Risk-targeted safety distance of reinforced concrete buildings from natural-gas transmission pipelines

Natural-gas pipeline accidents mostly result in major damage even to buildings located far away. Therefore, proper safety distances should be observed in land use planning to ensure target safety levels for both existing and new buildings. In this paper, a quantitative risk assessment procedure is presented for the estimation of the annual probability of direct structural damage to reinforced concrete buildings associated with high-pressure natural-gas pipeline explosions. The procedure is based on Monte Carlo simulation and takes into account physical features of blast generation and propagation, as well as damage to reinforced concrete columns. The natural-gas jet release process and the flammable cloud size are estimated through SLAB one-dimensional integral model incorporating a release rate model. The explosion effects are evaluated by a Multi-Energy Method. Damage to reinforced concrete 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 derived 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/assessment of buildings and to define the path of new natural-gas pipeline networks.