结构监测案例研究。Resensys

在 Fredericks 电解倾斜传感器的帮助下,提供世界上最节能的无线监控解决方案。

介紹

There are over 612,000 bridges in the United States and as of February 2017, almost 10% of them need to be repaired or replaced according to The American Road and Transportation Builders Association. That means that there are currently over 55,000 bridges that require real-time monitoring in order to avoid a catastrophe like the 2007 bridge collapse in Minneapolis, Minnesota.

什么是Resensys?

Resensys提供具有成本效益和可扩展性的解决方案,帮助评估这些桥梁和其他公路桥梁的结构稳定性,以便准确定位结构问题,并计划进行必要的维护和修理,以确保桥梁的安全性和使用寿命。

他们的无线结构健康监测解决方案SenSpot™适用于现有桥梁和在建桥梁,其特点是体积小、成本低、易于安装的无线传感器,可测量影响桥梁性能的各种变量。

Resensys公司总裁兼首席技术官Mehdi Khandani博士在马里兰大学进行的研究中诞生,是实时地质结构监测领域的领导者,并提供了最耐用的无线桥梁监测系统,其最低预期寿命为10年。欲了解更多信息,请访问http://www.resensys.com

The Challenge

尽管市场上还有其他用于监控基础设施的传感器,但瑞思思设备的与众不同之处在于其超低的功耗,仅使用约4微瓦,约为普通灯泡的1亿倍。这意味着SenSpot传感器只需使用一块½-AA的小电池,就能拥有至少10年的使用寿命。

为了提供如此高效、准确的监控系统,Resensys需要找到一种分辨率高达千分之一度的倾斜传感器,同时还要提供低功耗、耐用性和至少10年的产品寿命。

解决方案 

Dr. Khandani and his team thoroughly evaluated a variety of MEMS and other electrolytic tilt sensors and concluded that the Fredericks Single-Axis Narrow-Range Electrolytic Tilt Sensor (PN 0703-0711-99) significantly outperformed competing products in terms of long term repeatability and resolution.

“Qualitatively, Fredericks’ devices were an order of magnitude better than both MEMS and competing electrolytic sensors,” says Dr. Khandani. “In our application, repeatability is very important and none of the competing products did as great as Fredericks products did.”

结果 

With the help of Fredericks’ electrolytic tilt sensors, Resensys is able to offer the world’s most energy-efficient wireless monitoring solution that helps keep travelers safe with around 5,000 SenSpot™ tilt units in use in the US and around the world.

“Our decision to use Fredericks products was driven by the excellent accuracy and durability of their tilt sensors,” Dr. Khandani adds. “Such long term and high-quality measurements help capture the smallest movement and instability on critical bridge components.”

SenSpot™在行动。Patapsco河大桥

In the Spring of 2014, cracks were spotted in the girders and piers of the I-70 Patapsco River Bridge near Baltimore, Maryland. Engineers found that non-responsive bearings had caused damage to piers and steel girders of the bridge, which led to its closure in June 2014.

Repairs were made, retrofits were applied, and a SenSpot™ monitoring system was installed in July 2014 to detect any further changes. More than 40 SenSpot™ units were mounted on the bridge, including 12 tilt sensors located on the bridge’s rocker bearings to monitor the movement pattern and detect non-responsiveness or over-responsiveness. In addition, six high-resolution tilt sensors were mounted on the bridge’s piers to monitor the deflection and rotation of the bridge rocker bearings caused by cold temperatures.

Early results from August to November 2014 found that the bearings on two piers were non-responsive to temperature changes and an additional bearing saw only 20% of expected movement. Data collected through Spring 2015, however, showed that the bearings had an unprecedented response to the robust retrofits (combined with especially cold winter), and by March 2015 all piers and respective bearings were fully responsive.

 

Prior to February 2015, the bearings and retrofits weren’t responding properly to changes in temperature, but by mid-Spring, they proved to be fully responsive and have seen continued success in the years since.

 

Dr. Khandani notes, “After more than four years of continuous monitoring, we are pleased that the Fredericks devices used in SenSpot™ sensors produce very consistent, repeatable, and high-quality measurements of tilt and inclination at sub-arc-second resolution.”

Before alerting the Maryland State Highway Administration, the Resensys team worked with engineers at Fredericks to confirm the data. At Fredericks, we take a partnership approach to our relationships with customers, and customer satisfaction is a priority. We have dedicated representatives and engineers committed to providing highly responsive service, and our customers have anytime-access to our leadership team, made possible in part by our “not too big, not too small” operation.