We provide the basis for thoughtful and accurate solutions. Our technology was based upon the vision of offering a method to rapidly measure how structures perform and turning this measurement into useful information. Years of research have been conducted to develop and prove various techniques for analyzing structures based on structural dynamics. Many of these techniques are commonplace is mechanical engineering, aerospace engineering and civil engineering (for large structures) and are dictated through the principles of physics and fracture mechanics. However, taking measurements on most civil structures was traditionally difficult to achieve, expensive and few understood how to extract useable information from the measurements.
STRAAM Group’s unique skill set has allowed us to develop a platform which yields unparalleled useable information in the most efficient way possible. It is based on the premise that all structures are “systems” and they are moving all of the time. Additionally if we can accurately capture their movements, and know where to measure, we can accurately define how each system performs.
We have put together a complete and rapid method for measuring and identifying the system properties to yield the detailed characteristics of structures. A measure of a structure’s performance is called the Dynamic Signature and represents the structure’s ‘as is’ condition. This signature is analogous to an ‘EKG’ for a structure. The most effective way to measure is to capture the movements of the structure. This can be accomplished by using very expensive mechanical shakers/vibrators or by allowing natural excitation (such as by wind) that is monitored continuously so that the response can be processed into its unique Dynamic Signature. To that end, our technology is designed to be flexible to integrate our advanced services and proprietary elements with ‘off the shelf’ equipment and standard techniques to provide the best solution for each project and customer. Our advanced technology integrates highly precise equipment, cloud based data collection and processing, advanced algorithms and expertise in structural dynamics for a rapid and accurate measure of a structures performance. We have unique expertise in Structural Dynamics which was instrumental in developing this platform. STRAAM Group offers standard as well as advanced service used to assess structures and track changes or damage in order to meet the needs of our customers.
When some parameter (such as vibration, temperature, strain etc.) is varying, we digitize the data stream to make the storage and analysis of the data usable by the most up-to-date techniques. We typically digitize data at 200 times a second, so that the detail of changes to parameters are easily seen, and records of events (such as a vehicle passing, a wind gust, or an earthquake) can be observed in great detail. The rate of digitization also allows detailed analysis of the time varying parameter, so that the response of a monitored structure can be reduced to a baseline and continuing comparisons with that baseline.
A device that responds physically to a change in a parameter (such as vibration, temperature, strain etc.) can be placed so as to retrieve useful information. While it is possible to use many different types of sensor, and transduce the varying parameter into a digital form, the main workhorse of the STRAAM family is a type of accelerometer that is the most sensitive measuring device available. These servo-type accelerometers were developed for military purposes, but are particularly useful for civil engineering because of their sensitivity and precision. This means that even a very small force acting on a structure gives enough movement that the accelerometers will distinguish that movement. In practical terms this means that movements that are much smaller than can be seen are easily measurable.
The digitized data measured by STRAAM are placed into a secure repository in the cloud. This means that data can be viewed and retrieved from anywhere in the world at a moment’s notice. Analysis is performed on the data, and since the analysis emphasizes the resonances of a structure (everything resonates – it’s a physical requirement), even very small motion is also representative of the behavior of the structure at large amplitudes of response. While this principle doesn’t extend into the ultra-high amplitude range (such as would be caused by large earthquakes), it is representative of how the structure behaves in the elastic range (which is the basis of the majority of design). Analyses performed on the data in the cloud, also give information about localized responses in the structure caused by imperfections (such as cracking). Because this information comes from an analysis of whole-body motion it means that even when imperfections cannot be observed, their presence is signaled through the signature retrieved from the motion of the structure.
Various thresholds can be generated from the analyzed data and used as an early warning for potential damage. The alarms can be set to be triggered from overall vibration intensity levels, from tilt figures, from stress measurements, or from an analysis of the non-linear damping characteristics of a mode of vibration that is significant as well as the more basic monitoring such as PPV, strain and displacement. In all cases an email alert is sent to identified recipients with an advice about the conditions that created the alarm to be raised.
STRAAM Group has a data base of the dynamic response of various types of structure from all over the world.
This data base holds over 600 entries, including the most comprehensive data about induced vibration tests on full-scale structures.
The data consist of frequencies of resonance, damping values, and mode shapes of response.
The data include non-linear measurements of frequencies and damping.
The data are arranged so that they show the normal behavior of different types of structure (tall buildings, bridges, dams, offshore structures).
The database includes various predictors of frequencies of resonance and damping (including non-linear characteristics) for structures in various parts of the world.
As a result of this comprehensive data set STRAAM is able to assess the response of a building under investigation and compare its behavior with what is normal.