Study in the Improvement in Strength and Stiffness Capacity of Steel Multi-sided Monopole Towers Utilizing Carbon Fiber Reinforced Polymers as a Retrofitting Mechanism

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Date

2005-01-07

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Abstract

Wireless service is a fast developing market which places inherent demands on providers to maintain constant, reliable networks through which the service is offered. In order to facilitate this growing need, wireless providers must install equipment which creates and strengthens these networks. Telecommunication towers are popular solutions for placing antennas at elevations which develop the line of sight trajectory and signal coverage the networks demand. However, as telecommunication towers have a finite limit to the amount of equipment installation, they must be strengthened to support additional equipment expansion. Research completed at North Carolina State University proposes a strengthening solution utilizing high-modulus carbon fiber polymers as a retrofitting mechanism for monopole telecommunication towers. The experimental program, along with development of an analytical model, investigates the behavior and validates the effectiveness of carbon fiber in increasing the flexural capacity of existing monopole tower structures. The experimental program consists of testing three large scale monopole towers using high-modulus sheets, high-modulus strips and intermediate-modulus strips to determine their respective effectiveness in increasing the flexural strength enhancement. The three tests are designed using approximately the same reinforcement ratios, as well as identically sized monopole towers, to compare the effectiveness of the three strengthening systems regarding the increase in strength and stiffness. Design nominal strength and stiffness increases were in the range of 20 to 50% which was found in the measured values. The three tests were subjected to the same load setup and tested until failure to capture the elastic and inelastic behavior and the strength increases, as well as the failure mode of the strengthened tower. The analytical models were designed to simulate the monopole?s behavior before and after strengthening using conventional methods of analysis typically applied to tower design. The analytical model is based on moment-area and transformed section theories to predict the strain and deflection behavior in the elastic range of the steel and carbon fiber. Parametric studies are conducted to study the effect of the numerous variables with respect to strengthening these types of towers.

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Keywords

carbon fiber reinforced polymers, CFRP strengthening, monopoles

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Degree

MS

Discipline

Civil Engineering

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