The Influence Of The Failure Of Columns To The Progressive Collapse Control For Reinforced Concrete Frame Structures Under Accidental Load

Due to accidental loading, the structural progressive collapse, which has made great damage of casualties and serious economic losses, has caused the widespread concern of domestic and international scholars as well as engineers. With the characteristics of unestimated position, large quantity, short time and unestimated feature, the accidental loading did great technical problems for structure design. Although scholars over the world all have done a great number of researches and explorations on accidental loading, we have done little research on structural progressive collapse which is owing to accidental loading.This paper studies on how to prevent structural progressive collapse because of accidental loading.Using PMSAP linear static methods, this paper studies on the flexural bearing capacity of frame beams rate and the influence of vertical displacement of failure node after dismantling column.218models are presented in this paper, according to different location of the column and the total number of layers and different seismic fortification intensity, the height and different thickness, to study the response of the structure after dismantling column. Analysis results show that the increase of the seismic fortification intensity, height, thickness can be beneficial to the prevention of the structural progressive collapse. While with the increase of the layer number, it’s not good for the structural progressive collapse prevention. Dismantling different layers of column we found that bottom column made the most obvious influence for the whole structure and the sixth makes the least. Different locations in the same layer column also make different influence, with the corner column makes the most obvious influence and the middle column makes the least. After dismantling column, the structure of vertical direction is more than that of the horizontal direction.By using SAP2000nonlinear static method after the split column analysis, we do research on the effect of progressive collapse prevention performance after the column failure. Defining plastic hinge on the frame beam and column end, we do nonlinear analysis with different seismic fortification intensity and position, the total number of layers, different column as variables, and observe the influence of final plastic hinge distribution, the beam end bending moment-displacement curve, and the node displacement. Analysis results show that it is same as using PMSAP linear static methods. The appearance of plastic hinge in the frame beam is at the same time, this is mainly due to the influence of the components at the bottom of the reinforcement, more force is smaller than the underlying structure, but the upper structure itself cause structural plastic hinge appeared at the same time.By using SAP2000nonlinear dynamic analysis method are analyzed. With different seismic fortification intensity and the total number of layers as a variable, and introducing the time factor, considering the structure of the instantaneous effect, we observe its final plastic hinge distribution, the beam end bending moment displacement curve, the influence of the node displacement. Analysis results show that it is same as other methods; The increase of the total number of plies is adverse to the structural progressive collapse prevention; Instantaneous effect after the completion of the structure response didn’t stop, but to continue to a certain amount of time, during this period, a plastic hinge component showed the following characteristics:the component within the bending moment almost doesn’t increase, corner change tends to a fixed value and the change of the vertical displacement increases.Finally, compare the three methods of analysis. Linear static method has the most conservative results. This is mainly due to that the linear static method has a number of assumptions, without considering the mutual influence between force and with more calculation simplifying. Nonlinear static method has fewer assumptions than linear methods and the calculation process is relatively complicated, but it does not take the influence of dynamic effect and function of time into account. Only nonlinear dynamic method has fully considered the influence of various factors, with fewer calculation assumptions and more open results. Considering the advantages and disadvantages of the three methods, proposed in the analysis of nonlinear static method preferred process engineering, this method not only considering the material nonlinearity, to calculate the results and won’t take up too much time.