Report highlights causes of building collapse


A team of structural engineers from the United States with global expertise in disaster assessment has analysed the key reasons for building failures in the recent earthquake and provided recommendations in an official report on ways to improve safety of Nepal’s buildings.

The report focuses on the main types of buildings found in Kathmandu and surrounding areas. The majority of historic and older construction as well as new homes in rural areas are Unreinforced Masonry (URM) structures, comprising either brick with mud mortar or adobe construction. These types were the worst performers in the earthquake, although URM structures with cement mortar appeared to outperform URM with mud mortar. The report advises banning mud mortar, with exceptions made only for low-rise buildings in rural areas.

“This is the result of very hard work from international experts and will be very valuable, especially for reconstruction of Kathmandu structures. It will also help give a new direction for code development and in developing policies as we go forward for reconstruction,” said Yogeshwar Parajuli, Development Commissioner of the Kathmandu Valley Development Authority.

The team of 16 experts from the US, New Zealand and Australia assessed over 3,000 buildings in the aftermath of the earthquake, including homes, schools, colleges, hospitals, heritage sites, high-rise apartments and public buildings.

“This report will serve as a useful reference to Nepali engineers and will be circulated widely among different departments,” said Minister for Urban Development Narayan Khadka while receiving the report.

While Nepal’s current building codes and standards should be updated, taking steps to improve enforcement and quality of construction is more important at this point than improving the code, the report said. “The code can say anything but means nothing if it is not followed or enforced,” the report warned.

The structural engineers with expertise in disaster assessment, retrofitting and historic preservation were brought to Nepal by Global Fairness Initiative (GFI) and worked in partnership with the Government of Nepal, Nepal Engineering Association (NEA), Brick Clean Group Nepal (BCN), Minergy, the Building Back Right campaign and volunteers.

Many recommendations focus on the need for more accountability and oversight to ensure that buildings are not only safe on paper but in practice. It calls for accountability for the design teams and contractors as well as onsite field investigations during construction to ensure that contractors follow the approved documents while erecting or altering buildings.

“A study of the building codes and standards showed many excellent features. However, many buildings that were observed either did not meet the code or were subsequently modified with interior renovations and vertical or horizontal additions, making them non-compliant,” the report said. “Without effective enforcement, codes and standards cannot be effective at safeguarding against unacceptable losses due to earthquakes. “

Newer urban buildings tend to be Reinforced Concrete (RC) frame structures, but only a small percentage, such as high-rise apartments and business complexes, are engineered for the site. The vast majority of RC frame structures follow a prescriptive design using ‘mandatory rules of thumb’ laid out in Nepal’s building codes, and are designed by builders without formal training.

“It is not easy to characterise the performance of these buildings because… significant height violations of the (prescriptive rules) were commonplace,” the report noted. “From what was observed, this design was used for buildings, in some cases, exceeding seven stories in height resulting in overstressed beams, columns and foundations.”

Based in Washington, DC, GFI has been working in Nepal with local partners.