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Advancements in sensing and computer technologies have made vibration-based techniques in structural health monitoring viable methods of structural assessment. An accurate estimation of modal parameters using vibration tests may be achieved only if an optimum monitoring time is chosen. In this paper, the limitations of the currently available criteria are discussed in detail. A new set of criteria is recommended for monitoring time that encapsulates the effect of input excitation other than white noise. The new criteria consider bias and variance error trade-offs for achieving the optimal monitoring time and the number of windows used in the Welch method for spectral analysis. The recommendations in this paper allows one to select an optimum monitoring time for excitations with narrow and broad band spectral densities. A series of numerical parametric studies were conducted to validate the new recommendations. The proposed criteria are also validated using ambient vibration test data collected from a cable stayed bridge in Canada. The experimental study results were also used to demonstrate the trade-off between the spectral analysis parameters on the accuracy of estimations.

This paper presents the application of a hybrid structural health monitoring approach for condition assessment of cable-stayed bridges. Information from the structure’s quasi-static response, global vibration behaviour, visual inspection, traffic data, global positioning system, and local vibration test of cables are incorporated into the assessment process. Signal processing techniques and monitoring parameters to achieve an accurate identification is discussed in detail. A rigorous hybrid assessment method was used to evaluate the structural integrity of cables through incorporating visual inspection, ultrasound test, and local and global vibration analysis data. The framework was applied to a long-span case-study bridge in New Brunswick, Canada. Condition of primary structural members including stay-cables, bridge girders, and the orthotropic steel deck were successfully identified. Other structural parameters such as the bridge deck non-structural mass was also evaluated.

Tapered piles are used in place of cylindrical piles for their improved geotechnical performance. When tapered piles are subjected to axial dynamic loading, as is the case with machine foun...

Advances in research and development have led to the application of high-strength timber plates to flooring-slab construction. It is envisaged that floors built from timber plates will have...

This paper presents a series of experimental and analytical studies on the ductility requirements of bolted double-angle shear connections. Five full-scale connection configurations were tested, and their load-deformation behaviour was monitored using the digital image correlation technique. The yield line patterns observed from the experiments differ from the assumed pattern used in the derivation of the ductility equations currently available in design guidelines. The identified deformation contours were used as the basis for further development of analytical formulations applicable to the flexibility requirements of connections. The yield line theory was employed to evaluate the induced moment on the connections at the ultimate shear capacity. The details of the experimental setup including test parameters, loading scenarios, and the digital image correlation technique are fully outlined. Finally, the developed formulation was validated through a comparison with previously published experimental results. The results show the proposed solution provides an accurate estimation of the moments induced on double angle shear connections at ultimate capacity rotations.

Cross-laminated-timber (CLT) floor slabs have clustered modal frequencies, with higher order modes significantly influencing motions caused by dynamic footfall forces. Presented analyses address dependence of predicted slab motions on construction details and modal frequency filtering decisions. Based on the results, ideas are presented for creating robust vibration serviceability design methods applicable to CLT floor slabs. Those ideas are consistent with ISO limits on human toleration of motions under defined conditions, and design code classifications of building occupancy conditions. Ongoing research is implementing them.

New ultralight materials like cross-laminated-timber (CLT) enable attainment of longer floor spans than are possible with traditional shallow-profile timber construction. Their low modal mass to stiffness ratios make ensuring satisfactory dynamic responses under normal building occupancy conditions a primary design consideration. This paper presents numerical techniques for accurate prediction of modal frequencies, which are essential input to contemporary floor vibration serviceability design criteria. Recommendations are made for minimum requirements for design level prediction of modal responses of CLT floors, based on numerical and experimental studies of effects engineering design variables have on such characteristics.

Practicing engineers generally obtain stiffness and damping coefficients for dynamic design of pile foundations from design charts. The design charts require multiple interpolations and produce approximate frequency-independent coefficients. Explicit expressions consistent with the underlying theory for the vertical vibration of single piles are presented in this technical note. These expressions are easily implemented in a computer program, such as a spreadsheet, for design use. The proposed method preserves the frequency-dependent nature of the dynamic coefficients and enables one to account for the true condition of the pile tip. The effectiveness of the proposed method is illustrated with numerous examples.