Experimental comparative study on progressive collapse behavior of cast-in-place and monolithic precast concrete spatial frame substructures

In this study, three two-third scaled concrete spatial frame substructures with three beams and four columns were tested to evaluate the progressive collapse resistance. The first specimen was a cast-in-place reinforced concrete (RC) structure, the other two specimens were constructed by anchorage in which the 90° hook connection and welded anchor plate were used. The force-displacement controlled pseudo-static loading was applied to the mid-column. According to the structural performance including the load-carrying capacity, deformation, crack distribution, rebar strain and failure mode, the progressive collapse resistance mechanism of the specimen was analyzed. The test results show that the crack development is more concentrated at the beam end of PC specimens, but the crack distribution of RC specimen is more uniform there, which is favorable for structural stress. The progressive collapse resistance of RC specimen is better than that of the PC specimen. There is little difference between the two in the arching stage. However, the maximum load of the RC specimen is 167 kN in the catenary stage, which is 1.57 and 1.22 times, respectively, of that of the PC specimens using 90° hook connection and welded anchor plate. The steel bar of the RC specimen breaks later, because it has a better space for plastic development. © 2020, Editorial Office of Journal of Building Structures. All right reserved.