Experimental Study of Concrete Sandwich Panel Behavior under Bending Loads

What is it about?

This content is an experimental investigation of a concrete sandwich panel subjected to four-point bending load. The study examines the structural behavior of concrete sandwich slabs composed of two thin reinforced concrete layers isolated by a thermal core layer and tied by steel truss shear connectors. The study analyzed load-central deflection response, crack patterns, and failure modes of the specimens. The results reveal that all the specimens behave as composite members until they break down, and their performance under flexural load is comparable to that of common reinforced concrete one-way slabs. The type of steel truss shear connector embedded in the concrete ribs has a significant effect on the flexural behavior of the specimens under test. An increase in the insulation thickness enhances the ultimate flexural load capacity by 22%, and an increase in concrete compressive strength enhances the load-carrying capacity. The specimens failed in the flexural mode, and the stiffness of the specimens decreases as the load increases due to factors such as the creation and widening of cracks, especially in the bottom wythe of the slab, and the yielding of steel bars in the bottom mesh. The study concludes that the stiffness drop observed in the load versus central deflection curve is attributable to material strength limitations rather than a loss of shear transmitting ability.

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Why is it important?

This research is important because it provides valuable insights into the structural behavior of concrete sandwich slabs, which are a new type of composite construction material. Understanding their behavior under flexural loading is crucial for designing and building safer and more efficient structures. The findings of this study can contribute to the development and optimization of concrete sandwich slabs, leading to improved performance and reduced material usage, thus promoting sustainable construction practices. Key Takeaways: 1. The use of steel truss shear connectors in concrete sandwich slabs is adequate for achieving composite activity. 2. Concrete ribs placed along the spanning direction in the insulation layer can improve the failure mode, failure load, and load-central deflection behavior of concrete sandwich slabs. 3. The flexural behavior of concrete sandwich slabs with concrete ribs is similar to that of conventional RC one-way slabs. 4. Adding concrete ribs to the insulation layer and using other truss types can increase the ultimate flexural load capacity of concrete sandwich slabs. 5. The failure of concrete sandwich slabs with truss shear connectors embedded in concrete ribs occurs in the flexural mode. 6. Increasing the thickness of the insulation layer and the concrete compressive strength can increase the ultimate load-carrying capacity of concrete sandwich slabs with concrete ribs.