One Mile House Viaduct Erections Structures A and C, Saint John, NB

 

The One Mile House Viaduct is one of the largest interchange projects in NB. Harbourside Engineering Consultants (HEC) completed erection designs for both Structures A and C portions of the interchange structure.

Structure A consists of 5 span continuous (30.44m-33m-53m-53m-37.56m) 2m deep horizontally curved steel plate girders. HEC completed a detailed erection procedure installing single girder segments over the Pier supports using horizontal and vertical cables along with counterweights to provide the required temporary stability. Individual drop-in girder segments were then erected between previously installed Pier girder segments using temporary vertical and horizontal cables to increase overall girder stability. HEC completed all required analysis using full 3D finite element models accounting for girder torsion and warping under long unbraced lengths well beyond current code analysis. HEC completed design of all required temporary works including bearing locking frames, cable clamps, cables, cable anchorages and deadmen anchors. HEC also assessed girder strength and stability during lifting operations.

Structure C consists of 4 span continuous (68m-78.5m-78.5m-65m) 3.3m deep horizontally curved steel plate girders. HEC completed 2 different detailed erection procedures. The first detailed erection plan involved installation of single girders over the Pier supports using horizontal cables, vertical posts and counterweights to provide the required temporary stability. Single drop-in girder segments were then erected between Pier girder segments using a temporary top flange stability truss to provide the required stability to the compression flange of the long unbraced girder lengths. This stability truss was an innovative modular design with bolted segments allowing for installation on a variety of spans. Clamp connections to the existing girder top flange were developed which required no welding to the girder flange or removal of existing shear studs. HEC completed analysis using full 3D finite element modeling including the stability truss. The second detailed erection plan involved the incorporation of a variety of stabilizing techniques. Generally double girder lifts were incorporated to increase girder stability and eliminate the need for top flange stability trusses. It also incorporated temporary bents during installation of Pier girder segments to provide both vertical and lateral stability eliminating the need for vertical cables, horizontal cables or counterweights. Where double lifts were not possible, temporary jackable bents were designed to provide the required support to the long 78.5m unbraced erection spans. Additionally, where girder phasing was required due to site constraints did not allow for proper installation sequence with plan braced girders installed first, HEC developed temporary top flange bracing incorporating clamped top flange connections to allow paired girders to be installed as per the required sequence. As with all other erection sequences, HEC completed analysis using full 3D finite element modeling accounting for girder torsion and warping under long unbraced lengths well beyond current code analysis. HEC also designed all required temporary works including temporary bents, bearing locking frames, girder tilting frames and temporary plan bracing.

Client: E.S. Fox & Cherubini Metal Works

Value: $64 M (Approximate total construction costs)

Year: 2011-2012

Role: Erection Engineer