The Utah Dept. of Transportation’s one-year-old Beaver Creek Bridge is located between the cities of Spanish Fork and Price. The scenic U.S. 6 mountain pass is “notorious for wildlife hits,” says UDOT Structural Designer Rebecca Nix. “The new bridge is an effort to reduce those accidents,” by providing a generous space under the bridge for wildlife to cross in addition to a creek crossing. Many safety projects, such as road widening, bridge replacement and other new crossings, have been completed on U.S. 6 in the last several years.

除了提高安全性外，该桥还为新的增强材料提供了测试地面，可以延长混凝土甲板的寿命。Beaver Creek的混凝土甲板面板使用玻璃纤维增​​强的聚合物或GFRP，而不是传统的钢钢筋。

乌索特（Udot）副结构工程师弗雷德·杜林（Fred Doehring）说：“桥梁降解的第一起是在混凝土内生锈的钢。”桥梁的设计可持续75年或更长时间，而甲板仅持续40至45年。UDOT工程师希望通过在混凝土甲板中使用GFRP来延长桥梁的寿命。

Building Beaver Creek Bridge

The bridge itself was built using accelerated bridge construction, which speeds up projects for the benefit of road users; precast concrete substructures were transported then assembled onsite. Beaver Creek’s deck consists of 24 precast deck panels on precast, prestressed girders with cast-in-place abutments. The deck panels are longitudinally post-tensioned using steel strands threaded through ducts, then secured and grouted.

The GFRP bars used in the concrete deck panels look similar to steel rebar. Since GFRP is much lighter than steel, the deck panels were relatively easy to transport and place. Tensile strength of the GFRP bars exceeds steel at 95,000 psi compared to steel at 60,000 psi. GFRP has lower elasticity, however, which means greater deflection over steel.

Design of the Beaver Creek Bridge deck accounts for that greater deflection; first, by increasing the number of GFRP bars over steel and second, by increasing the thickness of the deck. Two GFRP mats were placed in the top and bottom of each 9.25-in.-thick deck panel.

Since building bridges using GFRP is a relatively new technology, more information is needed about how the material functions under normal freeway traffic. UDOT is partnering with the Dept. of Civil and Environmental Engineering at the University of Utah to monitor the panels for two years to evaluate the suitability of GFRP for future use. U of U Prof. Chris Pantelides is heading the project, which focuses on long-term and short-term monitoring of the GFRP reinforced panels.

According to Pantelides, “GFRP rebar is seen as a breakthrough material expected to extend concrete life by a factor of four times due to its corrosion resistance.” Similar material used in 60-year-old boats shows that “no significant degradation in material strength can be detected.

“虽然大多数改进钢筋的改进都会逐步改善混凝土结构的寿命，但在混凝土暴露于繁重的循环载荷（例如桥梁甲板，装载码头，铁路交叉路口和车道）的应用中，预计将持续20倍长20倍比钢筋混凝土，” Pantelides说。

测试，测试…

在甲板面板内和桥梁上安装了测量应力，温度，举重应力和挠度的设备。预制期间，在两个桥甲板面板中将两种类型的应变测量值连接到GFRP条上。电抗性 - 应变测量测量振动应力和挠度，而振动线 - 应变仪测量桥梁甲板板内的应力和温度。

将位置传感器连接到将甲板连接到大梁的中间隔膜上。将六个加速度计放在大梁的拱腹拱形上，以检测垂直加速度。将集成来自位置传感器和加速度计的数据，以提供有关重载如何导致桥梁运动的信息。

Monitoring of the deck panels using these devices began at the precast yard and continued during transport to the site and through post-tensioning “to investigate the presence of any cracks during handling and monitor the stress levels during lifting, transportation and initial stressing,” says Pantelides. “These are believed to be higher than the stresses that the decks will see in service.” The gauges will continue to monitor the panels for more than five years.

此外，当传感器表明将甲板压力为预定义的扳机值时，现场摄像机会拍摄照片。该照片由手机连接发送给犹他大学研究人员，并与UDOT共享。

UDOT和U的U收集的信息将为GFRP的未来使用做出重大贡献。U的U研究人员正在开发用户友好的软件，这些软件最终将被桥梁检查员使用。Nix正在帮助评估新信息，并认为，通过在现实世界中收集的GFRP数据，UDOT最终将知道如何“基于真正发生的事情设计”。