Ancient Chinese wooden structures exhibit remarkable organic characteristics, reflected in their highly integrated construction and exceptional seismic performance. To explore the seismic-resistant wisdom inherent in ancient wooden structures, this study provided an in-depth interpretation of traditional construction techniques and carried out quasi-static and dynamic tests on two timber structure models designed with characteristic Song dynasty architectural features. The structural characteristics of key joints and their deformation behavior were clarified, the energy dissipation mechanism and its correlation with seismic performance were analyzed, and the stiffness differences among various structural layers and their collaborative seismic-resisting mechanism were revealed. The results demonstrate that the ancient wooden structures possess the advantages of “weak connections yet strong deformability,” “weak energy dissipation yet strong seismic resistance,” and “weak resonance yet strong synergy.” These findings systematically reveal the seismic mechanisms of ancient wooden structures and offer valuable insights for the seismic design and improvement of modern buildings.

In Shanxi Province, China, concrete foundations of substations are widely exposed to environments with sulfate erosion, which results in severe damage. There are various avenues to enhance sulfate resistance, and one promising approach involves optimizing high-performance water reducers. Chain extender, which is an integral component of a water reducer, serves as a pore-blocking agent to effectively counter sulfate erosion. This study delves into the impact of a chain extender in the water reducer on the sulfate resistance and adaptability of ordinary concrete. The assessment begins with gauging the sensitivity of concrete to sulfate erosion, utilizing a 0–1 scoring method. Comparable conditions are maintained, allowing for a direct comparison between concrete with and without chain extender based on predefined criteria. A score of 1 denotes superior performance, while a score of 0 indicates a poorer performance. Following the evaluation of each criterion, scores are aggregated by the water reducer type, with higher scores signaling superior adaptability. The findings highlight that chain extender enhances the internal porosity of concrete, resulting in a more compact microstructure, heightened impermeability, and improved resistance to sulfate erosion. Its influence on mixture performance, however, is marginal. From an erosion product standpoint, using the semi-immersion method, chemical erosion predominates in the immersion zone, while both chemical and physical erosion are observed in the alternate wet–dry zone. Employing a 0–1 scoring method, Water Reducer 3^# (with chain extender) scores 20 points, whereas Water Reducer 3^#–1 (without chain extender) scores 4 points. Taking into consideration all factors, the chain extender demonstrates excellent adaptability to ordinary concrete. To validate the effectiveness of the 0–1 scoring method, it is applied to assess fly ash and slag double-blended concrete. Water Reducer 3^# (with chain extender) scores 13 points, while Water Reducer 3^#–1 (without chain extender) scores 10 points. Taking all aspects into consideration, the chain extender component exhibits commendable adaptability to fly ash and slag double-blended concrete.

To investigate the correlation between construction dimensions and seismic performance of Song-dynasty official and local timber structures, two scaled models were subjected to horizontal cyclic quasi-static loading tests. One model is the Goddess Mother Hall of Jinci, and the other is the 7th-grade timber frame described in Yingzao Fashi. The models have similar vertical-layer proportions but differ in bay width, E-fang cross-sectional dimensions, Dou-gong cai-height, and column-top tenon cross-sections. The relative ratio method was used to mitigate the effects of material and scale differences and to focus on the relative contributions of the column-frame and Dou-gong layers to the overall frame. For the Goddess Mother Hall model, which is characterized by a wide bay and thin E-fang, the ratio of the equivalent viscous damping coefficient of the column-frame layer to that of the overall frame remains above 1.0, indicating greater energy dissipation efficiency than the overall structure. However, its stiffness degradation is more pronounced under high vertical loads. The enlarged column-top tenon cross-section and slightly reduced cai height produce a stable increase in the stiffness contribution of the Dou-gong layer, whereas its relative contribution to energy dissipation proportion is smaller than that in the Yingzao Fashi model. The results show that dimensional differences are associated with distinct trends in the stiffness and energy dissipation of the column-frame and Dou-gong layers and that these trends vary with vertical load. This study reveals the coupling relationship between dimensional adjustments and structural performance in official norms and local construction practices, providing a basis and directions for further research on the mechanical effects of dimensional variations in ancient timber structures.