Estimation of the risk amplification in steel buildings subject to seismic actions using Monte Carlo simulation

The estimation of the amplification of the seismic risk of steel buildings, as compared with that allowed for the maximum seismic acceleration, is examined. To this end the structural reliability of steel buildings, defined by the probability of exceeding design threshold limits of the entire structure and its components, is estimated for thousands of models analyzed by Monte Carlo simulation. The limit states that have been recorded as outputs in the simulation are: the failure by anchor tension; yielding by tension in the total section of the columns, braces and union elements; compression buckling in braces and columns; yielding of flexural beams; yielding caused by shear in beams; and buckling by combined flexural and axial force stresses in columns. The input random variables are the dead and live loads and earthquake accelerograms, on the one hand, and structural properties, on the other. The latter include the yielding limit, the modulus of elasticity, the cross-section area and moment of inertia of the steel members. The generation of the artificial earthquake accelerograms is carried out with an algorithm created especially for the city of Manizales (Colombia). In order to determine the causes of risk amplification into the structure, the output results are examined under the exceedance threshold criterion of a ten percent probability, which is the same one allowed for the maximum seismic acceleration in the life cycle period of fifty years for the building.