Ductility and performance assessment of high strength self compacting concrete (HSSCC) deep beams: An experimental investigation Mohammad Mohammadhassani, Mohd Zamin Jumaat, Mohammed Jameel, Hamid Badiee, 1. Introduction Identifying structural behaviors has become a major challenge for design engineers especially with the advent of innovative technologies in the field of materials and construction; this is especially so in high seismic hazard areas. The discovery of one such technol-ogy is the deep beam which is currently a subject of considerable relevance in developing countries that are experiencing rapid growth in the construction industry. Deep beam has various struc-tural applications, e.g. transfer girder in tall building, floor slabs under horizontal loads, shear walls, pile caps, foundation, offshore structure, nuclear power plants and many more. The main objec-tive of this study is to investigate the performance (i.e. strength and ductility) of simply supported HSSCC deep beams. Deep beams are defined as beams having a span-to-depth ratio, ln/h, of about 5 or less, or having a shear span less than about twice the depth. The behavior of deep beams is signifi-cantly different from that of normal beams. Deep beams behave two-dimensional rather than one-dimensional due to their geo-metric proportion. The design of these structural elements is not adequately covered in existing codes of praĐtiĐe; For edžaŵple, the ĐurreŶt British Code ;BS ϴϭϭϬ, ϭϵϴϱͿ ĐlearlLJ states that for desigŶ of deep ďeaŵs, refereŶĐe should be made to specialist lit-erature. The ŵajor Đodes aŶd ŵaŶuals that disĐuss oŶ deep ďeaŵ ďehaviors are the ACI ;AŵeriĐaŶ CoŶĐrete IŶstitute Code, ϭϵϴϲ); the Eurocode 2 (1984); CSA (Canadian Standards Association, 1984) and CIRIA (Construction Industry Research and Information Association Guide No. 2, 1977); these are all based on empirical investigation. There is no manual and code with exact theoretical study for the design of deep beams. The behavior of these structural elements is imprecise and due to their high stiffness, the deflection at ultimate state is insignif- icant. Therefore, this study aims to investigate the need for safe designs and determine a ductility coefficient of HSSCC deep beams. Ductility is defined as the ability of a material or member to sustain deformation beyond its elastic limit while maintaining a reasonable load- carrying capacity before total collapse or failure. The predominant failure mode for deep beams is shear failure (Mohammadhassani et al., 2011). The probable effective variables for ductility of deep beams are included as reinforcement ratio for tension steel (_) in percentage, compressive strength of concrete (f_c), yield strength of steel reinforcement (fy), the load and support point width and web reinforcement ratio (_s). The tensile rein-forcement ratio is potentially an important factor that affects the ductility of the concrete beam section. There are few studies and test data on the ductility of over-reinforced HSC beams (Maghsoudi and Shari, 2009; Ho et al., 2010). Based on these test results, it was evident that there is a need to revise the definition of bal-ance design for HSC section with modification of stress block at the compression zone of a concrete section. Due to more steeper and parabolic shape of the stress block in the compression zone, the design equations are affected more significantly by the shape of the compression block. This complexity of strain distribution is more apparent when the tensile bars used are more than maximum lim-its suggested by the design codes as it results in neutral axis depth variation. The design of deep beam structural elements is not covered in the existing codes. Experimental studies since 1965 (De Paiva and Siess, 1965; Chemrouk and Kong, 2004; Chemrouk, 2009; Yang et al., 2007; Ashour and Yang, 2008) had helped develop some empirical methods. However, test data on HSC deep beams above 100 MPa are rather limited and are insufficient in determining the strain distribution in the section height for the investigation of cur-vature ductility. The strain distribution is nonlinear along beam length and across the section height of the element (Ray, 1985). Thus the rectangular stress block assumption is not valid for deep beam sections. Horizontal and vertical web reinforcements are important in the behavior of deep beams. Web reinforcement increases the shear capacity of the beams. The key role of web reinforcement is to restrict the