China's longest wooden arch bridge burned down and collapsed. What are the key points of fire prevention for cultural relics and ancient buildings?

Sad! Wan'an Bridge, the longest existing wooden arch bridge in China with a history of more than 900 years, burned down on the evening of August 6. Why do fires frequently occur in cultural relics and ancient buildings? What are the key points of fire prevention?

Compiled by New Media Editor Lv Bingxin

On the evening of August 6, a fire broke out at the Wan'an Bridge in Pingnan, Ningde, Fujian, a national key cultural relic protection site and the longest existing wooden arch bridge in China. After the fire, the main body of the Wan'an Bridge was basically burned and collapsed, and only part of the frame remained. The cause of the fire is still under investigation.

▲Wan'an Bridge Fire

After the news broke, netizens expressed that it was heartbreaking that such an important historical monument was burned down by the fire.

Wan'an Bridge was first built in the Song Dynasty

Pingnan County, Ningde City, Fujian Province is located in the middle of Jiufeng Mountain Range. The unique geographical environment has trained the local people to build roads through mountains and bridges across rivers. The wooden arch bridges, which embody the wisdom of craftsmen, span the surging rivers and connect the roads outside the mountains. Wan'an Bridge, the longest existing ancient wooden arch bridge in my country, is located here.

▲Wan'an Bridge before the fire (Photo source: Xinhua Daily Telegraph)

Wan'an Bridge is a five-pier, six-arch wooden arch bridge. The bridge is 98.2 meters long and 4.7 meters wide, with boat-shaped piers and unequal spans. The shortest span is 10.6 meters and the longest span is 15.2 meters. The bridge has 38 bays, 156 columns, a through-beam wooden frame, a double-slope roof, and wooden benches on both sides.

According to the "Yutian Zhilue", the bridge was first built in the Song Dynasty. It has a history of 917 years. It was burned down in the 47th year of Emperor Kangxi's reign in the Qing Dynasty, and rebuilt in the 7th year of Emperor Qianlong's reign (1742). It has been repaired in successive dynasties. On May 25, 2006, it was announced as one of the "Northeast Fujian Corridor Bridges" as the sixth batch of national key cultural relics protection units .

The wooden arch bridge is the most technologically advanced type of traditional wooden bridge in my country. In the book "History of Chinese Science and Technology: Bridges", Tang Huancheng, a famous bridge expert, said that the wooden arch bridge "is unique to China in the history of bridges in the world". In 2008, the "traditional construction techniques of wooden arch bridges" were included in the second batch of national intangible cultural heritage list. One year later, this construction technique was included in the "List of Intangible Cultural Heritage in Need of Urgent Protection" by UNESCO.

Since ancient times, covered bridges have been an important and commonly used public space in China besides temples, ancestral halls, and opera stages, and have received much attention and concern from the general public. To this day, there are still more than a hundred wooden arch covered bridges dating back to the Song Dynasty in the mountainous areas of southern Zhejiang and northern Fujian.

According to the Pingnan County Annals, there are more than 50 wooden arch bridges in Pingnan. After the Wan'an Bridge burned down, there are 12 wooden arch bridges built in the Song, Yuan, Ming and Qing dynasties, making Pingnan one of the counties with the largest number of wooden arch bridges in China.

Fires frequently occur in domestic cultural relics and ancient buildings

In fact, in recent years, fire accidents of varying degrees have frequently occurred in cultural relics and ancient buildings in many parts of the country, causing irreparable losses.

Nanping City, Fujian Province

On March 25, 2022, a fire broke out in Ruiyan Temple, a thousand-year-old temple in Wuyi Mountain, Nanping City, Fujian Province. The ancient Buddha Hall and Guanyin Hall that were burned covered an area of ​​about 400 square meters.

Shenyang City, Liaoning Province

At around 8 am on February 16, 2022, a fire broke out at the Jinxianghui Evening Tea Restaurant on Shiyiwei Road, Heping District, Shenyang City, Liaoning Province. It is understood that the restaurant on fire is located in a historic preserved building. The building was originally the site of Citibank in the United States. In 2008, the building was identified as one of the first 70 immovable cultural relics in Shenyang.

Lincang City, Yunnan Province

On February 14, 2021, a fire broke out in the Wengding Primitive Tribe Cultural Tourism Area in Cangyuan Wa Autonomous County, Lincang City, Yunnan Province. The fire destroyed 104 houses in the old village and caused direct property losses of 8.1348 million yuan.

Accidents keep happening, what’s the reason?

Shan Jixiang, former director of the Palace Museum, once said that most of China's cultural relics buildings are mainly made of wood frames, which have large fire loads, low fire resistance levels, and small fire protection distances. Their fire characteristics are generally characterized by easy occurrence, easy spread, and easy to cause major losses and impacts. Therefore, it can be said that fire is the most important factor threatening the safety of cultural relics. In particular, as the scope of cultural heritage protection continues to expand, the situation facing the safety of cultural relics buildings has become more severe. Once a fire occurs, the losses are immeasurable and the social impact is great.

Specifically, the causes of fires in cultural relics and ancient buildings are basically the following:

Natural factors

1. Lightning strike.

Lightning is a common discharge phenomenon in nature. It is a physical phenomenon of sound, light and electricity that occurs in the atmosphere. When negatively charged clouds approach the ground, protrusions and metals on the ground will be induced with positive charges. As the electric field gradually increases, thunderclouds form downward leaders, and objects on the ground form upward flash currents. When the two meet, they form discharges to the ground, which can easily cause lightning disasters. There are countless cases of ancient and modern buildings being struck by lightning or burned down by lightning. As recorded in the literature, the three main halls of the Forbidden City in Beijing were struck by lightning and burned down three times during the Ming Dynasty; on July 24, 2010, the main hall of Puhui Temple in Ulanhot City, Xing'an League, Inner Mongolia caught fire due to lightning.

2. High temperature.

Long-term drought and high temperature can also easily cause ancient buildings, especially wooden structures or the accumulations between them, to spontaneously combust, thus causing fires.

Electrical factors

On January 19, 2003, the ancient buildings of Yuzhen Palace in Wudang Mountain Scenic Area, known as the "World Cultural Heritage", were reduced to ashes. After investigation, it was estimated that the cause of the fire was a short circuit in the wires. Most of the ancient buildings have the phenomenon that ordinary insulated electrical lines are directly laid on the beams, columns, purlins, rafters, railings, wall panels and floor slabs of the building without pipe protection. There are also many cases where the lines are directly laid through building holes, holes and corners without pipe protection. What's more, the power distribution facilities are directly installed on combustible materials. This kind of "randomness" is one of the culprits that lead to the disappearance of cultural heritage.

Human Factors

1. Smoking.

According to tests by the US Fire Department, the temperature of a burning cigarette ranges from 288°C (the temperature of the cigarette surface when not smoking) to 732°C (the temperature of the center of the cigarette when smoking). In addition, a cigarette placed on a flat surface can be lit for 24 minutes. For ancient buildings with low fire resistance, an unextinguished cigarette butt is enough to cause a fire.

2. Careless use of fire in daily life.

With the development of social economy, various ancient building units have gradually introduced some tenants or hired ancient building management personnel. Some of them, for the convenience of life, have used liquefied gas and stoves for cooking and heating in or around ancient buildings for a long time. The dangers and fire hazards are so great that it is worrying.

3. Arson.

Fires in ancient buildings have a great impact and cause great losses throughout the country and even the world, and some lawless elements take advantage of this to achieve their own goals. Therefore, arson is also one of the important factors causing fires in ancient buildings.

4. Burn incense and worship Buddha.

Most of the ancient buildings are temples, which attract many tourists and pilgrims, and they burn incense all year round, which can easily cause fires.

Once again sounding the alarm for ancient building fire prevention

The Wan'an Bridge fire has undoubtedly once again sounded the alarm for fire protection of ancient wooden structures in my country. Zhou Qian, an expert in ancient building protection and a researcher at the Palace Museum, said that no matter what the cause of the fire, it is reasonable to effectively avoid large-scale damage to ancient bridges through early warning or daily prevention measures.

In fact, there are many excellent practices for fire protection of ancient wooden structures in ancient my country. Taking the Forbidden City as an example, the first thing is to ensure that there is sufficient water for firefighting. The Jinshui River in the Forbidden City and the copper or iron vats filled with water in front of the major palaces can provide sufficient water for firefighting in the first time; the second is to add fire-proof masonry materials between wooden structures to prevent the fire from spreading quickly to adjacent buildings. In addition, the "Eight Banners Fire Squad" and "Fire Barrel Office" specially set up in the Forbidden City can better protect the ancient wooden structures from fire damage by establishing strict fire prevention regulations, holding fire drills regularly, and conducting fire inspections.

With the development of modern science and technology, modern scientific and technological equipment such as fire warning devices, automatic sprinkler devices, and robot fire extinguishing devices can also provide more effective means for fire prevention and fire fighting of wooden ancient buildings. However, Zhou Qian emphasized that the fundamental premise of all fire prevention measures is that the cultural relics management department attaches great importance to it. Only by doing a good job in daily fire prevention inspections and eliminating various fire hazards in advance can we achieve "fire prevention before it happens."

(Source: Nandu Weekly, China News Service, Science and Technology Daily, Chengdu News, etc.)

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