China.org.cn by Ma Yujia, May 26, 2009
A report from a joint investigation team – Analysis of building damage in 5.12 quake – suggests that the proportion of school buildings damaged beyond repair in the Sichuan earthquake was four times higher than government buildings, and goes on to examine some of the reasons for the collapse of these buildings.
According to China Economic Weekly, the report was written by a joint investigation team from Tsinghua University, Southwest Jiaotong University and Beijing Jiaotong University. It reveals that 13 percent of 54 government buildings investigated were considered damaged “beyond repair”; while the proportion among 44 investigated school buildings was 57 percent, 4 times higher than government buildings.
School buildings suffered the most serious damage
After the 5.12 devastating earthquake, experts from Tsinghua University were sent to Sichuan to commence an investigation into building damage, coordinating with other qualified academics from Southwest Jiaotong University and Beijing Jiaotong University.
The experts divided buildings under investigation into 7 different categories: school buildings, government buildings, industrial buildings, residential buildings, hospital buildings, and others. According to the statistics from the report, among 384 checked buildings, school buildings and industrial buildings suffered the most damage in the earthquake.
The report says many school buildings in the quake zone were designed with a masonry structure and contained large rooms, big windows and external corridors, which rendered these buildings susceptible to earthquake damage. Similarly, industrial buildings in some villages were also based on a masonry structure, with poor earthquake-resistance. However, most government buildings were framed structures, capable of resisting an earthquake.
Following the quake, concerns were voiced both at home and abroad over construction quality in the quake zone. Responding to these suspicions, Vice Governor of Sichuan Province Wei Hong said that in such a devastating earthquake the collapse of school buildings was inevitable.
Professor Lu Xinzheng from Tsinghua University thinks that China’s weak social and economic conditions have resulted in the low earthquake-resistance level on the intensity scale in some areas. He feels it should be raised by 1 to 2 grades.
Various factors combined to damage school buildings
“For many years, schools in China were designed with the same resistance level as standard residential buildings, while in Japan, the level for schools was 1 grade higher on the quake-intensity scale,” said Feng Peng, a member of the investigation team, in an interview with China economic weekly. “We should increase this level and make school buildings the safest places, capable of serving as safe havens during critical events.”
In July 2008, the Ministry of Housing and Urban-Rural Construction and the General Administration of Quality Supervision, Inspection and Quarantine released a revised Code for Seismic Design of Buildings and Standard for Classification of Seismic Protection of Building Constructions, which require that new schools must be designed with a higher resistance-level than standard residential buildings, one grade higher on the quake intensity scale.
According to Feng, there were “quality problems” with some school buildings; however, other factors too, such as poor design, might have combined to result in damage to thousands of school buildings during the catastrophic earthquake. For example, the roof-span of a classroom is usually wide, it is therefore more vulnerable to strong quakes. It was also the case that older schools, and those not built in conformity with construction norms, generally suffered greater damage.
An expert from a domestic building research institute, who was sent to quake-stricken areas to conduct research, said: “Most buildings designed in line with seismic code and according to higher construction standards did not collapse, even in high-level intensity areas. During his investigation, “quality issues” were indeed identified, such as poor design and use of substandard building materials.
Local economic factors restrict ability to increase resistance level
According to Feng Peng, there are only a few cities in China where residential buildings have been designed with a resistance specification of grade 8 on the intensity scale. The higher the level of resistance, the better a building is capable of resisting an earthquake.
However, local economic development is a major barrier to increasing the resistance level. Analysis indicates that an increase of one grade in resistance level can raise a building’s construction costs by 5 to 10 percent.
“For example, many regions in Shanxi Province lie in areas subject to a threat level of grade 9, but nobody is willing to invest in building to this standard due to the enormous cost,” said Feng. “At present, buildings in China are generally completed to the national minimum standard. Our government should encourage people to build themselves safer houses with a higher-resistance level.”
