Search Results (8)

Column frames connected using Tang Dynasty straight tenon joints represent a unique structural system characterized by historical significance and architectural ingenuity. Consequently, an experimental model, resembling the straight tenon joint style of the Tang Dynasty Foguang Temple East Hall, was constructed using two square beams (Fangs) and three columns in this study. Through low-cycle repeated load tests, hysteretic curves, stiffness degradation, energy dissipation capabilities, and certain other indicators were analyzed under four distinct vertical load levels. The results reveal that increasing the vertical load can effectively improve the fullness of the hysteresis curve and the peak restoring force of the column frame. Moreover, a pronounced pinch effect was found in the hysteretic curve of the column frame, indicating that a higher vertical load can strengthen the frame’s restoring force within a specific range of horizontal displacement, thereby maintaining its structural stability. With increasing vertical loads, the maximum restoring force and stiffness of the column frame are elevated, enhancing the structure’s energy dissipation capacity and partially mitigating its stiffness degradation. However, it is noteworthy that as the horizontal load displacement increases, higher vertical loads result in a more rapid decline in the frame’s restoring force, reducing the effectiveness of improving the energy dissipation capabilities of the column frame. Full article

The straight mortise and tenon joints (SMTJs) of Tusi Manor, situated in the Yunnan–Tibet region of China, tend to undergo decay. This study aims to investigate the mechanism performance degradation of SMTJs due to decay. Five full-scale SMTJs were constructed and incubated with wood-rot fungi for 0, 6, 12, 18, and 24 weeks. Cyclic loading tests were conducted to assess the damage mechanisms and extent of mechanical property degradation at these different stages of decay, supported by ABAQUS finite element simulation software. The results revealed a progressive increase in damage with prolonged decay time. Comparison between decayed and undecayed specimens showed a maximum load-bearing performance degradation rate of 5.17%, 11.83%, 17.34%, and 23.54% after 6, 12, 18, and 24 weeks of fungal incubation, respectively. The cumulative energy efficiency degradation rates were 8.38%, 9.51%, 23.13%, and 33.31%, respectively. SMTJs mechanical performance degradation is correlated with wood mechanical property degradation as a function of the S-family. Finite element simulations further indicated a reduction in tenon strength from the outer parts towards the inner parts of the structure. Full article

For the study of the mechanical properties of straight-tenon joints in traditional wooden structures, three specimens of T-shaped straight-tenon joints were made according to actual structures and subjected to reciprocating loading tests. The variation rules of different seismic performance indexes such as moment-rotation hysteresis curve, skeleton curve, stiffness, and energy dissipation capacity of the specimens were analyzed through tests. Based on the geometric deformation and static equilibrium conditions, the moment-rotation theoretical model of straight-tenon joints is derived and compared with the experimental results. The studies show that the hysteresis curve of joints under reciprocating loading consists of four stages: ascending, stress relaxation, descending, and sliding. The moment capacity of joints increases gradually with the rotational deformation, but the internal gap of the joints increases synchronously, resulting in a serious attenuation of the stiffness. Tenon and mortise plastic extrusion deformation and friction can dissipate energy, as the rotational deformation increases energy consumption, while the hysteresis loop “pinch” effect is more serious, and the equivalent viscous damping coefficient is gradually reduced. The prediction results of the joint moment-rotation theoretical model are closer to the experimental results, which can provide a theoretical basis for the overall seismic analysis of traditional wooden structures. Full article

This paper comprehensively investigates the moment-rotation relationship of straight mortise-tenon joints commonly used in Chinese antique timber buildings, focusing on analyzing the local compression mechanism at the tenon end-mortise and the tenon neck-mortise contact areas. Different compression tests were performed, and the experimental compressive stress-strain curves displayed a typical bi-linear response comprising an elastic increasing response followed by a plastic stage. The specimens subjected to middle local compression tests exhibited higher yield stress, elastic modulus, and plastic modulus than the others. Cyclic loading tests were conducted on twelve mortise-tenon joints with varying lengths, widths, and heights of the tenon to investigate the rotational behavior of the joints under alternating loading directions. The hysteresis curves of the tested specimens generally showed a “Z” shaped pinching effect, indicating limited energy dissipation of the joints during cyclic loading. The length and width of the tenon were observed to have a significant influence on the joint rotational behavior. Finally, a theoretical model was proposed to predict the moment-rotation relationship of the mortise-tenon joint, considering the proposed bilinear stress-strain relationship for wood under compression perpendicular to the grain. The predicted results obtained by the proposed theoretical model were generally validated by the experimental results. Full article

The steel–concrete composite truss adopts a new type of steel-concrete composite joint with high rigidity and load-carrying capacity. In order to more conveniently and clearly grasp the working mechanism of Perfobond Leiste (PBL) shear keys in the core area of new composite structures such as steel–concrete composite trusses, the lack of strong theoretical support for the theoretical formula of load–slip relationships in the entire loading process of single PBL shear keys is solved. By proposing a straight–curved–straight three-stage simplified load–slip curve with respect to the PBL shear key, the stress process of the PBL shear key is divided into three stages—the elastic stage, plastic stage, and strengthening stage—based on the compressive yield and failure critical point of tenon concrete in the shear key. With reference to the calculation method of the bearing capacity of the order pile under horizontal loads and by calculating the shear stiffness of the shear key, a theoretical formula suitable for separating the load–slip relationship of a single PBL shear key in the entire loading process of the ear plate composite joint is proposed. The results show that, in the elastic section, the slope of the curve is related to the concrete reaction coefficient and the material parameters of the penetrating steel bar; moreover, in the strengthened section, the coefficient is related to the shear modulus of the penetrating steel bar, and a more uniform length distribution of the penetrating steel bar between the two joint plates will improve the initial stiffness of the PBL shear key to a certain extent. The results of the proposed method are in good agreement with the finite element results and experimental values. This research study’s results can provide a convenient design method for the design of the internal PBL shear keys of new composite structure joints, promoting the promotion and application of new composite structures and advancing the development of the engineering field. Full article

To improve the seismic performance of Chinese traditional wood-structure houses, this paper proposes to strengthen their mortise and tenon joints by applying an innovative metal damper. According to the dimensions of the “Yikeyin” wood-structure houses in the Tonghai area of Yunnan Province, two groups of six samples of three types of mortise and tenon joints were manufactured, in which one group was mounted with dampers made of Q235 steels. Subsequently, a low-cycle repeated loading test was conducted to examine the overall behavior of these joints. Various characteristics of seismic performance indexes, such as the moment–rotation hysteresis curve, skeleton curve, stiffness degradation, energy dissipation capacity, residual amount of tenon and the removal before and after reinforcements of straight, penetrated and dovetail tenon joints were analyzed. The test results show that these tenons exhibit good deformation capacity, their hysteresis curves became fuller and their “pinch” effects were significantly reduced, all after their joints became strengthened, indicating that their joint slips were reduced during the loading processes and their residual amounts of tenon removals were under effective control. Compared with the blank group, the joint stiffness was substantially improved, and the increase in the reverse stiffness turned greater than that of the positive stiffness at each stage of loading, while the degradation curve of the whole joint stiffness became steeper. After mounting the dampers, the bearing capacity and energy dissipation of the joints were significantly improved, the equivalent viscous damping coefficients of the straight and penetrated tenon joints were increased, but that of the dovetail joint was slightly reduced. These study results can provide a reference for the reinforcement and protection of traditional wood-structure houses. Full article

The stress mechanism of a straight mortise-and-tenon joint with wooden pegs in traditional residential wooden structures was analyzed, and a theoretical moment-rotation model of the joint was derived. To verify the model, three full-scale joint specimens were fabricated and subjected to low-cycle reversed loading tests. All specimens showed tensile cracking parallel to the grain at the top or bottom of the tenon neck. The theoretical calculation results are consistent with the experimental results. The results of the parametric analysis based on the theoretical model show the following: the rotational stiffness and bending moment of the joint increase as the beam width increases; as the beam height increases, the moment increases, but the initial stiffness of the joint is only slightly impacted; as the column diameter increases, the initial stiffness and moment increase, and the free rotation of the joint decreases; as the gap between the mortise and tenon increases, the initial stiffness and moment decrease; as the sliding friction coefficient increases, both the rotational stiffness and moment of the joint increase, and the increase is greater after the joint yields than before. Full article

In this article, the finite element method is used to build the analytical model of a traditional Chinese timber frame with straight mortise-tenon joints. The analytical model is then subjected to the lateral cyclic loading and verified based on the results of an experiment. Three types of damage in the straight mortise-tenon joint, including the gap between the mortise and tenon, damage in the top and the end of tenon, are proposed and idealized so that the analytical model can be modified accordingly. The hysteresis curve, stiffness and energy dissipation capacity derived from these damaged models with different damage extents are analyzed. The results indicate that the proposed damages of the joints have adverse influences on the lateral behavior of the timber frame. Both stiffness and energy dissipation capacity of the timber frame are weakened by these damages. Full article