Details:

Creators:
Saber, Aziz
Corporate Creators:
Louisiana Tech University. College of Engineering
Corporate Contributors:
United States. Federal Highway Administration
Subject/TRT Terms:
[+]
Axle Loads Fatigue (Mechanics) Girders Gross Vehicle Weight Highway Bridges Live Loads Load Tests Trucks Weigh In Motion
Publication/ Report Number:
FHWA/LA.13/509
Resource Type:
Tech Report
Geographical Coverage:
Louisiana
Corporate Publisher:
Louisiana. Dept. of Transportation and Development
Abstract:
The bridge in this study was evaluated and a monitoring system was installed to investigate the effects of heavy loads and

the cost of fatigue for bridges on state highways in Louisiana. Also, this study is used to respond to Louisiana Senate

Concurrent Resolution 35 (SCR-35). The superstructure of the bridge in this study was evaluated for safety and reliability

under four different kinds of truck configuration and loads hauling sugarcane. The bridge model was verified by performing

live load tests using 3S3 trucks with a gross vehicular weight (GVW) of 100,000 lb. on the structure. The bridge finite

element model was analyzed under the different kinds of loading and the effects were listed and compared. The results of

the analyses show that the pattern of response of the bridge under the different cases follows the same trend. Among the

four different cases of loading configurations, case 4, which was GVW =148,000 lb. and a vehicle length of 92 ft., produced

the largest tensile and compressive stresses in the members. The results from the bridge deck analyses confirm that the

bridge deck is under a stable stress state, whether the stresses are in the tension zone or the compression zone. The heavy

load as indicated in SCR-35 will cause damage to bridges.

The data from the monitoring system indicates that the average number of heavy loads during October, November, and

December is 3.5 times higher than the rest of the year. The bridges are exposed to high cycles of repetition of heavy loads

that will reduce the life span of the bridges by about 50%. The bridges that are built to last 75 years will be replaced after

about 40 years in service. This seasonal impact is due to the sugarcane harvest and confirms the cost of fatigue, $0.9 per

truck per trip per bridge, as determined in the previous study.

Based on the results of the studies presented in this report, increasing the gross vehicle weight of sugarcane trucks is not

recommended. The heavy loads indicated in SCR-35 will cause premature fatigue damage to the main structural members

and could cause their eventual structural failure. In addition, the majority of the Louisiana bridges currently in service were

designed to accommodate lower loads than the bridge tested on this project. Therefore, based on the test results, one should

expect that the proposed trucks to significantly shorten the remaining life span of Louisiana bridges. All these bridges

should be rehabilitated prior to implementing SCR 35. The data from the monitoring system will provide a good source of

information to review the current serviceability criteria used by the Louisiana Department of Transportation and

Development (LADOTD) for the design of prestressed concrete bridge girders.


Format:
PDF
Funding:
LTRC Project Number: 10-1ST ; State Project Number: 736-99-1662
LTRC Project Number: 10-1ST ; State Project Number: 736-99-1662 Less -
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:72207dab2eac8ef75d4263bd0a487406b3e7f12cde7d265454d7de6513be8891
Download URL:
https://rosap.ntl.bts.gov/view/dot/22292/dot_22292_DS1.pdf
File Type:

Supporting Files

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