Fracture Mechanism And Ductility Of Box-column And H Beam Joints

The elliptical yield model together with an elliptical fracture model was used in the box-column and H beam joints’finite simulation and analysis. To make joints’ plastic rotation reach0.03rad that required by the FEMA interim guidelines, the diaphragm-through type steel boxcolumn and H-style steel beam joints with double linear enlarged junctures(DTDL joint) were putforward. Based on the finite element simulation results reasonable values of DTDL joints’parameters were discussed.The elliptical yield model together with an elliptical fracture model was quantified through thematerial test data. By the conventional joint comparative analysis of experimental results andfinite element results, obtained the fragmentation index MCI welding considering residual stressand welding defects.According to the results of finite simulation,4DTDL joints and1conventional joint was testedunder low-cycle loading. The experimental results indicate that the conventional the diaphragm-through type steel box column and H-style steel beam joints brittle fractures at beam flangesbutt weld and the plastic rotation does not reach0.03rad which is required by the FEMA interimguideline, and DTDL joint’s formed a longer plastic hinge formed at L2section,by which hasdiaphragm’s width changing with moment, and the plastic rotation reached0.03rad which isrequired by the FEMA interim guideline and the loading capacity increase to15%compared withthat of the conventional joint.All the joints in this test didn’t crack in the weld between column plate and diaphragm, so thediaphragm-through type steel box column and H-style steel beam joints didn’t have the problemexsited in inner-diaphragm type steel box column and H-style steel beam joints that the weldingbetween column plate and inner diaphragm of high difficulty, poor welding quality.According to the results from experiment and finite simulation, the values of DTDL jointsparameters were suggested.