3.2.2. Traditional seismic resistant building practices

3.2.1 Traditional seismic resistant building practices –

The study on ‘Seismic-resistant building practices resulting from Local Seismic Culture’ by J. Ortega & G. Vasconcelos M.R. Correia, formulates the characteristics of vernacular seismic-resistant constructions as: • The building should be symmetrical in both plan and elevation - reduces torsion. • Height to base ratio should be low - to minimize overturn. • Materials like timber which are ductile to resist tensile forces are preferred. • Stress concentrations are avoided • Failure of certain members is tolerated - e.g. masonry is collapsed but the frame is intact. • Good state of conservation, proper maintenance, post-earthquake repairs, and strengthening works.

The study also mentions the characteristic observations from the LSC in European Mediterranean16 countries as: • Elevation configuration - low centre of gravity • Use of timber elements • Structural timber frames • The connection between structural elements • Ties • Traditional joining system • Stabilization of floors and roofs - improving the diaphragmatic behaviour by reducing their excessive deformability. • Reinforcement of the openings • Elements neutralizing the horizontal forces • Urban reinforcing measures • Position within the urban fabric

16 Mediterranean countries – countries which surround Mediterranean Sea.

(left) Historical solution to out-of-plane mechanisms at an urban level (Borri et al., 2001); (right) Reinforcement arches in Dolce-Aqua, Italy (credits: Ferrigni et al.,1995).

Building complexes in: (left) Anavatos village in Chios Island, Greece (Efesiou, 2001); (right) Mandraki, in Nysiros Island, Greece (credits: Ferrigni et al., 1995).

Figure 15 Vernacular Urban Reinforcing measures, Source - (Correia, Carlos, & Rocha, Vernacular architecture?, 2015)

The central and eastern Asian regions is highly earthquake prone. Three approaches for LSC been discussed here (Ferrigni, The central and eastern Asian local seismic culture: Three approaches, 2015) : 1. Deformability approach 2. Rigidity approach 3. Passive approach

Buildings built on rocks are the safest structures in terms of seismic resistance. Rock minimizes the side effects. Deformability approach (resistance by friction) – The use of timber helps to deform the structure in shearing. In this approach the building height is not more than 3 floors and