Effect of helical pitch and tensile reinforcement ratio on the concrete cover spalling off load and ductility of HSC beams

[extract] In recent years a marked increase in the use of High Strength Concrete (HSC) has been evident in Australian building construction despite the fact that the current Australian design standard, AS3600 provides no design rules. HSC has been used extensively in civil construction projects world wide because it reduces the cross section and the weight for long construction members. High strength concrete and high strength steel are used together to increase the load capacity and reduce the beams' cross section. Using these two materials to design over reinforced beams will lead to huge reduction of cost, which is a desirable issue. However, the problem is the lack of ductility, hence such use is not allowed by the current codes of practice.