STOCHASTIC SECTION MODULUS REQUIREMENT FOR CARBON FIBRE REINFORCED PLASTIC PULTRUDED BEAMS

ABSTRACT

Six Carbon Fibre Reinforced Plastic (CFRP) pultruded beam section from The Pultex® Pultrusion Design Manual Volume 4 – Revision 8 Copyright © 2004 by Creative Pultrusions Inc., were assumed to be simply supported doubly symmetric I-section, with uniformly distributed load of 3.5kN/m2 applied over the length of 3.050m each. A comparative analysis of section modulus effect under the load and resistance factor design (LRFD) and allowable stress design (ASD) was considered based on computer program using FORM5 and ABAQUS 6.10 CAE that was used to generate results for reliability and finite element analysis respectively. Safety indices generated for reliability analysis from FORM5 based on load and resistance factor design (LRFD) and allowable stress design (ASD) format by varying load ratio and section modulus was analyzed. The general conclusion from the results are that, the safety of all the beam section increased with increase in section modulus by average of 1.1% for both load and resistance factor design (LRFD) and allowable stress design (ASD) format. The implication of this is that, when the load and resistance factor design (LRFD) and allowable stress design (ASD) design format is employed, the reserved elastic moment of the carbon fibre reinforced plastic (CFRP) beams are fully utilized, with the possibility of the beam reaching its full elastic moment at higher loading, hence section modulus can be reduced, that would result in lower beam section. Also for finite element analysis (FEA) considered using ABAQUS 6.10 CAE in which the stresses, displacement, strain on the carbon fibre reinforced plastic (CFRP) pultruded beams obtained are analyzed and graphically presented and based on the design parameters, the deformation and the Von Mises stress distribution obtained indicates that, the field of high stress is only shown in Model 1 with 661.2N/mm2 which is minimal under the said load when compared to bending and tensile strength of 3300N/mm2 for carbon fibre reinforced plastic (CFRP).

CHAPTER ONE

1.0  INTRODUCTION

1.1 General

Structures are designed and constructed to supply sufficient capacity against vertical and lateral load demands with the purposes of providing life safety and preventing collapse. However, many examples of catastrophic results such as failure or damage of buildings, bridge piers, etc., are seen all over the world. These can be due to intentionally or unintentionally created deficiencies during service life and lack of control that needs to be provided both at the design and construction stages (Ümit, 2007). By definition, Fibre Reinforced Plastic (FRP) is a composite of two material groups: (1) reinforcing fibre which provides the strength; and (2) polymer resin matrix such as epoxy, to bind the reinforcements together (Nanni, 1999).

During the last two decades, Fibre Reinforced Polymer (FRP) composite materials have seen a steady increase in their applications for construction. They have been increasingly popular because of their advantages over conventional construction materials including a high strength-to-weight ratio, corrosion resistance leading to increased durability and lower maintenance costs, and their ability to be pultruded into various shapes whose mechanical properties can be custom-tailored for specific applications (Bank, 2006). However, significant barriers for wide-spread adoption still remain which include their high initial cost, the lack of understanding of their physical behaviour by practicing engineers, and the lack of a reliability based on Load and Resistance Factor Design (LRFD) standard governing their design (Ellingwood, 2003).