The majority of existing ancient timber structures have different degrees of damage. The looseness of mortise-tenon joints is a kind of typical damage type. In order to study the influence of looseness on the seismic performance of mortise-tenon joints, six through-tenon joints and six dovetail-tenon joints with scale 1:3.2 were fabricated according to the requirements of the engineering fabrication method of Chinese Qing Dynasty. Each type of joints consisted of one intact joint and five artificial loose joints, and the artificial defect was made to simulate looseness by cutting the tenon sectional dimension. Based on experiments of two types of joints under low-cyclic reversed loading, the seismic behaviors of joints such as failure modes, hysteretic loops and skeleton curves, strength and stiffness degradation, and energy dissipation capacity were studied. Moreover, the comparative analyses of seismic performance between two types of joints were carried out. The variation tendency of seismic behaviors of two types of joints has similarities, and there are some differences due to their different structural styles. The results indicate that squeeze deformation between tenon and mortise of two types of joints occurred. The shape of hysteretic loops of two types of joints is reverse-Z-shape, and the pinching effect of hysteretic loops becomes more obvious with the increase in looseness, among which of through-tenon joints is more obvious than that of dovetail-tenon joints. The carrying capacity, stiffness, and energy dissipation capacity of loose joints are significantly lower than that of the intact one, and the energy dissipation capacity of dovetail-tenon joints is better than that of through-tenon joints. The rotation angles of two types of joints can reach 0.12 rad, and the loose joints still have great deformation capacity.

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Lattice material is a typical periodic structural material, and the gaps of the lattice material are often used to carry filling materials. In order to satisfy the load-carrying requirements of a certain multifunction/structure integrated composite material, four different 3D periodic multilayer lattice materials were proposed in this paper, such as the square, the quadrate, the tetrahedron and the hexagon. The BEAM189 element in ANSYS was adopted to predict their static mechanical properties, and the Mises strength criterion was taken as the failure criterion. Based on the solution of FEM, the axial stress and displacement of the top surface were obtained. The results indicated that adopting the relative stiffness and the load-mass ratio as the overall assessment is effective to evaluate the overall bearing capacity of the multilayer lattice materials. Given the same cross-section size of the cellular configuration, the hexagon multilayer lattice material shows the relatively optimal overall bearing capacity in the four configurations, while the tetrahedron configuration performs the worst

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