Design Methodology - Design of the wall panels is done by the precast producer or their engineering consultant. The basic design methodology follows the PCI handbook, but with the proven contribution of the Nu-Tie shear connector furnished by Hughes Brothers. Design spreadsheets and validating reports are available to the licensed producer.
THiN Wall systems are only 25% as stiff as solid panels of the same span and thickness. Tall, slender THiN-Walls are designed with conservative assumptions: (a) P-Delta analysis is performed with only 25% of the stiffness of an ideally composite section, (b) cracking moment is reduced by 25% and also applied to factored load effects (no cracking allowed even under factored strength limit state), and (c) flexural strength satisfied with strands which also satisfy a requirement for minimum prestress 225 psi. This conservative approach has resulted in several million square feet of successfully completed projects around the US.
Thermal Bowing - All composite walls exhibit thermal bowing to various degrees. This behavior is accounted for by designers. One of the great advantages of THiN-Wall is the low modulus of elasticity of the connectors. They stretch and shorten as the outside temperature changes relative to the inside conditioned space. More pronounced bowing would result when stiff concrete block-outs and/or steel connectors are used to achieve composite action. The accompanying figures show the degree of composite action used in design of THiN-Walls and the relatively small bowing expected in service.
PCI peer review Paper - The peer reviewed paper, “Optimized NU Sandwich Panel System for Energy, Composite Action and Production Efficiency” describes the technical and performance aspects of the THiN-Wall insulated concrete wall panel system.
Engineering Design Tools - Design tools and additional resources are available to Licensed Precast Producers and directly from those producers to the designers who support them.