In order to study structural properties of Dingtougong mortise-tenon joints of Chinese traditional hall-style timber buildings built in the Song and Yuan dynasties, and to provide theoretical basis for structural analysis and scientific conservation of this type of architectural heritages. First, the main structural characteristics of the Chinese hall-style timber buildings built in the Song and Yuan dynasties were sorted out, including the structural forms, structural dimensions, and configurations of mortise-tenon joints. Then, the low cyclic loading tests of the six reduced-scale mortise-tenon joints were carried out, including the five groups of Dingtougong mortise-tenon joints, and the one reference group of mortise-tenon joint without Dingtougong. The results show that all the five groups of Dingtougong mortise-tenon joints have better structural performance than the one reference group of mortise-tenon joint on the aspects of ultimate capacity and rotational rigidity. In the five groups of Dingtougong mortise-tenon joints, the structural performance of the Dingtougong mortise-tenon joint with Dingtougong of through mortise-tenon joint is obviously superior to that of the Dingtougong mortise-tenon joint with Dingtougong of half mortise-tenon joint. Besides, considering material nonlinearity and contact nonlinearity, the finite element models of the six groups of mortise-tenon joints were built up by ANSYS, and the structural properties of these mortise-tenon joints under in-plane vertical load, out-of-plane horizontal load and torque load were analyzed and compared with the experimental results. The theoretical results very coincide with the experimental results. Under in-plane vertical load, the Dingtougong obviously improves the mechanical performance of the mortise-tenon joint. In addition, the relationships among the initial elastic rotational rigidity K_Y under in-plane vertical load, the initial elastic rotational rigidity K_X under out-of-plane horizontal load, and the initial elastic rotational rigidity K_R under torque load of these six groups of mortise-tenon joints were obtained, the results of which can provide theoretical base for structural analysis and conservation design of Chinese traditional hall-style timber buildings.

The protection coating is possible to be damaged during its service life, which may induce a more complicated temperature distribution of columns in fire. In order to find out the fire-resistance capacities of the steel columns with partial-damaged fire protection coating, a detailed study on the effect of partial-damaged fire protection coating on steel columns was conducted with the finite element method. The fire-resistance capacity of I-section steel columns with partial-damaged fire protection coating was studied for the different cases, and the heating condition was the international standard fire curve. It is verified that the partial-damaged fire protection coating can cause local longitudinal non-uniform temperature distribution for the whole column and sectional temperature difference for a segment of the column at the same time. The parametric analysis including the locations of defects on protection coating, the slenderness of columns and the load ratios were considered. The results show that the relatively small areas losses of the protection coating can significantly reduce the fire-resistance capacity of the steel columns. The degradation in fire-resistance capacity is more significant when the losing areas on the upper part of the column, and the cases with high load ratio (≧-0.7) are more sensitive to the negative effect of the losses of the protection coating. The residual fire-resistance capacity of the column decreases with the development of the defect length on the protection coating. The results can provide the basic assessments on fire-resistance capacities of steel columns with partial-damaged fire protection coating.

Square rebars were developed and used for decades in the early development of reinforced concrete (RC) structures; however, the objectives of modern concrete structure durability analyses and standards are centered on round rebars in past decades, which are not suited for RC buildings utilizing square rebars. Considering the absence of proper evaluation techniques to evaluate the square rebar RC structures’ durability accurately, a novel durability prediction method has been proposed for this type of historical building. The method is based on major parts as in-situ investigation, finite element model simulation, component importance analysis, and structural durability prediction. The durability prediction calculation method was established on the experimental results of the realistic historical concrete tests and corrosion-induced cover cracking experiments for square rebar components. It was found that the carbonization-resistant ability of historical concretes was relatively weaker than that of current concretes and the calculation method for critical corrosion depth of square rebar was different from that of round rebar. Furthermore, two typical application cases are presented to introduce the procedure of the method in detail. Consequently, the research outcomes can be directly used on the durability prediction and protection works for historical RC buildings.