Strengthening of seismically damaged reinforced concrete beam-column joints by means of FRP rope connections through the joint area

In areas of medium and high seismic hazard, reinforced concrete frame structures in seismic events often are damaged at the joints (beam-column connections) and then need to be repaired for further use of the structure. In the following, a new strengthening procedure and experimental investigations will be presented. Test specimens with previously generated moderate pre-damage are repaired with high-strength repair mortar and Carbon Fiber filament bundles (C-FRP) at the beam-column connection. The test results of a test specimen on a scale of 1:1 in the undamaged state (JA1V) as well as in the pre-damaged rehabilitated state (JA1FXb) are evaluated and compared. To simulate the earthquake effects, the undamaged test specimen is first cyclically loaded on the test bench. Subsequently, the same test specimen pre-damaged by the first test is strengthened with C-FRP in the node and beam area and again exposed to identical cyclic loads on the test bench. The essential measurement results of both tests are recorded and compared with each other with regard to load-bearing capacity, stiffness, absorbed energy (ability to dissipate energy). Furthermore, the applied rehabilitation technique is presented in detail. On the basis of the investigations carried out, it is shown that rapid and efficient rehabilitation of joints by high-strength cement without high-pressure injection is possible.