Behavior of Reinforced Concrete Beams Under Combined Axial and Lateral Loading.

摘要

Seventeen simply supported reinforced concrete beams were tested to collapse under combined flexural, axial, and shear forces. Each beam had a 12.5-foot span, a 9-by-15-inch cross section, and an effective depth of 12.5 inches. Reinforcement consisted of No. 2 stirrups, 6 inches on center. The beams were loaded laterally through a symmetrical two-point loading system and axially through the plastic centroid. Load was applied by a single hydraulic system designed to provide a constant ratio between axial and lateral loads for the duration of the tests. The two test parameters were axial-to-lateral-load ratio and shear-span-to-beam-depth ratio. Electrical measurements of beam behavior included steel strain on the longitudinal rebar, concrete strain, vertical deflections along the length of the beam, end rotations, and lateral and axial loads. In addition, a photoelastic coating sheet was bonded to one side of the beams and overlaid with a sheet of Polaroid film. The experimental results from the beam tests were compared with data calculated with an analytical behavioral model developed as part of this effort. The general beam behavior calculated from the analytical model agreed well with the measured results, especially in the region up to maximum load. (Author)