As buildings get taller, bigger, and are required to resist higher seismic forces, the amount of reinforcement needed becomes impractical. Even if theoretical sizes can be calculated, it may be impossible to construct tightly spaced rebar cages or congested joint connections. Using higher strength reinforcement is a natural solution to this problem. Research on the use of high-strength reinforcement (HSR) began in the late 1950s. The outcome of this research first appeared in ACI 318-71, Building Code Requirements for Structural Concrete, which allowed limited use of reinforcement with a higher grade than 60 ksi. …
Author Archives : Nate Warner, P.E.
Nate Warner is an Engineer with Arup’s Structural Group in San Francisco, CA. (nate.warner@arup.com)
There is a common misconception among the general public that buildings designed according to modern building codes will not be damaged in an earthquake. Many building owners are similarly unaware that the seismic performance objectives outlined in the code are intended only to provide life safety for occupants; they do not prevent damage or ensure post-earthquake functionality. Significant financial losses and downtime for repairs can occur after an earthquake, which likely does not meet the expectations owners have for their investments. …