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Repair and Rehabilitation of Industrial Steel Stacks

  • 09 Apr 2019
  • 11:45 AM - 1:00 PM
  • Maggiano's Little Italy North Park


This presentation illustrates the behavior, inspection, repair and rehabilitation of industrial stacks (chimneys). Stacks are an essential part of the industrial facilities. They allow the discharge of chemical waste gases from industries to the atmosphere, under stringent pollution control guidelines. The most commonly observed failure modes are discussed. A brief explanation of the European Code, CICIND (Comite International des Cheminees Industrielles), probably the first chimney code, and the U.S. design code, ASME STS-1 is provided. Essentially, depending on the condition of any existing structure, ASCE prescribed inspections are sometimes necessary before any rehabilitation work can be carried out. Analytical and numerical simulations were performed using MecaStack software (local model), RISA-3D software and SAP2000 software (global models). Analysis and design is based on the ASME STS-1-2011 standard code. Fatigue can be a significant issue in the behavior of steel stacks, and needs to be considered in the design.  Discontinuity around the manhole at the bottom was investigated with RISA-3D finite element software. Results in terms of deformation and principle stresses, including von Mises stresses, allowed recommendations, repair and construction documents to be prepared for the project.

Dr. Okelo, a graduate of UT Arlington, 2002, is currently a Senior Structural Engineer with APM & Associates, Inc., where he is involved with the design and review of bridge, commercial, industrial projects, consulting work for Dallas Area Rapid Transit (DART), and for Texas Department of Transportation (TxDOT). APM is on the design and built team for the DART Cotton Belt project. Additionally, his responsibilities include, the design and review of school facilities built to meet the ICC 500 code requirements for Storm Shelters. Some of these work was performed while working for BR Architects and Engineers, Inc. (BRAE). In conjunction with forensic engineering, he is involved with the development of economic repairs and rehabilitation of deficient structures.  Previously, he was with Chang, Patel and Yerby (CPY), where he also performed consulting work for DART. Furthermore, Dr. Okelo was on the faculty at: The University of Stuttgart, Germany; UT Arlington, and Lamar University, TX, US. He is the author or co-author of several peer-reviewed technical publications, as well as a reviewer for some technical journals.  

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