ACCOUNT OF SEISMIC EFFECT WITH INTENSITY AT ABOUT 7 MACROSEISMIC SCALE POINTS ON RESIDUAL EARTHQUAKE-RESISTANCE OF FULL-PRECAST BUILDINGS IN THE KAMCHATKA PENINSULA

Abstract

Based on seismic events that occurred near the Kamchatka Peninsula between 1971 and 2025, the article presents guidelines for conducting a computational assessment of residual earthquake-resistance of existing buildings, considering past moderate earthquakes. Moderate earthquakes are defined as seismic events that cause structural damage without leading to a complete loss of a building operational properties (serviceability). The study examines earthquakes with an intensity of approximately 7 points on the MSK earthquake-intensity scale in the city of Petropavlovsk-Kamchatsky on sites composed of medium soils. It is assumed that many existing full-precast buildings in Petropavlovsk-Kamchatsky may have been subjected to at least five similar earthquakes. A mathematical model for quantitative assessment of earthquake-resistance shortage (further Id ), previously presented by the author in 2023, are refined. The proposed Id -model foresees check computational assessment of a building using Pushover Analysis. Assumptions and backgrounds which allowed using of the Bayes' formula for providing of the Id assessment of existing buildings are presented. To verify objectivity of the proposed refinements, graphical dependencies reflecting relationship between Id value and service life of a building (Tex) are plotted. It has been determined that past moderate earthquakes may form in full-precast buildings a value of earthquake-resistance shortage which will exceed, under otherwise equal conditions, expected from a rare earthquake corresponding 9-points of the earthquake-intensity scale. The results of the residual earthquake-resistance assessment are presented on the example of a 4-story RC frame, adopted as a closest analogue of the KPS series buildings frame. The Id assessment was conducted using earthquake motion record according to the Shipunsky Earthquake of August 17, 2024 scaled to a peak ground acceleration of 0.35g. In the considered example, the residual seismic-resistance of the analyzed frame is determined to be 8.1 seismic intensity points