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Insulated precast concrete sandwich wall panels are commonly used for exterior cladding on building structures. The insulation is sandwiched between exterior and interior concrete layers to reduce the heating and cooling costs for the structure. The panels can be designed as composite, partially composite, or noncomposite. Shear ties are used to achieve these varying degrees of composite action between the interior and exterior concrete layers. A variety of shear ties are available for domestic construction. An experimental study was conducted to assess the relative strength and response of these commercially available ties. Fourteen different shear tie types were examined, the failure modes and responses were quantified, and simplified engineer level multilinear strength curves were developed for each connection. The test results indicate that shear ties used in sandwich wall construction have considerable variation in strength, stiffness, and deformability. The maximum shear strength of the discrete tie...

Owing to enhanced filling ability, self-consolidating concrete offers accelerated casting and superior quality control during construction. However, its high fluidity and high placement rate increase the lateral pressure on the formwork, necessitating an extensive supporting system to retain fresh mixtures in a desired shape. Current recommendations of formwork design for self-consolidating concrete adopt the concept of hydrostatic pressure, even though the measured pressure could be less than the recommended level. This study shows that mineral admixtures such as processed clays can appreciably lessen the formwork lateral pressure. In addition, the correlation between the formwork pressure response and the loss of slump flow is derived, providing an approximate method to estimate the reduction in formwork pressure.

A research program was conducted to assess the capability of conventional non-load-bearing insulated precast concrete exterior wall panels to withstand blast loadings. Typical construction details from the tilt-up and prestressed concrete industries were examined. The sensitivity of insulation type, reinforcement, foam thickness, and shear tie type on the flexural resistance was assessed. Forty-two single-span static experiments were conducted on 14 different panel designs. From the results of these experiments, resistance functions and deformation limits for insulated concrete sandwich panels were determined. The resistance functions were used to develop predictive dynamic models for panels subjected to blast demands. The models were found to be accurate in comparison to measurements from four full-scale blast detonations. The findings of the research indicate that both prestressed and non-prestressed insulated concrete wall panels meet current rotational limits defined by the U.S. Army Corps of ...

Self-consolidating concrete (SCC) is a recently developed innovative construction material. No additional compacting is needed because of its high filling ability; consequently, the labor cost of compacting is economical. SCC, however, needs a stronger formwork that can resist the higher lateral pressure of cases that use ordinary concrete. This study uses the proposed two-function model to: 1) characterize the pressure response of a fresh SCC mixture; and 2) evaluate the maximum pressure that develops on the formwork. Various SCC compositions were experimented with to show the validity of the evaluation. The experimental results and analytical interpretation suggest that the maximum lateral pressure allowed in the design of the SCC formwork could be determined from 2 parameters that depend on the placement rate and duration of the placement.