Real Risk

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EOGRAPHY PLAYS A

key role in construction practices in

Nepal. The high Himalayas, the middle hills and the Tarai

region all possess different construction practices, mainly

due to physical and meteorological properties governed by geog-

raphy. Building practices also depend on socio-economic and

political conditions: urban and rural areas of human settlement

differ much in building preferences and practices. A further influ-

ence on construction culture is the availability of construction

materials.

New buildings in Nepal are built by convention, rather than

being specifically designed. The overall process is informal to

the extent that technically ignorant owners and craftspeople

often make decisions on structural elements. Even in urban

areas where the building permit process is mandatory, actual

incorporation of seismic safety into the project is not uniform.

This has resulted in highly vulnerable buildings in Nepal, even

when these are constructed using modern materials and tech-

nologies. These buildings represent high seismic hazard and

low preparedness, and have resulted in a very high level of risk

to human life and property. Understanding the cultural and

socio-economic aspects of Nepal’s non-engineered and infor-

mal building construction, the Nepal National Building Code

Development Process in 1992-1994 took a pragmatic policy

decision – in contrast to the conventional approach of build-

ing codes, it classified the buildings in four groups, with the

aim of facilitating the incorporation of seismic safety in all

classes of buildings:

• State-of-the-art

• Professional engineered

• Pre-engineered

• Non-engineered.

The aim adapted was to move gradually though these classifica-

tions, from non-engineered to pre-engineered and then

engineered status. Accordingly, guidelines were developed for pre-

engineered construction as well as engineered construction.

If communities are to be made safer against earthquakes, all

buildings should be made earthquake resistant. To achieve this

goal, all buildings need to be designed for earthquake resistance.

However, this is not feasible due to the cost of design, and the

lack of trained manpower for earthquake-resistant design and

construction. This is a dilemma in itself, but considering the simi-

larities between residential buildings, solutions can be developed

by creating a set of standard designs, which would encompass

typical architectural drawings, structural designs, a bill of quan-

tities, specifications etc. This would assist the potential house

owner to choose a suitable standard building plan from the set

of designs. Such a scheme would help to move from the practice

of creating non-engineered buildings to pre-engineered practice.

The current research focuses on residential buildings

and

entails two principal objectives:

• Develop standard architectural designs and drawings of a set

of typical residential buildings, of different configurations

and sizes, to cater for the housing needs of people belonging

to different economic strata (low to medium)

• Develop structural designs and drawings of these buildings

with different structural systems that comply with the

requirements of the National Building Code, including prepa-

ration of an appropriate bill of quantities and specifications.

Although residential apartment-style buildings have been

constructed in Nepal, the process is still in its infancy. Generally,

such buildings are designed and supervised by technicians, and

are hence expected to be engineered.

A review of previous reports and articles helped to visualize the

building construction scenario. Current trends in construction

were discussed with stakeholders in the building construction

sector. All available information was thoroughly studied, and the

researcher drafted a survey format based on this, which seeks to

record:

• Building typology

• Number of storeys

• Plinth area

• Building design process

• Size of column

• Maximum length of beam

• Overall building dimensions

• Plan of building.

Analysis of the survey data also considered an identification of

deficiencies and positive practices in the buildings.

There is a wide variety of building typologies in Nepal. The

majority of buildings in the city area are of reinforced concrete

construction. Other typologies are brick in cement, brick in mud,

stone in cement, stone in mud, adobe etc. Reinforced concrete,

brick in cement, stone in cement and stone in mud cover most

of the non-engineered building constructions on the periphery

of cities and market centres, and there is a growing trend to

construct as compared to the load-bearing structures. Load-

bearing structures are also built significantly in urbanizing areas

and low strength masonry structures are widespread in rural

areas. Based on these facts, a number of standard designs was

fixed for each category: reinforced cement concrete (5), brick in

cement (2), stone in cement (2) and stone in mud (1).

Earthquake-safer construction: developing

a set of standard designs for building

Binod Shrestha, Geotechnical Engineer, National Society for Earthquake Technology, Nepal