Progressive collapse test of assembled monolithic concrete frame spatial substructures with different anchorage methods in the beam-column joint

In this study, three two-third-scale assembled monolithic concrete spatial frame substructures with three beams and four columns were tested to evaluate progressive collapse resistance. The test parameters are anchorage methods, such as 90 degrees hooked bar, lap splice in U-shaped assembled monolithic concrete beam, and headed bar using welded anchor plate. Force-displacement-controlled pseudo-static loading was applied to the mid-column. On the basis of structural performance, including load-carrying capacity, deformation capacity, crack distribution, rebar strain, and failure mode, the progressive collapse resistance mechanism of the specimens was analyzed. Test results showed that three types of cracks were developed: initial flexural cracks in beam-column joints, diagonal cracks due to compressive arch action, and tension cracks due to catenary action. The specimen using the headed bar exhibited the best progressive collapse performance, whereas the specimen using the lap splice connection showed the worst structural performance. Regardless of anchorage methods, bond failure did not occur during progressive collapse. The progressive collapse performance of the specimen was assessed based on Chinese and American codes.