Abstract: To increase the structural anti-collapse capacity, and to reveal the fragility of structural member and its failure effort on the structural performance, two evaluation indexes were established to measure the vulnerability and redundancy of structural member based on the sensitivity of strain energy of member to material elastic modulus. The change of structural strain energy caused by the failure of member was also taken as an important parameter in the redundancy index. Then, the members with high vulnerability and low redundancy were strengthened, and the ones with low vulnerability and high redundancy were weakened by the means of increasing or reducing the section area of member. By this way, the structural member failure sequence was changed, and all the members could be fully utilized. The results show that the coefficient value of redundancy and vulnerability can reflect the fragility and the failure effort of structural member, respectively. By adjusting the member section area according to the distribution of structural redundancy and vulnerability, the less-important members which have low vulnerability and high redundancy will be failed before the key members which have high vulnerability and low redundancy. Thus, the structural failure path will be transformed to a safe way, and the loading capacity and the ability to resist progressive collapse of the structure can be enhanced effectively.