Strain Sensors installed on the St. Joseph Church
Through the years of dome building we have always been playing a guessing game when it comes to reinforcement. So we finally found a way to find out once in for all, what is happening in these domes?
For about a year now we have been installing strain sensors into the Monolithic Domes. We installed them into the new Faith Chapel buildings, the Mile High Church in Denver, and now we are installing them in the St. Joseph Catholic Church.
It all starts with a little sensor that is welded to a piece of rebar. The rebar has to be grinded down so that there is a flat spot on it, then we use our fancy spot welder to weld them to the bar.
The bars are then hung into the dome shell and the wires are run into a small plastic box. The box will contain the data gathering unit. This data unit is a wireless box that is accessible from the ground using a laptop computer with a small USB antenna. We walk into the dome, wake up the unit, take a “trigger session”, and then put the unit back to sleep. That is done once a day, and the data is emailed back to the office for organization. These trigger sessions take about a hundred samples of strain within a few seconds.
These pictures are the two strain sensors that are going to be installed at St. Joseph next week. There will be one in the ring beam that is on top of the stem wall, and one in the bottom 4.