摘要
为有效保护古建筑,采用振动台试验方法,研究了中国明清官式木构古建的抗震性能。以故宫某单檐歇山木构古建为对象,制作了1∶2缩尺比例模型。模型含浮放柱底、柱架、斗拱、歇山屋顶、墙体等所有构造,且施工工艺完全符合中国明清官式木构古建施工规定。通过施加白噪声激励,获得了模型的基频和阻尼比。通过施加不同强度等级的1940年El-Centro波,获得了模型典型节点的位移和加速度响应,讨论了模型的减震系数,评价了浮放柱底、榫卯节点、斗拱、屋顶、墙体等构造的抗震性能。结果表明:模型的振动形式表现为平面内的扭摆,其原因与歇山式屋顶质量分布不均密切相关。模型的震前基频为1.47Hz,阻尼比为4.6%。地震作用下,模型的位移及加速度响应曲线近似稳定、均匀。尽管屋顶构造则对地震力有一定放大作用,但浮放柱底、榫卯节点、斗拱等构造能发挥较好的耗能减震作用。对于不同构造而言,榫卯节点的减震性能最好,其减震系数可降至0.30;斗拱次之,其减震系数可降至0.53;而浮放柱底与柱顶石之间的摩擦耗能性能最弱,其减震系数最小值为0.66。墙体在地震波强度增大过程中发生倒塌,但不影响结构整体稳定性。因此,单檐歇山式木构古建具有良好的抗震性能。
To effectively protect ancient Chinese buildings,the seismic performances of ancient Chinese buildings of the Ming and the Qing dynasties were studied by shaking table tests.A 1∶2 reduced-scale model of an ancient building from the Forbidden City and having a single layer gable and a hip roof was built.The model possessed all features of the real building,including free-standing columns,beams and column frames,tou-kungs(bracket set),a roof,filler walls and so on.The construction of the model also accords with the relevant construction rules for ancient Chinese buildings.Using white noise excitation,the dynamical characteristics of the model were obtained.Then the 1940 El-Centro earthquake waves of different intensities were applied to the model.Seismic responses such as displacement,acceleration and shock mitigation coefficient ratio,etc.of the model were studied.Seismic performances of the constituents such as the free-standing column roots,the tou-kungs,the mortise-and-tenon joints,the roof,etc.are also discussed.Results show that under the action of earthquakes,the main mode shape of the model is that of a level torsion pendulum,which relates closely to the uneven mass of the roof.The basic frequency of the model before the shock was 1.47Hz and the damping ratio 4.6%.The response curves of its displacement and acceleration were nearly even and stable,reflecting the good seismic performance of the model.Although the roof magnifies the earthquake forces to some extent,the other constituents such as the free-standing column roots,the tou-kungs and the mortise-and-tenon joints could mitigate the response of the model.The order of shock mitigation capability of the different constituents was:mortise-and-tenon joint>tou-kung>free-standing column root.The shock mitigation coefficient value of mortise-and-tenon joint could decrease to 0.30,the value of the tou-kung to 0.53 and that of column root to 0.66.The filler walls collapsed in the earthquakes,but that did not affect the stability of the whole structure.Thus ancient Chinese buildings with single layer gables and hip roofs have good seismic performance.
作者
周乾
闫维明
纪金豹
杨娜
ZHOU Qian;YAN Wei-ming;JI Jin-bao;YANG Na(School of Culture of History and Tourism,Datong University,Datong 037009,China;Palace Museum,Beijing 100009,China;Beijing Key Laboratory of Earthquake Engineering and Structural Retrofit,Beijing University of Technology,Beijing 100124,China)
出处
《文物保护与考古科学》
北大核心
2018年第2期37-53,共17页
Sciences of Conservation and Archaeology
基金
国家自然科学基金优秀青年项目资助(51422801),国家自然科学基金资助(51278013),北京自然科学基金资助(8151003)
关键词
单檐歇山
木结构
古建筑
抗震性能
振动台试验
Single layer gable and hip roof
Timber structure
Ancient Chinese building
Seismic performance
Shaking table test
作者简介
周乾(1975—),男,博士后,研究馆员,主要从事文物建筑振动控制研究。E-mail:qianzhou627@126.com
