Structural irregularity is a crucial issue in assessing seismic vulnerability of both new and existing buildings. European technical codes provide simple criteria to define irregularities in plan and in elevation, amplifying the seismic actions and/or introducing torsional effects. Nevertheless, this approach only considers geometrical irregularity. For existing buildings, another source of irregularity comes from the non-uniform distribution of the material strength. In particular, for existing reinforced concrete (r.c.) structures, it is possible to detect significant spread of the concrete compressive strength not only from different structural elements but also from different parts of the same member. In this work, non-linear static analysis is performed on two case-studies of r.c. buildings characterized by geometrical and mechanical irregularity. The resistance of each column is determined with an extensive experimental campaign with in situ and laboratory test (about 600 in situ tests). The results are analyzed considering both local and global effects in terms of resistance of the single elements and of the entire buildings. In this sense, shear and bending failure mechanism are taken into account. The effect of story flexibility is also considered in the models. Fragility curves are calculated for the buildings with random distribution of the compressive strength of the columns. The results are then compared with the approaches proposed by the Eurocodes evaluating in the standard approach proposed by technical codes is conservative or not.

This paper illustrates an innovative manufacturing procedure for producing handcrafted interlocking stabilized compressed earth blocks (ISCEBs). A comparison of the mechanical properties of ISCEBs is conducted to assess the influence of varying components. The ISCEBs are manufactured by employing different block densities with three distinct mixtures (earth, earth and lime, earth and straw) and by using a human-powered machine named Float RAM 1.0 Press. The manual press was conceived for regions with limited access to technology and allows the production of interlocking blocks via two modes of compaction: mono-directional and bi-directional. A production average of approximately 30 blocks/hour corresponding to the work of three people is achieved. Three-point bending tests and uniaxial compression tests are carried out to investigate the ISCEB mechanical behaviour. The improvements obtained by incorporating additives into the subset of ISCEBs made from a pure earth mixture are tested. The aim of this work is to identify, for this specific technology, the relationship between production parameters and the consequent behaviour of different stabilization methods. A correlation is found between the compaction force and the compression strength of ISCEBs. The addition of lime increases strength and causes the blocks to exhibit a brittle behaviour. Moreover, the incorporation of straw fibres improves the tensile strength and ductility without significantly affecting the compression strength of the blocks. Energy-based parameters are obtained for all the tests, allowing the assessment of the ISCEB mechanical and dissipation properties.