摘要
中国传统木拱廊桥采用较短的木材构件,形成了较大的桥梁跨度,其整体造型优美,结构巧妙,构造特殊,具有重要的历史价值、艺术价值和科学价值。我国现存的传统木拱廊桥仅有百余座,集中分布于我国浙南和闽北地区,大多建于明清至民国时期,是我国木构桥梁建造技术和古代人民智慧的体现,而近些年来由于台风洪水等自然灾害导致的传统木拱廊桥破坏甚至损毁的事件时有发生。现有的对于传统木拱廊桥的研究大多着眼于其历史艺术价值和建造技术工艺等方面,鲜有对于其结构性能的研究,尤其缺乏强风作用下木拱廊桥的风振响应性能的深入研究。本工作为研究中国传统木拱廊桥在强风作用下的风振响应性能,以典型传统木拱廊桥——浙江泰顺的文兴桥为例,基于几何尺寸的精确测绘,采用SAP2000建立有限元模型进行了木拱廊桥的动力特性分析。研究内容包括以下几方面:首先,采用线性滤波法,基于自回归(AR)法模拟风场,利用MATLAB软件编写脉动风速时程。此后,由于我国现行的规范没有给出适用于木拱廊桥这一结构类型的风压体型系数,本工作通过CFD软件FLUENT风洞数值模拟得到适用于文兴桥的风压体型系数。最后,将模拟编译得到的时程风压作用于文兴桥的有限元模型得到其风振响应。计算结果表明:结构主振型为第一阶横向水平振动;风荷载对三节苗和五节苗两边最外侧的斜苗影响较大,对五节苗平苗的影响较大;下部剪刀撑的最大拉、压应力超过抗拉、抗压强度;剪刀撑脱榫将使下部斜撑的轴压力突增从而导致整体结构抗侧能力大幅降低;强风作用下传统木拱廊桥的时程计算风振系数为1.43~1.75,由此可见木拱廊桥风动力效应不容忽视。本研究成果反映了我国传统木拱廊桥在风荷载作用下结构构件的受力规律和整体结构的动力特性,并为我国传统木拱廊桥的风振性能评估和抗风保护提供理论依据,更科学地保护这一宝贵的建筑遗产类型。
Traditional Chinese arched timber lounge bridges utilize short timber structural components to form a large bridge span.The arched lounge bridges have beautiful shapes,ingenious structures and unique types of construction.This type of ancient bridge has important historical,artistic and scientific value.Now in China remain only about 100 traditional arched timber lounge bridges,which are mostly found in southern Zhejiang Province and Northern Fujian Province.They reflect traditional bridge construction technology and the wisdom of ancient people of China.In recent years,the destruction or damage to traditional timber arched lounge bridges caused by natural disasters such as typhoons and floods has occurred from time to time.Present research on traditional arched timber lounge bridges focuses primarily on their historical and artistic value,and the development background of construction technology,but there is little research on their structural performance,especially in-depth research on the wind-induced vibrational response of traditional arched timber lounge bridges to strong wind.In order to research the wind-induced vibrational response of traditional Chinese timber lounge bridges,a case study of Wenxing Lounge Bridge was carried out.Based on a precise survey of geometric dimensions,a calculation model of Wenxing Lounge Bridge was set up using finite element software SAP2000 and the dynamic characteristics were analyzed.This study includes the following aspects:First,fluctuating strong wind was simulated by the linear filtering method and the auto-regressive(AR)model,and the wind speed time history was generated using mathematical software MATLAB;Second,wind pressure coefficients applicable to the bridge were obtained through the CFD wind-tunnel simulation with the software FLUENT,since the current load code does not provide the suggested coefficient values;Finally,the strong wind pressure was applied to the model and the internal forces,and the displacement of structure were obtained.The results show that the main vibrational mode of the structure is the third vibration mode,namely the horizontal vibration.The wind effect on the inclined tri-segment arch members is bigger than that on inclined penta-segment arch members,whereas the wind effect on horizontal penta-segment arch members is bigger than that on horizontal tri-segment arch members.The stress of tri-segment,penta-segment arch members and upper,middle scissor braces is within the allowable strength,but the tensile stress of lower scissor braces exceeds the allowable tensile strength.The slipping-off of scissor braces will cause a sudden increase of axial compressive force,and will greatly reduce the lateral rigidity of the whole structure.The wind-induced vibration coefficient of the arched timber lounge bridge is 1.43—1.75.Therefore,the wind-induced response of traditional timber arched lounge bridges cannot be ignored.This study uses,as an example,Wenxing Bridge in Taishun,Zhejiang Province.The research results reflect the loads transferring law of structural members and the dynamic characteristics of the overall structure of arched timber lounge bridges under wind loads,as well as providing a theoretical basis for the wind-resistance assessment and the wind-resistant conservation of this type of traditional arched timber lounge bridges.
作者
韩宜丹
淳庆
HAN Yidan;CHUN Qing(School of Architecture, Southeast University, Nanjing 210096, China)
出处
《文物保护与考古科学》
北大核心
2021年第5期102-112,共11页
Sciences of Conservation and Archaeology
基金
国家自然科学基金项目资助(51578127,51778122)。
关键词
木拱廊桥
文兴桥
强风作用
风振响应
Arched timber lounge bridge
Wenxing Lounge Bridge
Strong wind
Wind-induced response
