Laboratory Load Tests and Analysis of Bailey Bridge Segments

Abstract

This paper presents the experimental work of two full-scale Bailey bridge segment load tests. The Bailey bridge segments were tested using a 130-t Universal Tester. The midspan deflections of panel assemblies were observed during the loading. Axial strains of several critical members were also measured. The axial capacities of the top chord members are compared with the calculated AASHTO nominal axial compression resistances. Experimental results are also compared with elastic and inelastic analyses using unsymmetrical sections. Test results show that (1) the inelastic lateral buckling occurred in compression chord members; (2) AASHTO-LRFD Article 6.9.4 generally predicts conservative results; (3) the effect of partial fixity of connections on the response of the structural model is insignificant and may be neglected in the analysis; and (4) a two-dimensional nonlinear inelastic analysis predicts a higher load-carrying capacity because it is not able to capture the out-of-plan stability behavior. It is recommended that Bailey-type bridges may be tested in their actual loading conditions to investigate their exact behavior, and more work is needed in the area of numerical modeling to simulate nonlinear inelastic lateral torsional behavior of the Bailey-type bridges. The CALTRANS is currently working closely with several prefabricated modular truss bridge manufacturers to develop the guidelines for temporary prefabricated modular steel truss bridges. Research findings presented in the paper are beneficial to this development.