Retrofit of existing buildings

A linear dynamic analysis procedure was used to evaluate the safety margin of an aged steel building in a Department of Energy plant against natural phenomena hazards such as winds, floods and earthquakes. This is a common industry practice and it is generally justifiable. It was shown that the use of this conventional procedure over-estimated the structural response and, subsequently, resulted in cost-prohibitive modification schemes. An alternate procedure was developed to provide realistic results and to minimize modification cost. A three-dimensional finite element model of the subject building was developed to analyze the different load combinations. Analysis results revealed deficiencies in the existing vertical bracing system used to resist lateral loads. The vertical bracing consisted of single-angle X bracing. An external bracing system was designed in a manner that would not impact the operation of the 56,000 square foot facility which has been processing fuel for power generating plants since 1954