Non-linear Analysis On The Joints Of Specially Shaped Column Frame Structure

Joints are always considered as the weakest region of frame structures, and joints usually occurred shear failure in earthquakes. Specially shaped column frame structure is a new type of structure and there are not enough experiments and research on the joints, so it is necessary to take further research.The article uses a time-history analysis on a 7-floor specially shaped column frame structure by the software of ANSYS, and mainly studies the modal form, seismic action, displacement action and the failure mode of the frame as a whole under seismic loads. It shows that results of ANSYS and tests are basically identical, it shows that ANSYS is a practical analysis method. The results also show the weak region of the structure and the position of potential plastic hinges, so, it raises a computational method on the working capability of the structure under seismic loads.The article analyses 36 joints by non-linear FEM method, the purpose is to study the effects on joints' failure load by stirrups in joint region, concrete strength grade, reinforcements ratio of beams and columns and stirrups of beams and columns .The results show that, under the same situation, the failure load of L-shaped joint is about 60% of the failure load of T-shaped joints, and stirrups in joint region are the main aspect to influence the failure load of joints. Raising the number, area , strength grade of stirrups can promote the failure load of joints, and the number the stirrups plays a essential role among those three aspects. Raising the strength grade of concrete, reinforcement ratio of beams and columns, stirrups of beams and columns can also promote the failure load of joints, but these conditions have a different effect on different types of joints.