SEISMIC RELIABILITY ASSESSMENT OF EXISTING R C FLAT-SLAB BUILDINGS/

The reliability of existing reinforced-concrete flat-slab buildings, d esigned and detailed to resist gravity loads only, was studied for pun ching failure at connections under earthquake-type loading. Two flat-s lab buildings, three and 10 stories in height, designed according to t he ACI 318-56 building code, were used in the nonlinear dynamic analys is and reliability calculations. Results from previous experimental re sults on the seismic resistance of slab-column connections were employ ed to establish the effective slab widths, unbalanced moment-transfer capacity of connections, and their punching strength. The member dimen sions, material strengths, and live load were treated as random variab les and the effect of model uncertainty was included in the calculatio ns of reliability indices. Random earthquake time histories were gener ated with the Kanai-Tajimi power spectrum. The limit-state function wa s based on the punching failure capacity of the interior slab-column c onnections, Based on the reliability analysis, the probability of fail ure of existing flat-slab buildings are presented for different soil c onditions and peak ground accelerations varying from 0.05g to 0.2g.