Research On Effect Of Ratio Of Column-to-Beam Flexural Strength On Failure Mechanism Of Beam-Column Subassemblies With Fiber-Reinforced Concrete

In order to make the frame structure to form a reasonable collapse mechanism,the general method is to adjust the relative strength of the column-to-beam.However,the frame structure is difficult to achieve"strong column-weak beam"failure mechanism during an earthquake based on the current design code.Therefore,the further study on the method of controlling the frame structure collapse mechanism has important theoretical meaning and practical value for improving the seismic collapse resistance of the frame structure.Based on considering the effect of slab reinforcement in the flange width of 6-time slab thickness each side on the beam flexural strength,this article investigates the impact of the ratio of column-to-beam flexural strengthη_c-bua on the failure mechanism of frame structures.The main contents and achievements are as follows:（1）Quasi-static tests were conducted on five one-half scaled beam-column subassemblies with different ratios of column-to-beam flexural strength,four specimens used fiber reinforced concrete（FRC）in the expected damaged region,and one used normal reinforced concrete（RC）in whole.The seismic behavior,such as the failure mechanism,deformation,energy dissipation,bearing capacity,was analyzed.The results indicate that,compared with the RC beam-column subassembly,the specimen using FRC in the expected damaged region has a better behavior on strength,deformation and energy dissipation.The results show that,when theη_c-bua is 1.2,the RC beam-column subassembly failed to achieve"strong column-weak beam"failure mechanism,while the FRC beam-column subassembly can basically achieve"strong column-weak beam"failure mechanism.And when theη_c-bua is 1.4,the FRC beam-column subassemblies can completely achieve"strong column-weak beam"failure mechanism.（2）The ABAQUS software was used to simulate the beam-column subassemblies.The result shows that the model is reasonable by comparing the simulated results with the experimental results.（3）The RC frame structure was designed by current seismic code in 8 degree earthquake,and some frame structures with different values ofη_c-buawere designed based on the above prototype.The pushover analysis and the fragility analysis with PERFORM-3D software were carried out.The pushover results indicate that the impact of FRC material on structural bearing capacity and ductility is in agreement with the experiment results.The value ofη_c-bua has a significant effect on both the failure mechanism and the fragility,and it is more difficult to ensure the reasonable collapse mechanism than the acceptable collapse probability.