The Fred Hartman Bridge near Baytown, Texas is currently one of only two cable-stayed bridges in the Texas Department of Transportation (TxDOT) inventory. Recent concerns regarding the observed large amplitude vibration of stay-cables has prompted a review of the in-service performance of the bridge. 

The Fred Hartman Bridge is about 2-1/2 miles (4 km) long and crosses the Houston Ship Channel connecting Loop 201 in Baytown with State Highway 225 in LaPorte. The bridge consists of twin decks, each approximately 78 ft (24 m) wide. The main cable-stay unit is 2,475 ft (754 m) long and consists of five spans. The main span length is 1,250 ft (381 m). The cable-stay unit superstructure consists of steel girders, transverse floor beams, and a composite concrete deck. The 192 stay-cables project in a fanned configuration from each side of four diamond shaped concrete towers and attach to the outside edges of the bridge decks. The bridge was opened to service in 1995. 

Large amplitude stay-cable vibrations have been observed numerous times at the Fred Hartman Bridge, usually during a rain storm with relatively low winds. This phenomenon has been called rain-wind induced vibration, or just rain vibration, and has been observed on many cable-stayed bridges around the world. Approximately 100 welds connecting the steel stay transition pipes to the superstructure are known to have cracked or failed, presumably from large amplitude, low cycle fatigue caused by the vibrating cables. The large amplitude vibrations, transition pipe weld failures, and concerns regarding the durability of the stay-cable strands and corrosion protection grout prompted TXDOT to initiate an evaluation and repair of the bridge.

The evaluation consisted of several components including a design/construction document review, literature review, aerodynamic analysis, dynamic response analysis, component analysis, failure analysis, wind tunnel or flow chamber evaluation, field monitoring, field evaluations, and the development of various repair options. The repair options produced by WDP consisted of: 

• Restraining the stays with restrainer cables 
• Providing additional damping to the stays via the use of viscous dampers
• Use of aerodynamic dampers along the stays 

The evaluation was performed as a team effort between WDP, TxDOT, and several universities. WDP had the lead role acting as program manager and performing many evaluation tasks and nondestructive testing.

Services WDP used on this project included: 

• Vibration Testing 
• Fatigue Assessment 
• Dynamic Response Analysis 
• Repair Recommendations and Design
• Development and Evaluation of Repair Options 
• Program Management