Simulation of fatigue damage in cables of Rama IX cable-stayed bridge in Bangkok under random truck loads | |
| Author | Sugianto Pudjohartono |
| Call Number | AIT Thesis no.ST-90-11 |
| Subject(s) | Structures, Theory of Materials--Fatigue Bridges, Cable-stayed |
| Note | A thesis submitted in partial fulfillments of the requirements for the degree of Master of Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Abstract | The dynamic behaviour of Rama IX cable-stayed bridge under random truck traffic is analyzed and the fatigue life of the longest cable is computed using the standard fatigue analysis procedure proposed by the European Committee for Constructional Steelwork. The bridge is modeled as a plane structure with massless cables and only in-plane loads are considered. Multiaxle trucks are modeled as sprung single axle vehicles. The speed of each truck is assumed to be constant while crossing the bridge. The randomness of the truck traffic is modeled based on measured values of the truck speed and vehicle mass. The headway of trucks entering or leaving the bridge is described by a Poisson process. Using a random generator, the speed, mass, and headway of a truck are determined based on the corresponding probability distributions. The truck traffic during one peak hour was simulated assuming 600, 1200, and 2400 trucks per hour. Two types of analyses were carried out. In the first analysis, the inertial effects of the bridge-vehicle system were neglected; such an analysis is reliable for slow trucks and a perfectly smooth bridge pavement. In the second case, a rough surface consisting of three equally spaced bumps located at midspan was assumed. The geometry of these bumps was taken from actual measurements on the bridge. Inertial effects were taken into account in this case. A fatigue investigation was carried out for the longest cable of the main span. Both the stresses due to changes in the cable force and the bending moment in the anchor zone were considered. For the fatigue life calculation, the peak hour traffic was used as a basis in which the daily traffic volume was converted into an equivalent number of peak hour traffic. The results show that for smooth and rough pavement there is no fatigue problem if the steel has a well- defined fatigue limit, otherwise if no fatigue limit exists, the fatigue life for smooth and bumpy pavement and a maximum of 2400 trucks per hour is 114 years and 18 years . respectively. Finally , dynamic strain measurements were carried out in the longest cable of the main span. The strain records were analyzed by an FFT spectrum analyzer and by means of a computer. In terms of frequency content, measured and computed strains are very different; however , the RMS-values of the cable stresses were very similar. |
| Year | 1990 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Structural Engineering (STE) /Former Name = Structural Engineering and Construction (ST) |
| Chairperson(s) | Wireland, Martin |
| Examination Committee(s) | Gupta, Satyendra P. ;Worsak Kanok- Nukulchai ;Horii, Hideyuki |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 199 |