Seismic response of highly flexible structure under coupled horizontal and tilt ground motion

Testing and theoretical studies of seismic response of the highly flexible structure under coupled horizontal and tilt (CHT) ground motion were conducted. The dynamic equations for the highly flexible structure were derived, in which the additionalP-Δ effect caused by the tilt was considered as an equivalent horizontal lateral force and added into the equations as the excitation. Based on the different sensitivity caused by the tilt ground motion between the horizontal and vertical pendulum in the single-pendulum seismograph, the wavelet analysis was adopted to obtain the tilt component from the uncorrected horizontal component of ground motion. The shaking table tests of the scaled model for the highly flexible structure taking a television tower as the prototype under horizontal, tilt and CHT ground motion were carried out, and the test results were compared with the theoretical analysis. The results show that: the shaking table tests are consistent with the theoretical analysis adopting the developed dynamic equations and the correctness of the theoretical analysis is verified; the additionalP-Δ effect caused by the foundation tilt not only increases the seismic effect of highly flexible structure, but also leads to a remarkable asymmetrical displacement effect, resulting in a great increase of the horizontal displacement of the structure. Therefore, it should be paid attention to through the practical seismic design and computation process.