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This study explores the possibility of using frequency responses function curvature method and cubic spline interpolation to locate the storeys of a building that is damaged in an earthquake, and corresponding frequency responses function curvature of storey often change in the earthquake. The frequency responses function of a building in each floor is established from the full structural dynamic responses. Next, the frequency responses function of storeys that be obtained by cubic spline interpolation would be used to detect the damage location of a building. The effectiveness of the proposed procedure is verified using numerically simulated earthquake responses of the finite element model of an eight-storey frame.

This study explores the possibility of using stiffness-based method and cubic spline interpolation to locate the damaged storey of a building during a strong earthquake, and corresponding stiffness matrix of structure often change in the earthquake process. The time series model of a building is established from the full structural dynamic responses. Next, the coefficient matrix of the time series model could be solved by recursive least squares (RLS) algorithms. Then, the model parameters of a building are calculated by the coefficient matrix of time series model. Finally, the identified natural frequencies and mode shapes of structure that corrected by cubic spline interpolation would be used to construct the stiffness matrix of a building. Then, the damage location of a building could be detected by the identified stiffness matrix of a building. The effectiveness of the proposed procedure is verified using numerically simulated earthquake responses of the finite element model of a six-storey frame.

Structural damage detection based on the changes of dynamic properties is a major topic for structural health monitoring. In this paper, efforts are made to extend the flexibility-based damage localization methods, especially the damage locating vectors (DLVs) method, to the case of earthquake vibration, where the finite element model and mass matrices are not available. First, a new method using continuous Cauchy wavelet transform (CCWT) and ARX (autoregressive with exogenous input) model is applied to identify the modal parameters of a five-storey steel frame with seismic base isolation system LRB from its simulated acceleration responses under 10% and 100% of Chi-Chi Earthquake excitation (Taiwan, 1999). The DLVs, which determined from the change of flexibility matrix between two cases, are then used to monitor the shock isolation device in the structure through a weighted relative displacement index (WRDI). The proposed scheme is also proved to be superior to mode shape based methods (MAC, COMAC) in monitoring shock isolation system.

Proper material constitutive models for concrete-filled tube (CFT) columns are proposed and verified by the nonlinear finite element program ABAQUS against experimental data. The cross sections of the CFT columns in the numerical analysis are categorized into three groups, i.e., circular section, square section, and square section stiffened by reinforcing ties. Via the numerical analyses, it is shown that for circular CFT columns, the tubes can provide a good confining effect to the concrete especially when the width-to-thickness ratio D/t is small (say D/t30). The confining effect of square CFT columns with reinforcing ties is enhanced by the use of reinforcing ties especially when the tie spacing is small and the tie number (or tie diameter) is large. CE Database subject headings: Columns; Nonlinear analysis; Axial loads; Confinement; Parameters.

A procedure combining the dynamic stiffness method with the Laplace transform is proposed to obtain accurate transient responses of an arch with variable curvature. The dynamic stiffness matrix and equivalent nodal force vector for an arch with variable curvature subjected to distributed loading are explicitly formulated based on a series solution. The effects of shear deformation, rotary inertia, and damping are considered. As examples, the accurate transient responses of a parabolic and a semielliptic arch subjected to either point loading or base excitation are given. The effects of the shapes of the arches and the phase-shift in the multiple input for base excitation are also discussed.

The performance of embankment slopes along a section of I-77 is summarized. Slope failures occurred mostly in embankments constructed of red shales of the Conemaugh, Monongahela, and Washington formations. Soil moisture, soil suction, pore pressure, and slope movements were measured in four embankments. The results of measurements indicated that saturation of the embankment slopes occurred near the surface by infiltration of rainfall. Laboratory shear tests were used to measure the shear strengths of the embankment materials and of the red shales in their intact state and after various manipulations that simulated compaction and weathering. With seepage parallel to the slope, failure could occur if the in-situ shear strength was close to the lower limit of the peak shear strength measured in laboratory tests on samples of the embankment material. With vertical seepage, failure could occur if the in-situ shear strength was slightly less than the softened shear strength of samples of intact shale. Since it was not possible to verify the actual seepage conditions, both scenarios are considered possible.