How Building Codes Change

After a short vacation I’m back in professional mode trying to keep abreast of the latest structural engineering and building information modelling news. Perhaps with my background in architectural history I’m more apt to take an interest in the evolutionary changes which slowly occur within the field of structural engineering. Though of slightly more relevance to civil engineering, a recently released report of a January 2015 subway fire in Washington D.C. noted - among the many other safety short comings of the Washington D.C. metro system - that a contributing factor in the poor emergency response was that the tunnel had been built in the 1970s to 1970s standards where controlling temperature and heat had been main priorities. In the 80s, cumulative experience shifted this view instead to focus on the evacuation of smoke in an emergency and codes subsequently updated. Another example of this is what engineers learned from 2011 Japanese Tsunami; my connection being I use to live there. The article notes, “The debris fields along the devastated coastal areas of northeastern Japan quickly became a laboratory for investigating not only the direct hydraulic loads but also many related phenomena, such as building buoyancy, backwash and scour.” Concluding, “Concrete structures with deep foundations and good shear bracing survived, but others with weak foundation connections lifted and rolled.” Ultimately this has led for calls to change the building code for essential structures in coastal areas which could be used as places of refuge in an emergency. The article conveniently summarizes the recommended changes in one paragraph: “The new ASCE standards were developed based on a maximum considered tsunami (MCT) that has a 2% probability of being exceeded in a 50-year period, or a ~2,500 year average return period. The MCT is characterized by the site-specific inundation depths, run-up and flow velocities during inflow and outflow—all based on probabilistic tsunami hazard analysis”.