Probabilistic risk assessment of reinforced concrete columns to natural-gas pipeline explosions

Several accidents have shown that framed building structures may suffer significant loss of columns if they are relatively close to natural-gas pipelines. As column loss may trigger a progressive collapse of the structure, this kind of risk should be assessed and mitigated. In this paper, a quantitative risk assessment procedure is presented for the estimation of the annual probability of direct structural damage to reinforced concrete (RC) buildings associated with high-pressure natural-gas pipeline explosions. The procedure is based on standard Monte Carlo simulation and takes into account physical features of blast generation and propagation, as well as damage to RC columns. The natural gas jet release process and the flammable cloud size are estimated through SLAB one-dimensional integral model and Multi-Energy Method. Damage to RC columns is predicted by means of pressure‒impulse diagrams. The conditional probability of damage was estimated at multiple pressure‒impulse levels, allowing blast fragility surfaces to be plotted at different performance limit states. Finally, blast risk was evaluated and allowed the estimation of minimum pipeline-to-building safety distances for risk-informed urban planning. The probabilistic procedure presented herein may be used for performance-based design and assessment of buildings and natural-gas pipeline networks