A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Use of Ring Beams for Progressive Collapse Retrofit
The renovation of an existing office building to meet the progressive collapse requirements according to UFC4-023-03 is presented. The original building was composed of two structurally independent structures, both of which housed three indoor tennis courts. Both structures were column free in the interior and were constructed of built up wide flange perimeter columns and 6ft deep roof trusses for lateral and gravity load. A first building renovation transformed the original structure into two 3-story office buildings by adding a 2-story steel frame structure inside the original space. A second renovation added steel framing between the two buildings to create a single structure and provided support for a new cladding system. The office building relies on stair masonry walls for lateral support. Existing structural drawings were available only for the second renovation. In order to meet the UFC4-023-03 Progressive collapse guidelines, a system of hangers and ring beams was designed. In most cases the steel columns were used as hangers and their connections strengthened accordingly; in some cases rod hangers were provided. Ring beams were located at various levels depending on the column layout and additional blast retrofit requirements. In all cases, the ring beams were designed as continuous beams supported by the existing columns who behave as pins. This assumption results in heavier beams but avoids additional retrofit for the columns and the use of brittle and expensive moment connections. This paper presents details of the implemented retrofit as well as some of the challenges encountered during the design phase: the complexity of the geometry of the different structural systems, the definition of how many columns to be simultaneously removed and the applicability of the linear elastic method to the design of multiple elements of different ductility.
Use of Ring Beams for Progressive Collapse Retrofit
The renovation of an existing office building to meet the progressive collapse requirements according to UFC4-023-03 is presented. The original building was composed of two structurally independent structures, both of which housed three indoor tennis courts. Both structures were column free in the interior and were constructed of built up wide flange perimeter columns and 6ft deep roof trusses for lateral and gravity load. A first building renovation transformed the original structure into two 3-story office buildings by adding a 2-story steel frame structure inside the original space. A second renovation added steel framing between the two buildings to create a single structure and provided support for a new cladding system. The office building relies on stair masonry walls for lateral support. Existing structural drawings were available only for the second renovation. In order to meet the UFC4-023-03 Progressive collapse guidelines, a system of hangers and ring beams was designed. In most cases the steel columns were used as hangers and their connections strengthened accordingly; in some cases rod hangers were provided. Ring beams were located at various levels depending on the column layout and additional blast retrofit requirements. In all cases, the ring beams were designed as continuous beams supported by the existing columns who behave as pins. This assumption results in heavier beams but avoids additional retrofit for the columns and the use of brittle and expensive moment connections. This paper presents details of the implemented retrofit as well as some of the challenges encountered during the design phase: the complexity of the geometry of the different structural systems, the definition of how many columns to be simultaneously removed and the applicability of the linear elastic method to the design of multiple elements of different ductility.
Use of Ring Beams for Progressive Collapse Retrofit
Naderi, Dara (author) / Adaros, Macarena Schachter (author) / Wood, Scott (author)
Structures Congress 2015 ; 2015 ; Portland, Oregon
Structures Congress 2015 ; 1183-1194
2015-04-17
Conference paper
Electronic Resource
English
Use of Ring Beams for Progressive Collapse Retrofit
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