• 한국구조물진단유지관리공학회 논문집
• /
• 제18권1호
• /
• pp.19-30
• /
• 2014

본 연구에서는 강주탑 기부와 기초콘크리트 연결 구조에 대해서 국내에서 특수교량의 강주탑 기부 설계에 보편적으로 적용하고 있는 명석해협대교(明石海峽大橋) 시방기준과 비선형 FEM 해석결과를 비교하였다. 명석해협대교(明石海峽大橋) 시방기준은 1970년도에 만들어진 일본 기준으로 주탑 기부와 PS 강봉 및 기초콘크리트를 스프링으로 선형 모델링하여 설계하는 방법으로서 43년이 지난 지금까지도 간편성을 이유로 이 기준을 적용하고 있다. 그러나 비선형 FEM 해석결과의 비교를 통해 특수 장대교의 강주탑 기부의 해석 및 설계에 이 기준을 적용하는 것은 여러 가지 문제점이 있음을 알 수 있었으며, 풍하중, 지진하중에 주요하게 저항하면서도 다양한 부재들로 복잡하게 연결된 강주탑 기부에 대해서는 한계상태설계법으로 발전하려는 현 시대에 맞추어 실제 거동을 반영하는 비선형 FEM해석을 적용해야 할 것이다.

• Wind and Structures
• /
• 제10권1호
• /
• pp.1-22
• /
• 2007

The suppression of aerodynamic response of long-span suspension bridges during erection and after completion by using single TMD and multi TMD is presented in this paper. An advanced finite-element-based aerodynamic model that can be used to analyze both flutter instability and buffeting response in the time domain is also proposed. The frequency-dependent flutter derivatives are transferred into a time-dependent rational function, through which the coupling effects of three-dimensional aerodynamic motions under gusty winds can be accurately considered. The modal damping of a structure-TMD system is analyzed by the state-space approach. The numerical examples are performed on the Akashi Kaikyo Bridge with a main span of 1990 m. The bridge is idealized by a three-dimensional finite-element model consisting of 681 nodes. The results show that when the wind velocity is low, about 20 m/s, the multi TMD type 1 (the vertical and horizontal TMD with 1% mass ratio in each direction together with the torsional TMD with ratio of 1% mass moment of inertia) can significantly reduce the buffeting response in vertical, horizontal and torsional directions by 8.6-13%. When the wind velocity increases to 40 m/s, the control efficiency of a multi TMD in reducing the torsional buffeting response increases greatly to 28%. However, its control efficiency in the vertical and horizontal directions reduces. The results also indicate that the critical wind velocity for flutter instability during erection is significantly lower than that of the completed bridge. By pylon-to-midspan configuration, the minimum critical wind velocity of 57.70 m/s occurs at stage of 85% deck completion.

• Structural Monitoring and Maintenance
• /
• 제9권1호
• /
• pp.43-57
• /
• 2022

One of the instances which demand structural engineer's greatest attention and upgradation is the changing live load requirement in bridge design code. The challenge increases in developing countries as the pace of infrastructural growth is being catered by the respective country codes with bigger and heavier vehicles to be considered in the design. This paper presents the case study of India where Indian Roads Congress (IRC) codes in its revised version from 2014 to 2017 introduced massive Special vehicle (SV) around 40 m long and weighing 3850 kN to be considered in the design of road bridges. The code does not specify the minimum distance between successive special vehicles unlike other loading classes and hence the consequences of it form the motivation for this study. The effect of SV in comparison with Class 70R, Class AA, Class A, and Class B loading is studied based on the maximum bending moment with moving load applied in Autodesk Robot Structural Analysis. The spans considered in the analysis varied from 10 m to 1991 m corresponding to the span of Akashi Kaikyo Bridge (longest bridge span in the world). A total of 182 analyses for 7 types of vehicles (class B, class A, class 70R tracked, class 70R wheeled, class AA tracked, AA wheeled, and Special vehicle) on 26 different span lengths is carried out. The span corresponding to other vehicles which would equal the bending moment of a single SV is presented along with a comparison relative to Standard Uniformly Distributed Load. Further, the results are presented by introducing a new parameter named Intensity Factor which is proven to relate the effect of axle spacing of vehicle on the normalized bending moment developed.