The study presents a multi-layer genetic algorithm (GA) approach using correlation-based methods to facilitate damage determination for through-truss bridge structures. To begin, the structure's damage-suspicious elements are divided into several groups. In the first GA layer, the damage is initially optimised for all groups using correlation objective function. In the second layer, the groups are combined to larger groups and the optimisation starts over at the normalised point of the first layer result. Then the identification process repeats until reaching the final layer where one group includes all structural elements and only minor optimisations are required to fine tune the final result. Several damage scenarios on a complicated through-truss bridge example are nominated to address the proposed approach's effectiveness. Structural modal strain energy has been employed as the variable vector in the correlation function for damage determination. Simulations and comparison with the traditional single-layer optimisation shows that the proposed approach is efficient and feasible for complicated truss bridge structures when the measurement noise is taken into account.

Many researchers in the field of civil structural health monitoring (SHM) have developed and tested their methods on simple to moderately complex laboratory structures such as beams, plates, frames, and trusses. Fieldwork has also been conducted by many researchers and practitioners on more complex operating bridges. Most laboratory structures do not adequately replicate the complexity of truss bridges. Informed by a brief review of the literature, this paper documents the design and proposed test plan of a structurally complex laboratory bridge model that has been specifically designed for the purpose of SHM research. Preliminary results have been presented in the companion paper. IntroductionThe structural complexity of operational bridges poses a significant challenge for structural health monitoring (SHM) researchers. Reference [1] highlights that a 'primary source of epistemic uncertainty [in structural identification] is related to the relatively high level of structural complexity typical of constructed systems,' (p. 406). Ciloglu [2] found that structural complexity contributes significantly to the uncertainty of structural identification by operational modal analysis (OMA). Aktan et al. [3] argue that the basic assumptions that enable system identification of structures do not hold true for more complex constructed systems, particularly in a climate with daily temperature fluctuations of more than 10°C where temperature and humidity can have a significant effect on the vibration characteristics of an operational structure.

Many researchers in the field of civil structural health monitoring have developed and tested their methods on simple to moderately complex laboratory structures such as beams, plates, frames, and trusses. Field work has also been conducted by many researchers and practitioners on more complex operating bridges. Most laboratory structures do not adequately replicate the complexity of truss bridges. This paper presents some preliminary results of experimental modal testing and analysis of the bridge model presented in the companion paper, using the peak picking method, and compares these results with those of a simple numerical model of the structure. Three dominant modes of vibration were experimentally identified under 15 Hz. The mode shapes and order of the modes matched those of the numerical model; however, the frequencies did not match. IntroductionThis paper presents the preliminary modal testing of the structurally complex QUT Benchmark Structure (see Fig. 18.1), which was designed and constructed in response to an identified need to conduct structural health monitoring research on more complex structures, as argued in the companion paper [1].The numerical model of the structure is described. The aim of the experiment is presented. The equipment is listed, and the test method is detailed. Data are analyzed, and results are presented and discussed. The paper concludes with a discussion of the results that ties in with the aim of the experiment.

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Timber-framed shear walls are commonly used in residential buildings to provide lateral strength and stiffness against wind and earthquake loads. Wood-based panel products, such as plywood and oriented strand board, are typically fixed to timber framing with nails or screws to provide the necessary racking resistance of a shear wall. Plasterboard is a panel product used on walls to achieve a smooth finished surface. Plasterboard provides some strength and stiffness to the wall even though its primary function is architectural; however, most shear wall tests ignore the influence of plasterboard. The aim of this study is to quantify the influence of plasterboard on the structural performance of timber-framed shear walls. To achieve this aim, six (6) timber-framed shear walls (groups P1 and P2) were fabricated with 7mm F8 plywood sheathing on one side and 10mm plasterboard on the other side and tested under a monotonic loading protocol. Results were then compared with previous test results of three (3) similar timber-framed shear walls (group M1) without plasterboard. Results show that plasterboard improved the ultimate racking strength of these shear walls by up to 53%, a statistically significant result. Shear wall stiffness and failure modes were not affected by adding plasterboard.