Monitoring historic Harvard Stadium

Author:T/F/D

Harvard Stadium, which was completed in 1904, gained National Historic Landmark status in 1987. It was the first of many college football stadiums built in a U-shaped Colosseum style and the first construction using reinforced cast-in-place concrete on such a scale. As expected for a 100+ year old building with a pioneering construction technology, there is on-going corrosion to be contended with and the resulting maintenance costs are high. Its owner, Harvard University, needs to make annual decisions about the maintenance budget. In 2018 Harvard contracted structural engineering firmSilmanfor advice. To help guide Harvard to make appropriate decisions on the life-safety of the stadium, Silman developed a customised material testing and monitoring strategy. This included Leica Geosystems total stations and software, which collects real-time data about the building’s performance to inform recommendations about the landmark’s future.

Maintaining the home of the forward pass

哈佛大学体育场文化和具有重要意义architecturally. The dimensions of the stadium were even a factor in the evolution of American football. In 1906, a committee of colleges and universities met to set rules to make the early game safer and one suggestion was to make the pitch wider. The Harvard Stadium however was recently finished and could not be widened. Thus, the proposal was rejected in favour of allowing forward passing. A landmark piece of architecture, the Stadium is the first vertical concrete structure to use reinforced structural concrete. Lewis Jerome Johnson, professor of civil engineering at Harvard was the engineer responsible for the innovation at the time.

体育场是爱和的much visited. Yet, if left unattended, it can become an expensive building to maintain and keep safe. Justin Den Herder, Associate at Silman, explains, “because of the nascency of this construction technology, there were significant concerns that were not known by the engineers or contractors at the time; such as the need for expansion joints, lack of appropriate re-bar detailing, dowels and ties between structural elements or insufficient concrete cover, and even the chemical make-up of the concrete itself was found to be problematic. All of these issues contributed significantly to the rate and level of deterioration.”

数据驱动的维护决策方法

Every year Harvard University needs to balance the value of the landmark with the cost of repair. The purpose of the monitoring project was to pursue an additional data-driven approach to decisions. Den Herder says, “Our role was basically to get more information through a combination of material and electrochemical testing as well as real-time optical and vibration monitoring to better understand the buildings seasonal behaviour and therefore help Harvard make a more informed decision about the future of the stadium.”

Silman worked with partnerGeotech Instrumentsto devise the monitoring system. It included crack monitors, tilt monitors, a weather station and fiveLeica Nova TM50 total stations.Leica GeoMoS Monitorwas used for data acquisition and processing,Leica Geomos调整for the network adjustment and现在，Leica Geomos！for data visualisation and analysis. Den Herder explains, “We wanted to monitor the building almost in real-time to understand how it was expanding or contracting under different meteorological conditions and different loading conditions. Scott Kavalek, Geotech Instruments, chose Leica Geosystems instruments with imaging functionality and “helped us define the points that we wanted to monitor to achieve that.”

Pinpointing the Stadium's hotspots

Data from the crack and tilt monitors was processed by Geotech Instruments using Microsoft products. In contrast, the optical monitoring data from the total stations and the weather data was processed via Leica software. Using Leica GeoMoS Now!, Silman sorted the data into the time periods of interest to look at how areas of the Stadium had moved. The software generated graphs which were exported as easy-to-read reports to discuss with Harvard University. Comparing the different monitoring components gave the team a detailed picture of the building’s vulnerabilities. Den Herder says, “What’s useful about interpreting the geosystems data from the optical monitoring results is that we’re able to pinpoint the hotspots or the portions of the building that are moving more, relative to the rest of the building.” The areas of the building that are moving the most can be correlated to the areas with more cracks and corrosion

Making decisions based on the right information

根据数据，Silman团队可以预测和解释裂缝，并建议在哪里维修会产生最大的影响。“我们能够确定建筑物在哪里移动的位置，并预测需要维修或关节的位置。例如，在体育场的上层，相对于直接下方的地板，有四分之三的运动水平运动。这几乎总是对应于建筑物的破裂，剥落和恶化，因为水可以进入这些裂缝并开始腐蚀和恶化的材料。”

Stewardship of a National Historic Landmark is a challenging role. Fans of the Stadium would want it to last as long as its Ancient Roman inspiration. Yet making a 100-year old building meet modern safety standards comes at a high cost. One that needs justification. As Den Herder at Silman says, “We would love to find a way to ensure that the Stadium can remain useful and safely occupiable, so that’s our goal. But ultimately, we just want to present the hard data and draw appropriate conclusions from the right information.”

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