Oklahoma is known for its inclement weather, especially tornadoes, but recently we experienced a series of earthquakes.  You may have heard about them or even felt them yourself; we all know Kirk Herbstreit did.  The largest of the earthquakes, a 5.6 magnitude, occurred just after the Oklahoma State Cowboys football team had wrapped up a win against Kansas State.  It had everyone shaking in their boots and got me wondering about building codes. 

If Oklahoma continues to reinvent itself as quake country, will the building codes here need to change?  Seismic building codes are used in places known for strong earthquakes, such as California, to make buildings earthquake resistant.  The Transamerica Pyramid building, the tallest building in San Francisco was designed and constructed to be earthquake resistant.  This building was built on a base platform, which reduces shaking caused by earthquakes.  It has a 9 ft. thick foundation and the four story base has over 300 miles of steel rebar and 16,000 cubic yards of concrete.  The pyramid shape of the building helps prevent resonant amplifications.  In 1989, a 7.1 magnitude earthquake struck the area; the top floor of the building swayed about 1 foot from side to side, but the building was not damaged.    

Taipei 101, the second tallest building in the world, was built to withstand Taiwan’s strongest earthquakes.  The foundation consists of 380 concrete piles sunk 262 feet into the ground; each pile is 5 feet in diameter.  Constructed with high-performance steel, 36 columns support the tower, including 8 mega columns packed with 10,000 psi concrete.  Every eight floors, massive steel outrigger trusses span between the columns.  A Moment Frame System links the columns on all floors, reinforcing the structure.  The tower is also home to the world’s largest passive tuned mass wind damper, which can reduce the building’s movements by up to 40%.  A 6.8 earthquake occurred in 2002, while the building was under construction.  This showcased the stability of the design, as there was no structural damage to the building.

Will Oklahoma continue to get earthquakes?  Could they get stronger?  Will this change our building codes in the future?   Who knows?  Our buildings may not be designed to withstand large earthquakes, but we can be prepared.