Sayed-Ahmed, M.. Concrete Research Letters Vol. 4 (2) -2013 591 www.crl.issres.net Vol. 4(2) – June 2013 Nonlinear Time-Dependent Behaviour of Concrete Insulated Panel Mahmoud Sayed-Ahmed c Department of Civil Engineering, Faculty of Engineering, Architecture & Science Ryerson University, CANADA Abstract The insulated structural sandwich panel is a composite laminated structure, made of two stiff skin faces and lightweight thick core. The low-density low-shear rigidity laminated think core (foam, honeycomb) is structurally connected to the laminated skin faces by structural adhesive. The rigid skin (concrete, steel, wood) faces provide high bending stiffens for such lightweight structure, while the core resist the local buckling of the skin faces. The time-dependent deflection behaviour of the concrete insulated panel (CIP) varies with the change of the span-to-depth ratio for the instantaneous deflection, and the cyclic change of temperature and relative humidity over time. This paper discusses the nonlinear theoretical analysis for long-term creep deflection under sustained load that accounts for loads, time, temperature and relative humidity. Keywords: Sandwich Structure; Concrete Insulated Panel, Time-Dependent; Nonlinear Modelling. 1. Introduction The Insulated Panel Systems (IPS) is an engineered composite product composed of an insulating core i.e. foam core sandwiched to provide the insulation and rigidity, and two face-skin materials to provide durability and strength. The skin material may take the form of metal, concrete, or wood products [1]. The change of skin-faces types for the Insulated Metal Panel (IMP) leads to different commercial products like: Steel Insulated Panel (SIP) using galvanized steel sheets, or aluminium sheets. IPS may use concrete to form Concrete Insulated Panel (CIP), Insulated Precast Concrete (IPC), or use wood products to form Structural Insulated Panel (SIP), and Permanent Wood Foundation (PWF). All IPS are structurally compared to I-Beam where the foam core acts the web, while the skins act as the flanges. In case of flexural loading, all elements of the IPS are stressed; the skins are in tension and compression, while the core resists shear and buckling. Under in-plane axial loading, the facing of an IPS acts as slender c Corresponding Author: Mahmoud Sayed Ahmed Email: m.sayedahmed@alumni.ryerson.ca Telephone: +883.510.009.086.476 Fax: +20.2.26327563 © 2009-2013 All rights reserved. ISSR Journals