Research Activities: 2001

Strengthening of Martin Springs Outer Road Bridge, Phelps County, Mo.




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Sequential Number


Matching Research Agency

Missouri Department of Transportation (MoDOT)

Principal Investigator

Antonio Nanni
Jones Professor of Civil Engineering
Missouri University of Science and Technology
224 ERL
Rolla, MO, 65402
p(573) 341-4497
f(573) 341-6215

Student Involvement

(1) One graduate student

Project Objective

The proposed project aims at demonstrating the feasibility of fiber reinforced polymer (FRP) systems for the flexural strengthening of concrete bridge structures.

Project Abstract

The bridge selected for this demonstration project is the three-span concrete slab bridge located on Martin Springs Outer Road in Phelps County. This bridge is composed of a 14 in thick solid reinforced concrete (RC) slab for which posting can be removed as the result of the proposed strengthening scheme. In the state of Missouri and surrounding Mid-America states, several bridges experience similar conditions and are in urgent need of strengthening to remain functional. This demonstration will consist of three major tasks, namely; (1) design, (2) load tests before and after strengthening, and (3) field construction. It is envisioned that this strengthening technique will lead to a bridge strengthening protocol for consideration by MoDOT for future applications.

Anticipated Benefits

The proposed project will lead to a strengthening protocol for consideration by MoDOT for structurally deficient short-span bridges consisting of reinforced concrete solid-slab construction.

Modal Orientation

The objective of the strengthening is to provide the necessary transverse reinforcement so that load posting can be removed. Two commercially available carbon FRP systems are proposed for this demonstration. Some of the material specifications relative to the selected systems are presented in Table 4. Other systems of equivalent characteristics are available in the marketplace.

Two different techniques involving the use of FRP materials were considered for this project demonstration, namely: (1) Near Surface Mounted (NSM) tapes, and (2) externally bonded laminates. Both of these schemes are adopted in this project. FRP material properties used in the design calculations are reported in Table 4.

For the alternative using two (2) plies of 12 in-wide CFRP laminates (see Figure 8a), the cracking moment is achieved with a laminate spacing of 36 in on-center (fMn=16.5 k-ft). Using two (2) CFRP tapes placed in each groove (see Figure 8b), the cracking moment is achieved with a 9-in groove spacing (fMn=15.5 k-ft). Figure 9 shows the two strengthening schemes proposed for this demonstration project for the three bays, while and Table 5 summarizes the amount of material needed for the bridge upgrading.



Project Start Date:02/06/2002
Project End Date:07/31/2002

Relationship to other Research/Projects

This research program expands the use of FRP, used as strengthening materials by proposing applications on civil structures. The outcomes of this study will be applicable to MODOT systems. Based on the findings, guidelines and recommendations are prepared to encourage a broader range of rehabilitations applications. The ability to repair existing bridges without taking them out of service has broad financial implications.

Technology Transfer Activities


Transportation Research Board Keywords

Three-span concrete slab bridge