Seismic Characteristics Analysis On The Reinforced-concrete Frame Joint

In the earthquake action, the reinforced concrete frame structure cannot reallyachieve the effect of "strong column weak beam". In the structure destroyed, columnoften appears with plastic hinge and beam appear later. Joint connects column and beam,which plays a key role in marinating structural integrity. In China, we adopts increasecolumn ends’ bending moment coefficient to ensure that "strong column weak beam"realization. In the calculation, designers do not consider the action of floor to beam, andincrease the stiffness and reinforcement of beam. At the same time, with the floorreinforced according to the normal calculation, beam’s bending capacity is furtherstrengthened. Because of strengthened effects of floor to beam, nodes show column hingedestroy on the destroy form.In order to reduce the role of floor to beam and abate beam’s bending ability, thefloors around joint of reinforced concrete frame structure set200mm or300mm sizeslots in the conditions which do not exert impact on joint’s bearing capacity. In theearthquake action, joint exhibits a failure type closer to the beam-pivot mode.A numerical quasi-static model is established with Adina software for each type ofbeam-column’s joints which include interior joint, exterior joint and angle joint on areinforced concrete frame. The results for traditional joint specified in design code andthat for the joint with slot around are compared. It is shown that the stress in the reinforcebar for slab close to beam will increase significantly with the applied top displacement inthe horizontal direction, but increase slightly for slab far from the beam. It is also shownthat the yielding time of beam reinforce bar will shift to an earlier time, while the numberof cracks on column becomes less. The time intervals between the occurrence of plasticpivot on beam and on column become longer, which meets the standard of "strongcolumn weak beam" requirements. In consideration of the axial compression ratio, eachnode can also show expected results.