Employments of highly durable low carbon technologies are crucial for mitigation of climate change ensuring sustainable infrastructures. In this perspective, a challenging initiative for ultra-high durability low carbon prestressed concrete bridges utilizing sustainable zero cement concrete (STC-ZERO) and nonmetallic reinforcement is undertaken. STC-ZERO exhibiting high strength, low shrinkage, and low creep reduces carbon emission up to 70% compared to the conventional concrete as cement is entirely replaced. Aramid fiber PC tendons have no factor of deterioration of concrete thanks to nonexistence of corrosion. Accordingly, an AASTHO-PCI BT-72 PC girder bridge and a butterfly web bridge are designed incorporating this combination and compared with corresponding conventional bridges with respect to whole life carbon emissions. Since there are no repair and rehabilitation requirements, the whole life carbon emissions of next generation non-metallic bridges are expected to be reduced by around 70%.
Present study aims on evaluating the seismic performances of existing Masonry Infilled Reinforced Concrete (MIRC) buildings commonly found in many South and Southeast Asian countries utilizing appropriate masonry properties in Applied Element Method (AEM) models. First, masonry constituents and masonry composite properties were determined for different masonry meshes through extensive parametric studies verified through the experimental results of masonry prisms under uniaxial compression and half scaled masonry infilled RC frames under in-plane cyclic load. Next, the established infill properties were utilized for time history dynamic analysis of an existing 8-storied MIRC building for different AEM models including soft story, retrofitted soft story, infills in all floors and bare RC frames neglecting stiffness contribution of infills. The analytical results revealed: 1) the unpredicted soft story column failure compared to the similar bare RC frame, 2) the inability of infills to improve the seismic performance of the surrounding RC frames, 3) the effectiveness of steel plate jacketing for preventing soft story failure and, 4) the effect of the existence of overhead water tanks on the alteration of seismic behavior of RC buildings.
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 fullscale 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 /℃.
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