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.

Full document

References

[1] CBS 2014, Annual household survey. Gov.Nepal. Katmandú (2014).

[2] Bui, T.T., Bui, Q.B., Limam, A., Maximilien, S. Failure of rammed earth walls: From observations to quantifications. Constr. and Building Materials (2014) 51: 295–302.

[3] Bui, T.T., Bui, Q.B., Limam, A., Morel, J.C. Modeling rammed earth wall using discrete element method. Continuum Mech. Thermodyn. (2016) 28:523–538.

[4] Bui, Q. B., Morel, J., Hans, S., Meunier, N. Compression behaviour of non-industrial materials in civil engineering by three scale experiments: The case of rammed earth. Materials and Structures/Materiaux et Constructions (2009) 42(8): 1101-1116.

[5] Gomes, M.I., Lopes, M. And De Brito, J. Seismic resistance of earth construction in Portugal. Engineering Structures (2011) 33(3): 932-941.

[6] Lilley D.M., Robinson J. Ultimate strength of rammed earth walls with openings. In: Proceedings of the Inst. of Civil Eng. – Struc. and Buildings (1995) 110(3): 278 – 287.

[7] Jaquin P. A., Augarde C.E., Gerrard C.M. Analysis of historic rammed earth construction. In: Structural analysis of historical constructions, New Delhi (2006).

[8] Miccoli, L., Drougkas, A., Müller, U. In-plane behavior of rammed earth under cyclic loading: Experimental testing and finite element modelling. Eng. Struct. (2016) 125: 144–152.

[9] Nowamooz, H., Chazallon, C. Finite element modelling of a rammed earth wall. Construction and Building Materials (2010) 25(4): 2112-2121.

[10] Bui, Q.B.; Bui, T.T.; Limam, A. Assessing the seismic performance of rammed earth walls by using discrete elements. Cogent Eng. 2016, 3, 1200835.

[11] Liu K, Wang YA, Wang M. Experimental and numerical study of enhancing the seismic behavior of rammed earth buildings. In: Advanced Materials Research Vols 919-921 (2014) pp. 925-931.

[12] El-Nabouch R., Bui Q.B., Plé O., Perrotin P. Assessing the in-plane seismic performance of rammed earth walls by using horizontal loading tests, Engineering Structures, (2017) 145: 153-161.

[13] Allinson, D., Hall, M. Hygrothermal analysis of a stabilized rammed earth test building in the UK. Energy and Buildings (2010) 42: 845–852.

[14] Soudani, L., Fabbri, A. Morel, J.C. Assessment of the validity of some common assumptions in hygrothermal modelling of earth-based materials. Energy and Building (2016) 116: 498–511.

[15] NZ 4297. 1998 Engineering design of earth buildings. New Zealand: Earth Building. Association of New Zealand.

[16] Maldonado Ramos, L., Castilla Pascual F. J., Vela Cossio F. La técnica del tapial en la Comunidad Autónoma de Madrid. Aplicación de nuevos materiales para la consolidación de muros de tapia. Informes de la construcción (1997) Vol. 49 452: 27-37.

[17] Ramage, M., Ochsendorf, J., Rich, P. Sustainable shells: New African vaults built with soil-cement tiles. Journal of the IASS (2010, December) Vol. 51(4): 255-261.

[18] Block, P., DeJong, M., Davis, L., Ochsendorf, J. Tile vaulted systems for low-cost construction in Africa. Journal of the African Technology Development Forum (ATDF) – Special Issue on Architecture for Development (2010) 7: 4-13.

[19] Block, P., Van Mele, T., & Rippmann, M. Structural Stone Surfaces: New Compression Shells Inspired by the Past. Architectural Design (2015) 85(5): 74–79.

[20] Bhattacharya, S., Ghosh, J.S., Sahoo, D. K., Dey N., Pal A. Screening of superior fiber- quality-traits among wild accessions of Bambusa balcooa: efficient and non-invasive evaluation of fiber developmental stages. Annals of Forest Science, Springer Verlag/EDP Sciences (2010) 67 (6).

[21] Kaminski, S., Lawrence, A., Trujillo, D., Feltham, I., Lopez, L.F. Structural use of bamboo. Part 3: Design values. Structural Engineer (2016) 94 (12).

[22] Sanchez Vivas, L., Mullins, G., Cunningham, J. A., Mihelcic, J. R. Mechanical properties of bamboo: a research synthesis of strength values and the factors influencing them. Journal of American Bamboo Society (2019, October) 29(7): 1-22.

[23] Awalluddin, D., Ariffin, M. A., Osman, M., Hussin, M., Ismail, M., Lee, H., Abdul S. L., Nor H. Mechanical properties of different bamboo species. MATEC Web of Conferences (2017) 138: 01024.

[24] Sharma, B., Gatóo, A., Bock, M. and Ramage, M. Engineered bamboo for structural applications. In: Construction and Building Materials (2015) 81: 66–73.

[25] Yiping, L., Yanxia, L., Buckingham, K., Henley, G., Guomo, Z. Bamboo and Climate Change Mitigation. (2010).

[26] Seema Jain, R. K., Jindal, U. C. Mechanical behavior of bamboo and bamboo composite. In: Journal of Materials Science 27 (1992) 4598-4604.

[27] Aiping, Z., Dongsheng, H., Haitao, L. and Yi, S. Hybrid approach to determine the mechanical parameters of fibers and matrixes of bamboo. Construction and Building Materials (2012) 35: 191–196.

[28] Tripura, D.D., Singh, K.D. Axial Load-Capacity of Bamboo-Steel Reinforced Cement Stabilised Rammed Earth Columns. Struc. Engineering International. (2016) 29 (10).

[29] Tripura, D.D, Singh, K.D. Mechanical behaviour of rammed earth column: a comparison between unreinforced, steel and bamboo reinforced columns. Materiales de Construcción (2018) 68 (332) 174.

[30] DeJong, M.J., Ramage, M.H., Travers, B., Terry, S. Testing and analysis of geogrid-reinforced thin-shell masonry. In Proceedings of the IABSE-IASS Symposium, London (2011, September).

[31] Ramage, M.H., DeJong, M.J. Design and construction of geogrid-reinforced thin-shell masonry. In Proceedings of the IABSE-IASS Symposium, London (2011, September).

[32] Nepal Building Codes (NBC-105). Seismic design of buildings in Nepal. Dep. of Urban Dev. and Buil. Constr. Min. of Housing and Physical Planning, Gov. of Nepal (1994).