Forum (Spotlight Weekly)

“Importance of Nepal National Building Code in Disaster Mitigation ”

By Lekh Nath Pokharel

Nepal is prone to various types of natural disasters. Most part of the country is seismically active. Hence, the geomorphology is very fragile. High mountains and the Himalayan range of Nepal are quite young. They stretch almost 2500 kms from east to west and they fall under the seismically active zone, which is considered to be the result of subduction of the Indian plate under the Tibetan plate.

According to the report of a study on earthquake disaster mitigation in the Kathmandu Valley, Nepal lies in an active seismic zone that extends from Java, Myanmar, the Himalayas, Iran all the way to Turkey. There are several faults in Kathmandu Valley and most of the existing buildings have severe deficiencies regarding earthquake. Urban areas are highly vulnerable to earthquake disaster and it is one of the biggest obstacles for sustainable development. Nepal has suffered huge losses of lives and properties due to ten major earthquakes since 12th century.

The budget for the fiscal year 2060/61 has been made public. Many new programs have been introduced in this budget. Among them, one is the announcement of implementing the National Building Code to promote economic, safe house building aimed at reducing human losses from natural disasters like earthquakes. Implementation of the National Building Code is very significant for disaster management. Thus, let us discuss in brief about the Building Code.

The National Building Code is the first such document prepared for Nepal in 1994 but it has not been implemented yet. The Code has been produced by a team of Nepalese and international consulting engineers and architects to a particular Terms of Reference. Most countries, which have successfully implemented building codes, have only done so over a very long period, extending in decades. The technical documents making up building regulations are normally the subject of a continual process of revision, correction and any necessary expansion. The degree to which national building codes and standards are enforced by law varies from country to country. In some countries, the national building code is taken by the courts of law to be a measure of good practice. India is one country, which has such a system. Uncontrolled building processes are rapidly producing structures, which the developers of this code believe carry an unacceptable degree of possibilities of risk or damage due to earthquake.

The National Building Code provides both regulations and guidelines for the construction of buildings in all areas of Nepal. The four different levels of sophistication of design and construction that are being addressed in the National Building Code are as follows and each of the four levels are introduced below.

International state-of-the art

Professionally engineered structures

Buildings of restricted size designed to simple rules-of-thumb

Remote rural buildings where control is impractical.

International State-of-the-Art; Because the major thrust of the Code is aimed at the typical and most common buildings currently being erected in Nepal, it deliberately does not suggest this as being practical for everyday consideration. The sophisticated design philosophies and analytical techniques that are included in the codes of more wealthy countries cannot be fully applicable in our situation. Moreover, these structures should be seen to be meeting the Nepalese requirements with respect to minimum design loads and configuration. There is then no reason for any designer to ignore the Nepal regulations in their entirety.

Professionally Engineered Structures; This contains the standard code requirements that all professionally qualified engineers shall recognize and must meet as a minimum condition while designing structures. It covers all usual structures such as hospitals, meeting halls, factories, warehouses, multi-storeyed buildings and residential complexes. Materials, analysis and design, construction safety and site considerations are all covered.

Mandatory Rules-of-Thumb: This part recognizes that it is not practical in Nepal at present to insist that professional advisers must design all small buildings for strength. Therefore, for classes of buildings not exceeding certain simple criteria of height, number of flats and floor area, mandatory rules-of-thumb are provided. The explanatory documents are such that an experienced overseer will be able to understand them and present sufficient details at the time of permit application to prove to a skilled appraiser at the Local Authority that the requirements have been met. The requirements are in terms of limits on spans and heights, minimum reinforcing and member sizes, positioning of earthquake-resisting elements and other similar rules.

Guidelines for Remote Rural Buildings: In the form of diagrams and descriptions aimed at the technical advisers to owner/builders in villages, these guidelines emphasize those changes that should be made to current practices to improve the seismic resistance of these buildings, which are not subject to modern quantitative analysis and rational design consideration. These structures are normally of earthen construction (unfired masonry, mud mortar, rubble, dry stone, wattle and daub, etc.)

Whereas these recommendations are described as guidelines, it is intended that it will be mandatory for such structures built in areas controlled by a building permit-issuing local authority.

Based on the report of the study on earthquake disaster mitigation in the Kathmandu Valley, the valley is going to be suffer serious damages if no quick steps are taken. If a tremor similar in intensity of that of Nepal-Bihar earthquake of 1934 occurs now, it is estimated that the number of possible damaged buildings would be 21 percent, the death toll 1.3 percent and the injured 3.8 percent.

Lastly, Earthquakes, as such, do not kill people. It is the falling buildings that do. Therefore, good house construction practice sticking with the existing building code will help to minimize the loss of lives and properties. Preparedness is the most important way to minimize the impact of an earthquake. So, implementation of National Building Code is very significant for disaster mitigation in Nepal.

(Pokharel has been involved in Disaster Management for the last six years. Having received national and international training on the subject, Pokharel has written a number of articles in different publications)