Abstract Tower structures are sensitive to hurricanes or earthquakes, whereupon they are easily damaged due to large deflection and dynamic responses. Herein, a method is proposed to accurately identify the location and extent of damage in tower structures. Firstly, a tower structure is divided into several sections along its height, and each section is regarded as a super element. Based on the finite element method (FEM), the displacement, mass, and stiffness matrices of a super element are constructed to establish the free motion equation of tower structures. Secondly, the stiffness of each component of the tower structure is included in a coefficient as the damage parameter. The first-order partial derivative of the frequencies and mode shapes of the structure for the damage parameters is obtained through Taylor expansion to construct overdetermined linear equations with the damage parameters as unknown. The values of the damage parameters can be obtained by solving the equations, and the locations and extent of damages of the structure can be obtained according to the number and values of the parameters. Furthermore, to greatly improve the accuracy of the damage identification, the modification of modal truncation error is proposed. Finally, the numerical simulation of a 12-story steel TV tower verifies the feasibility and effectiveness of the proposed method.

Abstract In this paper, a seismic-shielding structure is presented based on the phononic crystal theory, which is now used to control acoustic waves. An earthquake-proof barrier of seismic waves can be built by filling up the structure under the ground around the building that we want to protect. When the frequency of seismic waves falls into the band gaps of the structure, the seismic wave can be blocked. Herein, the frequency band gaps of the structure are determined theoretically, and the influence of geometric and material parameters on the frequency band gaps is analyzed.

Abstract In this paper, four concrete frame joints with high-strength stirrups and one with normal-strength stirrups were tested to investigate the mechanical properties of concrete beam-column joints with high-strength stirrups under low cyclic reversed loading. The influences of yield strength, volumetric ratio and section type of stirrups on bearing capacity, ductility, energy dissipation and shear deformation of concrete joints were analyzed, and the results indicate that increasing the yield strength of stirrups has limited effect on enhancing the bearing capacity of concrete joints, but can effectively improve the ductility, energy dissipation and restriction on shear deformation of concrete joints.

Resumen Con el objetivo de investigar las propiedades mecánicas de las juntas de viga-hormigón con estribos de alta resistencia, se probaron cuatro juntas de marco de hormigón con estribos de alta resistencia y una con estribos de resistencia normal bajo carga invertida cíclica baja en el papel. Se analizan las influencias del límite de elasticidad del estribo, la relación volumétrica del estribo y la forma del estribo en la capacidad de carga, ductilidad, disipación de energía y deformación cortante de juntas de concreto, y los resultados indican que aumentar la resistencia al límite del estribo tiene un efecto limitado en mejorar la capacidad de soporte del concreto articulaciones, pero puede mejorar efectivamente la ductilidad, la disipación de energía y la restricción en la deformación por cizallamiento de las juntas de concreto.