The Houghton Highway Bridge Duplication Project includes construction of a 2.7 kilometre-long bridge from the Redcliffe Peninsula to Sandgate across Bramble Bay in Queensland, Australia. The width of the bridge is 18m and includes 3 traffic lanes and 4.5m wide pedestrian/cycle way. The superstructure consists of 78 spans constructed from 1825mm deep precast T-Roff girders composite with 200mm minimum thick reinforced concrete deck. Kellogg Brown & Root Pty, Ltd. (KBR) in Brisbane is responsible for the design and providing design support during construction.

During construction, low hogs were observed in number of prestressed concrete girders and a concern was raised for potential consequence in the long term girder deflections. Low hogs may, in the long term, cause sagging to superstructure and high tensile stress at the bottom of the girders.

To identify the true behaviour of the girders, a detailed model was set up to take account of variability of the material properties, time-dependent effects and construction stage behaviour. The model was then used for calculating the girder hogs and stresses for short and long term. This paper presents an analysis and evaluation of the measured hogs versus the design hogs and assessment hogs in 30-100 years.

The model developed in this study allows the user to input variable material properties, construction staging and available instantaneous hog data to accurately predict the short and long term hog values for prestressed concrete girders.