1 AIT Asian Institute of Technology

A statistical study of traffic loads on highway bridges in Thailand

AuthorRajwanlop Kumpoopong
Call NumberAIT Thesis no.ST-00-22
Subject(s)Bridges--Thailand--Live loads

NoteA thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering
PublisherAsian Institute of Technology
AbstractLoad effects under traffic conditions and vehicle characteristics in Thailand are calculated to examine the appropriateness of AASHTO (1996) design loads for the design of highway bridges in Thailand. Bridge considered is the two-lane simple span slab-on-girder bridge. Span length varies from 10 m to 50 m. Load effects are the mid span moment and the support shear in the critical girders, which are the extreme left and right girders. Three cases of torsional rigidity of bridge structure are considered. They are low, medium, and high torsional rigidity cases. The data for traffic conditions and vehicle characteristics are obtained from many sources and real observations on highway No. 3214. Only heavy vehicles are considered in the calculations of maximum load effects. Heavy vehicles comprise buses, small trucks, and large trucks. The characteristics of these heavy vehicles are modeled to use in the calculations of maximum load effects. The calculations of maximum load effects are performed for small percentages of large trucks and large percentages of large trucks. The Monte Carlo simulation technique is introduced in the calculations of maximum load effects. The presence of one, two, three, and four heavy vehicles on the bridge are simulated separately in four categories. The time periods of simulations are one day, one month, one year, and 75 years for the presence of one, two, three, and four heavy vehicles on the bridge, respectively. The results of each category are extrapolated to obtain the maximum load effects in 75-year time period, which is the service life of the bridge. The maximum load effects in 75-year time period of each category are combined to obtain the total maximum load effects in 75-year time period. The AASHTO load effects are divided into two parts. The first part is the AASHTO load effects calculated by considering three cases of torsional rigidity of bridge structure. The second part is the AASHTO load effects calculated from the simplified procedures in the AASHTO specifications (1996). Three cases of girder spacing are considered in the second part. From the results of simulations, the presence of one heavy vehicle on the bridge governs the maximum load effects for all span lengths under consideration. The maximum load effects in the critical girders are greater in low torsional rigidity bridges than in medium and high torsional rigidity bridges. The percentages of large trucks have no effect on the load effects in the critical girders. From the results of comparison of simulated load effects with the AASHTO load effects, a nonconservative situation occurs in low torsional rigidity bridges. More uniform variations of load effect ratios over the span lengths are observed in high torsional rigidity bridges than in medium and low torsional rigidity bridges. Therefore, the AASHTO design loads are appropriate for the design of high torsional rigidity bridges. The AASHTO load effects calculated from the simplified procedures in the AASHTO specifications (1996) are conservative for larger girder spacings and nonconservative for smaller girder spacings. The consideration of torsional rigidity of bridge structure is required in the calculation of the AASHTO load effects for small girder spacing bridges.
Year2000
TypeThesis
SchoolSchool of Engineering and Technology (SET)
DepartmentDepartment of Civil and Infrastucture Engineering (DCIE)
Academic Program/FoSStructural Engineering (STE) /Former Name = Structural Engineering and Construction (ST)
Chairperson(s)Pennung Warnitchai;
Examination Committee(s)Worsak Kanok-Nukulchai ;Pichai Nimityongskul;
Scholarship Donor(s)Asian Institute of Technology Partial Scholarship;
DegreeThesis (M.Eng.) - Asian Institute of Technology, 2000


Usage Metrics
View Detail0
Read PDF0
Download PDF0