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The single-side superposed (SSS) shear wall is an innovative precast concrete sandwich panel that better meets the requirements of building industrialization. However, the seismic behavior of SSS shear walls remains inadequately understood. In this paper, a full-scaled horizontally spliced SSS shear wall using a concealed column and an integral SSS shear wall of the same dimensions were tested. The seismic behavior was investigated considering various aspects including hysteresis performance, bearing capacity, ductility performance, energy dissipation capacity, and stiffness degradation curve. The simulation models were established by the Abaqus, which provided the verification and further research for the test. Furthermore, two innovative splicing forms were proposed to optimize the existing specimens through the Abaqus. The experimental results indicated that implementing the vertical joint would lead to a decrease in the yield-bearing capacity by 24%, but it would also enhance the ultimate bearing capacity by 12.7%. Meanwhile, the deformation capacity would improve by 9.7%. The numerical simulations demonstrated that the suggested splicing methods effectively meet the demands of building industrialization. [ABSTRACT FROM AUTHOR]

A key issue in the control, health monitoring, and condition assessment of civil structures is the estimation of structural modal parameters based on measured structural responses. However, field measurements of structural responses from civil structures under strong wind or earthquake excitations usually exhibit non-stationary feature and therefore cannot be adequately deal with by traditional modal identification methods. In this study, a novel procedure is integrated for modal parameter identification of civil structures from non-stationary structural responses on the basis of the variational mode decomposition (VMD) technique. First, the VMD algorithm is applied to decompose measured vibration signals into individual mode components. Then, the random decrement technique (RDT) is employed to obtain free vibration response of each mono component. Next, normalized Hilbert transform (NHT) is used to estimate modal natural frequency and damping ratio. The performance of the developed approach is evaluated using simulated non-stationary responses of a frame structure, and the identified results are validated. The effects of crucial factors such as levels of noise involved in structural response and data length on the modal parameter estimations are examined through detailed parametric study. Furthermore, the approach is applied to modal identification based on field measured non-stationary responses of a high-rise building during Typhoon Nida. The case study illustrates that the integrated method is an efficient tool for estimating the modal parameters of civil structures from non-stationary structural responses. [ABSTRACT FROM AUTHOR]

The smooth orthogonal decomposition method (SOD) is an efficient algorithm that can be used to extract modal matrix and frequencies of lightly damped vibrating systems. It uses the covariance matrices of output-only displacement and velocity responses to form a generalized eigenvalues problem (EVP). The mode shape vectors are estimated by the eigenvectors of the EVP. It is stated in this work that the accuracy of the SOD method is mainly affected by the correlation characteristic of modal coordinate responses. For the damped vibration systems, biases will be contained in the results of using the SOD. Therefore, an iterative smooth orthogonal decomposition (ISOD) method is proposed to identify modal parameters of the damped system from the covariance matrices of the displacement, velocity, and acceleration responses. The modal matrix given by the SOD method is updated in each iteration step using a transformation matrix. The transformation matrix can be efficiently computed using a set of analytical formulations. Meanwhile, natural frequencies and damping ratios are obtained by using a simple search method. The performance of the proposed ISOD method is verified by numerical and experimental studies. The results demonstrate that, by considering the correlation of modal responses, the ISOD method can be used to extract accurately the modal information of vibration systems with coupled modes. [ABSTRACT FROM AUTHOR]

The study on damage evaluation induced by atmospheric corrosion of engineering structures has attracted more and more international concern over the past three decades. However, the effects of atmospheric corrosion on reticulated shells have not been systematically investigated. In this regard, the performance assessment of a reticulated shell subjected to atmospheric corrosion damage is actively conducted in this study. The atmospheric corrosion model of shell elements is first presented, and a refined exponential model for estimating the corrosion depth of steel materials is developed by using the pattern recognition technique. The sensitivity of stiffness matrix to element thickness is established by using Euler–Bernoulli beam element. The sensitivity of mass matrix to element thickness is developed based on lumped mass assumption. Then, the expression of natural frequency sensitivity to element thickness and mass is derived by considering the section loss induced by both the inner and outer surface corrosion. In addition, the explicit expression of frequency sensitivity to mass of spherical joints is also established in detail. The nonlinear static structural analysis is conducted to evaluate effects of atmospheric corrosion on the stress of structural elements. A real reticulated shell constructed in northern China is taken as the example structure to examine the feasibility of the proposed approach and to assess the potential damage caused by atmospheric corrosion to the structure. [ABSTRACT FROM AUTHOR]