수는 콘크리트의 압축강도로 범위는 57~184 MPa이며, 횡방향 철근비로 범위는0.35~1.49%이다. 실험에서 측정한 극한 비틀림 강도를 본 논문에서 제안한 값과 ACI 기준에 따른 값을 비교하였다. 그 결과 본 논문에서 제안한 이론에 의한 극한 비틀림 강도가 ACI 기준에 따른 값보다 더 좋은 결과를 보였다.