Benefit from long-term monitoring
Automated Electronic Crack Monitoring
We appreciate old things of significance, historic relics and memories that spark reflection of where we come from, events that shaped our culture, and how those before us lived and persevered. Preservation of these records against degradation is important and valued. Historical Structures are no different and are particularly vulnerable to deterioration for at least 2 reasons: 1) Less modern construction technique and technology are often not as durable and 2) the effects of time (soil movement, erosion, wear and tear, etc) are not friendly.
One of the first and fortunately most obvious signs of an aging structure in distress is cracks. All structures have cracks, the vast majority of little significance; however, as buildings, bridges, or other construction moves into “the historical realm”, certain cracks often provide insight into how a structure is holding up and are important to monitor in the desire to understand structural health and integrity.
Long term monitoring of cracks is an easy, inexpensive method to ensure infrastructure integrity and helps pinpoint specific problem areas. Placement of an array of monitors by knowledgeable engineers provides not only peace of mind, but also sounds early warning of necessary safeguards for budgetary and planning needs.
In 2016, Structural Health was contracted to monitor cracks in the Temple Railroad Museum which was built in 1911. Central Texas is notorious for thick black clay that swells and contracts significantly with moisture and this large structure with high vaulted ceilings was not immune to the natural effects of this clay.
Subsequent to a foundation
Stabilization project, SHDS installed six monitors in the historic building to track crack progress for 5 years. Beginning in 2016, an uninterrupted stream of 24 readings of vertical and horizontal movement were collected each day and displayed hourly along with temperature, battery strength, and signal intensity. This robust data set was available to all with access credentials to read directly from the website or download to a spreadsheet for more creative analysis if desired.
The beauty and ambience of this grand structure from the heyday of rail travel in this country provide great attraction to children and are pleasant day trips or inexpensive event venues today. The high vaulted ceilings made electronic reading especially desirable to avoid the necessity to maneuver ladders for access of difficult to reach locations.
In the below graphic from our website, we can see a typical crack record over 5 years. The foundation stabilization was completed in 2016/17 and we observe a very typical crack movement through winter and summer seasons over 5 years. The full range of this crack movement is approximately 1mm. The crack grows slightly in the winter as the building contracts, and it shrinks in the warmer months as the building expands. The seasonal range of the crack is more or less 0.5mm and it appears that over 5 years the crack may have expanded 0.4 – 0.5mm. Nonetheless, the ability for facility managers who see the cracks to know with certainty their exact magnitude over time provides pertinent and helpful understanding regarding whether to be concerned or not.
This plot is made from over 40,000 readings that were taken remotely without need of an engineer or technician interface and it showed empirically that the extensive repairs stopped building movement. The Movement Marker overcomes the variability from manual gauge reading and from the temporary affects of significant weather events that often mask movement characteristics. Because of the large and frequent volume of readings, the client is left with an accurate and very rich data set at a fraction of the cost from manual measurement.
While there are many advantages that come with electronic crack monitoring, we always come back to a bedrock principle:
Robust, accurate data that provides confidence and peace of mind in understanding what is moving