Zhou Qian: decoding the Forbidden City with science
2021-12-21
On November 3, 2021, a grand commendation meeting was held in the Great Hall of the people, and the 2020 National Science and technology progress award was announced. In the list of winners, among many colleges, universities and scientific research institutes, the words "Palace Museum" are like a classical beauty hidden among modern men of science and technology, reserved and graceful. Indeed, not only the Palace Museum, but also the whole cultural and Expo industry won this honor for the first time. Dr. Zhou Qian, research librarian of the National Palace Museum, won the award for the Palace Museum. For the Imperial Palace pull edge technology award On the morning of early winter, I made an appointment with Zhou Qian to meet at Shenwu gate. Shenwu gate is at the northernmost end of the Forbidden City. The tall palace walls are dignified and solemn. The orange veranda top glitters with gold against the sunrise. The five characters "Forbidden City Museum" written by Mr. Guo Moruo are dignified and full of charm. From a distance, I saw a man galloping out of the Shenwu gate. The Tibetan blue suit with white tourist shoes is the same as the photo sent by Zhou Qian when he received the award in the Great Hall of the people. This person is Zhou Qian. After a brief greeting, he followed Zhou Qian into the palace. Turn around seven times between the tall red walls and turn to a quiet courtyard. Entering through the small door where the staff went in and out, it suddenly became clear that the house was a hard peak of green glazed tiles. It looked quiet and gentle in the magnificence of red walls and yellow roofs. "This is the Forbidden City Institute, where I work." Zhou Qian took the initiative to introduce, "this used to be the place where the princes studied. It was called Nansan Institute, commonly known as a Ge Institute. Dean Shan said that this used to be the place to study, and now it is also suitable for academic research." Zhou Qian mentioned Shan Jixiang, former president of the Palace Museum. Go straight inside until you come to a house at the westernmost end. There is a B5 white paper pasted on the column at the door with the two words "Zhou Qian", which can't help but remind people of the working principle of "minimum disturbance to ancient buildings". The interview began with the national science and technology progress award. How does the 601 year old Forbidden City relate to scientific and technological progress? The multi-scale protection theory, key technology and application of China's urban architectural heritage, which won the first prize of the national science and technology progress award, was jointly completed by Southeast University, China Architectural Design and Research Institute, China urban planning and Design Institute, the Forbidden City Museum, the Institute of remote sensing and digital earth of the Chinese Academy of Sciences, China Construction Eighth Bureau and Zhejiang University, This is the first prize of the national science and Technology Progress Award in the field of architecture in China. In this list of award-winning units, the words "Palace Museum" are distinctive and elegant. The Palace Museum was able to participate in this project, mainly to scientifically evaluate the seismic mechanism of Chinese Ming and Qing official wooden ancient buildings, put forward the improved method of tenon and mortise joint reinforcement, and established the refined finite element analysis model of different structures, joints and structures of Ming and Qing official wooden ancient buildings, which improved the scientific protection level of wooden cultural relics in China. "This award is an honor for the Palace Museum and an affirmation of the scientific protection of ancient buildings by generations of people in the Palace Museum." Then Zhou Qian stood up, "let's go and have a look at the Taihe hall." When I first entered the palace, I met the hall of supreme harmony Three important buildings stand on the central axis outside the Forbidden City. From south to north, they are Taihe hall, Zhonghe hall and Baohe hall. Taihe hall, commonly known as Jinluan hall, is the largest building in the Forbidden City, the highest grade and the largest volume. It is also the largest existing wooden palace building in China. This is the place where the emperor held important ceremonies and witnessed many important historical moments. "I was very lucky. As soon as I entered the palace, I met the hall of supreme harmony." Zhou Qian said humorously. In 2003, Zhou Qian graduated from Beijing University of technology with a master's degree. His major is disaster prevention, mitigation and protection engineering, focusing on building structure analysis and safety assessment. Before graduation, Zhou Qian participated in a talent fair with several classmates. It was at this large talent fair that Zhou Qian submitted several resumes, one of which was submitted to the National Palace Museum. Soon, an architectural design institute decided to hire Zhou Qian. Just as Zhou Qian was preparing to become an architectural designer, the palace museum also threw an olive branch to Zhou Qian. Although he had only been to the Forbidden City once before, the world's largest mysterious ancient palace complex still had a great attraction to Zhou Qian. This once imperial home, today's cultural temple, is a classic of Chinese traditional architectural culture. "Enter the palace!" Zhou Qian gave up his career prospect of architectural design and came to the Forbidden City. "As soon as you enter the palace gate, it is as deep as the sea." Zhou Qian said with a smile, "the knowledge of the Forbidden City is too deep." Zhou Qian, a newcomer to the palace, was assigned to the Ministry of ancient architecture. When he came to report, he knew that Zhou Qian was the only one who majored in architectural structure in the whole Forbidden City. Moreover, the structural analysis and safety assessment of wooden ancient buildings have only been started in China for 20 or 30 years, and few engineers are really engaged in this work. Zhou Qian was lucky. As soon as he entered the palace, he caught up with the Centennial overhaul of the hall of supreme harmony. From 1697 to 2003, Taihe hall has never undergone major repair in more than 300 years. "Ancient craftsmen used oral instruction to build and repair buildings, which was passed from the master to the apprentice, mainly based on experience. This was also used in several repairs before the Taihe hall. This overhaul, the leaders asked me to conduct structural mechanics calculation after on-site investigation, conduct safety assessment and come up with repair suggestions." Zhou Qian still has a vivid memory of the past 18 years ago. Zhou Qian was appointed by the hospital to be responsible for the structural safety analysis and evaluation of ancient buildings. In this once-in-a-lifetime opportunity, Zhou Qian was deeply impressed by the architectural wisdom of the ancients. At the same time, he began to think about how to better protect these beautiful ancient palaces. In the next two years, Zhou Qian conducted a series of "physical examinations" for the Taihe hall, which provided an important construction basis for the overhaul of the Taihe hall from the perspective of safety. In 2008, the two-year overhaul of Taihe hall was finally completed. The repair suggestions put forward by Zhou Qian after investigation, calculation and analysis were adopted. The hall of Supreme Harmony we saw today is what it looked like after the overhaul. "The overhaul of Taihe hall reflects the ability and level of Chinese ancient architecture protection personnel to take timely and effective protection of cultural relics." Zhou Qian said proudly. Starting from the Taihe palace, the ancient buildings of the Forbidden City began a large-scale "physical examination". So far, 39 ancient buildings have completed the construction safety assessment. From the perspective of modern structural mechanics, this is the first time to "check up" the ancient buildings of the Forbidden City. The construction site is the source of inspiration Zhou Qian loved to use his brain since he was a child. Although he was not top-notch in his homework, he was easy to ask "why". When he arrived at the University, Zhou Qian, who loved to think, was like a fish in water. His grades soon stood out among his classmates. After taking part in work, this good habit was brought into full play by him. During the overhaul of Taihe hall, a prominent problem was the reinforcement of tenon and mortise joints. Zhou Qian and his colleagues found that there was a serious tenon sinking problem along the main beam of Taihe Hall three times, the sinking amount was about 0.1M, and the mortise and tenon of the child column connected with the tenon cracked, while other parts of the along beam were intact. What's going on? While learning the basic knowledge of large wood structure of ancient buildings from experienced colleagues, Zhou Qian inquired relevant literature and established the mechanical analysis model of along beam combined with finite element analysis method. He found that the main reason for the damage of the tenon is that the weight transmitted from the roof to the along beam is too large, resulting in the local stress damage of the tenon. The main reason why the damage occurred at the tenon and mortise joint and other parts along the beam were intact was that part of the section of the tenon and mortise was cut off during the manufacturing process, which reduced the resistance of this part. After repeated research and comparison, Zhou Qian provided several feasible reinforcement schemes. After expert demonstration, the project finally adopted the traditional "gantry berm" roof support method to strengthen the longitudinal beam. The reinforced longitudinal beam is still intact. Five years later, Zhou Qian graduated from the civil engineering major (on-the-job) of Beijing University of technology. The title of his doctoral thesis is "Research on seismic performance and reinforcement methods of tenon and tenon structures of ancient Chinese buildings". The research object of this thesis is the tenon of the sunken straight beam in the overhaul project of Taihe hall. On May 12, 2008, a magnitude 8.0 earthquake occurred in Yingxiu Town, Wenchuan, Sichuan, with a maximum intensity of 11 degrees. Jueyuan temple in Jiange County, 189 kilometers away from Yingxiu Town, was damaged in the earthquake. In July of the same year, at the request of the local cultural relics protection department and recommended by the State Administration of cultural relics, Zhou Qian and his colleagues from the Ministry of ancient construction and the engineering management office went to Jueyuan temple to carry out earthquake damage exploration and assessment of ancient buildings. The objects of this appraisal include the main hall of Jueyuan temple, the Sutra collection building, east-west wing rooms, Guanyin Pavilion, Luyou Pavilion, Wenchang palace and other buildings. With inconvenient transportation, poor conditions, hot sun exposure and frequent aftershocks, Zhou Qian and his teammates tried every means to overcome various difficulties, took more than 3000 photos in a week, and completed the preliminary analysis report on the safety assessment of ancient building structures of about 30000 words. As the only mechanical professional member of the team, the heavy task of post earthquake assessment undoubtedly falls on Zhou Qian. Before five o'clock every day, Zhou Qian got up early before dawn, carefully analyzed the photo data of the survey the previous day, drew the sketch of the buildings to be surveyed that day, and debugged various survey equipment. Starting at dawn, Zhou Qian and his teammates cherish every second, take photos, draw pictures, measure, discuss and record, do not miss every detail of ancient buildings, and strive to record the post earthquake status of ancient buildings completely, perfectly and scientifically. When we returned to the station in the evening, we discussed issues related to the protection of ancient buildings and customized the work plan for the next day. Knowing that the assessment report was urgently needed in the disaster area, after returning to Beijing, Zhou Qian kept sorting out the exploration images and data, quickly established the seismic assessment mechanical model of ancient buildings, simulated the damage of Wenchuan earthquake to the above ancient buildings, analyzed the earthquake damage causes of different ancient buildings, and put forward scientific and effective protection suggestions. These suggestions were later adopted by the local cultural relics management department. Opportunities always favor those who are prepared. After completing the earthquake damage assessment and seismic reinforcement of Jueyuan Temple ancient buildings, Zhou Qian, based on his research experience and from the perspective of mechanics, He has written papers such as research on earthquake damage of ancient buildings in Wenchuan earthquake, research on earthquake damage of mural cultural relics caused by Wenchuan Earthquake -- Taking the mural of the main hall of Jueyuan temple in Guangyuan City as an example, research on slight earthquake damage of ancient buildings in Wenchuan earthquake, analysis on earthquake damage of wooden structures with embedded walls in Wenchuan earthquake, and that wall collapse is an important seismic mechanism of wooden structures of ancient buildings in China, This paper comprehensively interprets the structural characteristics, seismic mechanism and seismic damage characteristics of wooden structures of ancient buildings in China, as well as the establishment method of mechanical analysis model, seismic performance evaluation method, scientific protection and reinforcement method, which provides valuable images and data for the seismic protection, maintenance and reinforcement of ancient buildings in China. Decoding ancient earthquake resistance wisdom Standing in front of the palace and looking at the beams, columns, doors and windows of the palace, Zhou Qian had a feeling of dialogue with the ancients - how many secrets can you crack in the Forbidden City?
Edit：Yuanqi Tang Responsible editor：Xiao Yu
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