The collapse evaluation method of steel moment-resisting frames based on dynamic increase factor

Considered the application of structural vibration characteristic parameters in the field of structural health monitoring and damage identification, the relationship between the structural dynamic increase factors (DIFs) and the collapse resistance of structure under the column removal scenario, is studied. Referring to previous researches, the load-displacement curve of structures under static collapse condition is simplified to be a multiparameter broken line, which is used as the analysis and calculation model for the structural DIFs under the column removal scenario. Based on the model, the displacement-based DIF (DIFu) and the load-based DIF (DIFp) are derived with the help of energy balance method, and the development laws of DIFs are nalysed under different strength of catenary effect and ductility of structures. It is found that the value of DIFs in the catenary stage of structures is positively correlated with the ductility and strength of catenary effect of structures. A new structural collapse evaluation method is proposed based on the evaluation laws of DIFs. By dint of previous experiments the finite element model is established and the collapse evaluation method is verified. Finally, the different strain rates of steel are introduced in the FEM. It is found that the effect of medium and high strain rate of steel on the limit displacement of structures against column removal could be neglected, which further improves the evaluation method.