Preliminary Approach for a Prototype of Sustainable Antiseismic Dwelling in Nepal Based on the Historic Vernacular Tradition

== Abstract ==

The  effects  of  the  2015  Gorkha  earthquake  in  Nepal  revealed  deficiencies  in  the   most recent vernacular architecture,   which no longer   uses wooden reinforcements  due to   national anti-deforestation laws. It also highlighted the shortcomings found   in  reinforced  concrete architecture, which is generally scanty and poorly reinforced due to the high import cost of construction steel. The geography of Nepal has led to the  development  of  a  wide   variety  of  vernacular  architecture  using local  materials  such  as  stone,  brick  or  earth  in  the   form of rammed earth and adobe walls  [1]. Moreover, although its tradition in the construction of vaults is not as prominent as in  neighbouring  regions  of  India,  Nepal  has  developed its own tradition in the construction of vaults and domes, which are generally self-supporting and made of brick or adobe with lime mortar. The design of a prototype of seismic house  in  Nepal  aims  to  use  a  modular  housing  unit  with  rammed  earth  walls  and/or  walls   made  of  materials  recycled  from  previous  earthquakes,  as  well   as  tile  vaults   with  bamboo   sleepers, and possibly vegetable fibre  grids. These avoid the use of imported materials,   favouring km0 and sustainable  materials  while  following local tradition.  Several  potential housing units have undergone linear seismic analysis on finite element models, with  variations in planimetric layout and the types of tile vault, from the simpler barrel vault to the sail  vault.  Both are analysed searching for the best shape in terms of seismic efficiency,  evaluating stress and strain state.   The results obtained from this preliminary study  clearly   show  that,  under  seismic  actions, the  response  from  the  construction  system  using depressed  sail vaults and rammed earth walls with bamboo reinforcements   is   more  efficient and   homogeneous in terms of tension and   deformation. This is due to the  geometric symmetry   which determines the same response in several directions, unlike vaults with a characteristically  strong  directionality  (barrel  vault).  The  seismic  
response  of  the  prototype  described  is  examined  by  assessing  the  influence  in  terms  of thrust  and  deformation  of  bamboo  reinforcements  inside  the  walls.  For  this,  laboratory  tests are  used  to  identify  the   mechanical  characteristics  of  bamboo  to  be  employed  in  the finite element modelling and   calculation,  as  the  values  found  in  the  literature  vary depending  on  the  physical  and chemical characteristics of the material. This study therefore proposes a more sustainable architectural model with greater antiseismic resistance, always in keeping with local constructive tradition.

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