RESISTANCE OF STEEL FASTENERS SUBJECTED TO SHEAR AT PUBLIC ARENAS IN NORMAL AND FIRE TEMPERATURES – PROBABILISTIC APPROACH

The buildings with great grandstands are the public places where consequences of failure are very high. For this reason, according to EN 1990 they belong to CC3 class consequence of failure. The reliability class RC3 is associated with the consequences class CC3 [7, 8] and is defined by the b = 4.3 reliability index with probability of failure p_f ~= 8.54·10^–6. Shear connections have to transfer forces between structural members – steel body and bolts with adequate degree of safety. The load-carrying mechanism of bolted shear connections is complex and analytical methods for predicting the shear resistance are not applicable. Instead the resistance of the connections may be determined using empirical formulas. The distributions of horizontal and shear resistance within steel body – bolts will be described depending on material characteristics of steel body and bolts components. The characteristic resistance of steel shear connection is obtained as minimum of two variables: bolds resistance and steel body resistance. Probability function of this minima will be defined and described in this paper. Laboratory tests provide the only practicable basis for specifying safety margins for ultimate strength connections. The determination of partial safety factors within shear connections will be presented according to EN1990. Design value of such resistance is specified as suitable fractile of log- normal probability distribution, calculated with the assumption that the acceptable probability of down-crossing is not greater than p_f,ult ~= 2.91·10^–4. It means that the target reliability index, defined for the resistance, is taken as b_R,req = 3.44, in accordance with the European recommendations (EN 1990).

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