The inverted-trapezoid sectioned dovetail (ITSD) mortise-tenon joint was popular during the Chinese Song Dynasty. To investigate the particular features of the ancient wood joint, three 1:4 scaled models of a double-span timber frame with two exterior joints and an interior joint were fabricated according to the construction method commonly used in Chinese traditional wood structures, and tested subjected to fully reversed cyclic loading. Investigated were the mechanical properties of the ITSD mortise-tenon joints such as the connection stiffness and flexibility, hysteretic model and the relationship between the bending moment and relative rotation (i.e. the M-θ′ model). The constitutive parameters of the Kishi-Chen M-θ′ model for ITSD mortise-tenon joints were calibrated using statistical fitting methods. Besides, an assumption applicable to the connection type (e.g. pinned, semi-rigid or rigid joint) at a given connection bending-moment level was suggested with respect to practical engineering purposes. Furthermore, the M-θ′ model obtained for ITSD mortis-tenon joints was incorporated into the commercial software SAP2000, and the experimental hysteretic curves obtained for the three scaled specimens were compared with the curves obtained using finite element method (FEM), it was found that the M-θ′ model validated by this study was applicable to the ITSD mortise-tenon joint.

The fractal characteristics and energy dissipation of basalt fiber reinforced concrete (BFRC) with five kinds of fiber volume contents (0.0%, 0.1%, 0.2%, 0.3%, 0.4%) after exposure to different temperatures (20 °C, 200 °C, 400 °C, 600 °C, 800 °C) under impact loading were investigated by using a 50 mm diameter split Hopkinson pressure bar (SHPB) apparatus. Scale-mass distribution rules and fractal dimension characteristics of fragments were studied based on the screening statistical method and the fractal theory. Furthermore, the relationship between the energy consumption density and the fractal dimension of fragments was established, and the effects of fiber content, temperature and impact velocity on fractal dimension and absorption energy were analyzed. The results show that the crushing severity of fragments and fractal dimension increase with the impact velocity under the same fiber content. The energy consumption density increases first and then decreases with increasing fiber content, and also decreases with increasing temperature. When the temperature and fiber content remain unchanged, the energy consumption density increases linearly with the increasing fractal dimension, and under the same impact velocity and temperature, there is no obvious linear relationship between energy consumption density and fractal dimension.

The unified solution for shear strength for unsaturated soil in terms of two independent state stress variables is presented based on both Unified Strength Theory (UST) and Fredlund's shear strength theory for unsaturated soil, which can be especially versatile in reflecting the effect of intermediate principal stress. Considering different distributions of matric suction, the unified solution of active earth pressure for unsaturated soil is deduced, which could avoid some shortages of Rankine's active earth pressure. The influence of the intermediate principal stress and matric suction on the active earth pressure is also investigated. It is shown that the active earth pressure decreases significantly with an increase in the unified strength theory parameter or matric suction.

The dynamic mechanical properties of basalt fiber reinforced concrete (BFRC) with different fiber contents (0.0%, 0.1%, 0.2%, 0.3%, 0.4%), confining pressures (0 MPa, 5 MPa, 10 MPa, 15 MPa) and exposed to different temperatures (20 °C, 200 °C, 400 °C, 600 °C, 800 °C) were investigated by using a 50 mm split Hopkinson pressure bar (SHPB) apparatus, and the factors such as fiber content, temperature and confining pressure effect on the dynamic mechanical properties were analyzed. The results show that the dynamic peak stress increases first and then decreases with the increase of fiber content. At different temperatures, the peak stress and its corresponding strain correspond to different fiber content, and the optimal fiber content is between 0.1% and 0.3%. When the temperature was from 20 °C to 400 °C, the dynamic peak stress decreased less, while when the temperature reached 600 °C and 800 °C, the dynamic peak stress decreased greatly. The confining pressure can significantly increase the dynamic peak stress and change the crushing morphology of specimens. The damage variable was built based on the Weibull distribution. A dynamic damage constitutive model combining statistical damage and viscoelastic model was established based on component combination model. The fitting curve of this model fitted well with test curve by identifying fewer undetermined parameters compared with Zhu-Wang-Tang (ZWT) model; therefore, this model can well describe the dynamic properties of BFRC under impact load.