Study On The Failure Mode Of Frame Structure Under Earthquake Action

Focusing on the failure mode of the earthquake, the papers do the following work：(1) The paper set out to explore the components of earthquake damage criteria,with the aim to summarize the three elements of the plastic hinge: the chronologicalorder, the spatial distribution and the rotation degree. Upon the different combinationsof three elements, the conclusion summarized the typical failure mode of the framestucuture under earthquake, thus analyzed the most important factors. According to theU.S. seismic code, the surrounding frame column can be used as the seismicforce-resisting system. The design of failure mechanism for the structure is veryimportant under severe earthquake in Japan. Learning from the two approaches, for themost common failure mode of beams mixed hinge, we present the failure mode inwhich the hinges lays in the middle and bottom columns and beams. The layer yieldingmechanism can be better avoided.(2)Taking the rough judgment of the failure mechanism into consideration, whichis also have no quantitative indicatiors to meet the needs of performance-based seismicdesign method. Using the Park-Ang parameters of seismic damage model, the papersummarized the evaluation indicators of the earthquake damage model, taking thedamage of the beams and columns as the macro-level quantitative indicators todistinguish the failure mechanism, taking the floor damage as the reference indicator toassess the risk of layer, taking the whole structrure damage as the macro-quantitativeindicatior.(3)The paper used the OPENSEES program, taking the impact of the cast beams,the fiber model and the flexibility of the unit of analysis into consideration. The papersummarized eight examples: first in strict accordance with regulatory requirements, at7(0.1g and0.15g),8(0.2g and0.3g),9degrees (0.3g) fortification intensity, for a totaldesign5typical frame example, to study the failure mechanism of the frame structure10specification; example design37degrees0.15g,0.2g,8degrees and8degrees0.3gfortified area, and the other side column to strengthen the framework for comparativeanalysis.The conclusion was as follows:①Under the horizontal earthquake effect of7degree(0.1g) and9degree(0.4g) ofof high-level fortification intensity, the frame structures desigened according to thelastest codes collapse due to beam side-way failure mechanism.While Under the horizontal earthquake effect of7degree(0.15g),8degree(0.2g) and8degree(0.3g),theabove structures collapse due to the column side-way and beam side-way mixed failuremechanism,and may have a risk of collapsing due to the inter-story post-yieldmechanism.②The ratio of columns’damage and beams’ damage can become as a quantiveindications distinguishing different failure modes. If the ratio is big,then the structure ismore possible to collapse due to the beam side-way failure mechanism.On thecontrary,the ratio is small,the structure have a big possibility to collapse due to columnsside-way failure mechanism.Coluded from the limited examples in this paper,when theratio is more than5,the structure may collapse due to the beam side-way failuremechanis;when the ratio is less than0.2,the structure may collapse due to the columnside-way failure mechanism;when the ratio is between0.2and5,the structure maycollapse due to the column side-way and beam side-way mixed failure mechanism.③Strengthen the side columns in the typical structures in the distracts of7degree(0.1g),8degree(0.2g) and8degree(0.3g),the ratio of the middle columns’ damageand the side columns’ damage is about uppering to6from2at first. The hinges in themiddle columns is less,the hinges rarely lays in the side columns.Morever,the structure’swhole damage indications decreases when the side columns are strengthened,and theratio of the beam’s damage and column’s damage increases. The hinges’ layout is morereasonable.The inter-story post-yield mechanism is mainly prevented.As for the mostcommon column side-way and beam side-way mixed failure mechnasim,it is possible toprevent the hinges laying in the middle columns and the bottom of the first floorcolumns by strengthening side columns.