I-75 Near Naples, FL

The Problem

The bridge, located on I-75 near Naples, Florida, is 170 ft. long and has three simple spans. The main span is 105 ft. long and consists of an 8 inch thick concrete deck supported by seven AASHTO Type IV prestressed concrete girders spaced at 6 ft. centers. The bridge was designed to carry two lanes of AASHTO HS-20 loading.

The bridge was severely damaged in 1998 when a construction vehicle carrying a large crane attempted to cross under the bridge. The driver failed to recognize the height clearance limitation and did not lower the boom of the crane. The severe collision resulted in extensive damage to several girders.

The seven prestressed Type IV concrete girders were damaged to different degrees. The extensive damage to three girders forced the closure of one lane on I-75 until a structural evaluation was conducted.

View of Damaged Girders

All damaged girders exhibited severe cracking, section loss, and loss of prestressing strands. Prestressing strands were exposed in two locations for a distance of approximately 15 feet.

The severity of the damage and the location of the bridge presented an emergency situation. The option of closing the bridge and replacing the three severely damaged girders would have been a last resort due to the heavy traffic on I-75.

The MAS2000 Fiber Wrap System presented the best option for restoring strength to the girders and completing repair work with minimum impact on traffic. In addition, the cost of repair was considerably less than utilizing conventional repair methods.


Typical Damage to Bottom Flange	Damage Inspection

The Solution

Standard rehabilitative measures could not be used; severe cracks propagated from the damaged region to the diaphragms on either side. Structural evaluation revealed that the bridge was no longer capable of withstanding service load stresses. The MAS2000 Fiber Wrap System is an engineered carbon composite lamination system designed to restore strength to the original level and provide long-term durability.

The damaged girders were analyzed using a non-linear finite element program developed by SDR engineers. The program is designed to take into account all existing conditions. The program was developed and calibrated through extensive laboratory and field-testing and yields extremely accurate results. The results of the analysis were used to design the optimum restoration solution.

The cross section was first restored to the original shape using high quality concrete capable of achieving full strength within 24 hours. The section restoration was followed by surface preparation according to SDR specifications. The MAS2000 Fiber Wrap System specially designed composite laminates were then applied to the concrete girders over a distance of 50-ft., resulting in complete restoration of the girders.

Since I-75 is a major transportation artery, the damage to the bridge presented an emergency situation requiring the fastest method of repair. The rehabilitation crews were able to apply the MAS2000 Fiber Wrap System and return the bridge to full traffic in less than one week.

The original appearance of the structure was restored and enhanced by painting the laminates with a specially designed ultraviolet (UV) coating.

The MAS2000 Fiber Wrap System proved to be economical, quick and easy to apply.


Application of MAS2000 Fiber Wrap System	Rehabilitated Girders