Influence of Shrinkage and Temperature on a Composite Pretensioned - Reinforced Concrete Structure

Defective design and construction became a reason of a damage of a complex structure of a heliport. Shrinkage and temperature made additional problems. Reinforced concrete frames, pretensioned double T beams and reinforced concrete slab on the top create the structure. The frames support the beams and the slab strengthens the last elements. Since it was unclear what initiated and developed the damages, modelling of the composite structure helped to solve the problem. The paper presents the damages of the structure, construction process and environmental conditions which were essential in the evaluation of damages and their causes. The major part is devoted to presentation of modelling of the structure behaviour during construction and under dead loads, shrinkage and temperature. Due to the complexity of the problem nonlinear analysis was conducted. The analysis included staged construction process which required stress redistribution. It was found that destruction was initiated in the area where the structure was faultily designed. Since the environmental temperature and the shrinkage were not considered in the design additional damages appeared. They were enhanced with insufficient area of designed reinforcement and even less built in.