Graduate Studies

 

First Advisor

Marc Maguire

Department

Engineering

Date of this Version

Spring 2024

Document Type

Dissertation

Comments

Copyright 2024, Salam A. Al-Rubaye. Used by permission

Abstract

Insulated concrete panels (CIPs) have been used for over 60 years for their both structural and thermal resistance. The flexural behavior of CIPs has been investigated in recent years. The CIPs are rapidly becoming ubiquitous in the precast industry, and the tilt-up industry is initiating a study to determine their effectiveness as a tilt-up product. There are several known challenges associated with a tilt-up version of a partially composite wall and likely other unknown challenges. This study was initiated to investigate the behavior of load-bearing concrete insulated wall 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. This dissertation contains information related to the testing of solid and partially composite insulated wall panels that integrated proprietary wythe connection systems. 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 to observe such slenderness ratios and identify significant second-order panel behavior. In addition, 24 small-scale panels of 11 ft-long were monitored for shrinkage and tested under flexural load to determine the effect of shrinkage and the reinforcement ratio on the cracking moment and tension stiffening model. Using the unique experimental information herein, The Shear Flow method and a new method termed The Shear Slip Method were evaluated to estimate horizontal shear failure. The Shear Flow method, when used properly, results in perhaps an overly conservative prediction of horizontal shear strength but does not match the observed data well. The Shear Slip Method relies on an assumption of the failure slip mechanism (as observed from these and other experiments) and the double shear data to determine a maximum horizontal shear strength while incorporating the ductility of the connectors. This method was found to predict horizontal shear failure both accurately and conservatively. A Modified Slender Wall Method was developed to estimate the contribution of connector slip to the shear deformations in a straightforward way. When using this method to predict the deformations at failure for panels that experienced flexural failure it produced accurate and conservative results. For panels that are controlled by horizontal shear failure, this method can be overly conservative for flexural deformations because it is intentionally simplified. Another method termed the K123 method was demonstrated that can better predict panel deflections and horizontal shear failures using matrix analysis or other methods. The results from the experimental program and the panels from the literature were used to calibrate the OpenSees model. A large parametric study consisted of 648 models using OpenSees to evaluate different lengths of CIPs and connector types that were outside of the experimental program scope to demonstrate the effect of the slenderness and axial load. The parametric study confirms that the proposed methods agree well with Opensees models and confirm the findings from the experimental program. This project’s findings serve as a foundation for developing a design guide for Tilt-up CIP.

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