الفهرس 
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Abstract
Recent interest in Glass Fiber Reinforced polymers (GFRP) for structural members has been driven by the need for better-performance materials in construction, including improved resistance to environmental conditions and higher durability. GFRP offers advantages such as lightweight, high strength-to-weight ratio, corrosion resistance, and Non-conductive. Filament Winding, Vacuum Bagging, Centrifugal and Pultrusion processes are considered the most important and widely used mechanical fabrication techniques for FRP structural members around the world. Centrifugal process is used now in Egypt to produce GFRP poles. The main problem of these poles is the lower stiffness and more prone to deformations compared to steel and concrete.
The main goals of this research are to:
Investigate the stiffness and strength characteristics of the GFRP poles with and without openings considering the effect of shear deformations,
Propose three different techniques used to improve stiffness of the GFRP poles (internal bracing - outer steel angles - internal steel stub),
Develop mathematical and numerical models to study the effect of some important parameters on stiffness and strength characteristics of the GFRP poles,
Create a decision support model for pole selection. The decision support system model can aid in selecting optimal electrical poles from different materials based on customer and producer demands.
The research program includes four different phases (experimental, mathematical and numerical phases) as follows:
The experimental phase was done on five full scale GFRP poles and coupons cut from the poles and tested according to ASTM standards to determine the GFRP material properties. All the stiffness and strength of the poles together with the material properties were determined. This part studied the effect of three different techniques used to control the lateral deformations of the GFRP poles. Also, the effect of presence of openings in the GFRP poles was also investigated.
The mathematical phase was done by modifying some mathematical equations driven from the well-known beam theory and used to calculate the most important stiffness properties (Flexural modulus “E” & Shear modulus “G”). This phase studied the effect of shear deformation and decide when it has to be considered and when it can be ignored without a significant error.
The numerical phase was done using finite element (FE) method. Firstly, the numerical model was verified using the obtained experimental results to ensure the accuracy of the model and then the proposed model was used to investigate the effect of some important parameters. The considered parameters are the thickness of GFRP poles, location of the opening, corner radius of the opening and the dimensions of the supporting steel stub and base steel plate.
The last phase of the research provides a decision system systematic approach for selecting the most appropriate poles for specific applications, taking into consideration the specific requirements and constraints of the project.
The main conclusions of the research are:
• Non-homogeneity of FRP Material affects the Strength characteristics more than Stiffness characteristics.
• Due to large deformations of GFRP poles, the values of shear deformations have to be considered in the design calculations.
• For design purposes, the flexural modulus E = 36705 MPa, shear modulus G = 638 MPa and a flexural strength = 270 MPa can be used rather than the conservative values given by the manufacturer.
• The presence of an opening hole has a Minor effect on Stiffness (6 %) and a Major effect on Strength (70 %).
• Increasing the Component of the Steel Supporting System will result in a decrease in the ultimate load due to the local failure of these components.
• The used fixation method of “outer steel angles” is considered the best one.
• In order to neglect the effect of shear deformations with an error does not exceed 10%, the span to radius of gyration (L/r) should be higher than 100 for design purposes.
• The Stress Gradient and the Scale effect have a major effect on the Strength Properties.
• The proposed FE numerical model can be used accurately to evaluate stiffness and strength of GFRP poles considering all the parameters affecting their values within an error does not exceed 3%.
• The suggested decision system systematic approach enables decision-makers and designers to choose the best system for different types of electrical poles based on client satisfaction KPIs and carry out analytical research to make informed decisions