The earthquake behaviour of low-rise houses made by either reinforced concrete, partially reinforced masonry or a novel steel composite system

This paper discusses features for the seismic design of low-rise houses made by three different construction techniques. A typical two-storey residential house with a basement is chosen for examination. This house, with the same dimensions in elevation and plan, is being built by three different construction techniques, thus resulting in three different structures. The first is that of conventional reinforced concrete construction whereas the second is that of partially reinforced masonry. The 2^nd construction technique utilizes such hollow ceramic bricks that longitudinal as well as transverse reinforcement can be accommodated within the vertical walls built with these bricks. The compression, flexural and shear behaviour of such masonry walls has been documented by a series of experiments conducted for this purpose. The novel 3rd construction technique utilizes steel structural elements in the form of sheets for the slabs or cold-formed sections for the beams and columns in order to form the structure, together with a special light weight concrete mix (SLWC). The mechanical properties of the SLWC mix were found from a series of laboratory tests. This investigation is mainly numerical, making use at the same time of the mechanical properties of the materials utilized in each one of the three different construction techniques as determined through laboratory testing, especially those of the innovative Super Light Weight Concrete. The seismic design follows the provisions of the Greek seismic code or those of the Euro-Codes; it utilizes the dynamic spectral method that is incorporated in the commercial software SAP2000. The main dynamic response characteristics are first established and discussed for each one of the three different structures made by the three distinct construction techniques mentioned before. Next, the demands to be used in the earthquake design at critical sections of the various structural elements are also computed and compared with the design strengths as provided by the relevant codes. Use is made here of strength data documented during the laboratory tests. The maximum design quantities for the same two-storey structure built by the three different techniques, in terms of storey drifts, and base shear as well as in terms of slab deflections are compared and discussed.