Considerations to blast loading by potential terrorist attacks have been increased in structural designs since September 11. Essential government and transportation facilities as well as symbolic private sector buildings have been targets of terrorists. Publicly available approaches to designing structures against blast loadings are not suitable for such urban structures, because the approaches were developed mainly for military projects, in which certain stand-off distances can be maintained from publicly open streets. Due to congested nature of urban environment, essential structural members are often exposed to the public with little or no stand-off distances. For this reason, the analysis to design urban structures against blast loading should be performed differently with a detonation with little or no stand-off distances. State-of-the-art software packages are useful to analyze blast effects on urban structures. However, they are not commonly used in structural design offices, because numerical modeling and simulation using the software are time-consuming and not practically affordable.

The purpose of this exploratory research is to develop a novel simplified approach for blast analysis and design of steel structures with little or no stand-off distances for use by general structural engineers without access to the sophisticated software. The main focus of this study is on the riveted built-up shapes that are commonly used in aging urban transportation structures. A series of numerical simulations will be performed and used to quantify damage levels of structural members subjected to blast loads. The simulations will be based on detailed nonlinear explicit dynamic analyses for investigation of high-intensity and short-duration blast effects on structures using a fully coupled interaction technique between computational fluid and structural dynamics. Parametric studies of such analysis would result in certain patterns, which will then be used to develop quantifiable damage curves or equations of steel members for efficient mitigation design.