BEHAVIOUR, ANALYSIS AND DESIGN OF FRP SANDWICH STRUCTURES

Abstract

FRP sandwich structures possess enhanced durability, outstanding strength and light weight properties and represent a new and promising solution to the shortcomings of several traditional materials. FRP sandwich structures have a great potential to integrate into the bridge infrastructure. However, the application has some design difficulties due to the complicated behavior of sandwich composites and presence of multiple design variables and objectives. This leads to a complex design problem and the optimization of FRP sandwich structures is rarely straightforward. Although many experimental and numerical studies have been conducted, yet there is no simplified protocol available for the design of FRP Composite bridges. The codes and standards do not have explicit provisions for designing composite materials in bridges and this limits its full and widespread utilization. This research focuses on the development of a methodology for the design optimization of FRI sandwich structures for bridge deck application. The idea of using a FRP sandwich deck is to provide an alternative to the existing decking of bridges. A two stage Finite Element Analysis has been used to design the panel. The validity of the design methodology has been established by fabricating an experimental panel and then carrying out its testing in laboratory. The good agreement between the experimental performance and the numerical predictions shows that the proposed design methodology can be effectively used to design FRP sandwich deck panels. An innovative optimization technique wherein the FE model of the sandwich deck panel has been coupled with an iterative optimization scheme has also been developed during the research work. The proposed technique has the capability to carry out structural as well as material optimization and has been used to demonstrate the potential of the technique by carrying out the optimization study for a deck panel of a classic Portable bridge subjected to IRC Class 70 R loading. The thesis also presents a simple procedure for design of bolted joints for FRP deck panels. The procedure is based on bolted connections for steel structures and is suitably modified keeping in view of the anisotropic behavior of FRP composites. The novel features incorporated in the design and optimization methodology have been highlighted and the performance comparison of sandwich deck panels with the existing decking setups shows that the overall man-effort and the time taken to launch and dc-launch portable bridges can be significantly reduced by using these panels.