建物の構造強度に関する評価指標を用いた進行性崩壊の危険性予測

DOI 機関リポジトリ HANDLE Web Site Web Site 被引用文献1件 参考文献2件 オープンアクセス

書誌事項

タイトル別名
  • RISK PREDICTION OF PROGRESSIVE COLLAPSE USING EVALUATION INDEX FOR STRUCTURAL STRENGTHS OF BUILDINGS
  • タテモノ ノ コウゾウ キョウド ニ カンスル ヒョウカ シヒョウ オ モチイタ シンコウセイ ホウカイ ノ キケンセイ ヨソク

この論文をさがす

抄録

 In case of emergency such as intense fire or collision of some objects to buildings, there is a risk of progressive collapse; a phenomenon which occurred to the World Trade Center (WTC) towers during the 9.11 terrorist attacks. The official statements released by the Federal Emergency Management Agency (FEMA) in 2002, and also by the National Institute of Standards and Technology (NIST) in 2005 and in 2008, concluded that the heat of burning jet fuel induced additional stresses into the damaged structural frames while simultaneously softening and weakening these frames, and this additional loading and the resulting damage were sufficient to induce the collapse of the towers. It also said that the details of the failure process after the decisive initial trigger that sets the upper part in motion were very complicated and their clarification would require large computer simulations.<br> The main objective of this study is to investigate the relation between the evaluation index for structural strength of buildings and the damage due to progressive collapse. The collapse behaviors of steel framed buildings were simulated using the ASI (Adaptively Shifted Integration) -Gauss code, which can explicitly express member fracture and element contact in the collapse process. The progressive collapse phenomena were initiated by removing specific columns from the models designed based upon different axial force ratios. The locations of removed columns were restricted to a single floor, and some patterns of removed columns were investigated. The total potential energy values of structural members after the collapse were used to estimate the damage of the buildings. In this paper, two indexes are used as the evaluation index for structural strength of buildings. One of them is an allowable load ratio, and the other is a key element index. The allowable load ratio is a ratio of the elastic strength of the lower structure to the total weight of the upper structure. The key element index is a parameter which indicates the contribution of a structural column to the vertical capacity of the structure.<br> By evaluating the numerical results using the allowable load ratio, it is found that the smaller the ratio, the higher the risk of progressive collapse. The threshold of allowable load ratio to cause a large-scale progressive collapse tends to depend on the location of the removed columns, and it cannot be generally decided. This is due to the fact that the allowable load ratio is calculated on the assumption of vertical impact of upper structure. Therefore, the allowable load ratio can be used as an index to predict and compare the risks of progressive collapse even in different models, when the location of removed columns is fixed and the shapes of the models are similar. By evaluating the numerical results using the key element index, it is found that the larger the sum of key element index, the higher the risk of progressive collapse; however, some peculiar tendencies are observed in the cases of removed columns with extremely symmetrical or asymmetrical locations. The threshold of the integrated value of key element index to cause a large-scale progressive collapse tends to depend on the strengths of models, and it also cannot be generally decided. This is due to the fact that the key element index is a parameter which does not relate to the strength of the building itself. Therefore, the key element index can be used to predict and compare the risks of progressive collapse in the same building, when various locations for the removed columns are assumed.

収録刊行物

被引用文献 (1)*注記

もっと見る

参考文献 (2)*注記

もっと見る

キーワード

詳細情報 詳細情報について

問題の指摘

ページトップへ