Structural Evaluation of Torsional Rigidity of New FRP–Aluminum Space Truss Bridge with Rigid Transverse Braces

Le Zhu,Dongdong Zhang,Fei Shao,Qian Xu,Qilin Zhao 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.7

A unique fiber-reinforced polymer (FRP)–aluminum spatial truss structure with upper I-type, transverse beam braces was developed for deployable bridging, yielding the operational advantages of bestraddled erection bridges. Experimental testing and numerical simulation were performed to evaluate the torsional rigidity of a fabricated cantilever, full-scale experimental structure. The predictions obtained based on a computational finite element model were strongly consistent with the experimental results. Moreover, a numerical decomposition and reconstruction procedure was employed to understand the load-bearing mechanism of the structure. The results demonstrated that the improved transverse braces possessed adequate capacity for providing sufficient rigidity and lateral stability to the complete twin-treadway structure under torsion. The torsional center of the improved structure was located at the axis of symmetry of the twin-treadway bridge deck. The representative torsional rigidity of the twin-treadway module was approximately 87.5 kN·m2/degree. Compared to the original construction, the improved structure exhibited only minor discrepancies regarding the torsional rigidity, and consistent characteristics in terms of the load-bearing mechanism. The torsional rigidity of the improved twin-treadway structure was primarily generated by the vertical bending rigidities of its two parallel single treadways through the rigid transverse braces. This significant finding specifically pertains to the unique twin-treadway hybrid bridge. The results presented in this work are expected to provide valuable insights, which could, in turn, lead to further the development of similar lightweight structural systems.

Effect of rigid connection to an asymmetric building on the random seismic response

Taleshian, Hamed Ahmadi,Roshan, Alireza Mirzagoltabar,Amiri, Javad Vaseghi Techno-Press 2020 Coupled systems mechanics Vol.9 No.2

Connection of adjacent buildings with stiff links is an efficient approach for seismic pounding mitigation. However, use of highly rigid links might alter the torsional response in asymmetric plans and although this was mentioned in the literature, no quantitative study has been done before to investigate the condition numerically. In this paper, the effect of rigid coupling on the elastic lateral-torsional response of two adjacent one-story column-type buildings has been studied by comparison to uncoupled structures. Three cases are considered, including two similar asymmetric structures, two adjacent asymmetric structures with different dynamic properties and a symmetric system adjacent to an adjacent asymmetric one. After an acceptable validation against the actual earthquake, the traditional random vibration method has been utilized for dynamic analysis under Ideal white noise input. Results demonstrate that rigid coupling may increase or decrease the rotational response, depending on eccentricities, torsional-to-lateral stiffness ratios and relative uncoupled lateral stiffness of adjacent buildings. Results are also discussed for the case of using identical cross section for all columns supporting eachplan. In contrast to symmetric systems, base shear increase in the stiffer building may be avoided when the buildings lateral stiffness ratio is less than 2. However, the eccentricity increases the rotation of the plans for high rotational stiffness of the buildings.

한국형 저상버스 복합소재 차체에 대한 비틀림 강성 평가

임송규(Song-Gyu Leem),김연수(Yeon-Su Kim),목재균(Jai-Kyun Mok),장세기(Se-ky Jang),조세현(Se-hyun Cho) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11

Low Floor buses have no steps to get on or get off the main cabin to provide the old and the handicapped with easy access. The car body for the low floor bus was designed to consider Korean physical standard, passenger capacity (standee, seated, handicapped), arrangement of vehicle components, and bus law or regulations. It was designed as an one body, without any reinforcement armature, which has light-weight sandwich constructions with glass epoxy skins, aluminum honeycomb cores and inner-frames. In this paper, torsion rigidity of the designed car body was evaluated and compared with that of a car body with reinforcement armatures in the cabin. Finite element method verified that the designed car body without reinforcement armatures could satisfy requirements of torsion rigidity.

연안역 조립식 경골잔교(Fish-bone Girder Pier)의 해석모델에 관한 연구

김화랑(Kim, Hwa-Rang),임남형(Lim, Nam-Hyoung),박종섭(Park Jong-Sup),윤경민(Yun, Kyung-Min),윤기용(Yoon Ki-Yong) 한국산학기술학회 2013 한국산학기술학회논문지 Vol.14 No.12

연안역 조립식 경골잔교는 단일거더 시스템이므로 비틀림에 큰 영향을 받는 구조물이다. 본 연구에서는 이 잔교를 합리적으로 해석하고 설계하기 위한 해석모델을 개발하고자 하였다. 뒴강성을 포함한 7자유도 보요소를 사용 한 해석모델의 구속조건을 조절하여 해석모델을 선정하였으며, 선정된 해석모델은 실물크기의 실험체를 이용한 정적 하중재하 실험을 통하여 검증하였다. 실험결과와의 비교분석을 통하여 개발한 해석모델을 입증하였으며, 이 해석 모 델을 이용하여 연결부의 단면력을 산정함으로써 합리적인 연결부 설계를 가능하게 하였다. A fish-bone girder pier affects torsion severely because of the one girder system. This study was performed to develop an analytical model to analyze and design a fish-bone girder pier properly. This model consisted of a beam element with 7-degrees of freedom considering the warping rigidity. Several beam-column connection conditions were considered. The static load test was performed using a real size specimen. The validity of this model was tested by a comparison of the analytical results with the experimental results. This analytical model is useful for designing the bolt connection of a Spine girder.

이단 사이클로이드 드라이브의 비틀림 강성

김경홍(Kyoung-Hong Kim),이춘세(Chun-Se Lee),안형준(Hyeong-Joon Ahn) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.11

This paper presents a finite element (FE) analysis of the torsional rigidity of a two-stage cycloid drive. The cycloid disk makes contact with a number of pin-rollers simultaneously and eccentric shafts transmit not only torque of the spur gear stage to the cycloid disk, but also that of the cycloid disk to the output disk. Contacts between the disk and pin-rollers are simplified as linear spring elements, and the bearing of eccentric shaft is modeled as a rigid ring that has frictional contact to the disk and an elastic support. FE analysis for an ideal solid cycloid drive was performed and verified by a theoretical calculation. Accurate contact forces were then estimated by iterating between FE analysis for contact forces and Hertz theory calculations for nonlinear contact stiffness. In addition, torsional rigidity of the cycloid drive is analyzed to show that the bearing and nonlinear Hertz contact theory should be considered in analysis and design of a cycloid drive, which was verified with experiments. Finally, the effects of contact stiffness, bearing stiffness and cycloid disk structural stiffness according to the cycloid disk rotation on the torsional rigidity were investigated.

Shear forces amplification due to torsion, explicit reliance on structural topology. Theoretical and numerical proofs using the Ratio of Torsion (ROT) concept

Nikolaos Bakas 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.61 No.1

The recently introduced index Ratio Of Torsion (ROT) quantifies the base shear amplification due to torsional effects on shear cantilever types of building structures. In this work, a theoretical proof based on the theory of elasticity is provided, depicting that the ratio of torsion (ROT) is independent of the forces acting on the structure, although its definition stems from the shear forces. This is a particular attribute of other design and evaluation criteria against torsion such as center of rigidity and center of strength. In the case of ROT, this evidence could be considered as inconsistent, as ROT is a function solely of the forces acting on structural members, nevertheless it is proven to be independent of them. As ROT is the amplification of the shear forces due to in-plan irregularities, this work depicts that this increase of internal shear forces rely only on the structural topology. Moreover, a numerical verification of this theoretical finding was accomplished, using linear statistics interpretation and nonlinear neural networks simulation for an adequate database of structures.

UPPER AND LOWER BOUNDS FOR ANISOTROPIC TORSIONAL RIGIDITY

Song, Jong-Ghul Korean Mathematical Society 1995 대한수학회논문집 Vol.10 No.2

Some bounds for anisotropic torsional rigidity with one plane of elastic symmetry perpendicular to the axis of the beam are derived by making use of the isoperimetric inequalities, complementary variational principles, and the maximum principle. Upper and lower bounds are obtained by applying the isoperimetric inequalities. While the upper bound investigated by the variational principles and maximum principle. The analysis is patterned after the work of Payne and Weinbeger [J. Math. Anal. Appl. 2(1961). pp. 210-216].

FE analysis of torsional rigidity of a cycloid gear considering tolerance

TheLinh Tran,DucCanh Nguyen,AnhDuc Pham,KangJo Hwang,JaeSeong Jeong,HyeongJoon Ahn 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11

Impact Analysis of Tolerance and Contact Friction on a RV Reducer using FE Method

Hyeong-Joon Ahn,Byeong Min Choi,Young Hwan Lee,팜안덕 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.7

Since RV (rotation vector) reducer has a high reduction ratio with compact size, high efficiency and stiff ness, the reducer is extensively used in applications requiring high precision in the restricted space like industrial robotic joints. Since the cycloid disk of the RV reducer makes contacts with many pin-rollers simultaneously, tolerance and friction between the cycloid disk and the pin-rollers significantly affect the contact force of the cycloid disks as well as the performance of the RV reducer. This paper presents an impact analysis of tolerance and friction on the RV reducer using FE method. A FE model for a two-disk RV reducer and the eccentric shaft is built considering tolerance and friction between the cycloid disk and the pin-rollers. Then, the FE analysis of an ideal rigid cycloid reducer was performed and verified with the theoretical calculation. The effects of tolerance and friction on multi-contact and the output torque of the RV reducer were investigated. Since the contact forces vary according to both tolerance and friction, the resulting torsional rigidity and output torque are affected considerably. Precisely, the tolerance mainly decreases the torsional rigidity while the friction primarily increases the output torque fluctuation.

Effect of vehicle flexibility on the vibratory response of bridge

Lalthlamuana, R.,Talukdar, Sudip Techno-Press 2014 Coupled systems mechanics Vol.3 No.2

In the recent times, dimensions of heavy load carrying vehicle have changed significantly incorporating structural flexibility in vehicle body. The present paper outlines a procedure for the estimation of bridge response statistics considering structural bending modes of the vehicle. Bridge deck roughness has been considered to be non homogeneous random process in space. Influence of pre cambering of bridge surface and settlement of approach slab on the dynamic behavior of the bridge has been studied. A parametric study considering vehicle axle spacing, mass, speed, vehicle flexibility, deck unevenness and eccentricity of vehicle path have been conducted. Dynamic amplification factor (DAF) of the bridge response has been obtained for several of combination of bridge-vehicle parameters. The present study reveals that flexible modes of vehicle can reduce dynamic response of the bridge to the extent of 30-37% of that caused by rigid vehicle model. However, sudden change in the bridge surface profile leads to significant amount of increment in the bridge dynamic response even if flexible bending modes remain active. The eccentricity of vehicle path and flexural/torsional rigidity ratios plays a significant role in dynamic amplification of bridge response.