Model test on behavior of direct air cooled condenser support platform under service load and earthquake action

The direct air cooled condenser support platform is a special industrial building, and it appears with the application of air cooled technology in thermal power plants. The structural form and its mechanical performance are very complex. Employing 1/4 substructure, imitating the boundary condition, a 1/8 scale model was constructed and tested to study its mechanical behavior under excitation of fans and earthquake action. The structural dynamic properties, the resonance vibration frequency of structure and fans, the amplitude-frequency curve under different rotational speed and work state of fans, and the dynamic strain of typical structural members were measured. Then in the pseudo-dynamic test, the model was subjected to El Centro wave, and the dynamic response of the structure was measured. The variation of natural frequency of vibration and damping ratio, the deformation performance, the hysteretic behavior and the failure mode of the model were analyzed. The skeleton curve of the model and its characteristic points were presented in this paper. Finite element analysis was performed using commercial computer codes, and the calculation results show agreement with the experimental results. The study indicated that torsion was one of the main vibration shapes of the structure, so the couple of vibration shapes must be considered. The vibration response of the structure under the multiple harmonic resonance excitations of fans was very weak, and the structural response at low resonance vibration frequency was larger than high frequency. The direct air cooled condenser support platform was a single-prevention system, and the equipment system was in elastic working state when the structure system yielded under seldom-occurred earthquake action and the structure failed in the column hinge mechanism.