This article, by using mathematical expressions, offers a scientific framework for understanding how the grading system of Qing′s structural carpentry determines the design and construction in the grand style timber...This article, by using mathematical expressions, offers a scientific framework for understanding how the grading system of Qing′s structural carpentry determines the design and construction in the grand style timber architecture.The Qing′s grand style timber structure, which is ready for prefabrication and assembly, is extremely hierarchical oriented and significantly standardized. The general procedure in designing a grand style timber structure is to start with the grade that defines the basic module (dou kou); next comes with the number of bracket set (cuan), the number of longitudinal bays and the number of purlins which affect its plan and cross section; thirdly choose a roof type that determines its longitudinal section and the facade as well. A series of formulae are conducted to help depict the layout, cross sectional roof curvature and special longitudinal treatments in 4 sloped and 9 spined roofs respectively.展开更多
The air-dried density, bending strength (MOR) and compressive strength parallel to grain of different grades of rotten wood were measured with test specimens of 100-130 year-old larch (Larix sp.) collected in Wu Ying ...The air-dried density, bending strength (MOR) and compressive strength parallel to grain of different grades of rotten wood were measured with test specimens of 100-130 year-old larch (Larix sp.) collected in Wu Ying Dian, the Forbidden City. In addition, the MOR of specimens was measured by Resistograph and the correlations were analyzed between resistance value and mechanical properties of wood. The correlations are significant for quantitative evaluation of wood structural condition by Resistograph. The results showed that wood air-dried density, strength properties and resistance values decreased significantly with the increase of decay degree, and there were remarkable differences among various grades of wood. Based on the rotten degree, the attenuation rate is in the following order: MOR> compressive strength parallel to grain > air-dried wood density > resistance value, and the above 4 indexes were 32%, 53%, 73% and 74% of those of intact wood, respectively, when the degree of rotten wood reached grade 3. Significant positive correlation at 0.01 level was showed between the wave trough values and wood air-dried density, MOR, compressive strength parallel to grain. The correlations between the wave peak values and the average value and air-dried wood density, MOR reached 0.01 level, and the correlations between the wave peak values and the average value and compressive strength parallel to grain reached 0.05 level. Based on the correlation between resistance value and physico-mechanical properties of wood, the values could be analyzed quantitatively.展开更多
文摘This article, by using mathematical expressions, offers a scientific framework for understanding how the grading system of Qing′s structural carpentry determines the design and construction in the grand style timber architecture.The Qing′s grand style timber structure, which is ready for prefabrication and assembly, is extremely hierarchical oriented and significantly standardized. The general procedure in designing a grand style timber structure is to start with the grade that defines the basic module (dou kou); next comes with the number of bracket set (cuan), the number of longitudinal bays and the number of purlins which affect its plan and cross section; thirdly choose a roof type that determines its longitudinal section and the facade as well. A series of formulae are conducted to help depict the layout, cross sectional roof curvature and special longitudinal treatments in 4 sloped and 9 spined roofs respectively.
基金This work was supported by Ministry of Science and Technology Project (No.2004DIB5J187) and State Administration of CultureHeritage Project (No. 2003022)
文摘The air-dried density, bending strength (MOR) and compressive strength parallel to grain of different grades of rotten wood were measured with test specimens of 100-130 year-old larch (Larix sp.) collected in Wu Ying Dian, the Forbidden City. In addition, the MOR of specimens was measured by Resistograph and the correlations were analyzed between resistance value and mechanical properties of wood. The correlations are significant for quantitative evaluation of wood structural condition by Resistograph. The results showed that wood air-dried density, strength properties and resistance values decreased significantly with the increase of decay degree, and there were remarkable differences among various grades of wood. Based on the rotten degree, the attenuation rate is in the following order: MOR> compressive strength parallel to grain > air-dried wood density > resistance value, and the above 4 indexes were 32%, 53%, 73% and 74% of those of intact wood, respectively, when the degree of rotten wood reached grade 3. Significant positive correlation at 0.01 level was showed between the wave trough values and wood air-dried density, MOR, compressive strength parallel to grain. The correlations between the wave peak values and the average value and air-dried wood density, MOR reached 0.01 level, and the correlations between the wave peak values and the average value and compressive strength parallel to grain reached 0.05 level. Based on the correlation between resistance value and physico-mechanical properties of wood, the values could be analyzed quantitatively.
