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A Decision Support System for FRP Laminate Strengthening of Bridge Girders Based on Lifecycle-Cost Analysis

I. Research Problem Statement
Bridge maintenance often leads to situations where bridge officials are faced with tough decisions to make. A classic scenario is that of a deficient bridge that is up for evaluation for which it is not clear whether a full bridge replacement or a limited strengthening operation is better. In general, the alternatives available are:
X Do nothing solution
X Limited strengthening
X Large scale strengthening
X Replacement of superstructure
X Replacement of entire bridge

Obviously, decisions are solely made on cost basis. However, determining of the cost of each alternative is not straightforward simply because of the uncertain nature of the future of most repair schemes. It may cheaper to accept a limited repair alternative, however further work will need to be done in 2 years. On the other hand, a replacement of the superstructure may be costly, but would obviously last a lot longer. In other words, the initial cost is not what should be considered in making strengthening decisions. The approach which relies on the cost over the entire life of the structure is often referred to as "Life-cycle Cost Analysis". As described in the following section, certain information is needed to perform such analysis. Sometimes such information is readily available, but in some cases, it needs to be developed such as the case for FRP strengthening which, falls under limited strengthening solution.

II. Literature Search Summary
A review of the literature shows that many issues related to this research topic have not been studied. Most of the work in literature describes experimental programs that covered a limited range of parameters. Currently, there are no guidelines for how FRP strengthening would cost over the life of the structure. In other words, the following questions have no answers:
1. How long before the bridge needs to be re-strengthened?
2. Is it possible to reapply the FRP material, or are new materials needed?
3. In case of extreme deterioration of an FRP strengthened bridge that requires a complete re-strengthening of the bridge, does the previous strengthening history (e.g. surfaces modified by presence of epoxies) prevent such strengthening?
4. Does FRP strengthening require extra inspection since it is relatively new?

It is believed that a Decision Support System (DSS) which relies on the life-cycle cost analysis of structures is in the best interest for state DOTs. Such a DSS would help officials in making sound FRP strengthening decisions based on a scientific approach.

III. Research Objective
The objective of this project is to produce guidelines and recommended procedures for Decision Support System (DSS) which relies on the life-cycle cost analysis for FRP Strengthened structures.

IV. Estimate of Problem Funding and Research Period
Recommended Funding: $300,000

Research Period: 18 Months

V. Urgency, Payoff Potential, and Implementation
There are few guidelines or recommended field procedures available to evaluate the life cycle cost analysis of FRP strengthened structures. It is anticipated that the results from this research will help officials in making sound decisions regarding FRP strengthening of bridges based on a rational approach. The DSS will be transparent such that it can be utilized by users with little or no background on the complicated formulations behind it.

The proposed research will develop a rational approach for rehabilitated bridge systems, and is expected to produce design recommendations for strengthening of bridges using FRP. The need to have design techniques available, and personnel trained in design with FRP will become increasingly apparent as the technology moves into widespread use.
The long-term benefits of this research include lower maintenance costs and longer service lives for FRP bridges. This will reduce the annual backlog for bridge replacement, resulting in lower costs to maintain or improve the transportation system. The results of this research will be used by bridge design engineers, bridge maintenance personnel, contractors, specialty (FRP inspection/repair) subcontractors, and FRP manufacturers.
The proposed research will address AASHTOs identified business need (See NCHRP 20-7, Task 121) to develop and apply sustainable materials, products, structural systems, and technologies that reduce life-cycle costs, extend useful life, and improve the constructability of bridges. Specifically, it addresses the objective of developing policies, procedures, and methodologies that enable the acceptance and adoption of new technologies.

Research results will be implemented with the production of an AASHTO Recommended Practice for life cycle cost analysis of FRP repair bridges, bridge inspection and maintenance, and repair of existing FRP strengthened bridges.

VI. Person(s) Developing the Problem
Mohsen Shahawy
President, SDR Engineering, Inc.
2434 Oak Dale St.
Tallahassee, Fl 32308
Tel: 850-222-2737
Fax: 850-386-9197
E-Mail: shahawy@sdrengineering.com

VII. Date and Submitted by
Issam Harik
E-Mail: Issam Harik

Sponsoring Committee:AKB10, Innovative Highway Structures and Appurtenances
Date Posted:12/28/2006
Date Modified:10/29/2010
Index Terms:Bridge girders, Life cycle costing, Life cycle analysis, Fiber reinforced plastics, Fiber reinforced polymers, Fiber reinforcement, Laminates, Decision support systems, Bridge maintenance, Strengthening (Maintenance), Guidelines,
Cosponsoring Committees: 
Bridges and other structures

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