A novel sensor placement criterion is proposed for structural health monitoring after five influencing criteria are critically reviewed. The objective of the proposed criterion is to achieve best identification of modal frequencies and mode shapes through almost unbiased estimation of modal coordinates. The proposed criterion derived by the Representative Least Squares method depends on both the characteristics and the actual loading situations of a structure. It selects sensor positions with the best subspace approximation of the vibration responses from the linear space spanned by the mode shapes. Furthermore, the connection between the Effective Independence and the approximate Representative Least Squares estimator is obtained through matrix perturbation analysis. It is found that the Effective Independence is a step-by-step approximation to that of the Representative Least Squares criterion.

This paper highlights a two-level optimization process combined with ant colony optimization algorithm (ACO)，which is applied to design the shape of the transmission tower structure, and compiles optimization design procedure for the solution of the structure shape with the MATLAB language. By comparing the different methods of the transmission tower structure optimization design, the ACO algorithm is demonstrated to be more accuracy and practical in dealing the complex optimizations problem, i.e. the combination of continuous variables and discrete variables. These calculation examples illustrate that the two-level optimization method is reliable and versatile.

Optimal sensor placement (OSP) technique plays a key role in the structural health monitoring (SHM) of large-scale structures. In this paper, an optimal sensor placement (OSP) method based on a new intelligent algorithm, i.e., monkey algorithm (MA) is proposed. Considering the limitation of MA and the characteristics of OSP, the integer encoding to solve the location of the monkeys is proposed. The diversity of the monkeys is increased by introducing the hamming distance in the initial location, in order to improve the capacity of global search, and the random disturbance mechanism of the Harmony search is introduced in the process of climbing to improve the capacity of local search. Finally, taking the Dalian World Trade Building as an example, the OSP schemes are chosen. The numerical example demonstrated the feasibility and effectiveness of the proposed method.

Ductile frame structures are generally designed with column over-design factors (COF) to assure plastic hinges occurring in all beams and avoid unpreferable failure modes. In order to avoid story mechanisms of frame structure constructed with elastic-plastic materials, target COF has been investigated where the relative occurrence probability of most likely story mechanism is limited within a specific tolerance. In the present paper, the concept of basic and optimum column over-design factor for avoiding story mechanism are proposed and the value of them for multi-span multi-story ductile frames are presented based on a comprehensive investigation on the occurrence order of story mechanisms. The basic COF is defined as the critical value that the preferable failure mode and unpreferable failure mode are with the same failure probability, and it is the low limit assuring the entire beam-hinging pattern prior to story mechanisms. For a structure designed with a COF less than basic COF, the plastic hinges are easier to occur in partial stories to form story mechanism. The optimum COF is the most effective and economy COF to enhance the safety of structure, and it is resulted from the shift of priority of plastic hinges in different stories. The relationships between the basic and optimum COF with calculation parameters are also analyzed in this paper.

The dynamic behavior affected by strain rate effect of the high-rise reinforced concrete shear wall structure subjected to seismic loading are analyzed by finite element software ABAQUS. The damaged plasticity model for concrete was used, and the strain rate effect of concrete and steel were considered. The nonlinear dynamic response results with strain rate effect are compared with the results without strain rate effect. The distribution of strain rate can not only influence the concrete and steel, but also have some effects on the dynamic response of the high-rise reinforced concrete shear wall structure. The strain rate effect is more prominent under the stronger seismic wave.