The performance and behavioral characteristics of an old through-plate girder railway bridge are presented. Strain gauge instrumentation was used to monitor structural responses under current operating conditions. Loading spectra of crossing trains were measured with a train weighing system and used as applied loads in subsequent finite element models. The experimental and analytical results indicated that the stress responses of the bridge structure were controlled mainly by axle loads and axle spacings. A certain degree of continuity was observed at the stringer-to-floor-beam connections. Consequently, the typical assumption of simple shear connection could give unrealistic estimates of stress responses in the stringers. The structural responses in floor beams and plate girders were, however, less sensitive to the degree of continuity at the connections. On the basis of Miner's hypothesis, the fatigue damage accumulation and the equivalent number of stress cycles in main bridge members were evaluated. Although freight trains had greater axle loads, the fatigue damage was dominated by passenger trains because of their large number of stress cycles. The equivalent number of cycles per train crossing was found to be considerably less than the value provided in the Manual for Railway Engineering of the American Railway Engineering and Maintenance-of-Way Association. The findings provided favorable information for the performance and fatigue evaluations. The structure was shown to have an adequate capacity for current operating conditions. In addition, use of the research results would provide a more accurate estimate of the fatigue life.

This paper presents the results of the test of six reinforced concrete bridge column specimens and of six analytical specimens subjected to constant axial load and cyclic lateral load. The objective of the investigation is to report the strength and ultimate displacement of the square columns having different amount and arrangement of tie bars. Fiber element inelastic analyses were conducted to verify the test results and were in reasonable agreement with the experimental study results. It was found that the criterion of limiting lateral strain in the concrete core gave satisfactory estimate of the maximum column deflection. Further analytical study of six columns with different tie reinforcement ratio and subjected to varying cyclic loads was performed. Based on the experimental and analytical studies of reinforced concrete columns subjected to the axial loads ranging between 0.05f ' c A g and 0.12f ' c A g , tie reinforcement ratio, ρ s = 0.50% which corresponds to approximately 60% of the minimum amount required by the AASHTO seismic provision exhibits moderate ductility ratio being 4.3 and 7.3 for axial loads of 0.12f ' c A g and 0.05f ' c A g respectively.

Composite beams are made of steel sections connected with slabs of concrete held together with shear connectors. The beams enhance the loading capacity and stiffness according to AISC and AASHTO design standards. In this study tests on three restrained steel-concrete full composite beams subjected to a cyclic point load and monotonic loading were conducted and their performances on stiffness, strength, ductility and energy dissipation capacity were analyzed and compared with the results of monotonic loading cases. It was found that the degree of the shear connectors and the type of loading and the position of the load were the major factors influencing the stiffness and cumulative energy dissipation capacity of the full composite restrained steel beams.

Composite structures are made from steel connected with slab concrete holding together with shear connectors. This facilitates in loading capacity according to AISC and AASHTO standard design. The test on restrained steel-concrete beams under monotonic loading and cyclic loading condition is with the fully composite and the partially composite. The result of this research is that the fully composite is more loading capacity than the partially composite. Moreover, the study also focuses on the deformation capacity ratio between the fully composite and the partially composite under both mentioned conditions. In this aspect, it is found that the deformation capacity of the fully composite is less than the partially composite. From the study, it is suggested that the steel-concrete composite be design for the fully composite because it can hold the highest strength, prevent slipping between steel and slab concrete, and increase the durability.