STRUCTURAL AND LIFE SAFETY ALTERNATIVES IN URBAN LANDSCAPE UNDER EXTREME ACTIONS IN SEISMIC ZONES OF ROMANIA

摘要

The paper investigates alternatives for design and/or strengthening of buildings, for structural and life safety, under extreme loadings, starting from earthquake engineering constraints. The Romanian Earthquake Code P100-1/2006 and EC 8 relate the life safety ultimate state and life safety criteria to collapse prevention through the mean recurrence interval of the design action. The recent EN 1991-1-7:2006 refers only to some accidental actions and internal explosions, but excludes external blasts, military actions and sabotage or tornadoes. The paper aims to cover this gap by a multi-hazard approach, with an integrated design of architectural and structural members. In Romania, many low-rise buildings are stiffer, made of masonry and concrete, while high-rise reinforced concrete structures are slender and are more vulnerable to Vrancea long-period seismic motions. The new urban landscape evolves to higher steel structures, with glass envelopes, atria, covered canopies, outside elevators, underground and overground spaces, where there is a danger of blast pressure and fire spreading on vertical and horizontal direction. Advanced earthquake resistant design is an asset but some members are sight exposed, have higher risk exposure and reduced redundancy to other extreme actions. We have studied plan and volume solutions vs. robustness and progressive collapse criteria and the use of safe rooms against risks caused by collapse or shattering and projection of debris. A strengthening solution was tested in INCERC on masonry specimens under diagonal compression, using CF plates, with good results.