| Abstract: | When the first type of bridge structure stability safety factor is 4, it deserves the research that whether it will guarantee the structure reliability index reaches target reliability index under the more-likely- to- happen second type of collapse situation. The paper makes the first and the second type of stability calculation separately for single layer and single span rigid frame bridge. Basing on critical load got from the first type of stability calculation, supposing the first type of stability safety factor is 4, taking the first order reliability method to programme, the reliability index is attainable. Then, load effect under the first type of stability reliability index calculation and the second type of critical load are employed to calculate the second type of reliability index. The rationality of structure stability safety factor evaluation is discussed according to reliability index. Based on the discussion above, two types of stable critical load are parameter analyzed; the influence of critical load change on reliability index is researched. The result shows: stability analysis should identify collapse state; when the first type of stability safety index is 4 and the structure has the second type of collapse, the reliability index can not be guaranteed to reach target reliability index. |
