Evaluation of torsional stiffness in beam and slab bridge decks based on load testing

In this paper, evaluation of torsional stiffness in beam and slab bridge deck elements is presented. a beam and slab bridgedecks structurally behave as a grillage. a grillage has an efficient transverse load distribution due to transverse asymmetricload. in the case of bridge deck without transverse beams in the span, transverse load distribution depends on the torsionalstiffness of longitudinal beams, transverse beams over the supports and deck slab. the results of load testing conducted onseries of bridges in croatia are compared with results obtained on different numerical grillage models in which torsionalstiffness of main structural elements was varied. five different numerical models for each tested bridge are used. to evaluatetorsional stiffness of main structural elements of the bridge the transverse distribution coefficients are introduced. the designvalue of the coefficients of torsional stiffness reduction for verification of the serviceability limit state (sls), with assumptionof normal probability distribution is determined. the same coefficient is calculated using recommendation for torsionalstiffness reduction in concrete elements defined by model code ceb-fib 1990 (mc 90). according to conducted analyses thedesign value of the coefficient of torsional stiffness reduction for verification of the serviceability limit state of main structuralelements of beam and slab bridge deck is proposed.