午门城台结构受力性能的主要影响因素

以午门城台为对象,在现场勘察及长期监测的基础上,利用数值模拟和试验设计相结合的方法,从冻融循环、局部饱水作用、底部不均匀竖向变形作用、上部竖向荷载4个因素以及因素间耦合影响的方面分析结构的受力性能。研究发现:对结构应力影响方面,上部竖向荷载、底部不均匀竖向变形、局部饱水作用均是高度显著因子,冻融循环次数、冻融循环次数与局部饱水作用时长的交互作用对拱券顶部最大拉应力同样为高度显著因子;对城台变形影响方面,局部饱水作用、底部不均匀竖向变形、上部竖向荷载均是高度显著因子。研究结果揭示了古建筑城台结构受力性能的主要影响因素及影响规律,为该类古建筑日常维护和预防性保护方案制定提供了科学依据。

Main influential factors in mechanical performance of Meridian Gate platform structure

On the basis of field investigation and long-term monitoring results, the main factors that affect the mechanical performance of the Meridian Gate platform structure are studied by combining numerical simulation and experimental design method. This paper presents the results of the study in performance variation mechanism of the Meridian Gate platform structure through different aspects, i.e. freeze-thaw, partial water-saturation, differential vertical displacement at the bottom of platform, vertical load at the top of platform and coupled effect between the factors.The results show that the vertical load at the top, the uneven vertical deformation at the bottom and the partial water-saturation are main influential factors for the structural stress, and the number of freeze-thaw cycles, the coupled effect between the number of freeze-thaw cycles and the duration of partial water-saturation are also key factors for the maximum tensile stress in the area of arched doors; In the aspect of structural deformation of the Meridian Gate platform structure, the partial water-saturation, the differential vertical displacement at the bottom of platform and the vertical load are the significant factors. This study reveals the major factors and the influencing law of the mechanical performance of the platform structure and provides a scientific basis for the routine protection and preventative protection of similar heritage masonry structures.