Zhu Yiyi, 19, of Jiangxi province, in the hospital after amputation of part of her left leg. She was hit by falling shards of glass from a broken window in Hangzhou, Zhejiang province, on July 8. [Photo/provided to China Daily]

SHANGHAI - The city will ban glass curtain walls at new schools, hospitals and residential buildings under a new draft of the Shanghai Glass Curtain Wall Construction Management Regulation, which is aimed at addressing safety concerns.

The walls, seen by many as a symbol of modern architecture, will also be restricted in the city's historic and scenic areas.

Though buildings with glass curtain walls are often found in financial or central business districts, Rao Rong, a professor at Tsinghua University's School of Architecture, said it's a relief to see limits on their use.

"The safety of glass curtain walls is directly related to the engineering design of the building, the material quality of the glass, and the skill used in its installation and maintenance. Any negligence in the details might lead to an accident," said Rao.

"Technically speaking, the glass curtain wall is a relatively mature technology as it was introduced to China in the 1980s, but many human factors such as the lack of maintenance may contribute to accidents causing injury or damage," she said.

The draft also mandates safety inspections every four years.

A more comprehensive investigation involving inspections of glass curtain walls, aluminum alloy extrusions, steel and more, is required for class-clad buildings older than eight years.

"Repair and maintenance are not cheap," said Yu Hui, a professor at the School of Architecture and Fine Arts at Dalian University of Technology. "For some glass high up in the air, checking each square meter costs several hundred yuan."

Penalties from 10,000 yuan ($1,566) to 100,000 yuan are included in the draft to deter owners from skipping inspections.

Several glass curtain walls in high-rises have burst without warning since this summer, leading to growing concerns about the cause of such incidents.

In Hangzhou, Zhejiang, a 19-year-old girl was hit by falling shards of glass from an exploding window as she walked down the street on July 8, and part of one of her legs had to be amputated.

In Zhejiang province's Yiwu, a 20-meter-high glass dome in a garment market came crashing down on Aug 20, injuring several children.

Though Shanghai has been lucky in terms of having no serious injuries, 30 panes of glass rained down upon a residential area in its CBD two days after typhoon Muifa swerved past in August.

Shanghai has the highest number of glass-clad building in China - at least 4,000. More than 900 of the buildings are older than 15 years.

"At least 1,134 of them have potential safety problems", said Tu Haiming, a political adviser of Shanghai.

Tu is also directing a comparison of high-rise and underground transportation safety in Shanghai, Hong Kong and Macao.

According to Tu, in Hong Kong and Macao, the probability of a cracking glass incident involving a high-rise building is one in 10,000. "In Shanghai, this figure is as high as one to two in a thousand," he said.

More than 100 panes of glass have fallen from a famous high-rise in Pudong's Lujiazui area since it was built three years ago, said Tu, referring to the 51-story One Lujiazui that sits next to the Jinmao Tower.

"Glass can explode due to a few major reasons - when it is hit by an external force or stressed by (the difference between) high external temperatures and an air-conditioned interior," he said.

The local government is seeking public comment on the draft measure before it is formally introduced.

He Na contributed to this story.