Research of long-term behaviour of non-prestressed precast concrete beams made continuous

• Long-term experiment on non-prestressed precast beams made continuous is presented in details.
• The development of restraint moment at the continuity joint with time is investigated.
• Simplified method for calculation of the restraint moment is proposed.
• Impact of the values of creep coefficient and shrinkage strain on the restraint moment is analyzed.

Despite the extensive analytical and numerical research carried out in the last two decades on the long-term behaviour of continuous concrete beams composed of precast units, only limited number of experimental data is currently available in the literature. This paper presents an experimental study of the time-dependent behaviour of continuous concrete beams that has been carried out at the University of Belgrade. Two beams were made of precast reinforced elements with cast in situ upper part and continuity joint at middle support. Two cast in place continuous beams of same span and load were also tested. All beams were subjected to equal sustained load for a period over 4 years and deflections, strains and reactions were measured. Experimental program is described and the results are presented. The experiment was also analytically simulated. Analysis of this type of structure should incorporate effects of creep, shrinkage and cracking of concrete.Simplified procedure that involves the AAEM method and the bilinear approach is proposed for calculation of the restraint moment. Calculated values obtained using measured concrete properties are close to the experimental values. Experimental results presented in the paper offer data for calibration of more complex theoretical procedures.