Multi-factor coupling causes the building to vibrate up and down?
This report, entitled "Report on the Shaking of SEG Plaza Building in Huaqiang North Street, Futian District, Shenzhen (Continued 2)", said that according to the judgment of provincial and municipal experts, firstly, the SEG Building in Shenzhen is shaking up and down, not from side to side; Secondly, the tremor is caused by the coupling of many factors, mainly the influence of wind, as well as the influence of subway operation (two subways pass downstairs) and temperature (the temperature has risen in the past two days, and the temperature difference has reached 8 degrees, which has a great impact on steel structures); Third, after on-site investigation and consultation by experts, the main structure of SEG Building is safe, the internal structure is firm and all kinds of ancillary facilities are in good condition.
According to the circular, at present, Shenzhen has set up an on-site headquarters, and organized experts and technicians in structural engineering, geotechnical engineering, engineering earthquake resistance and other aspects to monitor the settlement, inclination and vibration of SEG Building, and further formulate an emergency response plan.
According to the report, according to experts' measurement, the current inclination rate of SEG Building is between 0.0 1%-0.02%, which is less than the allowable inclination of 0.2% and far less than the requirements of the code. Experts agree that SEG buildings are not inclined. Shenzhen will judge the reopening time of the building according to the structural investigation of the building. In view of the fact that there is no damper installed in the building, experts suggest that dampers can be installed in the next step to improve the wind and earthquake resistance and comfort.
It is understood that damping is a physical term, which refers to the attenuation of force and the dissipation of energy, and has the meaning of buffering. Dampers are considered as "building-fixing artifacts" and applied to super high-rise buildings. When strong winds strike, they can reduce shaking and help super-high-rise buildings maintain the stability and safety of buildings. In August, 20 18, the super typhoon "Lichima" landed in East China, and the damper of the 632-meter-tall Shanghai Tower in China experienced the biggest swing since it was officially put into use in 20 16.
Although the above report thinks that the main cause of tremor is the influence of wind, according to the report of Shenzhen Meteorological Bureau 18 in the afternoon, the maximum gust of Seg Square on that day was only 9.9 m/s (level 5).
Because many merchants in SEG Square are selling cryptocurrency mining machines such as bitcoin, it is speculated that the operation of the mining machine causes the stairs to vibrate. However, some insiders bluntly said that this is just a "paragraph".
It's not just SEG Square that shakes, but the share price of Shenzhen SEG also moves. 19, Shenzhen SEG shares opened lower, once falling by 7%. As of the close, the closing price fell by 4.88%, and the company's total market value was nearly 6 billion yuan.
More than 40% of the high-rise buildings in the world are located in China.
According to CTBUH standards, buildings over 300 meters are super high-rise buildings. According to public information, SEG Plaza was invested by Shenzhen SEG Group and completed on 1999, with a total height of 355.8 meters, 79 floors above ground and 4 floors underground, with a total construction area of170,000 square meters.
Seg Square was the second tallest building in Shenzhen when it was completed, second only to Wang Di Tower, which is about 384 meters high. After years of construction, SEG Plaza and Wang Di Tower have become the twin stars of skyscrapers in Shenzhen. It was not until 20 1 1 year and the 44 1.8-meter Jingji 100 building was completed that SEG Square retired to the third place.
After that, the population continued to gather, and Shenzhen, which was relatively scarce in land resources, began to grow upward. In recent years, super high-rise buildings such as Ping An Financial Center (about 600 meters, now the tallest building in Shenzhen) and Sun Chun Tower have been put into use one after another. According to CTBUH statistics, there are 297 buildings in Shenzhen with a height of1.50m, which is second only to 482 buildings in Hong Kong, ranking second in the list of cities in the world. Among them, buildings over 200m in Shenzhen 104, buildings over 300m 14.
This is not over. The altitude of Shenzhen is still rising. Shimao Shenzhen-Hong Kong International Center, the Longgang Universiade Center under construction, has been reported that its building height is about 700 meters, but it has not been officially announced yet. China resources lake Beta, the original design height reached 830 meters, and then reduced to 500 meters.
Looking around China, skyscrapers are springing up in many big cities. According to the Review Report of 20 18 High-rise Buildings issued by CTBUH, in 20 18, there were 678 high-rise buildings of 200 meters and above in China, accounting for 45.9% of the global total. The Annual Review of High-rise Buildings in 2020 released by this organization shows that in 2020, a total of 106 buildings with a height of 200 meters or more were built in the world, of which 56 were built in China, accounting for more than half. According to the data, there are 2395 buildings over 0/50m, 823 buildings over 200m and 95 buildings over 300m in China, ranking first in the world.
However, with the building getting higher and higher, the external reflection also began to increase. Song, a professor at the School of Architecture of Tsinghua University, said in an interview with Zhongxin Jingwei client that after years of practice, there is not much technical difficulty in building super high-rise buildings, but it is necessary to consider whether it is necessary. Building super high-rise buildings in areas with scarce land can alleviate the shortage of land. For many cities and regions, the intensity of land development is not so great, and there is no need to build super high-rise buildings. Enterprises, governments and other stakeholders have this impulse for their own consideration. The construction cost and operation and maintenance cost of super-high-rise buildings are high, but the return on rent and selling price is not ideal, and it also faces the challenge of unpredictable special circumstances such as fire safety.
As far as high-rise and super-high-rise residential buildings are concerned, Li Xiaojiang, former president of China Urban Planning and Design Institute, wrote that high-rise residential buildings are high in consumption, high in cost and high in carbon emission. High-rise residential buildings need to consume more building materials in the construction process. Due to traffic, fire protection, structure and other reasons, the actual use area rate of buildings is low. In operation and maintenance, elevators, heat preservation and lighting consume more energy, and it is more difficult to update equipment; In the process of demolition, its cost, difficulty and waste output are also high. From the analysis of green low-carbon effect and life cycle financial cost, high-rise residential buildings are buildings with high consumption, high carbon emission, high construction, high use and maintenance costs. Research shows that the construction cost of high-rise residential buildings is 50% to 100% higher than that of multi-storey residential buildings.
The "height limit order" restricts the height of the city
In April 2020, the Ministry of Housing and Urban-Rural Development and the National Development and Reform Commission issued the Notice on Further Strengthening the Management of Urban and Architectural Styles to curb the enthusiasm for building high-rise buildings in various places. Among them, it is proposed that the blind planning and construction of super-high-rise "skyscrapers" in various places should be strictly restricted, and buildings over 500 meters should generally not be built. Due to special circumstances, it is really necessary to build in various places, and special demonstration and strict examination should be carried out on fire protection, earthquake resistance and energy saving. Those that pass the examination shall be reported to the Ministry of Housing and Urban-Rural Development and the National Development and Reform Commission for examination, and those that fail to pass the demonstration, examination or examination shall not be built.
The notice also said that according to the Code for Fire Protection Design of Buildings, it is necessary to strictly limit the height of buildings to more than 250 meters. If construction is really necessary, the Provincial Department of Housing and Urban-Rural Development shall, in conjunction with relevant departments, review the construction plan in combination with special demonstrations such as fire fighting, and report to the Ministry of Housing and Urban-Rural Development for the record. /kloc-new buildings over 0/00 meters should be fully demonstrated, centralized layout, and strictly implement the examination and approval system for seismic fortification of over-limit high-rise buildings that is suitable for urban scale and spatial scale and fire rescue capacity. Small and medium-sized cities should strictly control the construction of super-high-rise buildings, and county houses should be multi-storey.
Regarding the impact of this policy, CTBUH thinks that the output of buildings over 200 meters in China has dropped significantly from 20 18 to 20 19, from 92 to 57. Compared with the peak reached in the past ten years, the combination of the "super-large, heterogeneous and grotesque" building policy promulgated in 20 16, and the subsequent local government measures to limit height and curb debt expenditure will probably slow down the construction process of super high-rise buildings in China.
In the past two years, a number of planned super high-rise buildings have been "cut high". China Shipping Real Estate had planned to build a 677-meter super high-rise building in Chengdu, but after the land acquisition, this landmark building did not make much progress, and then the news that the height was cut down came out. On May 14 this year, the project passed the over-limit review in Beijing, and the final building height was 488.9 meters. Baoneng GFC, built by Baoneng Group in Shenyang, is 568 meters high and is the tallest building in Northeast China. By the end of April 2020, the building height will be reduced to 500 meters.
At the end of March this year, the Ministry of Housing and Urban-Rural Development issued the Notice on Strengthening Green and Low-carbon Construction in County (draft for comments), proposing to limit the height of residential buildings in county. New residential buildings in the county are mainly six floors, and the proportion of residential buildings with six floors and below should be no less than 75%. The maximum number of new residential buildings in the county is 18 floors. If it is really necessary to build a residential building with 18 floors or above, it should be strictly and fully demonstrated, and the construction of fire emergency and municipal supporting facilities should be strengthened.
Yan Yuejin, research director of the think tank center of Yiju Research Institute, believes that such a policy can constrain the development of high-rise buildings and better coordinate the county's green ecology, infrastructure construction and residential building planning. (Zhongxin Jingwei APP)
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