Blast effects on spatial glass shells for a long-span roof structure

Modern railway stations are often designed architecturally to embed long-span roof structures to enhance portal bird-eye views for commuters and dwellers. Commonly, slender-by-nature spatial glass shell elements are installed over such the long-span roof structure. The span/depth ratio of the shell elements often causes excessive responses and high sensitivity to dynamic actions (e.g. wind, Earthquakes, explosion, etc.). The issues are pronounced when thin-walled glass roof structures experience shock loads. At present, terrorist attack is one of the global grand challenges for engineers to resolve. Especially in Europe, the railway stations are considered to be at extreme risk of terrorist exposure. This implies that the activity could occur imminently. Also, many railway critical infrastructures were built or designed long before the explosive actions being taken into account. In this study, the blast simulation and transient effects on a long-span glass roof structure are thus highlighted. The focus is placed on spatial glass shell elements, which are ones deemed to be at risk. Nonlinear modeling, validation and transient analyses of the station roofing structure have been carried out using a finite element package, LS-Dyna. The explosion is simulated by rapid and abrupt release of energy using LS-Dyna code. The explosion effects are highlighted in a waveform of high intensity pressure that spreads outward from the source to the surrounding air. It is designed to place the blast load close to the escalators because the location can affect most people/structure. Nonlinear transient dynamic results can be obtained. In this study, critical fragility and vulnerable component analyses will be presented so that railway and structural engineers can develop risk-based retrofit program against terrorist attacks for the railway station. Sensitivity of explosion intensity has been evaluated to quantify structural capacity and vulnerability of the glass shell roof. The insight into this transient behavior will help railway and structural engineers to establish strategic retrofitting methods to minimise catastrophic damage to and potential losses of train passengers, the public & rail assets.