A study of the correlation between bridge response parameters and vehicle characteristics for 13 steel flyover bridges in Bangkok | |
| Author | Sethachai Srithong |
| Call Number | AIT Thesis no. ST-99-2 |
| Subject(s) | Bridges, Iron and steel--Thailand|xBangkok Structural dynamics Bridges, Iron and steel--Thailand|xBangkok Structural dynamics |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering. |
| Publisher | Asian Institute of Technology |
| Abstract | Traffic-induced response is one of the major concerns in the design and analysis of highway bridges. In Thailand, most highway bridges were designed based on bridge design specifications proposed by the American Association of State Highway and Transportation Officials (AASHTO). The direct application of AASHTO specifications without serious studies may cause some problems because the traffic conditions and the vehicle characteristics in Thailand are different from the United States. For this reason, field measurements of 13 steel flyover bridges in Bangkok were carried out during 1997 to 1998. The analyses included weight-in-motion analysis, fatigue damage and level of vibration. More suitable design criteria were also proposed. This study adopts the data from field measurements. The data are classified into two types. The first one is time history of strains at the main longitudinal girders, which were kept in the digital format. They are analyzed by employing the signal processing technique, bandpass filter, to the free vibration responses. The results are dynamic properties of bridges including natural frequencies, vibration modes and damping ratios. The fundamental natural frequencies are in the range of 1.51-3.50 Hz. At least two modes participate in responses of each bridge. One is the flexural dominated mode and another one is torsional dominated mode. For plate girder bridges, the fundamental mode is torsional dominated mode because its torsional rigidity is low. While for box girder bridges, the fundamental mode is flexural dominated mode. The natural frequencies relate to span lengths. As span length increases, the natural frequency decreases and this relation conforms well to the past empirical formula. The damping ratios are quite low between 1 % to 2%. The second one is the so-called vector data obtained from applying the lowpass filter to the time history of strains and acceleration at the main longitudinal girders. Vector data consist of vehicle characteristics and bridge responses, e.g., peak acceleration, dynamic amplification factor (DAF). The measured DAF for strength limit state and for fatigue limit state comply well with the factor specified by the AASHTO LRFD design specifications (1994). The measured DAF for strength design of the heavy vehicle are much less than the specified value of 1.33. Based on the proportion of 10-wheel truck to trailer, the fatigue truck and DAF for fatigue design are proposed. The fatigue truck weighs 31.87 tons and the value of DAF is 1.10. Both values are lower than the specified values of 33.13 tons and 1.15 respectively. It is expected that all results will be valuable information to be incorporated in the developments of Thailand highway bridge design specifications in the future. |
| Year | 1999 |
| Type | Thesis |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Construction Engineering and Infrastructure Management (CM) |
| Chairperson(s) | Pennung Wamitchai;Pennung Warnitchai; |
| Examination Committee(s) | Worsak Kanok-Nukulchai;Gupta, Satyendra P.;Nii, Kazuyoshi;Taweep Chaisomphop; |
| Scholarship Donor(s) | Royal Thai Government; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1999 |