Strengthening of Precast RC Frame to Mitigate Progressive Collapse by Externally Anchored Carbon Fiber Ropes

Abstract

The robustness of precast reinforced concrete (RC) frames is relatively poor, while the precast RC frames are strengthened to mitigate progressive collapse, avoiding “strong beams and weak columns” and the anchorage failure of strengthening materials under large deformation condition are the key problems. Aiming to discuss these problems, this paper carried out an experimental research of strengthening on three half-scale assembled monolithic frame subassemblages to mitigate progressive collapse. One specimen was strengthened by implanting carbon fiber rope (CFR) with polymer into concrete, one specimen was strengthened by binding CFR with special knot, and the last one was not strengthened. The failure mode, collapse failure mechanism and strengthening effect of subassemblages were discussed. Analytical models of load capacity increment contributed by CFR and construction suggestions of precast RC frame to mitigate progressive collapse were proposed. The results indicated that none of the strengthened specimens had anchorage failure. The two strengthening methods significantly increased the load capacity of the subassemblages in the catenary action (CA) stage with little effect on the flexural action (FA) stage and compressive arch action (CAA) stage.

Research on Impact Resistance of Reinforced Concrete Beams Strengthened with Carbon Fiber Reinforced Polymer Grid and Engineered Cementitious Composites

“…At present, the use of FRP for reinforcement and strengthening of concrete structures [ 1 , 2 , 3 , 4 , 5 ] is more and more extensive, among the more recent methods are FRP bar strengthened ECC [ 6 , 7 , 8 , 9 ] and FRP sheet strengthened ECC [ 10 , 11 , 12 ], etc. The strengthening methods for RC beams under impact loading are mainly strengthened with FRP sheet/plate [ 13 , 14 , 15 , 16 , 17 ], fiber reinforced concrete [ 18 , 19 ], externally bonded steel plate [ 20 , 21 ], high strength steel wire mesh and high-performance mortar [ 22 , 23 ], etc.…”

Assessment of Different Retrofitting Methods on Structural Performance of RC Buildings against Progressive Collapse

“…Researchers have recently become interested in the effect of secondary components, such as bracing, on progressive collapse performance. The strengthening of reinforced concrete (RC) frame structures against progressive collapse have various challenges: (1) The application of typical strengthening methods for RC frame construction continues to be researched because progressive collapse is a significant deformation behavior; (2) The degree of strengthening against progressive collapse is significant, which could result in "strong beams and weak columns" and have an impact on seismic performance; (3) Anchorage is the primary issue in strengthening reinforced concrete structures against progressive collapse, and dependable and rapid construction anchorage solutions for minimizing progressive collapse strengthening are urgently needed [6].…”