Case Study on the Effect of 690 mpa (100 ksi) Steel Reinforcement on Concrete Productivity in Buildings

Abstract

High-strength steel reinforcement in buildings had previously been limited to specialized applications, but recently published design guidance allows expanded use. A case study, conducted to investigate productivity benefits of using 690 mpa (100 ksi) versus 414 mpa (60 ksi) reinforcement, found that there was little to no benefit in using 690 mpa (100 ksi) steel in slabs, post-tensioned girders, and columns, but the beam reinforcement weight was reduced by 36%. The 2010 material cost ratio of 690 mpa (100 ksi) to 414 mpa (60 ksi) reinforcement was two, outstripping the weight reduction. However, labor cost is a function of weight, bringing the overall cost of 690 mpa (100 ksi) reinforcement to within 35% of 414 mpa (60 ksi) reinforcement cost. The material cost ratio will presumably decrease over time; if it drops by 30% or more, 690 mpa (100 ksi) reinforcement will be more economical. Labor costs, which vary by location, strongly influence the productivity benefits of 690 mpa (100 ksi) reinforcement. The use of 690 mpa (100 ksi) reinforcement is more favorable in expensive labor markets and it appears to be currently competitive in some. The paper’s primary contribution to the overall body of knowledge is the quantitative understanding of the economic factors that influence the ability of 690 mpa (100 ksi) steel reinforcement to have a productivity advantage over the use of conventional 414 mpa (60 ksi) steel reinforcement. Practitioners, designers, and researchers can use this information to understand the cost and productivity impact of high-strength reinforcing steel.