De-Yi Zhang

Vector-Valued Uniform Hazard Spectra

Uniform hazard spectra (UHS) have been used as design earthquakes in several design codes. However, as the results from scalar probabilistic seismic hazard analysis (PSHA), UHS do not provide knowledge about the simultaneous occurrence of spectral accelerations at multiple vibration periods. The concept of a single “design earthquake” is then lost on a UHS. In this study, a vector-valued PSHA combined with scalar PSHA is applied to establish an alternative design spectrum, named vector-valued UHS (VUHS). Vector-valued seismic hazard deaggregation (SHD) is also performed to determine the design earthquake in terms of magnitude, distance, and occurrence rate for the VUHS. The proposed VUHS preserves the essence of the UHS and can also be interpreted as a single design earthquake. To simplify the procedure for generating the VUHS, so that they can be easily incorporated into performance-based seismic design, an approximate method is also developed.

Shake-Table Test for a Typical Curved Bridge: Wave Passage and Local Site Effects

To study the effects of ground motion spatial variations on curved bridges, this paper presents a shake-table test for a 1/10-scale typical curved bridge under spatial ground motions, including wave passage effect, local site effect, and ground motion multidimensionality. The experimental results show that both wave passage and local site effects have significant influence on seismic responses of curved bridges. Wave passage effect on curved bridges is attributed primarily to the higher asymmetric modes and pseudostatic displacements induced by asynchronous excitations, whereas local site effect is more obvious for structures with fundamental frequencies close to the predominant frequencies of the sites. Compared with straight bridges, the curvature radius causes curved bridges to be more sensitive to ground motion spatial variations, especially the local site effect. Therefore, curved bridges may be damaged more seriously than straight bridges during the same earthquake. Furthermore, seismic responses of irregular curved bridges are more sensitive to ground motion multidimensionality than are those of straight bridges. In this experiment, the effects of bridge abutments and nonuniform sites along the bridge were not considered.

Effects of model updating on the estimation of stochastic seismic response of a concrete-filled steel tubular arch bridge

The objectives of this paper are to integrate the structural health monitoring (SHM) technique with the structural seismic analysis, and to make the SHM technique serve, benefit and promote the structural seismic analysis integrally. Therefore, considering a concrete-filled steel tubular arch bridge structure, the SHM technique is used to calibrate the finite element (FE) model through the model-updating scheme to minimise the structural response differences caused by FE model errors. Effects of model updating on structural seismic responses are investigated using the stochastic vibration analysis approach. It is observed that effects of model updating are significant on structural seismic responses, and these effects may become more evident in structural nonlinear dynamic analysis. Hence, it is of prime importance to calibrate the FE models through the SHM technique for seismic evaluations of some operational critical structures.