Structural concrete insulated panels (SCIPs) are an alternative construction technology to traditional wood framing and masonry units for use in residential homes and low-rise structures. SCIPs can be used to erect structurally sound buildings that are economical, energy efficient, and durable while incorporating sandwich technology. This study presents a novel type of SCIP that can be fabricated using off-the-shelf components. A precasting technology for such modular SCIPs is proposed. Full-scale experimental testing of one-way SCIP slabs with three different span lengths (short, medium, and long) was carried out to investigate flexural behavior, strength, ductility, and failure mechanisms. Testing showed good performance of modular SCIPs under gravity loads. Appropriate splicing details for longer-span SCIPs are developed and tested. Results show that the SCIPs tested in this research can provide a moment capacity equal to 66% of the capacity of a fully composite section.
The study of the interaction between reinforcement and concrete is important to ensure the composite action of the two materials. A high bond strength is desirable in the reinforcement–concrete interface to avoid pullout failure. The higher bond of reinforcing bars with concrete provides better performance and increases the capacity and service life of structural elements. Bond tests of smooth titanium alloy bars (TiABs) and 60 kips per square inch (ksi) (414 MPa) steel with concrete are conducted in accordance with the ASTM C234. Based on the experimental results, the bond strength of TiABs is generally found to be higher than that of the steel. The paper also presents some preliminary investigation for identifying appropriate and commercially available mechanical couplers for splicing the TiABs. Since TiABs are more expensive than normal rebars, it is necessary to limit their quantity and use in bridge piers (e.g., plastic hinge zone only). Products from a well-known producer of mechanical couplers in the United States are used in the research. A few mechanical couplers are investigated for splicing of #5 (15.9 mm diameter) and #6 (19.1 mm diameter) pseudo-threaded TiABs. Tensile testing is carried out in accordance with ASTM A1034 to address the 2017 AASHTO Load and Resistance Factor Design (LRFD) requirements and a suitable coupler was identified. The appropriate mechanical coupler was identified to be the coupler that is designed specifically for use with high-strength bars. It uses a cold swaged steel sleeve and is thicker.
<p>The research in this paper focuses on the use of Titanium Alloy Bars (TiABs) in concrete bridge piers located in high seismic zones. The paper discusses a new bridge pier system that incorporates both seismic resiliency and durability concepts. A large-scale bridge pier, reinforced with TiABs and spiral, is tested under quasi-static cyclic loading protocol. The results are compared against a benchmark cast-in-place pier with normal rebars and spiral under the same loading protocol. Based on the testing results, the use of TiABs in concrete piers would reduce rebar congestion up to 50%, provide adequate ductility, and would result in reduced residual displacement following an earthquake. The pier reinforced with TiABs reached higher drift ratios compared to cast-in-place pier. Furthermore, smaller flexural cracks that are likely to appear in the plastic hinge zone during moderate earthquakes are not a major concern for structural performance and durability of bridge piers reinforced with TiABs.</p>
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