Full Scale Thermal Stress Simulation of Multiple Span Steel Box Girder Bridge Evaluating Early Age Transverse Cracking Risk of Durable RC Deck Slab

Abstract

The present research aimed at evaluating early age thermal cracking risk of durable RC slabs incorporating slag cement and expansive additive on multiple span steel box girder bridges utilizing full-scale 3D FEM simulation. First, laboratory investigations were conducted to calibrate the material models of durable concrete. Second, the material models were utilized in several member level FEM models and the simulation procedure was verified regarding early age volume changes calibrating parameters for expansion energy and reduction factors for creep. Third, thermal and volumetric changes in RC slab were monitored and the simulation procedure was further validated in structural level utilizing full-scale FEM model of the real bridge. The simulated maximum tensile stress along bridge axis in RC slab signify the risk of early age transverse cracking where the accumulated stepping construction stress is comparatively large. The effectiveness of expansive additive in reducing the risk of transverse cracking is revealed from the simulation. However, parametric studies of the validated model indicate that the RC slab on the permanent form of seven span steel box girder bridge is vulnerable to early age thermal cracking regardless of ambient conditions and placing temperatures when coefficient of thermal expansion of concrete is larger than 6×10^-6/℃.