Proposed design methodology for titanium reinforcing bars in concrete

Abstract

The technical development and characterisation of deformed 6Al4V titanium reinforcing bars for concrete has been reported and the use of titanium reinforcing bars demonstrated. This paper describes aspects of reinforced concrete design using titanium reinforcing bars based on ACI practices. The stress-strain behaviour of titanium is similar to that of steel although titanium is half as stiff and twice as strong. A combination of ACI 318 provisions for strength and ACI 440.1R provisions for serviceability are recommended when designing with titanium. This paper describes the resulting hybrid design approach in the context of flexural design. A series of benchmark designs comparing comparable reinforced concrete slab and beam designs using A615 steel, GFRP and titanium reinforcing bars is presented. An additional benchmark design of a near surface mounted (NSM) titanium bar retrofit of a steel-reinforced concrete beam is presented. The hybrid design approach proposed provides initial recommendations for design of experimental and demonstration titanium-reinforced concrete structures and provides appropriate bases for comparing accepted reinforcing materials with novel material, specifically 6Al4V titanium reinforcing bars.