Palmetto Expressway - Miami, FL

The Problem

The Palmetto Expressway bridge over NW 167th street, located in Miami, Florida, was designed to carry two lanes of AASHTO HS-20 loading. The bridge with 80 ft. spans consists of an 8 inch thick concrete deck supported by seven AASHTO Type III girders spaced at 6 ft. on centers.

The bridge was damaged due to collision impact from heavy vehicles with heights exceeding the clearance limit. Several over-height vehicles impacted the exterior girder over a period of two days, which resulted in severe damage and a massive loss of concrete section.

View of Damage to Girders

Upon inspection it was evident that the most significant damage occurred in the exterior girder. Interior girders sustained minimal damage and their structural integrity was not compromised.

All prestressing strands in the exterior girder were exposed in two locations across a distance of about 12 feet. The impact resulted in total prestressing loss in four of the prestressing strands.

Almost as important as the loss of prestressing force was the change in cross-section caused by the spalling of concrete in the web and the severe cracking along the flanges of the girder.

The severity of the damage and the location of the bridge presented an emergency situation. The option of closing one lane and replacing the damaged girder was undesirable due to the heavy traffic in this congested area of the city.


Close-up Views of Damage to Exterior Bridge Girder

The MAS2000 Fiber Wrap System presented the best option for restoring the original strength of the girder and completing the repair work with minimum impact on traffic. In addition, the cost of this method was considerably less than that of utilizing conventional repair methods. The MAS2000 Fiber Wrap System provided the desired strength at much lower cost.

The Solution

The girder was first analyzed utilizing a non-linear finite element program developed by SDR engineers. The program is designed to take into account all existing conditions of the damaged girder during the analysis process. 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 MAS2000 Fiber Wrap System is a composite material lamination system capable of restoring the original design strength of the girder. The girder cross-section was first restored to the original shape using high quality concrete capable of achieving full strength within 24 hours.

Application of MAS2000 System

The section restoration was followed by surface preparation according to SDR specifications. Specially designed composite concrete laminates were then applied to the girder over a distance of 30 ft., resulting in complete restoration of the girder

Since traffic flow was extremely high both on and below the bridge, repair was performed late at night, thus reducing the impact on the public and minimizing the risk of accidents.

The repair was performed with a minimum work force consisting of two application engineers and two support staff. Total time for rehabilitation took less than eight hours. The bridge was returned to full service condition the next morning after completing the repair. A specially designed coating was applied to the structure to provide ultraviolet (UV) resistance and an aesthetic appearance.

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


View of Bridge After Repai (Prior to Application of Final Finish Coating)