BCP Social Sciences & Humanities ADCS 2022 Volume 15 (2022) 185 Risk Identification and Weight Analysis of Meteorological Disasters on Ancient Buildings Wenqing Liu 1, Junchi Zhou 2, a, Xiaobing Wang 2, Chen Chen 3, b, * 1. Jiangning Cultural Heritage Protection Center, Nanjing, China 2. Meteorological Disaster Protection Center of Jiangsu, Nanjing, China 3. Niushou Mountain Cultural Tourist Zone, Nanjing, China a zhoujunchi1985@163.com, b, * 364703295@qq.com Abstract. Meteorological disasters impose significant challenges on protection of ancient buildings. By use of Delphi method and Multi-subject research including architecture, meteorology and archaeology, this work identifies major meteorological disasters on ancient buildings. The hierarchical model of risk influential factors is established. It contains four first-grade factors such as wind, flood, lightning and snow disaster, ten second-grade factors and twenty third-grade factors. Then, Analytic Hierarchy Process (AHP) was utilized to calculate weight of those factors. The result showed that lightning disasters had largest threat on ancient buildings among the four major kinds of meteorological disasters. Its weight was the highest of 0.383, followed by that of flood and wind disasters with weight of 0.31 and 0.22 respectively. Snow disasters had the smallest weight of 0.09. Lightning protection measures have significant influence on vulnerability of ancient buildings and on lightning disaster risks. So, to protect ancient buildings against meteorological disasters, besides characteristics of the disasters themselves, all the mentioned factors such as architectural structure, building types and environment should be taken into consideration. Specific protection strategies are then implemented according to weights of different factors. Keywords: AHP; Protection Ancient Buildings; Identifies Major Meteorological Disasters. 1. Introduction China’s rich ancient civilization has left us huge number of cultural heritages, among which ancient buildings have significant status for their unique structure and inestimable historical value. These buildings witnessed China’s long-standing history. They are nonrenewable humanity resource and precious heritage of our ancient civilization. Meteorological disasters, caused by meteorological factors, are commonly seen natural disasters. They usually include floods, drought, tropical cyclones, strong wind and typhoon, hail, heavy snow, lightning disasters and their derivative disasters [1]. They pose a severe threat to human’s lives and assets, as well as ancient buildings. In August 2016, a Buddhist temple dating back to a thousand years ago was destroyed by Typhoon “Sangmei”. On 11th May 2004, an ancient temple in Yuncheng, Shanxi was hit by lightning. The derivative fire burnt down the temple and many priceless works of art inside the building. More than 160 pieces of immovable cultural heritage was damaged to different extent by the flood caused by heavy rains on 21st July 2012. Direct economic loss was beyond 800 million RMB and the affected area was over 210 thousand square meters [2]. This work tried to identify potential meteorological disasters faced by ancient buildings and analyze risk factors and their weights, thus contributing to protection of these cultural heritages against meteorological disasters. BCP Social Sciences & Humanities ADCS 2022 Volume 15 (2022) 186 2. Risk Identification 2.1 Method of Risk Identification 2.1.1 Delphi Method The Delphi Method, which is also known as a correspondence survey method through anonymous expert questionnaires, was designed by LAND Co. USA in 1946 [3]. In this study, we adopt the procedures as below. Firstly, we selected a group of experts related to meteorology and architecture. Secondly, each member of the group was sent a questionnaire with background information. Then, the questionnaires were returned to us with experts’ comment according to their analysis. After that, a copy of the compiled comments was sent to each participant, along with the opportunity to comment further. At the end of each comment session, all questionnaires were returned and based on which we decided if another round was necessary. These rounds could be repeated as many times as necessary to achieve a general sense of consensus, which was considered as the result of risk identification in our paper. Theoretically, we can’t guarantee that experts’ consensus is correct. But this method helped to achieve a more reliable result and weight estimation of meteorological disasters. So, we took this approach to identify the meteorological risk of ancient buildings. 2.1.2 Multi-subject Analysis Knowledge of one certain subject can hardly support research on meteorology risk assessment of ancient buildings, so it is a Multi-subject issue concerning meteorology, catastrophology, architecture, history, electricity and synoptics. Based on that, we decompose the risk into several layers and analyse the systematic factors of each layer in the perspective of system theory. 2.2 Result of Risk Identification 2.2.1 Strong Wind According to meteorology, wind disasters refer to casualties or property loss caused by typhoon, hurricanes and wind storms. In China, coastal provinces such as Guangdong, Fujian, Zhejiang and eastern Jiangsu suffer most [4]. A wind disaster could be classified into such three degrees as general, severe and extra-severe as is shown in Table 1 [5]. Table 1. Grade classification of wind disasters Disaster grade Wind grade Wind speed(ground surface)(m/s) General 6-8 10.8-20.7 Severe 9-11 20.8-32.6 Extra-severe >12 >32.7 Wind resistance of most ancient buildings is relatively poor because of their architecture structure and aging process during hundreds of years. So, they are commonly seen get damaged or even collapse in strong wind. Roof and side walls are particularly vulnerable. The roof of an ancient building often has a sloping incline. It is usually the pressure difference between the windward side and leeward side that causes roof damage of the ancient building [6]. A building of 20m height undergoes a basic wind pressure of approximately 0.80kg/m2 and a side pressure of as high as 240kg/m2. Many ancient buildings have hollow sidewalls and large room spans. This makes them weak in structure and more vulnerable to strong wind [7]. Ancient buildings are prone to be in mountains and woods for fine geomantic omen in traditional Chinese culture. When the wind goes parallel to the mountain slope or with a small angle, its velocity and intensity will be enhanced. So, the topographic feature exacerbates wind disasters to some extent. Compared to stone buildings, wood-built ones suffer more from strong wind. To sum up, the wind disaster risk of an ancient building (A1) is determined by dangerousness of the wind (B1) as well as wind-resistance of the building itself (B2). The former factor includes such BCP Social Sciences & Humanities ADCS 2022 Volume 15 (2022) 187 three sub-factors as wind classification (C1), wind velocity grade (C2) and occurrence frequency (C3). The latter is affected by the following two sub-factors: building structure and material (C4) and topography features (C5). 2.2.2 Lightning Lightning discharge could cause fierce physical effects like heating, blast waves and electro- magnetic radiation, which have massive destructive impact on ancient buildings and tourists inside. According to meteorology definition, the number of days in a year when a lightning discharge is recorded is called the thunder-day (T) in that area. As stipulated by technical code for protection of building electronic information system against lightning (GB 50343-2012) [8], an area with T>90 is defined as an extra-intense thunderstorm region. Likewise, an area with 40