Analytical and Experimental Behavior of a Simple-Span Girder Bridge A. OONALD SARTWELL, CONRAD P. HEINS, JR., and CHARLES T. G. LOONEY, Civil Engineering Department, University of Maryland, College Park The behavior of a simple-span, composite girder bridge is pre- dicted by the finite-difference method as used in the solution of continuous orthotropic plates on flexible supports. This method incorporates the use of several computer programs. Several modifications to the girder stiffnesses and effects of the parapets are examined, and equivalent orthotropic plate parameters are studied. In addition to the analytical study, exhaustive field tests were conducted on the bridge. Many longitudinal and transverse truck positions, in which the U.S. Bureau of Public Roads test vehi- cle applied the static load, were used and the effects were re- corded. The bridge was fully instrumented with both strain and deflection gages. Comparisons made between the analytical and experimental girder strains and deflections result in good agree- ment. •THE TESTING of the simple-span girder bridge was performed in order to verify the finite-difference analytical techniques as applied to continuous orthotropic plates on flexible supports. The need for an analytical method, which will predict the actual deflections and strains in any bridge structure, is part of a series of interconnected research programs that were initiated to answer the question: ''What are the effects of a new Maryland Vehicle Weight Law on structures?" The various research programs include (a) a statistical study of truck characteristics and of traffic, (b) an analytical study of the stresses and deflections caused by heavy trucks traveling on various bridge structures, (c) experimental testing of various bridge structures, and (d) a correlation of all the programs. Various parts of these programs have been completed. The analytical study, utilizing orthotropic plate theory (1), pre- sented the results of static-load effects on eight different types of existing highway bridge structures (2). Part of the statistical study has resulted in the presentation of data of heavy-truck-traffic (3) and induced bridge loads and moments (4) in the State of Maryland. The experimentai. testing has been conducted on a through truss bridge (5), a simple girder bridge (6), and a three-span continuous bridge (7). Work also has been completed on induced dynamic strains caused by random truck loadings (~). DESCRIPTION OF TESTS Static field tests were performed on one simply supported span of a three-span bridge structure. This structure carries the eastbound traffic on Route Md-4 over the Patuxent River. The tests were divided into three categories to investigate (a) midspan strains and deflections, (b) general overall bridge behavior, and (c) local loading effects on the slab. The structure that was tested had a composite concrete deck on rolled steel beams with welded cover plates. Details of this structure are shown in Figures 1, 2, and 3. Paper sponsored by Committee on Field Testing of Bridges. 113
Analytical and Experimental Behavior of a Simple-Span Girder Bridge
Jul 01, 2023
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