Flexural response of 3-D reinforced concrete sandwich panels with EPS Core

Reddy, Sai Supraj and K V L, Subramaniam (2019) Flexural response of 3-D reinforced concrete sandwich panels with EPS Core. Masters thesis, Indian institute of technology Hyderabad.

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Abstract

Flexural behavior of 3-D reinforced EPS core sandwich panel with concrete wythes is investigated. The sandwich panel consists of an integrated 3D reinforcement with an expanded polystyrene (EPS) core. The reinforcement is provided as wire meshes with welded truss connectors. The 3-D reinforced EPS core sandwich panel consists of two concrete layers separated by an internal insulation layer of EPS and are usually joined shear connectors. Depending on the level of shear transfer achieved between the two wythes the flexural response varies between fully composite, semi-composite or fully non composite. This type of construction is intended for use as floor slabs with the additional advantages of reduced weight, enhanced thermal comfort and improved acoustic performance. The behavior of sandwich panels is studied by testing the beams in three-point loading configuration at two different different shear-span to depth ratios (a/d) equal to 3.0 and 4.0. The cracking in the beam during the load response is evaluated using the surface displacements obtained using the Digital Image Correlation technique. The test results indicate that there is a large change in the flexural stiffness after cracking and the post cracking response is produced by the opening of flexural hinge at the location of cracking. The ultimate capacity derived from the application of beam theory assuming complete composite action compares favorably with the experimental value. The flexural response before cracking is accurately predicted using sandwich beam theory. The stresses in the wythes at a given section produced by flexure depend upon the effective shear modulus of the core consisting of the EPS and the diagonal steel truss connectors. The application of the sandwich beam theory predicts that the flexural cracking in the sandwich beam under applied flexure depends on the applied shear at that section. The flexural cracking moment is therefore not a section property as derived by the conventional beam theory, but must be derived considering the geometry and the loading. An increase in the applied shear at a given section leads to a decrease in the capacity in flexure. The stiffness of the sandwich beam can be improved by increasing the effective shear modulus of the core.

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