Zibignew ZEMBATY, Politechnika Opolska, Opole University of Technology

REVIEW OF VARIOUS APPROACHES TO QUANTIFY SEISMIC ROCKING EFFECTS ON TALL BUILDINGS AND SLENDER TOWERS
Each point on the ground surface can be subjected to three translational ground motions (along the axes x, y & z) and three ground rotations about all these three axes constituting a 6-compoent seismic record at a ground surface. From the 70-ties 20th century, the presence of rocking components that could substantially contribute to the seismic response of towers and tall buildings was postulated among engineers, however, due to a lack of credible measurements, only indirect methods served the numerical analyses. The situation dramatically changed from the beginning of the XXI century when more and more 6-component seismic records were acquired. A turning point was year 2014 when the first, strong motion 6-component record of MM intensity VII was acquired as one of Kefalonia aftershocks. This allowed to carry on the first realistic assessments of the contribution of rocking seismic excitations in overall seismic response. This lecture brings a literature review and examples of rocking response computations for a 160 m slender tower and a 30-story tall building. Results indicate a substantial 20-30% contribution of the rocking component in overall seismic response and rather conservative estimation of this seismic load in Eurocode 8 part 6.