Tilt-Up Partially Composite Insulated Wall Panels

Abstract

This research project was initiated to investigate the behavior of load-bearing concrete insulated wall (CIP) panels for use in tilt-up construction. The primary objective was to understand the inelastic behavior of these panels so that engineers could perform a proper second-order analysis for combined axial and out-of-plane loading. Toward this aim, the Tilt-up Concrete Institute (TCA) and wythe connector suppliers Innstruct, Thermomass, HK Composites, Dayton Superior, and IconX, funded this study. Since tilt-up panel testing of similar scope had not been done since the 1980s on panels of lower height, there were several goals for this testing. This represented an opportunity to validate the current ACI code alternate slender wall analysis method and provide a set of control panels for testing solid tilt-up panel behavior. Testing solid panels and CIPs of 40 ft span, a length typical of contemporary construction, was critical so that such slenderness ratios could be observed and significant second-order panel behavior could be identified. As part of this, the research team created a modified version of the slender wall design method to predict second-order load and deflection behavior in the post-cracking range in CIPs. For solid panels, the 1980s testing program popularized the “slender wall design method” outlined in ACI 551 and the goal of this newer methodologies is to do the same for CIPs. Additionally, horizontal shear failure analysis methods were investigated to enable design against such failures.